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3 1293 00908 560

This is to certify that the
dissertation entitled
Modified Atmosphere Packaging of

Fresh Table Grape Cultivars
Grown in Eastern United States

presented by

Fakher Elboudwarej

has been accepted towards fulﬁllment
of the requirements for

Ph.D. degree in Horticulture

 

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Major professor

 

Date 11 November 1991

 

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MS U is an Afﬁrmative Action/Equal Opportunity Institution 0-12771

 

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1 EHBMRY .
' Michigan State ;
‘ University '

  
   
   

  

PLACE IN RETURN BOX to remove this checkout from your record.

TO AVOID FINES return on or before date due.

DATE DUE DATE DUE DATE DUE

 

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c:\clrc\datedue.pfn3-c.l

MODIFIED ATMOSPHERE PACKAGING OF FRESH TABLE GRAPE
CULTIVARS GROWN IN EASTERN UNITED STATES

By

Fakher Elboudwarej

A DISSERTATION
.Submitted to
Michigan State University
in partial fulﬁllment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY

Department of Horticulture

1991

 

”44/

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4—.

ay- 7/

ABSTRACT

MODIFIED ATMOSPHERE PACKAGING OF FRESH TABLE GRAPE

CULTIVARS GROWN IN EASTERN UNITED STATES

By

Fakher Elboudwarej

The effects of girdling, gibberellin application and combination treatments
on postharvest storage life of ’Himrod’ table grapes at 0°C were investigated. In
addition, two postharvest treatments were examined including modiﬁed atmosphere
packaging with and without humidity control. For the postharvest treatment studies
3 additional cultivars were included, ’Vanessa’, ’Concord’, and ’Alden’ in addition to
’Himrod’.

To study effects of girdling, gibberellin and combination treatments on
postharvest behavior of the ’Himrod’ grape cultivar, grape clusters from ﬁeld treated
vines were sealed in polymeric packages and stored at 0°C. Grapes in packages were
evaluated for surface mold and general appearance at different durations. In general,

grapes that were harvested from girdled vines had poor storage life compared to

controls.

Reducing 02 to 2% and raising CO2 to 7-10% using modiﬁed atmosphere
packaging extended shelﬂife of ’Himrod’ and ’Concord’ grapes 40 and 70 days.
respectively, beyond that of control grapes, which were in unsealed packages. ’Alden'
grape fruit did not respond favorably to the low Ozlhigh CO2 environment compared
to unsealed controls.

Maintaining humidity generated by KNO3 and KCl, in sealed polymeric
packages reduced decay of most cultivars without determinental moisture loss
compared to controls. The relative humidity at 20°C was approximately 89 and 87%
for KNO3 and KCl, respectively. Again, ’Alden’ was the only cultivar that did not

respond well to modiﬁed humidity control in sealed packages.

To my mother, father, my wife
’Heidi’, and my children
’Omeed’and ’Emon’; and

In memory of my brother in love ’Hashem’ and his son ’Samir’

iv

 

 

ACKNOWLEDGMENTS

The author expresses his sincere appreciation to Dr. Robert C. Hemer for his
patient guidance, moral support, and realistic suggestions during this study.

The author is grateful to Dr. Gordon. S. Howell for his meaningful support

and encouragement.

Appreciation is extended to Drs. Bruce Harte, Arthur Cameron, and Donald

Ramsdell for their critical review of the manuscript.
Heartfelt appreciation is expressed to my wife, Dr. Heidi Hoojjat, and our

children, Omeed and Emon, for their sincere love, patience, and sacriﬁces during my

entire PhD program.

 

 

Guidance Committee:

This dissertation was written in the journal format in accordance with
departmental and university regulations. The thesis body is divided into 3 chapters,

Chapters 1, 3 were prepared in the style of the Journal of the American Society for

 

Horticultural Science. Chapters 2 and the literature review are written in the style

of American lgumal 9f Englogy and Viticulture.

vi

 

 

TABLE OF CONTENTS

LIST OF TABLES ............................................. x

LIST OF FIGURES ............................................

LITERATURE REVIEW ........................................ 1
Literature Cited ........... p ............................... 13

CHAPTER ONE:
INFLUENCE OF POSTHARVEST TREATMENTS OF ’HIMROD’ GRAPES ON

THEIR PROPERTIES DURING MODIFIED ATMOSPHERE STORAGE

Abstract .............................................. 25
Introduction ............................................. 26
Materials and Methods .................................... 29
Results ................................................ 34
Discussion .............................................. 41
Literature Cited .......................................... 44

CHAPTER TWO:
MODIFIED ATMOSPHERE STORAGE OF FRESH TABLE GRAPES UNDER

HIGH RELATIVE HUMIDITY CONDITIONS

Abstract ............................................... 49
Introduction ............................................. 50
Materials and Methods .................................... 53
Results ................................................ 5 8
Discussion .......... ‘ .................................... 70
Conclusion .............................................. 73
Literature Cited .......................................... 74

CHAPTER THREE:
MODIFIED ATMOSPHERE PACKAGING OF FRESH TABLE GRAPES WITH

IN-PACKAGE HUMIDITY CONTROL TO REDUCE MOLD GROWTH

Abstract ............................................... 81
Introduction ............................................. 82
Materials and Methods .................................... 86
Results ................................................ 91
Discussion ............................................. 103
Literature Cited ......................................... 106
SUMMARY AND CONCLUSIONS .............................. 111

APPENDIX A:
EFFECT OF GIRDLING AND GIBBERELLIN ON BIOCHEMICAL AND

BIOPHYSICAL CHANGES DURING MATURITY OF ’HIMROD’ GRAPE
BERRIES '

Introduction ............................................ 1 14

Material and Methods .................................... 117

Results ............................................... 121

Literature Cited ......................................... 125
APPENDIX B:

POLYMERIC FILM OXYGEN TRANSMISSION RATE MEASUREMENT 128

APPENDIX C:
MEASURING DESIGN PARAMETERS FOR MODIFIED ATMOSPHERE

PACKAGING OF TABLE GRAPES

Materials and Methods ................................... 133
Results ............................................... 135
Literature Cited ......................................... 149
APPENDIX D:
IN-PACKAGE RELATIVE HUMIDITY (%) DATA COLLECTED FOR SEALED
’HIMROD’ LDPE PACKAGES AT 20°C ........................... 150
APPENDIX E:
WEIGHT LOSS (%) OF DIFFERENT TABLE GRAPE CULTIVARS DUE TO
DIFFERENT PACKAGING TREATMENTS ....................... 155
APPENDIX F:

EFFECT OF DIFFERENT PIUEHARVEST TREATMENTS ON POSTHARVEST
INFECTION (%) AND GENERAL APPEARANCE OF PACKAGED ’HIMROD’
GRAPE CLUSTERS IN 1987 AND 1988 ........................... 159

APPENDIX G:

INFECTION DEVELOPED AT CAPSTEM SCAR AND CRACKS OF
PACKAGED ’ALDEN’ BERRIES AT 0°C .......................... 173

viii

LIST OF TABLES

Table.

Chapter one

1. Different treatments applied to ’Himrod’ vines during

1987 and 1988 growing seasons .........................

2. Different modiﬁed atmosphere packages with their
related gas mixture concentrations at steady state

conditon .........................................

3. Effect of different preharvest treatments on postharvest
infection (% mean) of packaged ’Himrod’ grape clusters

in 1987 ...........................................

4. Effect of different preharvest treatments on postharvest
infection (% mean) of packaged ’Himrod’ grape clusters

in 1987 ...........................................

5. Effect of different preharvest treatments on postharvest
infection (% mean) of packaged ’Himrod’ grape clusters

in 1988 ..........................................

6. Effect of different preharvest treatments on postharvest
infection (% mean) of packaged ’Himrod’ grape clusters

in 1988 ..........................................

meter—2

1. Visual rating scale used for evaluation of grape clusters

stored under different MA conditions ....................

Chapter 3

1. Visual rating scale used for evaluation of grape clusters

stored under different MA conditions ....................

ix

 

Page

......... 33

........ 35

........ 36

......... 39

......... 4O

......... 56

......... 90

 

 

 

[\J

Appendix A

.Different treatments applied to ’Himrod’ vines during
1987 and 1988 growing seasons ..........................

.Total soluble solids, total acidity, sugar/acid ratio,

and 100 berry weight of ’Himrod’ grapes as they were

inﬂuenced by ﬁeld treatments in 1987 ......................

.Total soluble solids, total acidity, sugar/acid ratio,

and 100 berry weight of ’Himrod’ grapes as they were

inﬂuenced by ﬁeld treatments in 1988 ......................

.Total yield (Kg.), total clusters, marketable and

non-marketable yields (Kg.') per vine of ’Himrod’ grape

harvested at two different dates ..........................

.Total yield (Kg.), total clusters, marketable and

non—marketable yields (Kg) per vine of ’Himrod’ grape

harvested at two different dates ..........................

Appendix C

. Values for constants of equations presented for 02

concentrations in ’Himrod’ and ’Concord’ packages as

a function of fruit weight at 0°C ..........................

.Values for constants of equations presented for C02

concentrations in ’Himrod’ and ’Concord’ packages as

a function of fruit weight at 0°C ..........................

.Film thickness, surface area and O2 permeability

constants of 2 and 3 mil low density polyethylene ﬁlms

used. Permeability constants were measured at 0°C ............

Agnew

.Relative humidities (%) generated inside sealed packages
of ’Himrod’ grape at 20°C ...............................

Appmdixi

L. Weight loss (%) of ’Himrod’ table grape due to differnt

postharvest treatments in 1987 and 1988 ....................

X

1"{“
CCCCCCCCC J

...... 121

...... 122

...... 137

...... 138

...... 140

...... 151

...... 156

 

2. Weight loss (%) of ’Vanessa’ table grape due to differnt

postharvest treatments in 1987 and 1988 .......................... 157
3. Weight loss (%) of ’Concord’ table grape due to differnt
postharvest treatments in 1987 and 1988 .......................... 158
Apmndix F

1. Effect of different preharvest treatments on postharvest
infection (% mean) of packaged ’Himrod’ grape clusters
in 1987 .................................................. 160

2. Effect of different preharvest treatments on postharvest
infection (% mean) of packaged ’Himrod’ grape clusters
in 1988 .................................................. 161

3. Visual rating scale used for evaluation of grape clusters
stored under different MA conditions ............................ 162

4. Effect of different preharvest treatments on postharvest
general appearance (r/4) of packaged ’Himrod’ grape clusters
in 1987 .................................................. 163

5. Effect of different preharvest treatments on postharvest
general appearance (r/4) of packaged ’Himrod’ grape clusters
in 1987 .................................................. 164

6. Effect of different preharvest treatments on postharvest
general appearance (r/4) of packaged ’Himrod’ grape clusters -
in 1988 .................................................. 165

7. Effect of different preharvest treatments on postharvest
general appearance (r/4) of packaged ’Himrod’ grape clusters
in 1988 .................................................. 166

8. Factorials analysis of variance table for 15 days evaluation
time of ’Himrod’ grape clusters in 1987 ........................... 167

9. Factorials analysis of variance table for 30 days evaluation
time of ’Himrod’ grape clusters in 1987 ........................... 168

10. Factorials analysis of variance table for 15 days evaluation ’0
time of ’Himrod’ grape clusters in 1988 ........................... 16,

xi

 

11. Factorials analysis of variance table for 30 days evaluation

1 —/N

time of ’Himrod’ grape clusters in 1988 ............................ ~.

12. Correlation coefﬁcient calculated between treatment total
soluble solids (TSS) and infection percentage on packaged
’Himrod’grape clusters in 1987 1

13. Correlation coefﬁcient calculated between treatment total

soluble solids (TSS) and infection percentage on packaged
’Himrod’ grape clusters in 1988 ................................. 1

xii

a-Wy

/ A

72

 

 

 

 

LIST OF FIGURES

Figure

Chapter 2

. Berry infection (A) and general appearance (B) of
’Himrod’ grape clusters in LDPE packages with different
thicknesses. Means with the same letter have no

signiﬁcant difference at P=0.05 ..........................

. Berry infection (A) and general appearance (B) of
’Vanessa’ grape clusters in LDPE packages with different
thicknesses. Means with the same letter have no

signiﬁcant difference at P=0.05 ..........................

. Berry infection (A) and general appearance (B) of
’Concord’ grape clusters in LDPE packages with different
thicknesses. Means with the same letter have no

signiﬁcant difference at P=0.05 ....................... .' . .

. Berry infection (A) and general appearance (B) of
’Himrod’ grape clusters in LDPE packages with different
thicknesses. Means with the same letter have no

signiﬁcant difference at P=0.05 ..........................

. Berry infection (A) and general appearance (B) of
’Vanessa’ grape clusters in LDPE packages with different
thicknesses. Means with the same letter have no

signiﬁcant difference at P=0.05 ..........................

. Berry infection (A) and general appearance (B) of
’Concord’ grape clusters in LDPE packages with different
thicknesses. Means with the same letter have no

signiﬁcant difference at P=0.05 ..........................

. Solid lines represent the best ﬁt for CO2 (A) and 02 (B)
concentrations in 1.75 and 2 mil LDPE ’Himrod’ grape
packages. Each package contained 200 g grape and the

package size: 20.3 x 22.9 cm ............................

. Solid lines represent the best ﬁt for 0; consumption and

C02 production in 3 mil LDPE ’Himrod’ (A), ’Vanessa’ (B),

and ’Concord’ (C) grape packages. Each package contained

....... 59

....... 60

....... 61

....... 63

....... 64

....... 66

....... 67

200 g grape and the package size: 20.3 x 22.9 cm .................. 68

xiii

 

9. Infected berries in 3 mil LDPE packages of ’Himrod’ (A)
and ’Concord’ (B) grapes as a function of modiﬁed
atmospheres generated by different grapes weights. Each
mean is the average of 8 samples ............................... 7:

Chapter 3

1. Solid lines represent the best ﬁt curves for relative
humidities inside the ’Himrod’ grapes packages measured
at 0°C. Each package contained 200 g grape and 20 g moisture
absorbant ................................................. 95

2. Solid lines represent the best ﬁt curves for relative
humidities inside the ’Himrod’ grapes packages measured
at 20°C. Each package contained 200 g grape and 20 g moisture
absorbant ................................................. 96

3. Effect of different in-package relative humidities on
weight loss, berry infection, and general appearance of ’Himrod’
grape clusters during storage at 0°C .............................. 97

4. Effect of different in-package relative humidities on
weight loss, berry infection, and general appearance of ’Vanessa’
grape clusters during storage at 0°C .............................. 98

5. Effect of different in-package relative humidities on
weight loss, berry infection, and general appearance of ’Concord’
grape clusters during storage at 0°C .............................. 99

6. Effect of different in-package relative humidities on
weight loss, berry infection, and general appearance of ’Himrod’
grape clusters during storage at 0°C ............................. 100

7. Effect of different in-package relative humidities on
weight loss, berry infection, and general appearance of ’Vanessa’
grape clusters during storage at 0°C ............................. 101

8. Effect of different in-package relative humidities on

weight loss, berry infection, and general appearance of ’Concord’
grape clusters during storage at 0°C ............................. 102

xiv

 

 

 

Appendix B

. O; permeability of LDPE ﬁlms with different thicknesses. Exp.
conditions: Air; 50m2 mask ﬁlm; 10 mV sensitivity; 5 Ohm

resistant at 22°C .........................................

Appendix C

.Effect of ’Himrod’ grape fruit weights on steady state 02 (A) and
CO2 (B) concentrations in 465 cm2, 0.00762 cm thickness LDPE

sealed packages held at 0°C ................................

.Effect of ’Concord’ grape fruit weights on steady state 02 (A) and
C02 (B) concentrations in 465 cm2, 0.00762 cm thickness LDPE

sealed packages held at 0°C ................................

.Effect of steady state 0; concentration of each ’Himrod’ grape
target weights (100 g to 600 g) on the calculated rate of

02 uptake of grape fruit sealed in LDPE packages ...............

.Effect of steady state Oz concentration of each ’Concord’ grape
target weights (100 g to 600 g) on the calculated rate of

02 uptake of grape fruit sealed in LDPE packages ...............

.Effect of steady state C02 concentration of each ’Himrod’ grape
target weights (100 g to 600 g) on the calculated rate of

02 uptake of grape fruit sealed in LDPE packages ...............

.Effect of steady state C02 concentration of each ’Concord’ grape
target weights (100 g to 600 g) on the calculated rate of

O2 uptake of grape fruit sealed in LDPE packages ...............

. Effect of steady state 02 concentration on the respiratory quotient
of ’Himrod’ grape fruit in sealed LDPE packages held at 0°Cl47

. Effect of steady state 02 concentration on the respiratory quotient
of ’Concord’ grape fruit in sealed LDPE packages held at 0°Cl48

XV

131

141

142

 

 

 

LITERATURE REVIEW

 

 

 

2
Table grape cultivars, ’Himrod’ (76), ’Vanessa’ (27), ’Alden’ (11), and

’Concord’ (95) are important fresh market table grapes grown in the eastern United
States. Among these cultivars the seedless, green berry cultivar ’Himrod’ (’Ontario’
x ’Thompson Seedless’) has good potential of becoming an important fresh table
grape in Michigan. This cultivar is currently grown in Michigan but the acreage is
limited. The problem of straggly ’Himrod’ grape clusters that result frOm poor fruit
set and small berry size must be solved before its commercial production could be
expanded.

GA3 has been used to increase berry size in most seedless grape cultivars and
to induce seedlessness in some seeded varieties by virtue of reducing or preventing
pollination (35, 75). GA3 applications made between bloom and fruit set are
generally most effective. The optimum response of grapes to exogenous application
of GA3 is influenced by cultivar, timing of application, - concentration of growth
regulators, and endogenous quantities of these hormones (17, 24).

Full bloom application of GA3 to increase fruit set in seedless grapes has been
shown to be unsuccessful (7, 16, 45, 89). However, a 20 mg/l GA3 application
resulted in successful flower thinning (T. Zabadal, personal communication, 1988).
This one time application at bloom should not be used on seedless grapes with
straggly clusters (9, 35). For many seedless cultivars a combination of 20 mg/l GA3
at bloom and 50 mg/l GA3 applied at shatter (fruit set) will produce desirable fruit
quality (18, T. Zabadal, personal communication, 1987). GA3 application also can

lower the cluster compactness due to a reduction in fruit set or elongation of the

3

rachis (24). As a standard commercial practice, ’Thompson Seedless’ grapes, are
treated at bloom with GA3 to thin the clusters. This application is followed by a
second application after fruit set which elongates the berries and ﬁlls the clusters.

Commercially, growers of table grapes girdle table grape vines to increase the
size of the berries (90). Experiments demonstrated that girdling when the total
soluble solids content of fruit was only 5 or 6 per cent usually resulted in the most
rapid maturation of the fruit (90). Girdling was demonstrated to hasten and increase
flowering and it was also associated with greater bud formation (22, 42). This
phenomenon was related to an increase in available carbohydrates above the rings
(22, 42). The stimulus resulting from girdling has its maximum effect during ﬂowering
or after berry shatter when the berries are actively growing (90).

GA3 and girdling, either singly or in combination, are used on thousands of
acres of grapes in California and worldwide to increase berry set and fruit size (7, 8,
9, 25, 28, 57, 75, 89, 90). Based on this, a combination of cane girdling and GA3
application has been suggested for successful ’Himrod’ grape production in the
eastern United States (15, 16, T. Zabadal, personal communication, 1987).

While considerable information exists about changes in chemical composition
of Vitis vinzfera (1, 2, 41, 48, 53), V. [abrusca (10), and V. rotundifolia (13) during the
growing season little is known about changes of the ’Himrod’ grape which is a cross
between V. vinifera and V. labrusca. It is also necessary to investigate the effect of

GA3 and girdling practices on maturity and postharvest behavior of table grapes.

 

 

 

4

In packaging table grapes into boxes, the shatter of berries in the boxes and
the occurrence of soft berries reduces the attractiveness of table grapes (75). GA,
increases pedicel thickness and strength of berry adherence (86). Preharvest-treated
’Thompson Seedless’ grape with four applications of GA, had the minimal number
of berries that fell with pedicels attached during cold storage (75). GA, treated
berries also were the ﬁrmest after 30 days in cold storage (75) and were shown to
have a lower rate of moisture loss (69).

Dry drop (abscission) of grape berries is correlated with the development of
an abscission layer (59). The formation of an abscission layer leading to fruit drop
can be delayed by preharvest gibberellin application (29, 51, 68). Most cultivars
develop wet drop which is common during storage (51). This type of drop is not
considered to be inﬂuenced by preharvest gibberellin application (29).

Girdling alone for ’Thompson Seedless’ grapes has been shown to improve the
shipping quality of the fruit by making the berries more ﬁrm and increasing their
adherence to the stem (42). Increased adherence to the stem reduces transpiration
rate from the stem scar and therefore reduces weight loss. Berry shatter also could
be minimized by better berry to stem adherence. These two factors therefore could
contribute to increased storage life of grapes.

Storage life of ’Himrod’ grapes is reported to be short compared to other
eastern grapes (V. labrusca); that is about 3 to 8 weeks (54). Increasing demand for
premium table grapes has placed renewed interest in determining better methods of

producing quality ’Himrod’ grapes and studying new means of increasing the storage

 

life.

Decay is one of the main factors that limits storage-life of grapes. Sulfur
dioxide is commercially used to control decay of V. vinz'fera L. (32, 37, 51, 59, 63, 64.
64, 65), V. labrusca (95), and V. rotundifolia grapes (6). The use of sulphur dioxide
(S0,) to control storage decays, especially Botrytis cinerea Pers. dates back to the
early 1930’s, when the gas fumigation technique was developed (3). However,
excessive SO, concentrations: 1) causes bleaching and it aggravates the problem of
’wetness’ (7); 2) can corrode most metal surfaces (72); 3) containers must be
relatively open so that the grapes are easily accessible to the gas, and therefore
vulnerable to appreciable shrinkage from water loss (64); 4) stored grapes must be
retreated at intervals since the control effect is temporary (58, 64); 5) the vapors are
very irritating to the mucous membranes and could be very dangerous to human
health (64); 6) the dose required is affected markedly by moisture conditions, which
in turn affect the capacity of containers and surfaces to absorb the gas (61); and
ﬁnally, 7) some cultivars are more sensitive to skin injury than others (6, 68). In
addition to the above-mentioned disadvantages of 30,, there is an increasing world-
wide concern about the presence of SO2 in stored table grapes because of human
health concerns particularly with those people allergic to SO2 (50).

Other fumigants like dibromotetrachloroethane (DBTCE) (61), and carbon
monoxide (CO) (24, 93) have been used to avoid the side effects of SO2 (24). Both
of these fumigants have been effective and performed well in terms of decay control

and reduced injury to grapes.

 

 

 

6

The second major factor that causes loss of quality in table grapes is the
desiccation of the rachis (50, 59). Rachis lose water faster than berries. Preliminary
work showed that stems would lose 10 times more water than the berries per unit
weight due to a higher concentration of lenticels and stomata through which water
vapor can readily escape (23). Rachis drying can also lead to berry shatter.

The third major factor involved in quality loss is rachis browning that is
considered a secondary symptom of water loss and has a serious effect on the
appearance of grape berries and clusters (50, 59).

Several researchers have used controlled atmosphere storage as a substitute for
SO, application to control decay. However the results are controversial. 2.5% oxygen
and up to 15% CO, controlled decay comparable to SO, treatments (60). Other
combinations also were used and in some cases the results were negative (50), and
in others they were quite encouraging (46, 55, 81, 87). Each study has recommended
different levels of O, and CO, composition for different grape cultivars. Generally
the oxygen concentration ranged from 2 to 5% and the CO, concentrations from 3
to 8%.

Low oxygen concentration and high CO, concentration around grape berries
inﬂuence the ﬁnal quality of fruit (34, 79). Low O, concentration mainly reduces the
metabolic activity of the tricarboxylic acid (T CA) cycle (36). High levels of CO,
chieﬂy results in malate build up through dark ﬁxation of CO, (38, 56, 69). Malic and

tartaric acids comprise about 80 to 90% of the total acids present in grape berries

(34, 47,48, 83).

 

 

7

Physical properties of each grape cultivar could inﬂuence decay development
during storage. A thinner epidermis that cracks easily and is sensitive to wet
conditions results in disease development (82). The pericarp is more viscoelastic than
the epidermis, therefore the epidermis may rupture and this speeds up the
deterioration process (19, 78, 82). Suberization of exposed cells around the split or
crack and/or high concentration of phenolic compounds in sub-epidermal cells. might
limit microorganism growth (82).

Modiﬁed atmosphere packaging (MAP) as an alternative approach to fumigant
application to grapes could be utilized to overcome the problems resulting from the
use of these fumigants. Modiﬁed atmosphere packaging (MAP) basically involves
sealing the produce in a semi-permeable membrane and allowing the respiration of
the product to lower oxygen levels and at the same time carbon dioxide increases.
MAP is cheaper to provide than CA conditions and under relatively constant
temperature during the entire handling process it is possible to maintain a desired
composition of gases inside the sealed packages, providing that the proper ﬁlm
permeability has been chosen and the package dimensions match the respiratory rate
of the product sealed inside the package.

Several research workers have used sealed polymeric packages to extend the
shelf life of fruits. and vegetables (12, 20, 40). However, problems such as

condensation, mold growth, off-ﬂavor, and physiological disorders remain a challenge
(4, 5, 43, 70, 80, 85).

Several simulation models have been developed to predict the atmosphere

 

 

8

generated by sealing fruits and vegetables in various polymeric ﬁlms (12, 37, 38. 41.
62). These simulation models are useful in predicting atmosphere composition but
these package designs must be tested to determine if the environmental conditions
in the packages result in increased shelf-life with acceptable quality.

Modiﬁed atmosphere packaging to extend the shelﬂife of fresh fruits and
vegetables requires the use of polymeric ﬁlms. The backbone of most of these ﬁlms is
a low density polyethylene monomer. These ﬁlms are somewhat permeable to O, and
C0,, however, their permeability to water vapor is low compared to other ﬁlms.
Moderate O, and CO, permeabilities can provide favorable environments for living tissue
sealed in these ﬁlms and the low water vapor transmission rate. reduces the rate of
moisture loss from fresh produce (4, 5, 21, 44, 59, 71, 85). Reducing the rate of
moisture loss from packaged fresh produce is mainly due to increased resistance to water
loss compared to fruit alone (31, 52, 73). Modiﬁed atmosphere packages with low water
vapor transmission rates and continuous moisture evaporation from fresh produce
generates a high water vapor pressure inside the package and saturates the package void
volume. Some moisture loss may be desirable and can be tolerated to a certain extent.

The ﬁrst noticeable effect of moisture loss of grape clusters is drying and
browning of stems and pedicels (30). This effect becomes apparent with a loss of only
1 to 2% of the weight of the fruit. The fruit loses its turgidity and softens when the loss
reaches 3 to 5% (30). Weight loss could be great enough to affect appearance, texture,
and ﬂavor (30). As grapes shrivel, they appear dull and lifeless. The pedicels are very

sensitive to water loss and lose water faster than the berries. The appearance of rachis

 

9

is an important market quality factor and is often used as a measure of total fruit quality
(59).

In storage of grapes, ninety percent relative humidity is the desirable minimum and
95% is being advocated commercially (31, 33). Relative humidity above 95 % increases
the level of infection by B. cinerea Pers. (66, 78), therefore, the use of higher humidities
is limited by the possibility of decay development. Free water on the fruit or high
relative humidity, or both, appear to be important factors contributing the rapid
development of B. cinerea Pers. (66). Low temperature does not prevent spore
germination but only delays it (34). Most postharvest decays are caused by pathogens that
infect grape berries through wounds and other weakened sites (82). The most frequent
loci for initial infections are pedicel scars. However, when a spore germinates, a short
infection tube is formed which is capable of penetrating the skin of the berry even though
there are no mechanical injuries or functional stomata (82). Relative humidity even less
than 90% also causes infection either due to invisible residual water around the pedicel
or rapid transpiration from that area (66). However, some moisture loss takes place
through lenticels formed under the nonfunctional stomata (82). The structural
arrangement of wax platelets, together with their hydrophobic surfaces, controls water
movement. This control is mainly due to restricting the evaporation pathway. It has been
suggested that these pathways consist of relatively long narrow and hydrophobic capillary
channels between the wax platelets (82).

An alternative to the use of SO, treatment or fungicides to reduce decay inside

polymeric packages is to reduce in-package relative humidity. Different desiccants such

 

 

 

10

as CaCl, have long been used to reduce in-package relative humidity. However, the
relative humidity generated by CaCl, is in the range of 31 to 40% and is not suitable for
storage of fresh fruits and vegetables (88). Recently, a new method of reducing in-
package relative humidity within fresh produce packages has been reported (74). The
ability to generate a stable relative humidity within sealed packages to reduce decay
problems is discussed in this report. Each sorption compound generates a specific
equilibrium RH over its saturated solutions (74, 92, 94). However, not all of the
desiccants are able to generate a stable relative humidity in the presence of fresh produce
weights. Sorption compounds that exhibit T ype-III isotherms were suggested to provide
stable equilibrium relative humidities (74). Chemicals that have Type-III isotherms take
up small amounts of water at low pressures. However, once the adsorption of the ﬁrst
layer of water molecules is completed, the water uptake behavior changes remarkably due
to hydrogen bonding among water molecules. As vapor pressure increases beyond this
point, a considerable increase in the water content of the sorbent takes place as a result
of the attachment of water chains of indeﬁnite length to the ﬁrst layer. Sodium chloride,
sorbitol, and potassium chloride have been shown to exhibit Type III sorption isotherms
(45 , 49, 74).

Modiﬁed atmosphere packaging of grapes does not control decay unless the
carbon dioxide levels are increased (22). Therefore in an unoptimized package
system fumigants like SO, or CO are required to reduce mold growth. Inclusion of
sodium metabisulﬁte (NaHSO,) in unvented polyliners has been shown to minimize

water loss and retain grape quality (32,58, 77). However, the main complicating

 

 

 

 

11

factor- is the development of free water in these packages. Even a very small
temperature reduction will result in condensation of water inside the packages (32).
SO, reduces respiration and by slowing down metabolic activities of the fruit it has

deﬁnite value in reducing loss of stored carbohydrates (68, 91).

 

 

 

l2
DISSERTATION OBJECTIVES:

Postharvest behavior of four different table grape cultivars including ’Alden‘.
’Concord’, ’Himrod’, and ’Vanessa’ were studied during storage at 0°C. The objectives
of this study were:

1. To study effects of preharvest cultural practices (i.e. girdling and gibberellin
application) on maturity indices, total yield of the ’Himrod’ table grape cultivar and
on post-harvest behavior.

2. To develop and optimize a modiﬁed atmosphere package for grape cultivars grown
in the eastern United States.

3. To examine postharvest behavior of table grape cultivars under different relative
humidities generated inside sealed modiﬁed atmosphere packages using moisture

sorption compounds.

 

 

l 3
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95. Zabadal, T.,J. A. Bartsch, G. D. Blanpied, T. J. Dennehy, R. C. Pearson, R. M.
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York Agricultural Experiment Station, Geneva, NY. (1988).

 

 

 

 

24

CHAPTER ONE
DECAY OF ’HIMROD’ TABLE GRAPE CLUSTERS UNDER
MODIFIED ATMOSPHERE CONDITIONS AS A FUNCTION OF

POSTHARVEST CULTURAL PRACTICES

 

 

 

25
ABSTRACT

The purpose of this research work was to investigate the effect of preharvest
treatments and modiﬁed atmosphere (MA) conditions on changes of ’Himrod’ grape
during storage at 0°C. ’Himrod’ grape vines were sprayed with gibberellin (GA,),
girdled, or were treated with a combination of GA, and arm girdling. Grapes were
harvested at two different maturity stages, namely one week prior to Optimum harvest
time and at the optimum maturity stage. Grape clusters were packaged in 2 mil low
density polyethylene (LDPE) ﬁlms. MA packages with 200 g of grapes and made of
2 mil LDPE ﬁlm generated in-package atmospheres of about 1% CO, and about 17
0,. Controls consisted of unsealed packages.

At intervals random samples were evaluated for surface mold and general
visual appearance. The results suggested that for two consecutive years, ’Himrod’
grape treated with GA, or GA, plus girdling had better storage characteristics than
those from controls (no treatment). Grapes from vines which were only girdled did

not store well in modiﬁed atmosphere packages at 0°C.

 

 

 

26
INTRODUCTION

Storage life of ’Himrod’, a complex interspeciﬁc hybrid grape (’Thompsort
seedless’ X ’Ontario’) is reported to be short compared to other eastern grapes ( Vitis
labmsca) which is about 3 to 8 weeks (Lutz, 1938). Increasing demand for premium
table grapes, has suggested ’Himrod’ as a promising cultivar which should be
investigated regarding its postharvest characteristics. The ’Himrod’ grape, is an early-
maturing seedless table grape cultivar grown in the eastern region of the U. S. (Slate
et. al., 1962; Himelrick, 1984). ’Himrod’ grapes have excellent quality fruit with a
pleasant ﬂavor (Himelrick, 1984). The berries have a very tender skin and the
cluster stems (rachis) are easily broken particularly if handled when cold, therefore.
this cultivar has low resistance to mold and decay because of injury during handling
(Haeslere and Yager, 1983).

Girdling to enhance berry size has long been used by commercial growers of
’Thompson Seedless’ grapes. Larger berries of ’Thompson Seedless’ can be produced
by applying GA, and girdling the vines after shatter following bloom but this practice
results in a high level of cluster compactness (Weaver and McCune, 1959). This
problem was resolved by applying low concentrations of GA, during bloom to reduce
the set of berries so that clusters would not be so compact (Weaver and Pool, 1971).

In packing table grapes into boxes, berry shatter and crushing of soft berries
reduces the attractiveness of table grapes (Singh et. al., 1978). GA, increases pedicel
thickness and strength of berry adherence (Venkataratnam, 1964). During cold

storage, ’Thompson Seedless’ grape treated with four applications of GA, had the

 

 

 

27

minimal number of shattered berries with pedicels attached (Singh et. al.. 1978). GA,
treated berries also were the ﬁrmest after 30 days in cold storage and were shown
to have a lower rate of moisture loss (Pool et. al., 1972; Singh, et. al., 1978).

Abscission (dry drop) of grape berries is the result of the development of an
abscission layer (Lavee, 1959) and the formation of an abscission layer can be
delayed by preharvest growth regulator application (Lavee, 1959; Gardener and
Marth, 1939; Pentzer, 1940). Most grape cultivars develop wet drop during storage
(Lavee, 1959). Wet drop is simply detachment of the berry from the capstem leaving
wet tissue attached to the capstem. This type of drop is not thought to be controlled
by preharvest growth regulator application (Gardener and Marth, 1939).

Girdling alone with no gibberellin application for ’Thompson Seedless’ grapes
has been shown to improve the shipping quality of the fruit by making the berries
more ﬁrm and increasing their adherence to the stem (Jacob, 1939). Increased
adherence to the stem reduces transpiration from the stem scar and therefore
reduces weight loss. Berry shatter also could be minimized by better berry to stem
adherence. These two factors therefore could contribute to increased storage life of
grapes.

Modified atmosphere packaging (MAP) as an alternative to conventional
storage has gained popularity recently for packaging of fresh produce and fruits
(Cameron et. al., 1989; Prince et. al., 1986; Zagory and Kader, 1988). MAP, using
polymeric ﬁlms helps to reduce weight loss, decrease mold growth and subsequent

loss of quality. The eventual concentration of gases inside the package is the result

 

 

 

28

of an equilibrium reached between the fruit respiration and gas permeation through
the plastic ﬁlm at a given temperature. The potential for MAP has increased because
a wide range of ﬁlms can be found in the market (Barmore, 1987).

The main purpose of this study was to investigate the effects of cultural
practices, mainly vine arm girdling and GA, application on decay of ’Himrod’ grape

clusters sealed in 2 mil thickness low density polyethylene (LDPE) packages.

 

 

29
MATERIALS AND METHODS

Mature vines of ’Himrod’ growing in an unirrigated commercial
vineyard at Lawton, Michigan, were used for this experiment (18). These vines
received routine care, and were trained to the 4-arm knifﬁn system. Pruning was
done in early April and minimum of 45 buds were left on the vines. The reason
for leaving these many buds was to have enough buds to survive frost and hail
damage. In early June (after fruit set) cluster thinning was performed to reduce
number of clusters per vine. A maximum of 30 clusters per vine was retained on
each vine, although not all of the vines had these many clusters.

The ﬁeld treatments used are outlined in Table 1. Control vines received
no treatment and were designated Treatment A. Treatments B and C,
respectively, consisted of vines that were girdled only or treated with gibberellin
only. Treatment D vines were treated with gibberellin and girdled. Treatment E
vines were treated with gibberellin, girdled and cluster berry thinned to 4 laterals
two weeks after fruit set. In the treatments that were girdled, vines were arm-
girdled using a 4.8-5 mm double blade girdling knife two weeks after shatter (fruit
set).
GA, application: The concentrations of GA, used and time of application are
listed in Table 1. All sprays contained 0.1% Triton B—1956, and were applied to
vines with a hand sprayer.
Harvest dates: To measure the effect of harvest dates (different maturity) on

postharvest behavior fruits were harvested at two maturity levels, namely

 

30

premature and mature stages in 1987 and 1988. Harvest time was chosen to
simulate the normal harvesting period of commercial operations. Total soluble
solids were used as maturity index for choosing harvest time. In 1987 and 1988 the
ﬁrst harvest times were 21 and 28 days after beginning of sampling the grape
berries. The second harvest time in both years was one week after the ﬁrst
harvest.

At harvest time, samples of approximately 5-7 Kgs of fruit were taken from
each 4-vine treatment, and the weight of removed berries was recorded. The
samples were transported to the laboratory in East Lansing, MI (distance of 80
miles). All decayed or damaged fruits were removed and a portion of the fruits
were analyzed for total soluble solids (TSS) and total acidity (TA). The remainder
was placed in plastic grape lugs and stored at 1°C overnight. After being cooled to
1°C, grapes were trimmed and placed into 2 mil low density polyethylene (LDPE)
packages (20.3 X 22.9 cm). The packages were heat sealed and stored at 0°C.
Table 2 presents steady state in-package O, and CO, concentrations for 2 mil
LDPE packages.

Evaluation - At approximately 2 week intervals, four grape packages for each
treatment (total of 20 packages) were randomly removed from storage, and
evaluations were performed on each package. Each treatment consisted of 20
packages (replicates). Evaluations included were; berry infection, and general
visual appearance (Appendix F). For calculating berry infection percentage, the

number of infected berries in each package was counted and divided by the total

 

 

 

31

number of berries.

Statistical analysis: To analyze the collected data and compare treatment means.
analysis of variance using the complete randomized design, factorial analysis and
the Duncan’s multiple range test were used. All the comparisons were done at the

5% probability level.

 

32

Table 1. Different treatments applied to ’Himrod’ vines during 1987 and 1988

growing seasons

 

Treatment Description of treatment

 

A. Control (not girdled, no GA, applied)
B. Girdled

C. Only GA, was applied,
1. 20 mg/l at shatter* (fruit set), and
2. 50 mg/l two weeks after shatter

D. Girdled, and GA, was applied,
1. 20 mg/l at shatter, and
2. 50 mg/l two weeks after shatter

E. Girdled, and GA, was applied,
1. 20 mg/l at shatter and 50 mg/l two weeks after shatter,
2. Clusters were berry thinned to 4 laterals by removing 1/5-
1/4 of the clusters 2 weeks after shatter (fruit set).

 

* When 50 - 70% open blooms on 50% of the clusters on vine could be seen.

 

33

Table 2. Different modiﬁed atmosphere packages with their related gas mixture

concentrations at steady state condition.

 

Packaging types % O, %CO,

 

1. Control 20.5 0

2. 2 mil low density
polyethylene 17 1

 

 

34

Results
WWMM
Storage study of 1987 for ’Himrod’ grapes
Grape berry infection-

There were 3 main decay organisms in these studies, namely,

Botrytis cinerea, Penicillium Sp., and Colletorichum Sp.

After 15 days in storage there was an increase in infection development of
the most of the treated grapes clusters in unsealed control and 2 mil low density
polyethylene (LDPE) packages (Tables 3 and 4). However, only grapes harvested
from vines that were girdled only showed a signiﬁcantly higher level of infection
when compared to grapes harvested from control vines.

After 30 days of storage, all the packages showed infection development
except grapes which were harvested from only gibberellin treated vines and were
packaged in 2 mil LDPE (Tables 3 and 4). Grapes harvested from girdled only
vines in unsealed packages showed signiﬁcantly higher level of infection when
compared to grapes from control vines. In sealed 2 mil packages, grapes from
girdled only and control vines had the same level of infection.
WWW—WW
Grape berry infection-

After 15 days in storage none of the ﬁeld treated grapes clusters in
unsealed and 2 mil sealed LDPE packages had any infected berries (Tables 3 and

4).

 

35

Table 3. Effect of different preharvest treatments on postharvest infection ( %

mean) of packaged ’Himrod’ grape clusters in 1987.

 

 

 

 

 

 

First harvest Second harvest

Treatments Sampling Control* 2 mil Control 2 mil

Time LDPE ** LDPE
ControlY 15 days 0.0z(b) 3.5(b) 0.0(a) 0.0(a)
Girdling
only 8.3(a) 4.7(a) 0.0(a) 0.0(a)
GA, only 2.6(b) 0.0(d) 0.0(a) 0.0(a)
GA, and
girdling 0. 8(b) 1.8(c) 0.0(a) O. 0(a)
GA,, girdling . '
and berry thinning 2.5(b) 0.0(d) 0.0(a) 0.0(a)
Control 30 days 7.8(c) 6.4(a) 8.8(c) 11.0(a)
Girdling
only 24.3(a) 6.4(a) 13.2(a) 12.4(a)
GA, only 7.1(c) 0.0(d) 87(0) 58(0)
GA, and
girdling 4.3(d) 5.0(b) 6. 14(d) 8.5(b)
GA,, girdling
and berry thinning 13.8(b) 2.2(c) 10.4(b) 7.9(b)

 

* Unsealed package.

** Low density polyethylene.

Y Vines that received no ﬁeld treatment. '

Z Means in each column for each sampling period (15 and 30 days) With the
same letter have no signiﬁcant differences at P = 0.05.Each mean IS the average

of four samples.

Table 4. Effect of different preharvest treatments on postharvest infection (%

mean) of packaged ’Himrod’ grape clusters in 1987.

36

 

 

 

 

 

First harvest Second harvest

Treatments Sampling Control* 2 mil Control 2 mil

Time LDPE ** LDPE
ControlY 15 days 0.0z(b) 3.5(a) 0.0(b) 0.0(b)
Girdling
only 8.3(a) 4.7(b) 0.0(c) 0.0(c)
GA, only 2.6(a) 0.8(a) 0.0(a) l.89(a)
GA, and I
girdling 0.8(b) l.8(a) 0.0(b) 0.0(b)
GA,, girdling
and berry thinning 2.5(a) 0.0(b) 0.0(b) 0.0(b)
Control 30 days 7.8(a) 6.4(a) 8.8(a) 11.0(b)
Girdling
only 24.3(a) 6.4(d) 13.2(b) 12.4(c)
GA, only 7.1(b) 0.0(d) 8.7(a) 5.8(c)
GA, and
girdling 4.3(c) 5 .0(c) 6. 14(b) 8.5 (a)
GA,, girdling
and berry thinning 13.8(a) 2.2(d) 10.4(b) 7.9(c)

 

* Unsealed package.

** Low density polyethylene.
Y Vines that received no ﬁeld treatment. _ . .
2 Means in each row with the same letter have no Signiﬁcant differences at

P = 0.05.Each mean is the average of four samples.

37
After 30 days in storage, grapes harvested from vines that were girdled only
and in unsealed packages had signiﬁcantly higher level of infection when

compared to grapes from control vines. The grapes from girdled only treatment in

2 mil LDPE packages had a higher level of infection although not signiﬁcantly

 

different than grapes from control vines (Tables 3 and 4). Grapes harvested from
vines that were only treated with GA, and in unsealed packages had the same
percentage of infection when compared to grapes from control vines. The grapes

from GA, treated vines in 2 mil LDPE sealed packages had a signiﬁcantly lower

 

level of infection when compared to grapes from control vines.
Smge study of 1988 for ’Hirnrod’ grapes - First hapvest (August 17. 1988)
Grape berry infection-

After 15 days of storage no signiﬁcant difference was observed in any of
the packages (Tables 5 and 6).

After 30 days in storage, grapes from the girdled only vines and in unsealed
packages had a signiﬁcantly higher percentage of infection when compared to
grapes from control vines (Tables 5 and 6). The same grapes in 2 mil LDPE had
lower percentage of infection when compared to grapes from control vines.
Although the difference was not signiﬁcant. Grapes harvested from only GA,
sprayed vines and in both packages (unsealed and 2 mil LDPE) had no signiﬁcant
differences when compared to grapes from control vines. However, the same

grapes had lower percentage of infection when compared to grapes from control

vines.

38
Storage study of 1988 for ’Himrod’ gr_apes - Second harvest (August 24, 1988)

Grape berry infection-

No detectable mold growth was seen on grapes packaged in 2 mil LDPE
and unsealed packages after 15 days of storage (Tables 5 and 6)

After 30 days in storage grapes from girdled only vines and packaged in 2
mil LDPE packages had signiﬁcantly higher percentage of infection. However, the
same grapes had lower percentage of infection in unsealed when compared to
grapes from control vines. However, the difference was not signiﬁcant at P=0.05

(Tables 5 and 6).

 

 

 

 

 

Table 5. Effect of different preharvest treatments on postharvest infection ( %
mean) of packaged ’Himrod’ grape clusters in 1988.

39

 

 

 

 

First harvest Second harvest

Treatments Sampling Control* 2 mil Control 2 mil

Time LDPE ** LDPE
ControlY 15 days 0.0z(a) 0.0(a) 0.0(a) 0.0(a)
Girdling
only 0.0(a) 0.0(a) 0.0(a) 0.0(a)
GA, only 0.0(a) 0.0(a) 0.0(a) 0.0(a)
GA, and
girdling 0. 8(a) 0.0(a) 0. 0(a) 0.0(a)
GA,, girdling
and berry thinning 0.0(a) 0.0(a) 0.0(a) 0.0(a)
Control 30 days 10.8(b) 5.3(ab) 10.3(ab) 0.0(c)
Girdling
only 25.8(a) 2.3(b) 4.06(b) 10.4(a)
GA, only 8.2(b) 5.8(ab) 10.8(ab) 0.0(c)
GA, and
girdling 3.1(b) 7. 6(ab) 14.2(ab) 7.0(b)
GA,, girdling
and berry thinning 4.6(b) 10.3(a) 20.6(a) 8.1(b)

 

* Unsealed package.

** Low density polyethylene.
Y Vines that received no ﬁeld treatment.
Z Means in each column for‘each sampling period (15 and 30 days) with the
same letter have no signiﬁcant differences at P = 0.05.Each mean is the average
of four samples.

 

 

 

 

1+

40

Table ’6'. Effect of different preharvest treatments on postharvest infection ( %
mean) of packaged ’Himrod’ grape clusters in 1988.

 

 

First harvest Second harvest

 

 

 

 

 

Treatments Sampling Control* 2 mil Control 2 mil
Time LDPE ** LDPE

ControlY 15 days 0.OZ(a) 0.0(a) 0.0(a) 0.0(a)

Girdling I

only 0.0(a) 0.0(a) 0.0(a) 0.0(a)

GA, only 0.0(a) 0.0(a) 0.0(a) 0.0(a)

GA, and

girdling O. 8(a) 0. 0(a) 0. 0(a) 0. 0(a)

GA,, girdling

and berry thinning 0.0(a) 0.0(a) 0.0(a) 0.0(a)

Control 30 days 10.8(b) 5.3(ab) 10.3(a) 0.0(b)

Girdling

only 25.8(a) 2.3(b) 4.1(b) 10.4(b)

GA, only 8.2(a) 5.8(ab) 10.8(b) 0.0(c)

GA, and

girdling 3.1(a) 7.6(ab) 14.2(c) 7.0(ab)

GA,, girdling

and berry thinning 4.6(b) 10.3(a) 20.6(a) 8.1(ab)

* Unsealed package.

** Low density polyethylene.

Y Vines that received no ﬁeld treatment.
Z Means in each row with the same letter have no signiﬁcant differences at
P = 0.05.Each mean is the average of four samples.

 

 

 

 

 

41

 

Discussion
From the results obtained in 1987 and 1988, two general conclusions could
be drawn; ﬁrst, grapes from vines that were only girdled or only treated with
gibberellin generally showed the highest and lower levels of infection in both
packages (sealed and unsealed packages); second, grapes developed less infection
under modiﬁed atmosphere packaging conditions.

Most postharvest decays are caused by pathogens that infect grape berries
through wounds and other weakened sites. The capstem scar is the major site of
entrance of pathogens into grapes (Ballinger and Nesbitt, 1982; Cappellini and
Ceponis, 1977). However, storage at 0°C makes this factor less important
(Ballinger and Nesbitt, 1982).

Grapes harvested before the normal maturity stage usually do not have the
pedicel thickness and sufﬁcient adherence to berries in order to minimize
moisture loss from the capstem scar. Consequently, moisture build up around the
capstem scar would provide a suitable condition for mold growth (Appendix G).

Grapes harvested from vines that were only girdled had higher levels of
infection in all of the experiments. This was probably due to weaker adherence of
berries to capstems and thinner skin compared to grapes treated with GA, (Singh
et a1, 1978; Venkataratnam, 1964). Also grapes from girdled vines are more
mature than grapes from gibberellin treated vines (Jacob, 1939; Singh et. al.,l978).
However, no signiﬁcant difference was observed between maturity index, i.e. total

soluble solids of only girdled vines and only gibberellin treated vines (appendix

 

 

 

42

A). A better criterion for assessing maturity of table grape berries would be berry

ﬁrmness measurement. This measurement could give more direct evidence
regarding general status of berries. Although, it should be used in combination
with other maturity indices.

Visual rating of grapes from ﬁeld treated vines were generally better than
grapes from control vines (Appendix F and Tables 3 to 6). This enhancement
were mainly due to better appearance of grape clusters due to a reduction in
browning and less fungal growth on berries and the rachis. Grapes treated with
GA,, in general had better overall appearance. This was mainly due to a larger
berry size and total appearance of the clusters before they were put into packages
(Appendices A and F). Berries treated with GA, have been shown to be ﬁrmer
and the number of berries that shatter was minimal (Singh et al, 1978). Firm
berries are an advantage during handling, resulting in less mechanical damage and
therefore better appearance.

One of the adverse effects of increased yield is a tendency for lowered
quality, i.e. lower soluble solids, higher titratable acidities, and lower sugarzacid
ratio (Howell et. al., 1987; Reynolds et. al., 1986). However, the data collected in
1987 and 1989 does not show any signiﬁcant differences between ﬁeld treatment
yields (Appendix A). Also, in both harvest dates in 1987 and in 1988 no signiﬁcant
difference was observed between TSS, TA and sugar/acid ratio of early maturing
grapes from girdled only vines and late maturing grapes from only GA, vines

when compared to grapes from control vines.

 

 

 

 

43

In a study on blueberries, a positive correlation between TSS of berries
during the growing season (weekly intervals) and deterioration in storage was
found (Woodruff et. al., 1959). However, no conclusive evidence suggests that one
week difference between harvest dates could have a distinctive effects on
deterioration of ’Himrod’ grape clusters in storage (Appendix F, Tables 12 and
13). More weekly intervals would probably provides more information regarding
the correlation between maturity indices and the behavior of grapes in storage.

From this study, it appears that ’Himrod’, grapes could be stored for a
relatively long time. However, cultural practices should be performed in a manner
to increase storage life. These results suggest that grape clusters with better
appearance mainly due to more developed characteristic color, larger berries,
thicker capstem and overall better storage capability. This was particularly true for
grapes from vines that were treated with GA3 or treated with GA, and girdled.
Grapes which were harvested from girdled only vines had very poor storage

characteristics.

 

 

 

44

Literature Cited

Ballinger, W.E. and WE. Nesbitt. 1982. Postharvest decay of ’muscadine’ grapes
’Carlos’ in relation to storage temperature, time, and stem condition. Am.
J. Enol. Vitic., 33: 3.

Barmore, C. R. 1987. Packing technology for fresh and minimally processed fruits
and vegetables. J. Food Quality 10:207-217.

Barritt, B. H. 1970. Fruit set in seedless grapes treated with growth regulators
Alar, CCC and Gibberellin. J. Amer. Soc. Hort. Sci. 95(1): 58 - 61.

Brown, E and J. N. Moore. 1970. Gibberellin and girdling on seedless grapes.
Eastern Grape Grower & Winery News, March - April Issue: 7.

Cameron, A. C.,W. Boylan-Pett, and J. J. Lee. 1989. Design of modiﬁed
atmosphere packaging systems: modeling oxygen concentrations within
sealed packages of tomatoe fruits. J. Food Science 54 (6) : 1413—1416 and
1421.

Cappellini, RA. and M.J. Ceponis. 1977. Vulnerability of stem-end scars of
blueberry fruits to postharvest decays. Phytopathology 67: 1.

Connolly, E. 1984. Two Finger Lakes trials reﬁne cultural practices for table
grapes. Eastern Grape Grower & Winery News. October - November
Issue: 55 - 56.

Gardener, FE. and RC. Marth. 1939. Spraying with plant growth substances to

prevent apple fruit dropping. Science 90: 208 - 209.

 

 

45

Guelfat-Reich, S.,and B. Safran. 1973. Control of decay and stem desiccation of
table grapes during simulated sea and air transport. Am. J. Enol. Vitic.
24: 91 - 96.

Haeseler, C., and L. Yager. 1983. Storage and marketing of eastern table grapes.
Eastern grape grower & Winery News: 29 - 30.

Harris, J. M., P. E. Kriedemann, and J. V. Possingham. 1971. Grape berry
respiration: effects of metabolic inhibitors. Vitis 9: 291 - 298.

Harvey, J .M. and W.T. Pentzer. 1960. Grape diseases in the market. USDA
handbook No. 189.

Himelrick, D.G. 1984. Table grapes: Opening up new markets in the east. Eastern
Grape Grower and Winery News April - May Issue: 24 - 26 & 47.

Howell, G. S.,T. K. Mansﬁeld, and J. A. Wolpert. 1987. Inﬂuence of training
system, pruning severity, and thinning on yield, vine size, and fruit quality
of ”Vidal Blanc’ grapevines. Am. J. Enol. Vitic. 38:105-112.

Jacob, H. E. 1939.Gird1ing vines for table grapes. Blue Anchor. June Issue: 6 - 7.

Lavee. S. 1959. Physiological aspects of postharvest berry drop in certain grape
varieties. Vitis 2: 34 - 39.

Lutz, J .M. 1938. Factors inﬂuencing the quality of American grapes in storage.
USDA Tech. Bull. 606.

Mainland, C.M.,W.B. Nesbitt, and RD. Milholland. 1977. The effect of ethephon
on detachment and keeping quality of ’Carlos’, ’Magnolia’. and

’Noble’ muscadine grapes (Vitis ratundifolia Michx.) Proc. 4th. Ann. mtg.

 

 

46
plant growth regulators working group 4: 244 - 245.

Pentzer, W.T. 1940. Studies on the shatter of grapes with special reference to the
use of solutions of NAA. Proc. Amer. Soc. Hort. Sci. 38: 379 - 399.

Pool, RM. and R.J. Weaver. 1970. Internal browning of ’Thompson Seedless’
grapes. J. Amer. Soc. Hort. Sci. 95: 631 - 634.

Pool, R.M., R.J. Weaver, and W.M. Kliewer. 1972. The effect of growth regulators
on changes in fruits of ’Thompson Seedless’ grapes during cold storage.

J. Amer. Soc. Hort. Sci. 97(1): 67 - 70.

Reynolds, A. G., R. M. Pool, and L. R. MAttick. 1986. Effect of shoot density and
crop control on growth, yield, fruit composition, and wine quality of
’Seyval Blanc’ grapes. J. Amer. Soc. Hort. Sci. 11:55-63.

Singh, K., R.J. Weaver, and J .O Johnson. 1978. Effect of application of gibberellic
acid on berry size, shatter, and texture of Thompson Seedless grapes.

Am. J. Enol. Vitic., 29: 4.

Slate, G. L.,J. Watson, and J. Einset. 1962. Grape varieties ...introduced by the
New York State Agricultural Experiment Station. New York State
Agricultural Experiment Station, Cornell University, Geneva, N. Y.
Bulletin No. 794.

Takeda, F.,M.S. Saunders, and J .A.,Saunders. 1983. Physical and chemical
changes in ’Muscadine’ grapes during postharvest storage. Am. J. Enol.
Vitic. 34:3.

Venkataratnam, L. 1964. Effect of gibberellic acid on Anab -e- Shahi grapes

47
(Vitis vinz'ferea L.). Proc. Am. Soc. Hortic. Sci. 84: 255 - 258.

Weaver, R. J ., and SB. McCune. 1959. Effect of gibberellin on seedless Vitis
vinz'fera. Hilgardia 29(6): 247 - 275.

Woodruff, R. E., D. H. Dewey, and H. M. Sell. 1959. Chemical changes of Jersey
and Rubel blueberry fruit associated with ripening and deterioration.
Journal of Horticultural Science. 75 :387-406.

Zagory, D. and A. A. Kader. 1988. Modiﬁed atmosphere packaging of fresh

produce. Food Technology 42 (9): 70-74 and 76-77.

 

 

48

CHAPTER 2

MODIFIED ATMOSPHERE PACKAGING OF FRESH TABLE GRAPES

UNDER HIGH HUMIDITY CONDITIONS

 

 

 

49
ABSTRACT

Four different grape cultivars, ’Himrod’, ’Vanessa’, ’Concord’ and ‘Alden‘ were
stored in low density polyethylene (LDPE) plastic ﬁlms. The polyethylene ﬁlm was
of 3 thickness; 1.75,2 and 3 mils. The controls were non sealed grape packages. All
the packages were 20.3 X1229 cm (465 cm2 total surface area) and contained 200 g
of grapes, were heat—sealed and then stored at 0° C. No humidity control inside the
packages was attempted. All four grape cultivars behaved similarly; the least weight
loss, the least decay and the best overall appearance was obtained for the longeSt
time at 0° C when the grapes were heat-sealed in 3 mil packages. ’Alden’ grapes
could not be successfully held under modiﬁed atmosphere conditions because of
berry-Splitting. ’Himrod’ and ’Vanessa’ grapes could be held up to 60 days with
excellent quality while ’Concord’ grapes could be held for up to 90 days. Different
weights of ’Himrod’ and ’Concord’ grapes from 100 to 600 g per 20.3 X 22.9 cm
package were evaluated for O, consumption and CO, production over time. Five
hundred grams of"Himrod’ generated a steady state of 2 O, and 6% CO, while

’Concord’ grapes generated an atmosphere of 2 O, and 10-11% C0,.

 

 

 

 

 

50
INTRODUCTION

Decay is one of the main factors that limits storage-life of grapes. Sulfur
dioxide is commercially used to control decay of Vitis vinz‘fera L. (16, 19, 27. 28, 29.
31, 33), Vitis labrusca (49), and Vitis rotundz'folia grapes (5). The use of sulphur
dioxide (S0,) to control storage decay especially Botrytis cinerea Pers. dates back to
the early 1930’s when the gas fumigation technique was developed (2). However.
excessive SO, concentrations could result in the following: 1) causes bleaching (27):
2) it is very corrosive to most metal surfaces (37); 3) containers must be relatively
open so that the grapes are easily accessible to the gas, and therefore vulnerable to
appreciable shrinkage from water loss (29); 4) storage grapes must be retreated at
intervals since the fumigant effect is only temporary (28); 5) the vapors are very
irritating to the mucous membranes and could be very dangerous to human health
(37); 6) the dose required is affected markedly by moisture conditions, which in turn
affect the capacity of containers and surfaces to absorb the gas (31); and ﬁnally, 7)
some cultivars are more sensitive to skin injury than others (5, 34). In addition to the
above-mentioned disadvantages of S0,, there is an increasing world-wide concern
about the presence of SO, in stored table grapes because some people are allergic
to sulfur in food products (24).

Other fumigants like dibromotetrachloroethane (DBTCE) (30), and carbon
monoxide (CO) (13, 48) have been used to avoid the side effects of SO, on grapes
and human health (13). Both of these fumigants have been effective and performed

well in terms of decay control and reduced injury to grapes.

 

 

 

51

The second major factor that causes loss 'of quality in table grapes is the.
desiccation of the rachis (24, 33). Cluster stems lose water faster than berries. Our
preliminary work showed that the rachis would lose 10 times more water than the
berries per unit weight due to a higher concentration of lenticels and stomata
through which water vapor can readily escape (12).

The third major factor involved in grape quality loss is rachis browning that is
considered a secondary symptom of water loss and has a serious effect on appearance
of grapes (24, 33).

Several researchers have used controlled atmosphere storage as a substitute for
SO, application to control decay. However the results are controversial. Two and a
half percent oxygen and up to 15 percent CO, controlled decay comparable to SO,
treatments (32). Other combinations also have been used and in some cases the
results were negative (24), and in others they were quite encouraging (23, 25,44, 47).
Each study has recommended different levels of O, and CO, composition for

different grape cultivars. Generally the oxygen concentration ranged from 2 to 5%

 

and the CO, concentrations from 3 to 8%.

The variation in response to different oxygen and carbon dioxide levels was
probably due to physical properties of the grapes that encouraged decay
development. A thinner epidermis that cracks easily and is sensitive to wet conditions
results in disease development (33, 45). The pericarp is more viscoelastic than the
epidermis, therefore the epidermis may rupture and this speeds up the deterioration

process (45). However, suberization of exposed cells around the split or crack and/or

 

 

 

 

52
high concentration of phenolic compounds in sub-epidermal cells might limit
microorganism growth (45).
Modiﬁed atmosphere packaging (MAP) basically involves sealing the produce in
a semi-permeable membrane and allowing the respiration of the product to lower
oxygen levels and at the same time carbon dioxide increases.

Several research workers have used sealed polymeric packages to extend the
shelf life of fruits and vegetables (8, ll, 18). However, problems of condensation,
mold growth, off-flavor, and physiological disorders remain a challenge (3, 4, 43, 46).

Several simulation models have been developed to predict the atmosphere
generated by sealing fruits and vegetables in various polymeric ﬁlms (8, 17, 18, 21.
35). These simulation models are useful in predicting atmosphere composition but
these package designs must be tested to determine if the environmental conditions
in the packages result in increased shelf-life with acceptable quality.

The objectives of this study were 1) to develop a modiﬁed atmosphere package
for fresh table grapes stored at 0°C, 2) to determine if grape cultivars grown in
Michigan could be held longer by using MAP in comparison with non modiﬁed
atmosphere storage pratices, 3) to determine the effect of different ﬁlm thicknesses

on weight loss, decay, and overall appearance.

 

 

 

 

5 3
MATERIALS AND METHODS

Plant materials. Fruits of ’Himrod’ (42), ’Vanessa’ (14), ’Alden’ (7), and ’Concord'
cultivars were harvested manually at commercial maturity in 1987 and 1988 from
different vineyards based on weekly analysis of total soluble solids (T SS) and total
acidity (TA). Clusters were inspected and sorted for obvious defects and then were
placed in unsealed low density polyethylene (LDPE) bags. The bags were put into
ice chests with about 5 cm of crushed ice at the bottom. A one inch thick sponge
separated the fruits from the ice in the chests. Fruits were then transported to East
Lansing (distance of about 80 miles). The grapes were held overnight at 1°C to reach
an equilibrium temperature before they were packaged.
Packaging. To determine the ﬁlm that provided the optimum gas composition LDPE
ﬁlm of different thicknesses were tested. In 1987, two ﬁlm thicknesses were used,
1.75 mil and 2 mil. In 1988, based on storage results obtained in 1987, a 3 mil ﬁlm
was used in addition to 1.75 and 2 mil. Two hundred g of grape clusters were heat
sealed in 20.3 x 22.9 cm (465 cm2 total surface area) pouches. Control consisted of
bags with six 7 millimeter holes. All grape packages were stored at 0° C with a
relatve humidity of 40%.
Oxygen depletion and CO, build up. To generate a range of O, and CO,
concentrations, the fruit weight to surface area should be optimized (see appendix
C).

Package gas composition was determined daily by withdrawing a gas sample

of 1 ml from the package with a medical-type syringe. The samples then were

 

 

 

54

injected into a gas chromatograph. The gas chromatograph consisted of an Ametek
oxygen analyzer (Model S-3A) and an ADC infra-red gas analyzer (Type 225 MK3)
connected in series and a strip chart recorder (Linear Instruments Corp., Model
1200) (39). Nitrogen gas was used as carrier gas at 100 ml per minute. By using this
system 1 ml gas samples are adequate and the analysis only takes about 10 seconds.
and the peaks produced on the strip chart recorder are proportional to the O, and
CO, concentrations. Gas sampling was terminated for those packages that had any
physical defect or contained any mold infected berries.

Evaluation. Eight grape packages were randomly inspected and periodically were
examined for weight loss, surface molds and rated for general appearance (Table. 1).

To measure weight loss over time each grape cluster was removed from the
package and weighed. The weight loss then was calculated as percent weight loss
based on the original weight of the cluster.

All decay organisms were identiﬁed by Dr. David L. Roberts a plant
pathologist at Michigan State University Multidisciplinary Insect and Plant Diagnostic
Clinic. To calculate the percent decay in each package total number of decayed
berries were counted and divided by total number of berries in each package. The
result was then multiplied by 100.

General appearance of grape clusters were rated using a scale chart developed
for this purpose. The rating is from 1 to 4 in which 1 is the worst quality and 4 is the
best. To validate our scaling scheme, periodically grapes were bought from local

stores and rated using the chart. Commonlygrapes available in the market for sale

 

 

 

 

55

were rated 2. Based on this, rating of 2 was considered the lower limit of

marketability.

 

 

56

Table 1. Visual rating scale which devised and used for evaluation of grape clusters

stored under different MA conditions

 

Scale Description

 

b .

(Excellent) No dry pedicels, rachises, or peduncles, no leaky, brown or

infected berries.

3 (Good) Minimum of 50% of the pedicels are dry, no leaky, brown, or infected
berries.

2 (Fair) All of the pedicels and a minimum of 50% of the'rachises are dry.
Minimum of 2 berries are brown, leaky, or are at the early stage of infection
(limit of marketability).

1 (Poor) All of the pedicels, rachises, and peduncles are dry. Minimum of two

berries are leaky, brown, or infected.

 

 

 

 

57

Statistical analysis - In both years 50 packages (replicates) per treatment were made.
To minimize experimental error all packages were stored in one walk-in cooler. A
complete randomized design was used for analysis of variance and and Duncan’s

multiple range test was applied to treatments means for statistical comparison.

 

 

58
RESULTS

1987 storage study,

 

Infection - For ’Himrod’ grapes, those in control packages (with holes) had
signiﬁcantly higher decay than those sealed in 1.75 mil and 2 mil packages after 40
days (Figure 1A). For ’Vanessa’ grapes, after 90 days storage, the controls had a
higher amount of decay than those sealed in 1.75 and 2 mil packages (Figure 2A).

For ’Concord’ grapes, after 40 days in storage there were signiﬁcant
differences between grapes in control packages and grapes sealed in 1.75 and 2 mil
packages (Figure 3A).

’Alden’ grape berries cracked heavily before the effect of modiﬁed atmosphere
packaging was evaluated on the grape pckages. Therefore no data was collected
for ’Alden’ grapes.

General visual appearance - In general no signiﬁcant differences were seen between
any of the treatments in terms of visual rating for all of the grape cultivars. ’Concord’
and ’Vanessa’ grapes were maintained in acceptable condition for the longest period
(up to 60 days) (Figurs 2B and 3B). ’Himrod’ grape clusters were rated acceptable
for up to 40 days in control packages and in those made of 2 mil LDPE (Figure 1B).

The ﬁndings in 1987 indicated that grapes held in the thicker ﬁlm (2 mil)

stored slightly better at 0° C than those held in 1.75 mil packages and control

packages with holes. Therefore, in 1988 a comparison was made between grapes

stored in 2 and 3 mil LDPE packages.

 

 

10 ’
WControl (6 7mm holes) ab
Mljs mll LDPE '
8 IE2 mil LDPE
R 1987
V 6
3 ea
':
U 4 2a
.9
-o
.8
i} 2
E
0:.
o 10 20, 30 40
Sampling Time (Days)
6 7 .
WControl (6 7mm holes) B

General appearance ( r/4 )

Figure
rape
eons

 

 

 

 

W175 mil LDPE
$2 mil LDPE

 

 

Limit of marketability = 2

OIUTUVIIIIIIrI’IIII'Ia‘doli'III'BB‘IE'I'UUI'I'III‘TUSO
Sampling Time (Days)

1. Berry infection (A) and general appearance (8) of 'Himrod'

clusters in LDPE packages with different thicknesses.
with the same letter have no significant difference at P=0.05.

 

 

 

 

60

 

 

 

20’
A
WControl (6 7mm holes) b
15 leS mll LDPE -
A E12 mil LDPE
,, 1987
.310
t
a)
.D
U
B 5
U
.9.
E
O mnnnnrmnn w .n. ”.1.” n.
O 40

 

80 100

 

 

u 4: tn 1
on

1987

 

   

r{Fatwa-{1’41-Control (6 7mm holes)
W175 mil LDPE
m2 mil LDPE

 

Limit of marketability = 2

TTITTIIIr‘IIIIfII‘FIIIIIIITTIII‘IUIIIT‘TrIITYITIIII

. 80 10
Sampling Time (Days)
Figure 2. Berry infection (A) and general appearance (B) of 'Vanessa'
grape clusters packaged in LDPE packages with different thicknesses.
Means with the same letter have no signiﬁcant difference at P=0.05,

 

0

General appearance (r/4)
‘4‘ N
W
0'1

 

61

 

 

 

 

 

 

 

 

50
WControl (6 7mm holes) A
W175 mil LDPE _
40 [312 mil LDPE +b
R 1987
J0 an
0153
.2 J
t f
020 r.
.a v;
.0
.8
310
L5
a
a
O:.. ...., ......... 1 lllllllll , .............. rmﬁ1m
O 20 O ”‘0? 100 1'20
Sampling Time Days)
5 _
B
i 42.:
L.
8 3
c
E
o
8.
e 2 b
_ WControl (6 7mm holes)
8 W175 mil LDPE .
g 1 E12 mil LDPE 33
8
Limit of marketability = 2
OiTrIIIj—IIIIIﬂTII[TI]IUm!Iﬁ1‘1WIIIT—I—IOIYTTIIﬁTIIXIITT‘rrJI
20 40 100 120

SamplinsgO Time agays)

Figure 3. Beery infection (A) and general appearance (8) of ‘Concord'
grape clusters packaged in LDPE packages with different packages.
Means with the same letter have no significant difference at P= OHOS

 

62
1988 storage study

Infection - For ’Himrod’ grapes the only signiﬁcant difference was between 2 mil

packages and controls 43 days after the beginning of the experiment (Figure 4A).
However, 83 days after storage, mold growth was statistically similar in all packaging
treatments.

’Vanessa’ grapes in control and 2 mil packages had about 5% decay 86 days
after storage while there was no decay in those held in 3 mil packages (Figure 5A).
By 100 days of storage, there was signiﬁcantly more decay in control and 2 mil
packages when compared to 3 mil packages.

There was little decay in ’Concord’ grape packages held for up to 5 months
(Figure 6A). While controls had up to 30% decay at that time.

’Alden’ grape berries cracked and decayed rapidly in all packages 5-7 days
after storage and no further evaluations were feasible on the packages (Appendix G).
General visual appearance - ’Himrod’ grapes in 3 mil packages looked superior in
comparison to both controls and 2 mil packages during the entire storage study
(Figure 4B). But it took about 2 months before the grapes reached a number 2 rating
that still was considered acceptable from a marketability stand point. Grapes from
control and 2 mil packages were not acceptable because of the decline in their
general appearance 43 days after storage.

’Vanessa’ grapes in 3 mil packages retained their general appearance very well

up to 86 days in storage (Figure 5B). Eighty six days after storage there was a

 

 

63

 

  

 

 

 

 

 

25
. A
205 W Control (6 7mm holes)
3 (3888-82 mil
3 m3 mil
A i a
515';
g i 1988 a
310% a
D :
‘U 5
3 i
3: 52
s. E
03 _.=/ .
010 20 so 40 so 50 70 so 90
SamplIng Time (Days)
6
I W Control (6 7mm holes) 8
3 (38888 2 mil
A «I 51515-51933 mil
‘1' I
E .
V 4‘
q, _
U 1
c at
E I
8 1
o. .
o. .
U 2..
33 I a
5 j a
O - . . ..
3 LImIt of marketabIlIty = 2
O...
0

10 20 30. 40 SE) 0 7D 80 90
_ SamplIng TIme Days
Figure 4. Berry infection (A) and general appearance (8) of 'Himrod'
grape clusters in LDPE packages with different thicknesses.
Means with the same letter have no significant difference at P=0.05.

 

64

N
U1
>

 

 

 

 

 

 

 

 
     
   
 
 

 

 

 

 

 

1 a
a a A
j W Control (6 7mm holes)
20; 999992 mil
I; g A-A-é-A-AB mil
3315-:
s
ﬂ :
13105
3 .1
o :
.9. 3
E s-E
1988
O-‘Irmi‘lI—TITTIIIIITT " ‘
20 4O 60 80 100 120
Sampling Time (Days)
6
8
$5 W Control (6 7mm holes)
} 999992 mil
v 99-9993 mil
«:4
U
C
E
33
a
a.
O
...2
E
a 1988 a
C
8‘ aa
Limit of marketability == 2
O [iITTIIITTIIIjTIlW—TIWIﬂ—IIme—TTTI[I‘IrTTI—YTIIIIﬂT
O 20 4O 60 80 100 120

Sampling T'Ime (Days)
Figure 5. Berry infection (A) and general appearance (8) of 'Vanessa'
grape clusters In LDPE packages wi h different thicknessese.
Means with the same letter have no significant difference at P=0.05.

 

 

65

signiﬁcant difference . in general appearance between grapes from 3 and 2 mil
packages and in comparison with controls. Grapes in control packages deteriorated
rapidly and were unmarketable after about 60 days in storage.

’Concord’ grapes in 2 and 3 mil packages were rated excellent for over 140 days
(Figure 6B). These grapes maintained much better appearance compared to controls.

By 100 days there were no differences between grapes packaged in control.
2 and 3 mil packages.

Regarding weight loss, grapes packaged in unsealed packages lost more weight

when compared to sealed packages (see Appendix E). In sealed packages grapes
packaged in thinner ﬁlm packages usually lost more weight compared to those in
packages made of thicker ﬁlms.
Package void volume gas composition - Figure 7 (A and B) shows the O2 and CO2
concentrations of 1.75 and 2 mil packages. As seen in the ﬁgure, the 02 level 2 weeks
after storage for 2 mil packages reached about 17% while the 02 concentration in
1.75 mil reached about 17.2%.CO2 concentration for 2 mil packages did not increase
more than 1.25% and for 1.75 mil never reached to about 0.826 days after storage.
However in 3 mil ’Himrod’ packages, 30 days after storage 02 concentration dropped
to about 10% and CO2 concentration increased to about 3% (Figure 8A). 02
concentration continued to decrease well beyond 30 days after storage.

The O2 and CO2 concentrations in 3 mil ’Vanessa’ packages are shown in
Figure 8B. The 02 concentration decreased to about 12% after 43 days in storage

and C02 concentration increased to about 4%.

 

 

 

 

66

 

 

 

 

 

 

4O
‘ A
2 W Control (6 7mm holes)
305 1388892 mil b
: see-993 mil
3 2
320-:
t: :
‘1’ I
.D ..
'0 I
310:
U ..
.33. :
E. 3 1988 ‘93
. A #ea
035...............-..,.. -
O 20 4O 60 80 100 120 140 160
Sampling Time (Days)
6

 

W Control (6 7mm holes) B
88888 2 mil
A8888 3 mil

1 l l l l l l L l

 

 

   

 

A
t
\
L.
v ‘3
‘J
Q.)
3
" ——E18
:3 4
L. .1
0 q
0 ..
Q all
(1 .i
O .-
_ 'l
C) d
L- a
C) 4
8 : tb
O 1
1

Limit of marketability = 2

 

D

 

TTTTITIII‘ITTTIIITT1IIITTTIITTTTTITTTIVTTTTTTTTTYTTTIITTI1TTTIITTTIII]XIII!

O 20 4O 60 80 100 120 140 160
Sampling lime (Days)

Figure 6. Berry infection (A) and eneral appearance (8) of 'Concord'

grape clusters In LDPE packages wi h different thicknesses.

Means with the same letter have no significant difference at P=0.05.

 

 

 

 

67

 

 

 

 

  

 

 

 

 

 

 

.3

i , A i

2 00000 CO; In 2 mIl package. R =2 0.91 3

« AAAAA CO: In 1.75 mIl package, = 0.82 -E
A u :
[£3- ..
:3 2': '2
c: '3 E
0 .- :
'3 . _:
O .. .1
L ..
.u .. 2
C d I
a 4 =
r: i: '5
O 2
° 2
n .5
O :1
o E

D [TTTT IIIII IF—TTTTIIIIITTTIIIUTIIIITIUIIUIII‘WTIIIIIFITji -
0 5 10 15 20 25 30
Sampling Time (Days)

3 5
f3 i: 5
D— "' u-I
520: E
c: I '5
O u d
'53 - :
0 - :
L d
H d d
C “‘ —
8 ~ 2

.4 H
:18. :
8 ~ =

j E] .1
In ., I
o . 2 :
0 2 0.0.9110 02 in 2 mil package. R =2 0.81

4 0.05208) 02 In 1.75 mIljackage, R = 0.80

16 WirﬁtxWt:IrrrIjTTttr—fTIt—rrTrrrlmlTrIrtrxTrlrrIrTil
0 ' 5 10 15 20 25 30

Sampling ‘l‘Ime (Days
Figure 7. Solid lines represent the best ﬁt curves for C02 (A) and
02 (8) concentrations in 1.75 and 2 mil LDPE 'Himrod' grape packages.

Each package contained 200 g grape and the package size : 20.3 X 22.9
cm.

 

 

 

 

N
4.

68

 

N
O

AlllAAILLLAIAJllllAnJL

...o
a:

Gas concentration (kPa)
N

   
     

(IIID C0; production
CHI]: 0; consumption

= 0.94

002 R:
0.98

02R

 

 

 

a
4
_ %

0‘ ttttttttt I ttttttttt I 1 rmr T r
24? 20 40 50
20‘3” cxrmca2 production

. CIIEDO, consumption
1 c0 R’ = 0.95
16. 0,2 R’ = 0.86

Gas concentration (kPa)
~38 on N
1‘ L1 1 l 1 a 1 L4 1 A. l 1 1

 

 
 
   
  
   
 

D

 

t

 

M
4h 0
844-0

-‘ N
0') O

'0

Gas concentration (kPa)

0

Fi ure 8.
C 2 production in 3 mil LDPE ‘Himrod'
'Concard‘ (C) gra
package sIze : 2

JlT—TTI

    

rTT I

20

4O

[Frrrr ITTY

{IﬁrrrTr

4O

TTIII1—TIII

60 60

(XIII) CO; production
CEEUJ 0; consumption

C02R: 0.59
01 R 0.90

 

60 80 100
Sampling Time (Days)

120

Solid lines represent the best fit for 0, consumption and

8.": ‘3x"

ckages. Each pa

(A), 'Vanessa‘ (8%. and
c age contained 00 g grape and the
22.9 cm

 

 

 

69

The 02 and C02 concentrations in 3 mil ’Concard’ grapes are shown in

Figure 8C. The C02 concentration increased to 5%, 87 days after storage and 03
decreased to about 7% at the same time. However, while CO2 concentration
increased moderately from now on, 02 concentration dropped with a faster pace to
a level of about 6%. It should be noted that the data presented were obtained from
unoptimized packages each containing 200g of grapes. The data obtained for

optimized packages of ’Himrod’ and ’Concard’ are presented in appendix C.

 

70
DISCUSSION

The data presented here support the beneﬁcial role of different modiﬁea
atmospheres in extending shelf life of fresh tabe grape cultivars. However, modified
atmospheres of 2% 02, about 6% CO2 for ’Himrod’ and 2% 02, 10-11% CO2 for
’Concard’ grapes have deﬁnite effects in prolonging the shelf life of both cultivars.

Several researchers have experimented with different gas composition to
extend the shelf life of grapes (23, 25, 32, 44, 47). These efforts examined the
possibility of CA application as an alternative to 802. However, none of them were
successful in extending the shelf life of all grape cultivars (24, 26). Lack of success
in using CA conditions to extend shelf life of fruit is partially due to limited studies
that did not consider all aspects of CA effects on different grape cultivars which were
tested (24, 26, 32).

As shown in ﬁgure 9(A and B) different cultivars do not respond similarly to
CA conditions. This demands extensive, detailed, and complete studies to obtain
information regarding the behavior of the grapes under different CA conditions.
Modiﬁed atmosphere packaging could provide an array of different MA conditions.
This would allow extensive MAP research and study in detail all aspects of the
storage behavior of grapes. However, high relative humidity build up inside the
packages would make the condition more favorable for mold growth. A study on
’Thompson Seedless’ showed that 2.5% 02 and up to 15% CO2 would generate the
same result comparable to SO2 application on grapes (32). In our study we achieved

nearly this goal for ’Himrod’ and ’Concord’ cultivars by utilizing 3 mil LDPE ﬁlm.

 

 

71

Based on our ﬁndings 500 g was considered to be the optimum weight for the
recommended package with the surface area of 465 cm2. Modiﬁed atmosphere
packaging by providing the desired atmosphere conditions in the package could
prevent mold growth (Figure 9 A and B). Also, since the decayed grapes are
contained inside the package, the possibility of spread of infection to other grapes
becomes limited. The container aspect of the package also prevents the shattered
berries to be lost in the storage facility.

Three mil LDPE ﬁlm had advantages over the other ﬁlms used. The 3 mil
ﬁlm itself is physically thick enough to reduce fruit bruising. The 3 mil thickness also
makes it more difﬁcult to be punctured. A hole in a ﬁlm prevents the establishment
of the MA condition around the fruit.

As it was mentioned before not all of the cultivars behave the same way under
modiﬁed atmosphere conditions. For instance ’Alden’ cultivar grapes did not
beneﬁtted from the generated MA conditions. The main reason for this failure was
inherent in the physical weaknesses of the grapes berrries themselves (Appendix G).
The major problem with ’Alden’ was berry splitting. Cracked berries allow juice to
come out which provided favorable conditions for bacterial and/or fungal growth.
Splitting involves rupture of cuticle, epidermis, subepidermal cells and many of the
large vacuolated cells of the outer pericarp (45). Also longer and thinner cells are
more resistant to rupture (10). However, there is no evidence for lack or presence
of these types of cells in ’Alden’ grapes.

As it was mentioned before all of our research efforts were carried out at 0°C.

 

 

72

20

 

rt'hG-‘Iliwlinll-Control (6 7 mm holes)
99999500 9 1
99999 600 g .

.4
U!
0 9.14914 4.1-1.141 1.LL1.1_L 1.1. i -u LLJLW

O

Infected Berries ( 96 )

 

ITIIInIII‘WIITTIYIIIIIIIerWIIITIIIIIIrzill’IIi{73).ATXTTT.0“

10 20, 30 0 50 50
SamplIng Time (Days

 

00

   

 

: l
j WControl (6 7 mm holes) I BE
2‘.- 99999500 9 g
3 99999 600 g ?
.3 .13.“ l
“-3 .3 C
4..) ..’._ [a t
5‘: - //¢.
3 i
OAilLI I i i T—YTI T ITT l I—TT Tjﬁ IT—f‘f T—nﬁi T—liT—r—Ti—‘FI %
0 ' '

l , 2
Samplmg lime (Months)

.. in 3 mil LDPE packages of ’Himrod (A; and
c ra‘ (E,I grapes as a functIon at modItIea atmospher 3 es
rent grapes weights. Each mean :3 the average at 8

w (0

 

 

73

Any change in storage temperature is known to affect the gaseous composition of
MAP systems for a number of commodities (22). Any temperature change could
change the in-package steady state 02 and CO2 levels due to effect of temperature
on ﬁlm permeability to gases and product respiration. Therefore it is advisable that
3 mil LDPE packages beiused only at 0°C or slightly close to this temperature. At
this temperature no ethanol or acetaldehyde was detected. Any abuse of temperature
could possibly cause anaerobic condition leading to ethanol and acetaldehyde
production that are not desired for the MAP system developed (39).
CONCLUSION

The data presented in this paper indicated that MAP could be utilized
successfully as a working approach and a feasible alternative for replacing SO2
application on grapes to extend their shelf life. This technique is not limited to use
only on small scale. By knowing the ratio of fruit mass:package surface area, larger
scale modiﬁed atmosphere packages, i.e. a grape plastic lug scale, could be devised

and used successfully.

 

74
LITERATURE CITED

1. Anonymous. Standard test method for oxygen gas transmission rate through plastic
ﬁlm and sheeting using a coulometric sensor. ASTM designation: D 3985 - 81.
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2. Asbury, C. E., C. O. Bratley, and W. T. Pentzer. Further observations and mold
control in grapes during transit and storage. Blue Anchor 6:8-9. (1936).
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Sci. 42:238-246. (1958). i
5. Balinger, W. E. Quality of Muscadine grapes after storage with sulfur dioxide
generators. J. Amer. Soc. Hort. Sci. 107(5):827-830. (1982).
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fruit. M. S. Thesis. Michigan State University. 73 p. (1986).
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Gruber. Fresh market grapes from Ohio vineyards. Ohio report. May-June
issue. (1985).
8. Cameron, A. C. Modiﬁed atmosphere packaging packaging: A novel approach for
optimizing package oxygen and carbon dioxide. Fifth proceedings of

international controlled atmosphere research conference. Wenatchee,

Washington, USA. (1989)

 

 

 

75
8. Cameron, A. C., W. Boylan—Pett and J. Lee. Design of modiﬁed atmosphere

packaging systems: Modeling oxygen concentrations within sealed packages of
tomato fruits. J. Food Sci. 54:1413-1416 & 1421. (1989).
9. Chiarappa, L.,J. W. Eckert, and M. J. Kolbezen. Effect of
dibromotetrachloroethane (DBTCE) and other chemicals on Botrytis
decay of ’Emperor’ grapes in storage. Am. J. Enol. Vitic. 13:83-90. (1962).
10. Considine, I. A. and P. E. Kriedmann. Fruit splitting in grapes: Dtermination of
the critical turgor pressure. Aust. J. Agric. Res. 23:17-24. (1972).
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product shelf life. Pack. Eng. l9(8):50. (1972)

12. Elboudwarej, A. F.,A. Shirazi, A. Cameron, and R. C. Herner. Measurement of
transpiration rate of different parts of grape clusters. Am. J. Enol. Vitic. (in
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13. El-Goorani, M. A. and N. F. Sommer. Suppression of postharvest plant
pathogenic fungi by carbon monoxide. Phytopathology 69:834-838.(1979).
l4.Fisher, K. H.,and O. A.Bradt. Vanessa grapes. Hort. Sci.20(1): 147-148. (1985).
15. Gerhardt, F. Use of ﬁlm box liners to extend the storage life of pears and apples.
USDA bulletin No. 965. (1955).
16. Ginsburg, L.,]. C. Combrink, and A. B. Truter. Long and short term storage of
table grapes. International Journal of refrigeration 1(3):l37-l4l. (1978).
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exchange of fresh produce in polymeric ﬁlm package. J. Food Sci. 40:186.

76
(1975).

18. Henig, Y. S.,and S. G. Gilbert. Computer analysis of the variables affecting
respiration and quality of produce packaged in polymeric ﬁlms. J. Food Sci.
40: 1033-1035. (1975).
19. Harvey, J. M., and M. Uota. Table grapes and refrigeration fumigation with
sulphur dioxide. International Journal of Refrigeration 1(3). (1978).
20. Hruschka, H. W. and Kauffman, J. Polyethylene for citrus. Modern packaging
27(6):l35-138 & 184. (1954).
21. Jurin, V. and M. Karel. Studies on control of respiration of McIntosh apples by
packaging methods. Food Technol. 17(6)104. (1963).
22.Kader, A. A.,Zagory, and E. L. Kerbel. Modiﬁed atmosphere packaging of fruits
and vegetables. Crit. Rev. Food Sci. Nutr. 28: 1—30. (1989).
23. Khitron, Ya. 1.,V. A. Tsutsuk, and V. Dogotar. Combined storage of different
cultivars of table grapes. Sadovodstvo, Vinogradarstvo iVinodelie Moldavii
No 7, 29-31. Kishinevskii Sel’skokhozyaistvennyi Institut, M. V. Frunze,
Kishinev, Moldavian SSR. (1981).
24.1aszlo, J. C. the effect of controlled atmosphere on the quality of stored table
grapes. Decidous fruit grower. December Issue. (1985).
25. Magomedov, M. G. Technology of grape storage in regulated gas atmosphere.
Vonodelie iVinogradarstvo SSSR. No.2:l7~l9.dagestanskii Sel’khozinstitut,

USSR. (1987).

77

26. Monzini, A.,F L. Gorini. The use of controlled atmospheres with citrus. grapes
and other fruits. Annali dell’Istituto Sperimentale per la Valorizzazione
Tecnologica dei Prodotti Agricoli, Milano 4:237-254.istituto Sperimentale per
la Valorizzazione Tecnologica dei Prodotti Agricoli, Milan, Italy. (1973).

27. Nelson, K. E.,F. E. Tomlinson. some factors inﬂuencing bleaching and wetnwss
of Emperor and Tokay grapes. Am. Soc. J. Hort. Sci. 71:190-198. (1957).
28. Nelson, K. E. Some studies of the action of Sulfur Dioxide in the control of
Botrytis rot of Tokay grapes. J. Amer. Soc. Hortic. Sci. 71:183-189. K. E.,
(1958).
29. Nelson, K. E., and H. B. Richardson. Further studies on factors affecting the
concentration of sulfur dioxide in fumigation atmospheres for table grapes.
Proc. Am. Soc. Hort. Sci. 77:337—350 (1961).
30. Nelson, K. E., L. Chiarappa, and G. Baker. Control of Botrytis decay in stored
grapes with Dibromotetrachloroethane. Am. J. Enol. Vitic. 14:105-113 (1963).
31. Nelson, K. E.,and G. A. Baker. Studies on the sulfur dioxide fumigation of table
grapes. Am. J. Enol. Vitic. 14213-220963).
32. Nelson, K. Controlled atmosphere storage of table grapes. Proceeding of the
national controlled atmosphere research conference at Michigan State

University. January 27 and 28. (1969).

33. Nelson, K. E. Harvesting and handling California table grapes for market.

Division of Agri. Sci. University of California. Publication 4095. (1979).

78
34. Pentzer, W. T ., C. E. Ashbury, and K. C. Hamner. Effects of fumigation of

different varieties of Vitis vinifera grapes with sulfur dioxide gas. Proc. Amer.
Soc. Hort. Sci. 29:339-344. (1932).

35. Prince, T. A., R. C. Herner, and J. Lee. Bulb organ changes and inﬂuence of
temperature on gaseous levels in a modiﬁed atmosphere package of precooled
tulip bulbs. J. Amer. Soc. Hort. Sci. 111:900-904. (1986).

36. Risse, L. A. and Miller, W. R. Individual ﬁlm wrapping of fresh Florida
cucumbers, eggplant, peppers, and tomatoes for extended shelf life. J. Plastic
ﬁlm and sheeting 2:163-17l.(1986).

37. Ryall, A. L.,and J. M. Harvey. The cold storage of vinifera table grapes. USDA
AgriMktg. Serv. Handbook 159,46 pp. (1959).

38. Saltveit Jr., M. E.,and W. E. Ballinger. Effects of anaerobic nitrogen and carbon
dioxide atmospheres on Ethanol production and postharvest quality of
’Carlos’ grapes. J. Amer. Soc. Hort. Sci. 108(3):462. (1983).

39. Shirazi, A. Modiﬁed humidity packaging of fresh produce. PhD dissertation.
Michigan State University. (1989).

40. Simms, W. C. Package Engineering, The 1983 Packaging Encyclopedia 28(4):68-
71, 74-79 & 82-99. (1983).

41. Slate, G. L.,J. Watson, and J. Einset. Grape varieties introduced by the New

York State Agricultural Experiment station. Cornell University,

Geneva, N. Y. Bulletin No. 794. (1962).

 

79

42. Smock, R. M. Controlled atmosphere storage of fruits. Horticultural reviews No.
1:301-336. (1979).

43. Stahl, A. L., and W. M. Fiﬁeld. Cold storage studies of Florida citrus fruits. 11.
Effects of various wrappers and temperatures on the preservation of

citrus fruits in storage. Iniv. Fla. Agr. Exp. Sta. Bul. 304. (1936).

44. Strel’nikov, A. N., S. Dzheneev, 8. Yu, and V. I. Ivanchenko. Storage of grapes
in CA. Sadovodstvo No. 9:33. Krymskii Sel.-Khoz Institut, Simferopol,
Ukrainian SSR. (1978).

45 . Swift,J . G., P. May, and E. A. Lawton. Concentric cracking of grape berries. Vitis
13:30-35. (1974).

46. Uota, M. Evaluation of polyethylene ﬁlm liners for packaging Emperor grapes
for storage. Proc. Amer. Soc. Hort. Sci. 70:197-203. (1973).

47. Voloshin, A. V., and A. V. L’vova. Storage of grapes in controlled atmosphere.
Sadovodstvo 12:19.Sovkhoz-Zavod Koktebel’, Crimea, Ukrainian SSR. (1976).

48. Yahia, E. M.,K. E. Nelson, and A. A. Kader. Postharvest quality and storage life
of grapes as inﬂuenced by adding carbon monoxide to air or controlled
atmosphere. J. Amer. Soc. Hort. Sci. 108(6):1067-1071 (1983).

49. Zabadal, T.,J. A. Bartsch, G. D. Blanpied, T. J. Dennehy, R. C. Pearson, R. M.
Pool, and B. I. Reisch. Concord table grapes. A manual for growers. New

York Agricultural Experiment Station, Geneva, NY. (1988).

 

 

 

80

CHAPTER 3

MODIFIED ATMOSPHERE PACKAGING OF FRESH TABLE GRAPES WITH

IN—PACKAGE HUMIDITY CONTROL TO REDUCE MOLD GROWTH

 

81

ABSTRACT

Grapes are commercially treated with sulfur dioxide (SOz) to preserve quality
during postharvest handling. Modiﬁed atmosphere packaging (MAP), using low density
polyethylene (LDPE) as an alternative could extend the storage life of grapes. Since
LDPE ﬁlms are excellent moisture barriers, near saturation relative humidity occurs
inside sealed packages and may increase decay. To reduce relative humidity inside sealed
packages, different sorption compounds equivalent to 10% of the grape berry weight
were sealed in pouches made of a commercial semipermeable ﬁlm, and were placed
together with grapes into sealed MA packages. The packages were 20.3 X 22.9 cm and
contained 500 g of grapes. Grape cultivars ’Himrod’, ’Vanessa’, and ’Concord’ were
exposed to different relative humidities generated by sorption compounds. These sorption
compounds were; potassium nitrate, potassium chloride, D-sorbitol, sodium chloride.
Potassium nitrate (KNO3) and potassium chloride (KCl) both provided optimum relative

humidity that decreased mold growth and prevented excess weight loss of all 3 cultivars.

 

82
INTRODUCTION

In modiﬁed atmosphere packaging to extend the shelﬂife of fresh fruits and
vegetables, polymeric ﬁlms usually are being used. These ﬁlms are somewhat permeable
to 02, C02, and water vapor. Moderate Oz and C02 permeabilities can provide favorable
environments for living tissue sealed in these ﬁlms and the low water vapor transmission
rate reduces the rate of moisture loss from fresh produce (Ayres and Denison, 1958:
Baghdadi and Smock, 1943; Kader and Zagory, 1989; Nelson, 1979; Risse and Miller,
1986; Uota, 1957). Reducing the rate of moisture loss from fresh produce is mainly due
to increased resistance to water loss inside the package (Sastry et al, 1978; Lentz et. al..
1971; Gentry and Mitchell, 1963). Water loss is primarily driven by a difference in the
water vapor pressure in the interior of the fruit or vegetable, and the water vapor
pressure of the surrounding environment (Sastry, 1978; Lentz et. al., 1971). Modified
atmosphere packages with low water vapor transmission rates and continuous moisture
evaporation from fresh produce generates a high water vapor pressure inside the package
and saturates the package void volume. This may increase decay. Some moisture loss
may be desirable and can be tolerated to a certain extent. The ﬁrst noticeable effect of
moisture loss of grape clusters is drying and browning of stems and pedicels (Gentry and
Stout, 1971). This effect becomes apparent with a loss of only 1 to 2% of the weight of
the fruit. The fruit loses its turgidity and softens when the loss reaches 3 to 5% (Gentry
and Stout, 1971). Under many conditions the loss may be great enough to affect
appearance, texture, and flavor (Gentry and Stout, 1971). As grapes shrivel, they appear

dull and lifeless. The pedicels are very sensitive to water loss and lose water faster than

 

 

83

the berries. The appearance of the rachis is an important market quality factor and is
often used as a measure of total fruit quality.

In storage of grapes ninety percent relative humidity is the desirable minimum in
California and 95% is being advocated commercially (Gentry et. al., 1963; Guillou et.
al., 1963). Relative humidity above 95% increases the level of infection by Botrytis
cinerea (Nelson, 1951; Snow, 1949), and the use of high humidities is limited by the
possibility of decay development. Free water on the fruit or high relative humidity, or
both, appear to be important factors contributing the rapid development of Borryris
cinerea (Nelson, 1951). Low temperature does not prevent spore germination but only
delays it (Ginsburg et. al., 1978). Most postharvest decays primarily are caused by
pathogens that infect grape berries through wounds and other weakened sites. The most
frequent loci for initial infections are stem scars. However, when a spare germinates, a
short infection tube is formed which is capable of penetrating the skin of the berry even
though there are no mechanical injuries (Ginsburg et. al., 1978). Relative humidity at
levels of less than 90% also can cause infection either due to invisible residual water
around the pedicel or rapid transpiration from that area (Nelson, 1951). However, some
moisture loss takes place through lenticels formed under the non-functional stomata and
lenticels (Swift, 1973). The structural arrangement of wax platelets, together with their
hydrophobic surfaces, controls water movement. This control is mainly due to restricting
the evaporation pathway. These pathways consist of relatively long narrow and
hydrophobic capillary channels between the wax platelets (Swift, 1973).

An alternative to the use of fungicides to reduce decay inside polymeric packages

 

 

84

is to reduce in-package relative humidity. Different desiccants such as CaCl2 have long
been used to reduce in-package relative humidity. However, the relative humidity
generated by CaCl2 is in the range of 31 to 40% (Weast, 1984) which is not suitable for
storage of fresh fruit and produce. Currently, a method of reducing in-package relative
humidity within fresh produce packages has been reported (Shirazi and Cameron, 1991).
The ability to generate a stable relative humidity within sealed packages to reduce decay
problems is discussed in this report. Each sorption compound generates a speciﬁc
equilibrium RH over its saturated solutions (Weast, 1984; Winston, 1969; Young, 1967).
However, not all of the desiccants are able to generate a stable relative humidity in the
presence of fresh producerSorption compounds that exhibit Type-III isotherms were
suggested to provide stable equilibrium relative humidities (Shirazi and Cameron, 1991). .
Chemicals that have Type-III isotherms take up small amounts of water at low vapor
pressures. However, once the monolayer sorption is completed, the water uptake
behavior changes remarkably due to hydrogen bonding among water molecules. As vapor
pressure increases beyond this point, a considerable increase in the water content of the
sorbent takes place as a result of the attachment of water chains of indeﬁnite length to
the ﬁrst layer. These mechanisms together give a parabolic shape to the isotherm
(Labuza, 1984). Among the selected compounds, sodium chloride, sorbitol, and
potassium chloride were found to exhibit Type III sorption isotherms (Kaufman, 1956;

Labuza, 1984; Shirazi and Cameron, 1991).
A better understanding of the desiccation process of grape clusters should help in

developing systems that reduce relative humidities inside polymeric packages. The overall

 

85

goal of this study was to gain information regarding the behavior of different grape
cultivars under a range of reduced relative humidities generated inside polymeric

packages during storage at 0°C.

86
MATERIALS AND METHODS

Plant materials. Fruits of ’Himrod’ (Slate, 1962), ’Vanessa’ (Fisher, 1985), ’Alden'
(Slate, 1962; Cahoon et. al., 1985), and ’Concord’ (Zabadal et. al., 1988) grape cultivars
were harvested manually at commercial maturity from different vineyards in Lawton,
Michigan (for ’Himrod’ and ’Alden’), Clarksville, Michigan (for ’Vanessa’), and East
Lansing, Michigan (for ’Concord’). The experiments were conducted in 1988 and 1989.
Harvested fruits were placed into plastic lugs. Grape clusters were inspected and sorted
for obvious defects. Fruits then were put in unsealed polyethylene bags. The bags were
placed in ice chests with about 5 cm of crushed ice at the bottom. A one inch thick
sponge separated the fruits from the ice in the chests. Fruits were transported
immediately to East Lansing and were held overnight at 1°C to reach an equilibrium
temperature before they were packaged. On arrival fruit temperature was 5°C.
Packaging. The package ﬁlm was made of a single resin, low density polyethylene
(LDPE). In 1988, based on our previous ﬁndings a 3 mil thick ﬁlm was used and grape
clusters were heat sealed in 20.3 x 22.9 cm (464.87 cm2 total surface area) pouches
(Elboudwarej et. al., 1991). Each package was equipped with a gas sampling septum
constructed of a short strip of electrical tape with a piece of tub/tiling silicone glue and
sealant (Boylan-pett, 1986). Three hundred g of fruits were sealed in each package.
To investigate the effect of different sorption compounds on different grape
cultivars, in 1988, four chemicals were tested. These compounds were sodium chloride
(NaCl), D-sorbitol, potassium chloride (KCl), and potassium nitrate (KNO3). Based on

results obtained in 1988, the investigation in 1989 included control, KNO3 and KCl.

 

 

87
Sorption compounds were heat sealed in small pouches (8 X 8 cm) made of Tyvek ﬁlm

(a DuPont product), a semipermeable low density polyethylene membrane. By having
sorption compounds in these pouches water vapor continuously is absorbed while no
liquid could move out of the pouch. Each pouch contained sorption compound equal to
ten percent of the original weight of the fruit. The sorption pouch was then inserted in
each fruit package and the package was sealed with the 500 g of grapes.

For each treatment 30 packages were made and all were placed in 0°C coolers
with relative humidities of 36-38%.
In—package relative humidity measurement. In 1988 the relative humidity was measured
in the void volume of the packages at 00C. To measure relative humidity, small plastic
funnels were cut and glued to each package surface area from the inside (Appendix D).
The Opening of the funnel was closed by a size 0 rubber stopper at all times except for
insertion of a temperature and humidity probe. The temperature and humidity probes
were connected to a hygrometer (General Eastern, Model No. 800B).

In 1989 relative humidity measurements were conducted at 20°C (Shirazi and
Cameron, 1991). A combined temperature and humidity probe (General Eastern, Model
No. 850) was inserted into each package. To ensure a complete seal, each package was
closed using two plexiglass pieces fastened together by bolts and sandwiching the ﬁlm
between them. Temperature and humidity values were collected using a data logger
(Omnidata international, Model No. 516B—32). -

Package atmosphere composition was determined daily by withdrawing a gas sample

of 1 ml from the package with a medical-type plastic syringe. The entry port was made

 

 

88

of a piece of tub/tiling silicone sealant. The samples were analyzed using a gas
chromatography. The gas chromatograph consisted of an Ametek Oxygen Analyzer
(Model S—3A) and an ADC Infra-red Gas Analyzer (Type 225 MK3) connected in series
and a strip chart recorder (Linear Instruments Corp., Model 1200) (Shirazi, 1989).
Nitrogen gas was used as carrier gas at 200 ml per minute. By using this system 1 ml
gas samples are adequate, the analysis only takes about 10 seconds, and the peaks
produced on the strip chart recorder are proportional to the O2 and CO2 concentrations.
The package gas sampling was continued well beyond the onset of steady state conditions
in the void volume of the packages. Gas sampling was terminated for those packages that
had any physical defect or contained any mold infected berries.

Evaluation. Eight grape packages were randomly inspected and periodically were
examined for weight loss, surface molds and general appearance (I able. 1).

To measure weight loss over time each grape cluster were removed from the
package and weighed. The weight loss then was calculated as percent weight loss based
on the original weight of the grape.

All decay organisms were identiﬁed by Dr. David L. Roberts a plant pathologist
at Michigan State University Multidisciplinary Insect and Plant Diagnostic Clinic. To
calculate the percent decay in each package total number of decayed berries were counted
and divided by total number of berries in each package. The result was then multiplied
by 100.

General appearance of grape clusters were rated using a scale chart developed for

this purpose. The rating is from 1 to 4 which 1 is the worst case and 4 is the best. To

 

 

89

validate our scaling scheme, periodically grapes were bought from local stores and rated
using the chart. Predominantly grapes available in the market for sale were rated 2.

Based on this rating of 2 was considered the limit of marketability.

 

 

 

90

Table 1. Visual rating scale which devised and used for evaluation of grape clusters

stored under different MA conditions

 

 

Scale Description

4 (Excellent) No dry pedicels, rachises, or peduncles, no leaky, brown or infected
berries.

3 (Good) Minimum of 50% of the pedicels are dry, no leaky, brown, or infected
berries.

2 (Fair) All of the pedicels and a minimum of 50% of the rachises are dry.
Minimum of 2 berries are brown, leaky,‘ or are at the early stage of infection
(limit of marketability).

1

(Poor) All of the pedicels, rachises, and peduncles are dry. Minimum of two

berries are leaky, brown, or infected.

 

 

91
RESULTS
In 1988, several compounds were tested‘and some of them showed potential for

reducing the relative humidity (Figure 1). Under the experimental conditions two
compounds showed stable RH’s in packages for up to 30 days. These two sorption
compounds were potassium nitrate (KNO3) and potassium chloride (KCl) which held
relative humidity at 97-98 and 92-93, respectively, over a period of 30 days after the
beginning of the experiment. The relative humidities inpackages containing D-sorbitol
and sodium chloride (NaCl) were not stable and both showed decreasing relative
humidity over a period of 50 days. The relative humidities in packages had a range of
87—91 and 85-88, for D-sorbitol and sodium chloride (NaCl), respectively.

1 In 1989, the void volume relative humidities generated by sorption compounds,
potassium nitrate (KNO3), and potassium chloride (KCl) were about 89 and 87,
respectively, in packaged with 200 g of grapes and 20 g of absorbent. In this and most
all other experiments, the relative humidity in control packages without any chemical was
97-100%. However, relative humidity in control packages at 0°C reached nearly 98%,
30 days after the sealing of the packages (Figure 1). The relative humidity of the internal
atmosphere of almost all fruits and vegetables is at least 99% (Hardenburg et. al., 1986).
Theoretically RH in sealed packages should be more than 99% (Cameron, 1982; Shirazi
and Cameron, 1991; Troller, 1978).

1988 storage study,
Weight loss. ’Himrod’ grapes exposed to different relative humidities inside the packages

showed different weight losses (Figure 3A). Holding grapes in all of relative humidities

92

caused linear weight losses over time. However, weight loss by sorption compounds.
sodium chloride (NaCl), and D~sorbitol caused unacceptable visible shrinkage of grape
clusters. KCl and KNO, had the lowest water loss of the sorption compounds tested.
’Vanessa’ and ’Concard’, generally exhibited the same trend of weight losses as
for ’Himrod’ (Figures 4A and 5A).
Decay. There were 3 main decay organisms identiﬁed in these studies, namely, Botrytis
cinerea, Penicillium Sp., and Colletotrichum Sp.
After about sixty days of storage at 0°C excessive mold was found on both ’Himrod’ and
’Vanessa’ grapes in packages with no sorption compounds (Figures 3B and 4B).
However, less than 5% infection occurred in packages with potassium nitrate (KN 03).
The other compounds resulted in less infection for both cultivars. No mold growth
developed on ’Concord’ grape clusters exposed to different relative humidities in the ﬁrst
60 days at 0°C (Figure 5B). After approximately ninety days of storage the level of
infection of ’Himrod’ and ’Vanessa’ grapes was unacceptable. In case of ’Concord’
grapes, after eighty days in storage only about 2% mold growth was observed in
packages with potassium nitrate while the control packages had less than 6% mold
growth. No mold growth was detected in any of the other packages. In ’Concord’ grapes
after 96 days of storage in packages with potassium nitrate (KN O3) and with no sorption
compounds the decay was 3% and 6%,respectively. Most of the other compounds used
had no decay after 90 days except sorbitol which was about 8%.
General visual appearance. For the cultivar ’Himrod’ the general appearance of the

grapes packaged with KCl and KNO3 had the highest rating throughout the experimental

 

 

93
period up to 60 days (Figure 3C). Controls (no humidity control) gradually lost

appearance throughout the storage experiment.

’Vanessa’ grapes packaged with all sorbants gradually lost overal visual
appearance over the storage period (Figure 4C). Those packaged with KCl had somewhat
better appearance than those packaged with other sorbants or the controls after 60 and
90 days of storage.

’Concard’ grapes packaged with KNO3 and KCl were maintained with close to
excellent overall visual appearance for over 90 days (Figure SC).

1989 storage study,
Weight loss. ’Himrod’ grapes packaged with KCl continued to lose weight throughout
the storage experiment and was higher than other treatments (Figure 6A).

For both ’Vanessa’ and ’Concard’ grapes the greatest weight loss was in those
packages with KCl (Figures 7A and 8A). Those packages with KNO3 were intermediate
in weight loss and the least weight loss was in those packaged with no sorbants.
Decay. ’Himrod’ grapes in packages with no sorption compound showed the highest level
of mold growth in all of the sampling times after 30 days (Figure 6B). After 70 days of
storage, signiﬁcant differences were seen between all of the treatments and the controls.
The differences were also signiﬁcant between all sorbants and controls after ninety days
of storage. ’Vanessa’ grapes packaged with different sorbants showed no signiﬁcant
differences between themselves and controls until 120 days after storage when signiﬁcant

differences were observed between all of the treatments and the control grapes (Figure

7B).

 

 

94

The level of infection for ’Concard’ grapes was signiﬁcantly lower when compared

to both ’Vanessa’ and ’Himrod’ grapes (Figure 8B).
General visual appearance. Up to 70 days after storage, ’Himrod’ grapes packaged with
KCl were rated good and the other sorbant treatments were rated fair (Figure 6C).
Grapes in control packages were rated poor. At 90 days all of the grapes in all treatments
were considered unacceptable.

’Vanessa’ grapes stored up to 90 days and exposed to RH’s generated by KCl and
KNO3 were rated fair (Figure 7C). Grapes in packages with no sorption compounds also
were rated good at this time. However, grapes exposed to RH’s generated by KNO3 were
rated less than fair. After 120 days storage, those grapes stored with and KCl were rated
acceptable in overall appearance.

’Concord’ grapes were rated as excellent up to 85 days after storage (Figure 8C).
After 120 days storage, ’Concord’ grapes packaged with KNO, and KCl were rated good

and controls were poor.

 

 

 

95

 

 

 

 

 

 

 

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Figure 1. Solid lines represent the best ﬁt curves for relativoe
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Each package contained 200 g grape and 20 g moisture absorbant.

 

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clus ers at O C

102

 

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grape clusters at O C.

 

103
Discussion
Modiﬁed atmosphere packaging reduces moisture loss from fresh produce.

but it also results in high relative humidities and moisture condensation on
produce. The results obtained in this experiment indicate that void volume relative
humidity could be controlled in order to reduce decay. In our study, two
compounds showed potential for reducing decay in polymeric packages with
different grape cultivars. These compounds were KCLand KN03.Both compounds
provided relative humidities which reduced decay. However, KCl also caused
unacceptable shrinkage in ’Himrod’ grape packages.

There are two major ways to control humidity in polymeric
packages: 1) provide enough large openings in packages to allow easy passage
of water vapor through them or, 2) provide sorption compounds inserted into
sealed polymeric packages to decrease void volume relative humidity. The second
technique although seemingly a simple approach, requires detailed understanding
of the behavior of both fresh produce and the sorption compound as a dynamic
system.

Cultivars differ from each other and they may behave different under MA
conditions. Differences in composition and morphology of cuticles exist between
and within Species, with plants of different ages, and between different plant organs
(Baker, 1974; Kolattukudy and Walton, 1972). In grape berries, the stuctural
arrangement of wax platelets, together with their hydrophobic surfaces decreases

water movement through the cuticle (Possingham et. al., 1967). The differences in

 

104

morphology of cuticles can inﬂuence transpiration rates of different grape cultivars.
Different transpiration rates might also contribute to different relative humidities
generated inside the package void volume. This may explain why each grape
cultivar showed different weight losses when exposed to the same relative
humidity. Each grape cultivar should loose some moisture to saturate the package
environment. This amount of water loss may not be the same for all cultivars and
therefore each cultivar ends up with different weight loss. The other factor
contributing to this weight loss is probably due to water loss of grapes durig the
weighing at room temperature.

Heat of respiration also could contribute to grape weight loss. However at
O0 C this can not be a major contributing factor to weight loss. The heat generation
tends to increase the vapor pressure within the commodity thereby increasing
moisture losses due to transpiration (Sastry et. al., 1978).

Another important factor that should be considered for moisture loss is, size
ofthe berries. Larger berries have a smaller surface area per unit weight than small
ones of the same variety, and hence, tend to lose less moisture on a per unit
weight basis.

This study showed that two compounds could be used to control in-
package relative humidities for grapes. These compounds were KCl and KNOa.
However, it should be noted that for each cultivar, a different RH may be beneﬁcial.
For long term storage, KClresulted in unacceptable ‘Himrod’and ‘Vanessa‘ grape

shrinkage.

 

 

105

The humidity control system described above provides a method of
generating different relative humidities inside the packages to extend the shelf life
of table grapes. Reaching a particular steady state RH in packages was primarily
a function of chemical compound and. grape cultivar in each package.

In conclusion, our study showed that there is some beneﬁt of reducing the
relative humidity inside grape MA packages. The RH generated in grape MA
packages must be a compromise between fruit weight loss and decay. This is
probably why KNO3 and KClwere both successful in controlling decay in ’Vanessa’
and ’Concard’ grape packages while only KNO3 was able to provide acceptable
shrinkage and decay control in ’Himrod’ grape packages. Therfore, for each grape
cultivar an extensive study is required to determine which chemical would provide

a stable relative humidity for reducing spoilage.

 

 

106
LITERATURE CITED

Anonymous. 1945. Creating and maintaining humidities by salt solutions.
Hygrodynamics technical bulletin No. 5. American Instrument Company. Silver
Spring, Md.

Ayres, I. C., E. L. Denison. 1958. Maintaining feshness of berries using selected
packaging materials and antifungal agents. Food Technol. 10:562—567.

Baghdadi, H. A., R. M. Smock. 1958. The comparative value of certain plastic
materials and waxes in checking moisture loss from apples. Proc. Amer. Soc. Hort.
Sci. 107(5):827-830.

Baker, E. A. 1974. The influnce of environment on leaf wax development in Brassica
var. gemmifera. New Phytol. 73:955-966.

Boylan-Pett, W. 1986. Design and function of a modified atmosphere package for
tomato fruit. M. S. Thesis. Michigan State University. 73p.

Cameron, A. C. and Reid, M. S. 1982. Diffusive resistance: Importance and
measurement in controlled atmOSphere storage. In: Controlled atmospheres for
storage and transport of perishable agricultural commodities. Oregon State
University., School of Agric. Symposium Series No. 1.

Cahoon, G. A., L. G. Anderson, G. R. Passewitz, D. E. Hahn, A. E. Oden,.and R.
Gruber. 1985. Fresh market grapes from Ohio vineyards. Ohio report. May-June
issue.

Come, D. 1970. "Influence Des Grains Sur La Conservation Des Pommes Golden

Delicious." Ecbrait Du Proxes-Verbal De la Seance Du , p. 869-886.

 

 

107

Elboudwarej, A. F., R. C. Herner, G. S. Howell. 1991. Modiﬁed atmosphere
packaging of table grapes. J. Amer. Soc. Enol. Vitic. (In preparation for
publication) .

Eaves, C. A. 1960. A modiﬁed-atmosphere system for packages of stored fruit. I.
Hort. Sci. 35(2):llO-117.

Fisher, K. H., and O. A. Bradt. 1985. Vanessa grapes. Hort. Sci. 20(1):147-148.

Gentry, J. P., F. G. Mitchell, K. E. Nelson. 1963. Weight loss of grapes and
nectarines as. related to humidity and air velocity of storage. Transactions of
Transactions of Am. Soc. of Agr. Eng. 6(3):254-266.

Gentry, J. P., B. A. Stout. 1971. Transpiration rates and epidermal permeabilities of
grapes based on an unsteady—state mass—transfer analysis.

Ginsburg, L., J. C. Combrink, A. B. Truter. 1978. Long and short term storage of table
grapes. International J. of refrigeration 1(3):l37-l41.

Gorini, F. L., A. Zanetti. 1972. ’La Perdita Di Peso in Alcune Pomacee.’ (Researches
about the weight loss in apples and pears). Annali Istituto Sperimentale Per La
Valoizzazione Technologia Dei Prodotti Agricoli, Vol. III.

Guillou, R., H. B. Richardson. S. Smock. 1963. Humidity control in fruit coolingand
Storage. llth. International Congress of Refrigeration in Munich.

Hardenburg, R. E., Watada, A. E., C. Y. Wang. 1986. The commercial storage of

fruits, vegetables, and ﬂorist and nursery stocks. UDSA, Agr. Hdbk. No. 66.

Kader, A. A., Zagory, E. L. Kerbel. 1989. Modiﬁed atmosphere packaging of fruits and

vegetables. Crit. Rev. Food Sci. Nutr. 28:1 - 30.

 

108
Kaufman, D. W. 1960. Low temperature properties and uses of salt brine, pp. 537-538.

In: kaufmann, D. W. (ed.). Sodium chloride: The production and properties of
salt brine.’ Amer. Chem. Soc., Monograpg Series. Reinholds Pub. Corp., New
York, NY.

Kolattukudy,P. E., T. J. Walton. 1972. The biochemistry of plant cuticular lipids. In
Progress in the chemistry of fats and other lipids, 13. R. T. Holman(ed.)
pergamon Press, Oxford.

Labuza, T. P. 1984. Moisture sorption2practical aspects of isotherm measurement and
use, p. 42. Pub., Amer. Assoc. Cer. Chem. St. Paul, MN.

Lentz, C. P., L. van den'Berg, R. S. McCullough. 1971. Study of factors affecting
temperature, relative humidity and moisture loss in fresh fruit and vegetable .
storages. J. Inst. Can. Technol. Aliment. Vol. 4(4):l46-153.

Nelson, K. E. 1951. Effect of humidity on infection of table grapes by Botrytis cinerea.

Phytopathology 41(10):859-864.

 

Possingham, J. V., T. C. 1967. Chambers, F. Radler, M. Grancarevic. Cuticular
transpiration and wax structure and composition of leaves and fruit of Vitis
vinifera. Aust. J. Biol. Sci. 20:1149-1153.

Risse, L. A., W. R. Miller. 1986. Individual film wrapping of fresh Florida cucumbers,

eggplant, peppers, and tomatoes for extended shelf life. I. Plastic ﬁlm and

sheeting 2: 163-171.

Sastry. S. K. Baird, C. D., D. E. Buffington. 1978. Transpiration rates of certain

fruits and vegetables. ASHRAE Transactions 84(2):237-255.

 

 

 

109
Shirazi, A., A. C. Cameron. 1991. Modiﬁed humidity packaging: a new concept

forextending shelf life of fresh produce. Hort. Sci. (In press).

Shirazi, A.‘ 1989. Modiﬁed humidity packaging of fresh produce. PhD dissertation.
Michigan State University.

Slate, G. L., J. Watson, J. Einset. 1962. Grape varieties introduced by the New York
State Agricultural Experiment Station, Cornell University. Geneva, N. Y. Bulletin
No. 794.

Snow, D. 1949. The germination of mold spores at controlled humidities. Ann. Appl.
Biol. 36:1—13.

Swift, J. G., P. May, and E. A. Lawton. 1975. Concenric cracking of grape berries. Vitis
13:30-35.

Troller, J. A. and Christian, J. H. B. 1978. Water activity and food, pp. 87—92, 146- 147.
157, and 215-216. Academic Press, New York.

Uota, M. 1957. Evaluation of polyethylene ﬁlm liners for packaging ’Eperor’ grapes for
storage. Proc. Amer. Soc. Hort. Sci. 70:197~203.

Weast, R. C., Ed-in-chief. 1977-1978. CRC handbook of chemistry and physics, 58th.
edition. pp. E-42, E~46.CRC Pres, Inc., Boca Raton, Florida.

Winston, P. W., D. H. Bates. 1960. Saturated solutions for the control of humidity in
biological research. Ecology 41(1).

Young, J. F. 1967. Humidity control in the laboratory using salt solutions—a review. J.

appl. Chem. 17.

 

 

 

 

 

110
Zabadal, T. J., Bartsch, J. A., Blanpied, G. D., Dennehy, T. J., Pearson, R. C..Pool.

R. M., Reisch, B. I. ’Concard’ table grapes. 1988. A manual for growers. New

York Agricultural Experiment station, Cornell University, Geneva, NY.

 

 

 

 

 

1 11
SUNIMARY AND CONCLUSIONS

In Chapter one the effect of preharvest cultural practices, the use of
gibberellin and girdling on postharvest behavior of ’Himrod’ grapes during storage
at 0°C is presented. A combination of gibberellin and girdling improved storage life
by minimizing decay and shatter. The worst treatment regarding postharvest behavior
was the girdling only treatment. Grapes harvested from girdled only vines had poor
shelf life and berry collapse was the major factor regarding reduced shelf life. Also,
it should be noted that grape clusters from girdled and GA3 sprayed vines had larger
berries and. more attractive clusters when compared to grape clusters from control
vines. Based on these ﬁndings, this combination treatment is highly recommended
. to be practiced on ’Himrod; grapes before harvest.

In Chapter 2 and 3 the feasibility of modiﬁed atmosphere packaging (MAP)
and modiﬁed humidity packaging (MHP) in extending the shelﬂife of table grape
cultivars is evaluated. The table grape cultivars studied were ’I-Iimrod’ and ’Vanessa’
(both seedless) and two seeded cultivars,’Concord’ and ’Alden. In chapter 2 and
Appendix C, the data presented show that a MA package made of 3 mil low density
polyethylene (LDPE) ﬁlm extended the shelflife of grapes from 20 days to 60 days
for ’Himrod’ grape and up to 90 days for ’Concard’ grapes at 0°C when compared to
controls.

Two moisture sorbing compounds, ’KNO3’ and ’KCl’, provided favorable
relative humidities and extended the shelflife of grapes beyond grapes held in sealed

3 mil packages. This procedure speciﬁcally prolongs the storage life of grapes by

 

 

 

 

112

lowering the relative humidity and condensation inside sealed packages. However.
we have to be aware of two factors; 1) not all cultivars will respond the same way to
a speciﬁc MA condition; 2) temperature dependency of modiﬁed atmospheres in
sealed packages makes it a challenge for keeping grapes for a long time. Research
should be 1) extended to include other table grape cultivars under different MA or
MH conditions, 2) determine the effect of temperature fluctuation of packaged
grapes, and 3) other sorption compounds should be tested in order to generate
favorable RH for speciﬁc grape cultivars.

The effort regarding development of MA packages also should be extended
toward using 3 mil LDPE and MA conditions to develop lug size MA packages or
be able to convert conventional storage facilities to smaller size modiﬁed atmosphere
containers. This recommendation Speciﬁcally is valuable in regions where limited
sources of energy prohibits use of storage facilities with controlled atmosphere

instrumentation.

 

 

 

 

 

 

 

 

113

APPENDIX A

EFFECT OF GIRDLING AND GIBBERELLIN ON BIOCHEMICAL

AND BIOPHYSICAL CHANGES DURING MATURIT Y OF

’HIMROD’ GRAPE BERRIES

 

 

 

1 14
INTRODUCTION

The seedless table grape cultivar ’Himrod’ (’Ontario’ x ’Thompson Seedless:
is becoming an important fresh market grape in eastern US. This cultivar is also
grown in Michigan but the problem of straggly clusters that result from poor fruit set
and the small berry size must be solved before its commercial production can be
expanded.

With the objective of producing attractive, well-ﬁlled clusters several
researchers have experimented with GA3 treatments on ’Himrod’ grapes (3,Zabada1,
personal communication, 1987). GA3 has been used to increase the berry size in most
seedless grape cultivars and to induce seedlessness in some seeded varieties by virtue
of reducing or preventing pollination (14,17).GA3 applications made between bloom
and fruit set are generally most effective; however, the speciﬁc developmental stage
at which optimum response occurs is different for each cultivar. The optimum
response of grapes to exogenous application of GA3 is inﬂuenced by cultivar, timing
of application, concentration of the growth regulator, and endogenous quantities of
this hormone (11).

Another result of GA3 application is the change in cluster compactness due to
a reduction in fruit set or elongation of the rachis (19). Full bloom application of
GA3 to increase fruit set has been shown to be unsuccessful (3, 8, 19). However 20
part per million (ppm) GA3 application resulted in successful ﬂower thinning
(Zabadal, personal communication, 1987). This application is not recommended if

it applied alone to seedless grapes with straggly clusters (5, 13). For many seedless

 

 

115
cultivars a Combination of 20 ppm GA, at bloom and 50 ppm GA, applied at shatter

(fruit set) will produce desirable fruit (9, Zabadal, personal communication, 1987).
GA, application also can change cluster compactness due to a reduction in fruit set
or elongation of the rachis (19). As a standard commercial practice, ’Thompson
Seedless’ grapes, are treated at bloom with GA, to thin the clusters. This application
is followed by a second application after fruit set which elongates the berries and ﬁlls
the clusters.

Commercially, growers of table grapes girdle vines to increase berry size (20).
Experiments carried out by different researchers have demonstrated that girdling
when the total soluble solids content of the fruit was only 5 or 6 per cent usually
resulted in the most rapid maturation of the fruit (15). Girdling was demonstrated
to hasten and increase ﬂowering and it was also associated with greater bud

formation (21). This phenomenon was related to an increase in available

 

carbohydrates above the rings (21). The stimulus resulting from girdling has its
maximum effect during ﬂowering or after berry shatter when the berries are actively
growing (15).
GA, and girdling, either singly or in combination, are used on thousands of
acres of grapes in California and worldwide to increase berry set and fruit size (3, 4,
5, 12, 14, 16). Based on this a combination of cane girdling and GA, application has
been suggested for successful ’Himrod’ grape production (9, Zabadal personal
communication, 1987).

While considerable information exists about changes in chemical composition

116

of Vitis vinifera (1, 2), Vitis labrusca (6), and Vitis rotundifolia (7) during the growing
season little is known about changes of ’Himrod’ grapes during maturation and as a
result of GA, and girdling practices.

Results presented here demonstrate the effect of GA, and girdling practices on

biochemical changes occurring during ’Himrod’ grape maturation and on ﬁnal yield.

 

 

l 17
Materials and Methods

Mature vines of ’Himrod’ growing in an unirrigated commercial
vineyard at Lawton, Michigan, were used for this experiment (18). These vines
received routine care, and were trained to the 4-arm knifﬁn system. Pruning was
done in early April and minimum of 45 buds were left on the vines. The reason
for leaving these many buds was to have enough buds to survive the frost and hail.
In early June (after fruit set) cluster thinning was performed to reduce number of
clusters per vine. A maximum of 30 clusters per vine was retained on each vine,
although not all of the vines had these many clusters.

The ﬁeld treatments used are outlined in Table 1. Control vines which
received no treatment and were designated Treatment A. Treatments B and C
respectively consisted of vines that only girdled or only treated with gibberellin.
Treatment D vines were treated with gibberellin and girdled. Treatment E vines
were treated with gibberellin, girdled and cluster berry thinned to 4 laterals two
weeks after fruit set. In the treatments that were girdled vines were arm-girdled
using a 4.8—5 mm double blade girdling knife two weeks after shatter (fruit set).

The experimental design consisted of a complete block design with four
replicates. Buffer vines were used between treatments to prevent drifting of spray
material from adjacent treatments.

GA, application: The concentrations of GA, used and time of application are
listed in Table 1. All sprays contained 0.1% Triton B-1956, and were applied to

vines with a hand sprayer.

 

 

 

118

Sampling: Samples were taken from grape clusters weekly beginning the last week
of July. Apical berries of randomly selected basal clusters from each vine were
used (22). In each sampling time 5 apical berries from each cluster were collected
and a total of ﬁve clusters per vine per treatment were sampled. By having 4 vines
per treatment, 100 berries total were picked. After each sample was collected, it
was sealed in plastic bags, returned to the laboratory, weighed and stored at 0°C
until analyzed (1 to 3 hours).

Harvest dates: To measure the effect of different cultural practices on yield, fruit
maturity and quality, fruits were harvested at two maturity levels, namely
premature and mature stages in 1987, 1988. Harvest time was chosen to simulate
the normal harvesting period of commercial operations. Total soluble solids, and
total acidity were used as maturity indices for choosing harvest time. In 1987 and
1988 the ﬁrst harvest times were 21 and 28 days after beginning of sampling the
grape berries. The second harvest time in both years was one week after the ﬁrst
harvest.

Berry weight: Berry weight was determined by weighing 100 berries collected at
random from 4 vines per treatment.

Total soluble solids (TSS) and total acidity (TA): TSS was determined with a
Bausch & Lamb (Model Abbe-3L) refractometer. Total acidity of grape juice was
determined by titration with NaOH (0.150 N) at pH of 8.2.The pH of expressed
juice was determined using a Fisher Accumet (Model 620) pH meter.

Statistical analysis: To analyze the collected data and compare treatment means.

 

 

 

 

119
analysis of variance was performed and Duncan’s multiple range test was used. All

the comparisons were done at 5% probability level.

 

 

 

 

 

120
Table 1. Different treatments applied to ’Himrod’ vines during 1987 and 1988

growing seasons

 

Treatment Description of treatment

 

A. Control (not girdled, no GA, applied)
B. Girdled

C. Only GA, was applied,
1. 20 ppm at shatter* (fruit set), and
2. 50 ppm two weeks after shatter

D. Girdled, and GA, was applied,
1. 20 ppm at shatter, and
2. 50 ppm two weeks after shatter

E. Girdled, and GA, was applied,
1. 20 ppm at shatter and 50 ppm two weeks after shatter,
2. Clusters were berry thinned to 4 laterals by removing 1/5-
1/4 of the clusters 2 weeks after shatter (fruit set).

 

 

* When 50 - 70% Open blooms on 50% of the clusters on vine could be seen.

121
RESULTS

Table 2. Total soluble solids (%), total acidity (g/100 ml), sugar/acid ratio, and
100 berry weight (g) of ’Hrmrod’ grape as they were inﬂuenced by ﬁeld treatments

 

 

in 1987.

Treatment Sampling T SS(%) Ph TA Sugar/acid 100
time mg/ 100 ml ratio berry weight
7/21/87

Control (A) 8.70 ab * 2.64 a 3.30 a 3.27 a 209 d

Girdling only (B) 9.55 a 2.64 a 2.37 a 4.31 a 231 b

GA; only (C) 7.65 b 2.64 a 2.03 a 3.87 a 203 ac

Girdling

& GA, (D) 9.25 a 2.58 a 2.29 a 4.10 a 243 a

Girdling, GA, and berry

thinning (E) 8.75 ab 2.55 a 2.97 a 3.63 a 241 a
7/28/87

A 11.70 abc 3.23 a 0.96 ab 12.17 b 251 b

B 12.24 a 3.26 a 0.86 b 14.52 a 297 a

C 10.84 c 2.99 a 1.03 a 10.50 b 244 b

D 11.30bc 3.03a 1.02 ab 11.15b 283 a

E 08.87ab 3.49a 1.098 10.20b 318 0
8/06/87

A 13.93 ab 3.15 a 0.72 ab 19.45 ab 266 b

B 14.75 a 3.12 a 0.71 b 20.87 a 298 a

C 13.40 ab 3.13 a 0.78 a 17.37 ab 268 b

D 13.83 ab 3.13 a 0.78 ab 17.93 ab 304 a

E 13.58b 3.09a 0.79a 17.30b 315 a
8/13/87

A 16.78 a 3.24 a 0.62 a 26.98 a 301 b

B 16.88 a 3.28 a 0.60 a 28.38 a 332 a

C 15.43 a 3.20 a 0.63 a 24.62 a 302 b

D 16.68a 3.17a 0.67a 25.24a 322 ab

E 16.45 a 3.23 a 0.67 a 25.24 a 350 a
8/21/87

A 17.05 a 3.71 a 0.61 ab 27.95 a 326 ab

B 17.95 a 3.77 a 0.56 b 31.96 a 357 a

C 16.88 a 3.50 a 0.65 ab 26.38 ab 308 b

D 17.40 a 3.61 a 0.68 ab 26.32 ab 353 ab

E 17.03 a 3.67 a 0.74 a 24.07 b 368 a

 

* Means in columns for each sampling time and with same letter have no

signiﬁcant differences at P = 0.05.

 

122

Table 3. Total soluble solids (%), total acidity (g/ 100 ml), sugar/acid ratio, and
10(1 586?), weight (g) of ’Hrmrod’ grape as they were inﬂuenced by ﬁeld treatments
1n

 

 

Treatment Sampling TSS(%) Ph TA Sugar/acid 100 berry
tlme ratio weight
7/20/88
C9ntrpl (A) 6.88 b * 2.55 a 3.03 ab 2.27 b 100 d
Glrdhng (B) 7.78 b 2.61 a 2.85 ab 2.80 b 121 0
GA; (C) 7.50 b 2.59 a 3.18 a 2.40 o 107 dc
Girdling and
GA: (D) 7.500 2. 61 a 2.15 ab 2.52 0 114 0c
Girdling, GA,, and
berry thinning (E) 9.00a 2.57 a 2.65 b 3.45 a 135 a
7/27/88
A 10.88b 2.77a 1.88a 5.800 153 0
B 10.450 2.80a 1.630 6.600 161 b
C 10.750 2. 76a 1. 83a 5.910 1560
D 10.830 2. 82a 1.590 6.880 1570
E 13.05 a 2. 81 a 1.560 8.43 a p 180 a
8/03/88
A 14.50 0c 3.14 a 0. 90 abc 16.24 b 184 be
B 13.90c 3. 25 a 0. 80c 17.380 195 b
C 14.40 0c 3. 28 a 0. 94 ab 15.32 0 192 b
D 15.20 b 3. 27 a O. 99 a 15.35 0 177 c
E 16.85 a 3.17 a 0.83 0c 20.71 a 220 a
8/10/88
A 16.05 b 3. 36 a 0. 58 a 28.02 a 215 b
B 15.350 3. 40a 0. 60a 26.07a 216 0
C 15.95 b 3. 34 a 0. 60 a 26.58 a 243 a
D 15.900 3. 39a 0.53a 31.23a 2110
E 17.70 a 3. 40 a 0. 63 a 28.49 a 223 0
8/17/88
A 18.80 ab 3. 40 a 0.47 ab 40.13 a 245 a
B 18.03 b 3. 35 a 0.45 0 40.60 a 234 a
C 18.83 ab 3. 39 a 0.48 ab 39.55 a 248 a
D 18.40 ab 3. 40a 0. 450 41.50a 237a
E 19.28a 3. 39a 0.54a 36.28a 251 a
8/24/88
A 20.28 a 3.43 a 0.33 0 62.23 a 249 a
B 19.87a 3.30a 0.320 63.20a 253 a
C 20.14 a 3.34 a 0.40 ab 52.30 ab 267 a
D 19.72 a 3.42 a 0.37 b 54.18 ab 259 a
E 19.40a 3.35 a 0.50a 39.670 266 a

 

* Means in columns for each sampling time and with same letter have no
signiﬁcant differences at P = 0.05 .

 

 

123

Table 4. Total yield (Kg. ), total Clusters, marketable yield (Kg. ), and non-
marketable yield per vine of ’Himrod’ grape harvested at two different dates

 

 

 

 

Treatment Total yield Clusters Marketable N on-marketable
per vine per vine yield yield

First harvest of 1987

Control 5.06a' 28a 3.79 (75")a 1.28 (25)a

Girdling

only 4.66a 23a 3.9 (84)a 0.76 (16)a

Gibberellin

only 5.32a 30a 3.98 (75)a 1.35 (25)a

Girdling and

GA, 6.76a 32a 5.70 (84)a 1.06 (16)a

Girdling,

GA,, and

berry thinn. 5.72a 26a 4.71 (82)a 1.01 (18)a
Second harvest 011987

Control 5.37a 26a 3.94 (73)a 1.43 (27)a

Girdling

only 5.8a 24a 4.76 (82)a 1.03 (18)a

Gibberellin

only 6.02a 25a 4.98 (83)a 1.05 (17)a

Girdling and

GA, 4.64a 28a 3.27 (71)a 1.37 (29)a

Girdling,

GA,, and

berry thinn. 4.70a 24a 3.54 (75)a 1.16 (25)a

 

LMeans in columns with the same letter are not signiﬁcantly different (P= 0. 05)

"Percent of total yield

 

 

124

Table 5. Total yield (Kg.), total clusters, marketable yield (Kg.), and non-
marketable yield per vine of ’Himrod’ grape harvested at two different dates

 

 

 

Treatment Total yield Clusters Marketable Non-marketable

per vine per vine yield yield

- First harvest of 1989

Control 2.11' 12a 1.80(85")b 0.54(15)a
Girdling
only 2.660 14a 2.11(79)b 0.55(21)a
Gibberellin
only 2.310 14a 1.92(83)b 0.46(17)a
Girdling and
GA, 5.45a 20a 4.79(88)a 0.66(12)a
Girdling,
GA,, and
berry thinn. 4.02ab 18a 3.45(86)ab 0.57(l4)a

 

Second harvest of 1989

 

Control 2.07a 12a 1. 15 (56)a l. 10(44)a
Girdling

only 2.74a 12a 1.57(57)a 1.35(43)a
Gibberellin

only 3 .53a 14a l.84(52)a 1.32(48)a
Girdling and

GA, 4.62a 17a 2.75(60)a l.88(40)a
Girdling,

GA,, and

berry thinn. 3.82a 17a 2.59(68)a l.73(32)a

 

Means in columns with the same letter are not signiﬁcantly different at P=0.05
Percent of total yield

 

 

 

125

Literature Cited

. Amerine, M. A. The acids of California grapes and wines. II. Malic acid. Food
Technology 5: 13-16. (1951).

.Amerine, M. A.,and A. J. Winkler. Maturity studies with California grapes I.
The balling-acid ratio of wine grapes. Proc. Amer. Soc. Hort. Sci. 38: 379-
387. (1941).

.Barritt, B. H. Fruit sets in seedless grapes treated with growth regulators Alar,
CCC and gibberellin. J. Amer. Soc. Hort. Sci. 95(1): 58—61.(1970).
.Bertrand, D. E., and R. J. Weaver. Effect of potassium gibberellate on growth
and development of ’Black Corinth’ grapes. J. Amer. Soc. Hort. Sci. 97(5):
659-662. (1972).

.Brown. E., and J. N. Moorf. Gibberellin and girdling on seedless grapes.
Eastern Grape Grower and Winery News. March/April Issue. (1970).

. Caldwell, J. S. Some effects of the seasonal conditions upon the chemical
composition of American grape juices. J. Agr. Res. 30: 1133. (1925).

. Carrol, D. E., and J. E. Marcy. Chemical and physical changes during
maturation of ’Muscadine’ grapes (Vitis rotundz'folia). Am. J. Enol. Vitic. 33:
3. (1982).

. Christodoulou, A. J., R. M. Pool, and R. J. Weaver. Prebloom thinning of
’Thompson Seedless’ grapes is feasible when followed by bloom spraying

with gibberellin. Calif. Agr. 20(11): 810. (1966).

 

126

9. Christodoulou, A. J ., R. J. Weaver, and R. M. Pool. Relation of gibberellin

10.

ll.

12.

13.

14.

15.

l6.

17.

treatment to fruit set, berry development, and cluster compactness in Vitis
vinifera grapes. Proc. Am. Soc. Hort. sci. 92: 301-310. (1968).

Connolly, E. Two ﬁnger lakes trials reﬁne cultural practices for table grapes.
Eastern grape grower and winery news, October/November Issue. (1984).

Dass, H. C.,and G. S. Randhawa. Effect of gibberellin on seeded V. vinifera
with special reference to induction of seedlessness. Vitis 7: 10-21. (1968).

Ezzahouani, A., A. M. Lasheen, and L. Walali. Effect of gibberellic acid and
girdling on ’Thompson Seedless’ and ’Ruby Seedless’ table grapes in
Morocco. Hort. Science 20: 3. (1985).

Fisher, H. Uberdie die Blutenbildung in ihrer Abhangigkeit vom lieht und
uber die blutenbildenden Substanzen. Flora 94: 478-490. (1971).

Halbrook, M. C.-, and J. A. Mortensen. Effect of gibberellic acid on berry and
seed development in ’Orlando Seedless’ grapes. Hort. Sci. 23: 2. (1988).

Kliewer, W. M. Inﬂuence of environment on metabolism of organic acids and
carbohydrates in V. viniferal. Temperature. Plant Physiology, 39: 6 (1964).

Lynn, C. D., and F. L. Jensen. Thinning effects of bloom time gibberellin
sprays on ’Thompson Seedless’ table grapes. Am. J. Enol. and Vitic. 17:
283-289. (1966).

Pratt. C.,and N. J. Shaulis. Gibberellin-induced parthenocarpy in grapes.

Proc. Amer. Soc. Hort. Sci. 77: 322-330. (1961).

 

 

18

19

20

21

Wj

127 ‘ l

. Slate, G.’ L.,J. Watson, and J. Einset. Grape varieties... introduced by the New
York State Agricultural Experiment Station. New York State Agricultural
Experiment Station, Cornell University, Geneva, N. Y. Bulletin No. 794.
(1962).

.Weaver, R. J ., and S. B. McCune. Effect of gibberellin- on seedless Vitis
vinifera. Hilgardia 29: 6. (1959).

.Weaver, R. J., and S. B. McCune. Girdling: Its relation to carbohydrate
nutrition and development of ’Thompson Seedless’, ’Red Malaga’, and
’Ribier’ grapes. Hilgardia 28: 16. (1959).

.Weaver, R. J., and McCune, S. B. Studies oe pre-bloom sprays of gibberellin
to elongate and loosen clusters of ’Thompson Seedless’ grapes. Am. J.
Enol. Vitic.l3:15-19. (1962).

.Wolpert, J. A., and G. S. Howell. Sampling ’Vidal Blanc’ grapes. 11. Sampling
for precise estimates of soluble solids and titratable acidity of juice. Am. J.

Enol. Vitic. 35: 4. (1984).

(

APPENDIX B

POLYMERIC FILM OXYGEN TRANSMISSION RATE MEASUREMENT

 

129

The oxygen gas transmission rates of the ﬁlms used were measured using the
American Society for Testing and Materials(ASTM) standard procedures (1) and
Oxtran 100 testing apparatus (see appendix).

The oxygen gas transmission rate was determined after the sample was
equilibrated in a dry-test environment. The specimen was mounted as a sealed semi—
0arrier between two chambers of a diffusion cell with a surface area of 100 cm2 at
ambient atmospheric pressure. One chamber was slowly purged by a stream of
nitrogen and the other chamber contained oxygen.The surface area of the chambers
was 100 cm2. As oxygen gas permeates through the ﬁlm into the nitrogen carrier gas.
it is transported to the coulometric detector where it produces an electrical current.
the magnitude of which is proportional to the amount of oxygen ﬂowing into the
detector per unit time. This method provides steady-state gas transmission rate
(OzGTR), The permeance of the ﬁlm to oxygen gas (P0,), and oxygen permeability

coefﬁcient (P0,) in the case of homogeeous materials.

Calculations - The steady state gas transmission rate (O,GTR) aws determined as

 

follows:
(E - E0 ) X Q
OzGTR =
A x R
Where:
E = steady state voltage level

E0 = zero voltage level

A = ﬁlm area

130

Q = calibration constant,

The permeance (PO2) of the specimen was then determined as follows:

P0, = OZGTR/p
where p = partial pressure of oxygen, which is the mol fraction of oxygen multiplied
by the total pressure (normally one atmosphere), in the test gas side of the diffusion
cell. The partial pressure of 02 on the carrier gas side is considered to be zero. The
oxygen permeability coefﬁcient (PO,) is as follows

P0, = P0, xt

Where t = average thickness of the ﬁlm.

 

Film Permeability

131

 

10000

75 mil F11m Per. = 7431. 9 ml Day. 2. otm.
.0 mil Film Per. 6088.7 ml Day.lvl2. atm.
0 mil Film Per. 4047.1 ml/Day.1‘vl2. atm.

52*”?
11

8000

i

6000

 

-.s--l.l..1 1- 1-1-1.1.1--1_L.1_L 1..i.-LJ_LJ..l.LL.1.J_1-.1_1 1.14.LL-L_L_1_1_1_1_1_L1

l

.\ ;

. I

i

4000 E
'1

l

l

coco . - - - -- . - l
---J‘-4 ﬁ . .1} Fl Y—FT’.—T I I fcﬁ ﬁI 4‘ e i T t I I I n I flrrf‘. i T T a I—l
-;o r-

2 .3 4 a

Fim thickness (mil)

.0 . , permeability of LDPE films wrth diffe rent
cxnesses :xp. Conditions: Air; :2 cm2 mask film;
"W." sensitivitv; 53 Ohm resists nt :3": 22‘3.

 

 

 

 

 

 

132

APPENDIX C

MEASURING DESIGN PARAMETERS FOR MODIFIED

ATMOSPHERE PACKAGING OF TABLE GRAPES

 

133
MATERIALS AND METHODS

To generate a range of O, and CO, concentrations, the fruit weight to surface
area should be Optimized (Cameron, 1989). The method employed in this study to
determine Optimum fruit weight consisted Of empirical packaging trials and data Of
oxygen concentrations obtained at equilibrium with various weights of ’Himrod‘ and
’Concard’ table grapes.

For each oxygen depletion test a certain fruit weight of 100, 200, 300, 400, 500
and 600 grams was placed in a 3 mil low density polyethylene package (Size: 21.9 X
22.3 cm), and the packages were heat sealed using a heat sealer machine, Model 420
from Audion Elekto, Holland. All the packages were stored at 0°C and ca. 40%
relative humidity.

Gas sampling was done by withdrawing 1 m1 samples Of gas from the package
headspace using plastic syringes equipped with a 25 gauge 1/2" hypodermic needle.
The needle was inseted through a silicone rubber septum ﬁxed to 1 cm2 piece Of
polyethylene electrical tape on each package (Boylan-Pett, 1986). Samples were
injected into a gas chromatograph analyzer as described in chpater 2. Concentrations
Of O, and CO, were monitored periodically until equilibrium was reached (about 50'
days after the beginning of experiment for both gases).

Modeling oxygen of a MA package

In modiﬁed atmosphere packaging (MAP) Fick’s law is being used to

understand gas diffusion through ﬁlm barriers and MAP units (Cameron. 1989:

Beaudry et al, 1991). Equilibrium of a MAP system is established when the oxygen

¥

 

 

 

 

 

134

concentration in the sealed package declined to a fairly constant value. Steady State
values of oxygen then are used to calculate ﬂux of oxygen through ﬁlm which is
expressed by Fick’s law as follows:
Immtozi = (Po, .A. DX“).(1021.... - 1021....) (1)
where:
J“"“[O,] = movement of 0, through the ﬁlm per hour (cm3 hr")
P0, = ﬁlm permeability to 0, (cm2 hr" atm")
A = surface area (cmz)
DX = thickness of the ﬁlm (cm)
[0,],m = partial pressure of oxygen in air and,
[0,]ng = partial pressure Of oxygen inside the package (atm).

In study state condition an average of 3 successive readings for package 0,
and CO, were averaged to perform all the calculations using Fick’slaw. Under Steady
state conditon, it is assumed that the oxygen movement through the ﬁlm represents
the amount of the O, that passes through the fruit skin. The ﬂux Of 0, through fruit
is then expressed as follow:

1”“"1021 = RRoz (IOzlprng (2)
where:
Jf”“[O,] = ﬂux of 0, per unit time into the fruit (cm3 hr“)
RR°,([O,]) = O, uptake (cm3 Kg“l hr“) and,
W = weight Of fruit (Kg)

combining eq. ( 1) and (2) allowed calculation Of the rate of respiration (O, uptake)

 

 

 

 

 

 

 

135

at equilibriumm as follows:

RRoz ([02])pr, = P62 .A.DX'1 . (1021.11, - [02]pkg)/W (3)

By knowing all the parameters in right hand Side of equation in steady state,

calculation Of respiration rate is Striaght forward from eq. 3.

RESULTS

The steady state concentration of 02 within 3 mil LDPE packages decreases
with time and increasing fruit weight (Figures 1A and 2A). The concentration of C0,
in the same packages increases with time and increasing fruit weight as Shown in
ﬁgures 1B and 2B.

The calculated respiration rates and C0, production at steady state for each
speciﬁc fruit weight then were plotted vs [021m and [C0,]m. The curves were then
ﬁtted to an equation curve for a 3 mil LDPE package as illustrated in ﬁgures 3 and
4 (0,) and 4 and 5 for C0,. The equations are as follow:

For ’Himrod’ grape;
[02]

Y = B(1)*(1.-EXP(-2(2)*X))*B(3) (4)
[C021

Y = B(1)*EXP(B(2)*X) + B(3) (5)
For ’Concord’ grape;
[021

 

 

 

136
Y = B(1)*(1.-EXP(-B(2)*X))*B(3) (6)

[C021
Y =B(1)*EXP(B(2)*X) + B(3) (7)
Similar equation has been shown to describe RRO, vs 0, for a number Of

other fruits (Cameron, 1989; Beaudry et al, 1991)

137

Table 1. Values for constatnts of equations presented for 0, concentrations in
’Himrod’ and ’Concord’ packages as a functon of fruit weight at 0°C.

 

 

Fruit package constatants
B(1) B(2) B(3)
’Himrod’ 0.7404E—01 0.1704 0.7896

’Concord’ 0.9933E—01 0.2763 1.2336

 

 

138

Table 2. Values for constants of equations presented for C0, concentrations in
’Himrod’ and ’Concard’ packages as a function of fruit weight at 0°C.

 

Fruit package Constatnts

 

B( 1) B(2) B(3)

’Himrod’ 0.4556E-01 0.7820E-01 0.8711E-02
’Concard’ 1.6621 0.5104E-02 —1.6285

 

 

 

139

The relationships presented in equations 4 to 7 could be used to generate data
of desired characteristics needed for a giVen fruit weight and desired oxygen
concentration at equilibrium.

To determine if the package developed causes any fermentation process in the
fruit itself, calculating respiratory quotient (R0) is helpful for checking purpose.
Figures 7 and 8 present the RQ’S Obtained for both ’Himrod’ and ’Concard’

packages.

 

140

Table 3. Film thickness, surface area and 0, permeability constant of 2 amd 3 mil

low density polyethylene ﬁlms used. Permeability constants were measured at 00C.

 

Film thickness (cm) (DX) Total surface area (cm2)' (A) P".A/DX

 

50.8”‘10‘1 (2 mil) 930 l2.083"‘104

76.2*10“(3 mil) 930 9886*10“

 

* Surface area of 465 cm2 for each side of the package

** Measured permeability to oxygen for 2 and 3 mil thick low density polyethylene

folms equals 0.66 and 0.81 n moles.cm.cm'2.hr“.atm".

 

O)

 

—L
N
n 1 l A n

 

 

Void volume 02 (kPa)

 

 

 

 

 

Void volume 002(kPa)

 

600 g
500 g
400 g

 

 

1llO‘ZlO'BIO'40'510'60'7'0'810'90

Time (Days)

Figure l.
(B) cancentratiang, 1n 465 cm,

sealed packages held at O C.

Effect Of 'Himrod' grape fruit2 weights on steady state 02

 

l

 

0.00762 cm thickness LDP

 

 

 

 

 

 

 

 

 

 

 

 

 

A 1 ‘ f
O 20‘ I I I r I I 1 1
0. Cl 400 g
6 16~ O 500 g j
N i 600 9
O ‘ .4
c0 12: _‘
E .
2 8- _
O « .
> I
‘2 4: -
g 1 H 1
O I . I r 1 4
0 60 70 80 90
14 I I I I ' I I l ' I ‘ I ‘ l ' l
A .
O 12- A , A -
§ . o 0 g 0.
Va 10- a 1:1 -
8 . a o -
8- B .-
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.3. 5i
O .11
> 4- a 400 g .
"O ‘ _
'5 2~ O 500 g ‘
> ‘ A 600 g
0

 

0‘110‘2101310‘4‘0‘5101610 70 80 90
Tune (Days)

‘ ' ' ' teady state 0, (A)
. ff t Of Concord grape fru1t weights on s .
(TrigngOE (E) egoncentratian§> in 465 cm2, 0.00762 cm thickness LDPE

sealed packages held at 0C.

 

143

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149
Beaudry, R. M., A. C. Cameron, A. Shirazi, D. L. Dostal. Modiﬁed atmosphere

packaging of bluberry fruit: effect of temperature on package oxygen and
carbon dioxide. J. Amer. Soc. Hort. Sci. 116 or 117 (in press). 1991.
Boylan- pett, W. Design and function of a modiﬁed atmosphere package for tomato
fruit. M. S. Thesis. Michigan State University. 73 p. (1986).
Cameron, A. C. Modiﬁed atmosphere packaging: a novel approach for optimizing
package oxygen and carbon dioxide. Fifth international controlled atmosphere

research conference proceedings. Vol. 2. (1989).

 

150

APPENDIX D

IN-PACKAGE RELATIVE HUMIDITY (%) DATA COLLECTED FOR SEALED
’HIMROD’ LDPE PACKAGES AT 20°C.

151

Table 1. Relative humidities (%) generated inside sealed packages of

’Himrod’ grape at 20°C.

 

 

T1me (Days) Control KNO, KCl
1 2 I 2 1 2

0 74.74 74.76 62.25~ -62.34 62.85 63.55
‘0.0034 81.04 79.66 63.3 63.93 66.1 65.90
0.0069 84.56 83.36 65.72 66.38 68.43 68.26
0.0104 86.52 86.97 67.92 68.60 70.26 70.11
0.0138 89.95 89.77 69.87 70.57 72.35 72.23
0.0173 92.03 92.44 71.91 72.63 74.21 74.11
0.0208 94.76 94.37 74.41 75.15 76.31 76.34
0.0243 96.41 96.49 76.65 77.42 78.04 78.98
0.0277 96.1 95.85 78.6 79.39 7 .5 80.46
0.0312 96.63 96.81 80.2 81.00 80.74 81.72
0.0347 96.36 96.82 81.5 82.32 81.82 82.81
0.0381 96.8 96.71 82.66 83.49 82.73 83.73
0.0416 96.99 96.93 83.79 84.63 83.46 84.47
0.0451 96.97 9 .2 84.77 85.62 84.05 85.07
0.0486 97.75 97.02 85.68 86.54 84.51 85.53
0.0520 97.4 97.41 86.41 87.27 84.84 85.87
0.0555 97.95 97.46 86.97 87.84 85.1 86.13
0.0590 97.38 97.29 8 .4 88.27 85.3 86.33
0.0625 97.77 97.69 87.75 88.63 85.46 86.49
0.0659 97.1 97.7 88.03 88.91 85.59 86.63
0.0694 97.39 97.16 88.27 89.15 85.71 86.75
0.0729 97.66 97.7 88.46 89.52 85.82 86.86
0.0763 96.9 97.8 88.62 89.68 85.9 86.94
0.0798 97.04 97.63 88.74 89.80 85.96 87.00
0.0833 97.11 97.72 88.84 89.91 86 87.04
0.0868 97.18 97.96 88.92 89.99 86.04 87 08
0.0902 97.28 97.64 88.98 90.05 86.07 87.11
0.0937 97.84 97.81 89.03 90.10 86.09 87.13
0.0972 97.44 97.79 89.06 90.13 86.09 87.13
0.1006 96.67 97.54 89.09 90.16 86.09 87.13
0.1041 97.1 97.92 89.11 90.18 86.09 87.13
0.1076 97.9 98.04 89.12 90.19 86.09 87.13
0.1111 97.41 97.65 89.13 90.20 86.1 87.14
0.1145 96.99 97.37 89.13 90.20 86.11 87.15
0.1180 97.03 97.82 89.14 90.21 86.12 87.16
0.1215 97.01 97.73 89.13 90.20 86.12 87.16
0.125 97.12 97.91 89.13 90.20 86.12 87.16
0.1597 97.12 97.87 88.75 89.82 85.92 86.96
0.2430 96.61 97.58 88.83 89.90 85.81 86.85
0.3263 96.9 97.63 88.67 89.73 85.56 86.60
0.4097 97.9 97.8 88.32 89.38 85.3 86.33
0.4930 97.1 97.7 88.53 89.59 85.57 86.61
0.5763 96.87 97.16 88.5 89.56 85.56 86.60
0.6597 96.59 97.7 88. 6 89.32 85.42 86.45
0.7430 97.08 97.69 88.5 89.56 85.77 86.81
0.8263 96.38 96.29 88.47 89.53 85.75 86.79
0.9097 97.47 97.46 88.23 89.29 85.6 86.64
0.9930 97.98 97.41 88.47 89.53 85.93 86.97
1.0763 97.49 97.52 88.43 89.49 85.9 86.94
1.1597 97.31 97.7 88.19 89.25 85.73 86.77

 

Table 1. Continued.

152

 

 

Tlme (Days) Control KNO; KCl
I 2 I 2 I 2
1.2430 96.86 97.45 $.44 89.50 86.07 87.11
1.3263 96.34 97.21 88.41 89.47 86,05 87.09
1.4097 96.88 97.32 88.18 89:24 85.85 86.89
1.4930 97.91 97.31 88.43 89.49 86.21 87.25
1.5763 97.4 97.2 88.41 89.47 86.17 87.21
1.6597 96.84 96.76 88.18 89.24 85.96 87.00
1.7430 96.34 96.34 88.43 89.49 86.31 87.35
1.8263 95.89 96.69 88.41 89.47 86.28 87.32
1.9097 96.09 96.5 88.18 89.24 86 87.04
1.9930 96.65 96.52 88.44 89.50 86.38 87.43
2.0763 96.43 97.07 88.44 89.50 86.34 87.38
2.1597 95.55 96.6 88.21 89.27 86.08 87.12
2.2430 97.39 96.87 88.49 89.55 86.45 87.50
2.3263 96.74 96.99 88.48 89.54 86.4 87.45
2.4097 96.6 96.35 88.27 89.33 86.13 87.17
2.4930 97.67 97.31 88.53 89.59 86.49 87.54
2.5763 97.55 97.32 88.55 89.61 86.47 87.52
2.6597 97.45 97.21 88.34 89.40 86.18 87.22
2.7430 97.6 97.43 88.63 89.69 86.57 87 62
2.8263 97.66 97.7 88.64 89.70 86.52 87.57
2.9097 97.1 97.52 88.39 89.45 86.11 87.15
3.0763 97.54 97.41 88.73 89.71 86.47 87.52
3.2430 97.44 97.46 88.82 89.80 86.57 87.62
3.4097 97.29 97.29 88.64 89.62 86.19 87.23
3.5763 97.67 97.69 88.95 89.93 86.59 87.64
3.7430 97.1 97.7 89.03 90.01 86.72 87 77
3. 7 97.72 97 16 88.74 89.72 86.22 87.26
4.0763 97.15 97.7 89.19 90.17 87.02 88.07
4.2430 97 97.8 88.99 89.97 86.51 87.56
4.4097 97.66 97.63 89.27 90.25 86.92 87.97
4.5763 97.18 97.72 89.33 90.31 87.03 88.08
4.7430 97.19 97.06 88.96 89.94 86.99 88.04
4.9097 97.6 97.64 89.38 90.36 87.16 88.21
5.0763 97.11 97.81 89.45 90.43 87.22 87.76
5.2430 96.46 97.79 89.27 90.25 86.8 87.77
5.4097 97.34 97.54 89.53 90.51 87.22 87.78
5.5763 97.05 97.92 89.55 90.54 87.31 87.88
5.7430 97.99 98.04 89.3 90.28 86.91 87.89
5.9097 97 97.65 89.6 90.59 87.47 87.59
6.0763 97.66 97.37 89.64 90.63 87.42 87.56
6.2430 97.22 97.82 89.42 90.40 86.91 87.12
6.4097 96.66 97.73 89.67 90.66 87.38 87.43
6.5763 97.57 97.91 89.71 90.70 87.48 87.56
6.7430 95.7 97.77 89.63 90.53 87.63 87.65
6.9097 97.36 97.58 89.74 90.64' 87.67 87.71
7.0763 97.92 97.92 89.75 90.65 87.59 87 56
7.2430 97.86 97.86 89.53 90 43 87 15 87.45
7.4097 96.56 97.56 89.79 90.69 87.57 87.34
7.5763 97.29 97.29 89.83 90.73 87.65 87.51
7.7430 97.24 97 24 89.61 90.51 87-21 87.32
7.9097 98.05 98-05 89 84 90.74 87.63 87 47

 

 

153

Table 1. Continued.

 

 

Time (Days) Control KN 0; KCl
1 2 l 2 l 2
8.0763 97.51 97.51 89.89 90.79 87.69 87.45
8.2430 98.14 98.14 89.66 90.56 87.22 87.23
8.4097 98.4 98.4 89.92 90.82 87.66 87.43
8.5763 98.46 98.46 89.93 90.83 87.75 87.65
8.7430 98.1 98.1 89.7 90.60 87.25 87.45
8.9097 98.83 98.83 . 89.95 90.85 87.75 87.09
9.0763 99.17 99.17 89.98 90.88 87.8 87.88
9.2430 98.81 98.81 89.76 90.66 87.34 87.34
9.4097 99.24 99.24 89.99 90.89 87.77 87.93
9.5763 98.88 98.88 90.02 90.92 87.86 87.56
9.7430 98.67 98.67 89.72 90.62 87.25 87 56

 

 

 

 

 

154

 

 

 

APPENDIX E

WEIGHT LOSS (%) OF DIFFERENT TABLE GRAPE CULTIVARS
DUE To DIFFERENT PACKAGING TREATMENTS

 

156

Table 1. Weight loss (%) of ’Himrod’ table grape due to different postharvest
treatments in 1987 and 1988.

1987 storage study

 

 

 

Treatments Time (Days)

8 22 40
Control 0.19 1 2 0.45 1.10a
(6 7mm holes)
1.75 mil low 0.10 0.14 0.17b
density polyethylene
(LDPE)
2 mil LDPE 0.05 0.09 0.10b

 

1988 storage study

 

 

 

Treatments Time (Days)

13 43 83
Control 0.84 2.20 3.318
(6 7mm holes)
2 mil low 0.64 1.19 1.24b
density polyethylene
(LDPE)
3 mil LDPE 0.37 0.97 0.97b

 

‘ Means in the same column and with the same letter are not signiﬁcantly different
at P=0.05 ‘

2 Percent calculated weight loss is based on the comparison of weight loss in each
date to the original weight of the grape.

Table 2. Effect of different preharvest treatments on postharvest infection <95;

packaged ’Himrod’ grape clusters in 1988.

 

 

 

 

First harvest Second harvest

Treatments Sampling Control 2 mil Control 2 mil

Time ‘ LDPE * LDPE
Control 15 days 002(0) 0.0(d) 0.0(b) 0.0(c)
Girdling
only 0.0(c) 0.0(d) 0.0(b) 0.0(c)
GA3 only 0.0(c) 0.0(d) 0.0(b) 0.0(c)
GA3 and
girdling 0.8(bc) 0.0(d) 0.0(b) 0.0(c)
GA3) girdling
and berry thinning 0.0(c) 0.0(d) 0.0(b) 0.0(c)
Control 30 days 10.8(b) 5.3(bc) 10.3(a) 0.0(c)
Girdling
only 25.8(a) 2.3(cd) 4.1(c) 10.4(a)
6A3 only 8.2(bc) 5.8(bc) 10.8(a) 0.0(c)
GA3 and
girdling 3.1(bc) 7. 6(ab) 14.2(ab) 7.0(b)
GA , girdling
and} berry thinning 4.6(bc) 10.3(a) 20.6(e) 8.1(ab)

 

* Low density polyethylene

Z Means in each column (second paranthesis) with the same letter have no
significant differences at P = 0.05.

 

158

Table 3. Visual rating scale used for evaluation of grape clusters stored under

different MA conditions

 

Scale Description

 

4 (Excellent) No dry pedicels, rachises or peduncles, no leaky,
brown, or infected berries,

3 (Good) Minimum of 50% of the pedicels are dry, no leaky,
brown, or infected berries,

2 (Fair) All of the pedicels and a minimum of 50% of the
rachises are dry. Minimum of 2 berries are brown, leaky, or are at
the early stage 0f infection (limit of marketability),

1 (Poor) All of the pedicels, rachises, and peduncles are dry.

Minimum of two berries are leaky, brown, or infected

 

APPENDIX F

 

160

Table 1. Effect of different preharvest treatments on postharvest infection 1%, 5r

V A

packaged ’Himrod’ grape clusters in 1987.

 

 

 

 

First harvest Second harvest

Treatments Sampling Control 2 mil Control 2 mil

Time LDPE * LDPE
Control 15 days 0.020) 3.5(0) 0.0(e) 0.0(e)
Girdling
only 8.3(c) 4.7(b) 0.0(e) 0.0(e)
GA3 only 2.6(de) 0.8(e) 0.0(e) l.89(d)
GA3 and
girdling 0.8(et) l.8(d) 0.0(e) 0.0(e)
6A3. girdling
and berry thinning 2.5(de) 0.0(0 0.0(c) 0.0(c)
Control 30 days 7.8(c) 6.4(a) 8.8(c) 11.0(a)
Girdling
only 24.3(a) 6.4(a) 13.2(a) 12.4(a)
GA3 only 7.1(0) 0.0(0 8.7(c) 5.8(c)
GA and
girciling 4.3(d) 5.0(b) 6.14(d) 8.5(b)
GA , irdlin
andeErry thinning 13.8(b) 2.2(d) 10.4(b) 7.9(b)

 

" Low density polyethylene

Z Means in each column with the same letter have no significant differences at
P = 0.05.

161

Table 2. Weight loss (%) of ’Vanessa’ table grape due to different postharvest
treatments in 1987 and 1988.

1987 storage study

 

 

 

Treatments Time (Days)

40 60 90
Control 2.891 2 3.41 6.90a
(6 7mm holes)
1.75 mil low 0.20 0.46 0.72b
density polyethylene
(LDPE)
2 mil LDPE 0.18 0.41 0.68b

 

1988 storage study

 

 

 

Treatments Time (Days)

60 86 103
Control 2.33 2.36 2.67a
(6 7mm holes)
2 mil low 0.53 1.01 1.48b
density polyethylene
(LDPE)
3 mil LDPE 0.37 0.87 0.920

 

1 Means in the same column and with the same letter are not significantly different
at P=0.05

2 Percent calculated weight loss is based on the comparison of weight loss in each
date to the original weight of the grape.

162

Table 3. Weight loss (%) of ’Concord’ table grape due to different postharvest
treatments in 1987 and 1988. '

1987 storage study

 

 

 

Treatments Time (Days)

19 24 44
Control 0.021 2 0.17 0.17a
(6 7mm holes) '
1.75 mil low 0.20 0.43 0.72b
density polyethylene
(LDPE)
2 mil LDPE 0.20 0.43 0.57b

 

1988 storage study

 

Treatments Time (Days)

 

 

48 71 99 148
Control 0.59 0.89 1.60 3.11a
(6 7mm holes)
2 mil low 0.50 0.72 0.96 1.02b
density
polyethylene
(LDPE)
3 mil LDPE 0.29 0.41 0.71 0.97b

 

‘ Means in the same column and with the same letter are not significantly different
at P=0.05

2 Percent calculated weight loss is based on the comparison of weight loss in each
date to the original weight of the grape.

163

Table 4. Effect of different preharvest treatments on postharvest general appearance
(r/4) of packaged ’Himrod’ grape clusters in 1987.

 

 

 

 

First harvest Second harvest

Treatments Sampling Control 2 mil Control 2 mil

Time LDPE * LDPE
Control 15 days 1.7Z(c) 2.3(a) . 1.0(a) 2(a)
Girdling
only 2.8(a) 2.5(a) 1.3(a) 1.3(a)
GA3 only 2.0(bc) 2.0(ab) l.8(a) 2.0(a)
GA3 and
girdling 2.4(ab) 2.5(a) . l.8(a) 2.3(a)
GA3, girdling
and berry thinning 2.8(a) 1.3(b) 1.4(a) 1.3(a)
Control 30 days 3.0(a) 3.7(a) 2.0(a) 2.3(ab)
Girdling
only 3.3(a) 3.0(b) 2.5(a) 2.0(ab)
GA3 only 3.3(a) 1.6(c) 3.0(a) 2.8(a)
GA and -
gird31ing 3.0(a) 2.8(b) 2.8(a) 2.5(ab)
GA , girdling
and3 berry thinning 3.3(a) 2.5(b) 2.5(a) 1-8(b)

 

* Low density polyethylene

Z Means in each column for each sampling period (15 and 30 days) with the same
letter have no significant differences at P = 0.05.

 

164

Table 5. Effect of different preharvest treatments on postharvest general appearance
(r/4) of packaged ’Himrod’ grape clusters in 1987.

 

First harvest

Second harvest

 

 

Treatments Sampling Control 2 mil Control 2 mil

Time LDPE * LDPE
Control 15 days 172(c)(4) 2.3(a)(bcd) l.0(a)(d) 2(a)(ab)
Girdling
only 2. 8(a)(abc) 2.5 (a) (be) 1 .3(a)(d) l.3(a)(b)
GA3 only 2.0(bc)(cd) 2.0(ab)(cde) l.8(a)(bcd) 2.0(a)(ab)
GA3 and
girdling 2.4(ab)(abcd) 2.5(a)(bc) l.8(a)(bcd) Zi(a)(ab)

GA3, girdling
and berry thinning

2. 8(a)(abc) l.3(b)(e)

l.4(a)(cd)

1-3(a)(b)

 

Control 30 days

Girdling
only

GA3 only

GA3 and
girdlin g

GA3, girdling
and berry thinning

* Low density polyethylene

3.0(a)(ab) 3.7(a) (a)

3.3(a)(a) 3.0(b)(ab)
3.3(a) (a) l.6(c)(de)

3 . 0(a) (ab) 2. 8(b)(bc)

3.3(a)(a) 2.5(b)(bc)

2.0(a)abcd)

2.5(a)(abc)
3.0(a)(a)

2. 8(a)(ab)

2.5(a)(abc)

2.3(ab)(ab)

2.0(ab)(ab)
2.8(a)(a)

2.5(ab)(a)

l.8(b)(ab)

Z Means in each row (first paranthesis) and column (second paranthesis) for each
sampling period with the same letter have no signiﬁcant differences at P = 0.05.

165

Table 6. Effect of different preharvest treatments on postharvest general appearance
(r/4) of packaged ’Himrod’ grape clusters in 1988.

 

 

 

 

First harvest , Second harvest

Treatments Sampling Control 2 mil Control 2 mil

Time LDPE * LDPE
Control 15 days 1.7 Z(b) 2.7(a) 2.0(bc) 4.0(a)
Girdling
only 2.5(a) 3.0(a) 3.0(a) 4.0(a)
6A3 only 2.5(a) 3.0(a) 1.5(c) 4.0(a)
GA3 and
girdlin g 2.5 (a) 2. 7(a) 2. 6(ab) 4. 0(a)
GA3, girdling
and berry thinning 2.5(a) 3.0(a) 2.6(ab) 4.0(a)
Control 30 days l.3(b) 2.0(ab) 2.0(a) 3.0(a)
Girdling 4
only 1.0(b) 2.3(a) 2.3(a) 2.0(b)
GA3 only l.7(ab) 2.3(a) 3.0(a) 3.8(a)
GA and
girdling 2.7(a) l.7(ab) 2.8(a) 3.0(a)
GA , girdling
and3 berry thinning 2.6(a) l.3(a) l.7(a) 2.3(b)

 

* Low density polyethylene

Z Means in each column for each sampling period (15 and 30 days) with the same
letter have no signiﬁcant differences at P = 0.05.

166

Table 7. Effect of different preharvest treatments on postharvest general appearance
(r/4) of packaged ’Himrod’ grape clusters in 1988.

 

 

 

 

First harvest Second harvest

Treatments Sampling Control 2 mil Control 2 mil

Time LDPE * LDPE
Control 15 days 1.7Z(c)(abc) 2.7(b)(ab) 2.0(bc)(ab) 4.0(a)(a)
Girdling
only 2.5(c)(ab) 3.0(b)(a) 3.0(b)(a) 4.0(a)(a)
GA3 only 2.5(b)(ab) 3.0(b)(a) l.5(c)(b) 4.0(a)(a)
GA3 and
girdling 2.5(b)(ab) 2.7(b)(ab) 2.6(b)(ab) 4.0(a)(a)
GA3, girdling
and berry thinning 2.5(a)(ab) 3.0(a)(a) 2.6(a)(ab) 4.0(a)(a)
Control 30 days l.3(b)(cd) 2.0(ab)(bcd) 2.0(ab)(ab) 3.0(a)(b)
Girdling
only l.0(b)(d) 2.3(a)(abc) 2.3(a)(ab) 2.0(a)(c)
GA3 only l.7(b)(bcd) 2.3(b)(abc) 3.0(ab)(a) 3.8(a)(a)
GA d
girciliii; 2.7(a)(a) l.7(b)(cd) 2. 8(a)(a) 3.0(a)(b)
GA , g' dl' g
and3 beiiy 1trlliinning 2. 6(a)(a) 1 .3(a)(d) l.7(a)(b) 2 . 3(a) (c)

 

* Low density polyethylene

Z Means in each row (first paranthesis) and column (second paranthesis) for each
sampling period with the same letter have no signiﬁcant differences at P = 0.05.

167

Table 8. Factorial analysis of variance table for 15 days evaluation time of ’Himrod’

grape clusters in 1987.

GROUP: Packaging treatments i.e.,control and 2 mil LDPE packages.

HARVEST. Harvest dates i.e e.,ﬁrst and second harvests.

COLOR: Field treatments.

$0090. of Variation

Main EffeCts

GROUP
HARVEST
COLOR

Z-Voy Interactions
GROUD HARVEST
GROUP COLOR

HARVEST COLOR

3-H0y Interactions
Gnoup HARVEST COLDR

Enolainea
8e31dua|

70:31

Sum of
Souares

180.922
1.311
103.196
76.415

125.064
8.290
27.534
89.240

34.257
34.257

340.243
55.132

395.375

0
u

u-oua»

tub-010

bib

19
$6
75

Mean
SOuIre

30.154
.311
103.196
19.104

13.896
8.290
6.883

22.310

3.554
8.554

17.908
.985

5.272

30.628
1.331
104.820
19.405

14.115
8.420
6.992

22.661

8.699
8.699

18.189

Sig

.000
.253
.000
.000

.000
.005
.000
.000

.000
.000

.000

Table 9. Factorial analysis of variance table for 30 days evaluation time

grape clusters in 1987.

168

GROUP: Packaging treatments i.e.,control and 2 mil LDPE packages.

HARVEST. Harvest dates i.e., ﬁrst and second harvests.

COLOR: Field treatments.

Source of Variat1on

Main Effects

GROUP
HARVEST
COLOR

Z-Hay Interactions
GROUD HARVEST
GROUD COLOR

HARVEST COLOR

3-WIy Interact1ons
GROUR HARVﬁST COLOR

EtalIinec
3231Ou81

Total

Sum of
Square:

1025.215

198.631
11.651
812.154

790.431
144.094
527.293
121.757

267.405
267.405

2083.051

20.448

2103.499

OF

6.4-40

hrb-‘U

bib

19

55

Mean
Sauare

170.869
198.631

11.651
203.038

87.826
144.094
131.823

30.439

66.851
66.851

109.634
.372

28.426

of ’Himrod’
Sig
F of F
459.591 .000
534.262 .000
31.337 .000
546.117 .000
236.227 .000
387.573 .000
354.566 .000
81.873 .000
179.611 .000
179.811 .000
294.886 .000

169

Table 10. Factorial analysis of variance table for 15 days evaluation time of ‘Himrod’
grape clusters in 1988.

GROUP: Packaging treatments i.e.,control and 2 mil LDPE packages.
HARVEST: Harvest dates i.e.,ﬁrst and second harvests.
COLOR: Field treatments.

Sum of Mean Sig
Source of Variation Squares 0F Souare F of F
Ma1n Effects .570 6 .095 1.039 .414
GROUP .111 1 .111 1.212 .277
HARVEST .138 1 .138 1.515 .225
COLOR .376 4 .094 1.027 .405
Z-Way Interactions .874 9 .097 1.062 .410
GROUP HARvesr .130 1 .130 1.422 .240
GROUP COLOR .306 4 .097 1.056 .390
HARVEST COLOR .490 4 .123 1.340 .271
3-way Interactions .382 3 .127 1.393 .256
GROUD 'HARVEST COLOR .382 3 .127 1.393 .253
Enolainec 1.626 18 .101 1.109 .377
98310031 3.840 42 .091

Total 5.666 60 .094

170

Table 11. Factorial analysis of variance table for 30 days evaluation time of ’Himrod’
grape clusters in 1988.

GROUP: Packaging treatments i.e.,control and 2 mil LDPE packages.
HARVEST: Harvest dates i.e.,ﬁrst and second harvests.

COLOR: Field treatments.

Sum of Mean Sig
Scureo of Vartation Sauaros OF Square F of F
Main Effocu 606.897 6 101.149 5.537 .000
GROuP 42.908 1 42.908 2.349 .133
HARVEST 347.692 1 347.692 19.033 .000
COLOR 254.979 4 63.745 3.489 .015
2-way Interactions 572.366 9 63.596 3.461 .00:
GROUP HARVEST 180.316 1 180.316 9.871 .003
63009 COLOR 363.653 4 90.913 4.977 .002
HARVEST COLOR 198.584 4 49.646 2.718 .042
3-Wa Interactions 562.935 3 187.645 10.272 .000
GROUR HARVEST COLOR 562.935 3 187.645 10.272 .000
Exola1nca 1742.197 18 96.789 5.298 .000
Residua1 767.247 42 18.268
Total 2509.444 60 41.824

171

Table 12. Correlation coefficient calculated between treatment total soluble solids
(TSS) and Infection percentage on packaged ’Himrod’ grape clusters in 1987.

 

 

 

 

First harvest Second harvest

Treatments Sampling Control* 2 mil Control 2 mil

Time LDPE ** LDPE
ControlY 15 days 0.00 0.74 0.0 0.0
Girdling
only -0.41 0.40 0.0 0.0
GA3 only -0.17 0.0 0.0 0.0
GA3 and
girdling 0.47 0.89 0.0 0.0
GA3, girdling
and berry thinning -0.65 0.78 0.0 0.35
Control 30 days -0.99 -0.53 0.96 -0.61
Girdling
only 0.86 -0.13 0.93 0.93
GA3 only -0.46 0.47 0.02 0.10
GA3 and
girdling 0.20 0.45 -0.25 0.41
GA3, girdling
and berry thinning -O.27 0.0 0.39 -0.34

 

* Unsealed packages.

** Low density polyethylene.
Y Vines that received no field treatments.

 

 

Table 13. Correlation coefficient calculated between treatment total soluble solids
(T SS) and Infection percentage on packaged ’Himrod’ grape clusters in 1988.

 

First harvest

Second harvest

 

 

 

Treatments Sampling Control* 2 mil Control 2 mil
Time LDPE ** LDPE

ControlY 15 days 0.0 0.0 0.0 0.0

Girdling

only 0.0 0.0 0.0 0.0

GA3 only 0.0 0.0 0.0 0.0

GA3 and

girdling -0.50 0.0 0.0 0.0

GA3, girdling

and berry thinning 0.0 0.0 0.0 0.0

Control 30 days 0.02 0.02 —0.60 0.00

Girdling

only -0.93 0.64 0.46 -0.67

GA3 only -l.00 0.32 -0.66 0.00

GA3 and

girdling 0.50 0.84 0.26 0.88

GA , girdling

and3 berry thinning -1.00 0.48 0.76 0.00

 

* Unsealed packages.

** Low density polyethylene.
Y Vines that received no field treatments.

 

 

 

 

173

APPENDIX G

INFECTION DEVELOPED AT CAPSTEM SCAR AND CRACKS OF

PACKAGED ’ALDEN’ BERRIES AT 00C

 

 

 

 

 

.1 . . . 111 1.1 1i. 1 1. . . M11111 1uid1btllt11111.11|111111111WW0.3 . 11.1“

UNI

111111111

.1.

204-
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