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PRELIMINARY STUDIES ON
PROCESSING OF FROZEN PACK
GREEN ASPARAGUS

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Thesis {or the Degree of M. :.
MICHIGAN STATE COLLEGE
CIarc H. RundIe
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charge from circulation records

 

PRELIMINARY STUDIES ON PROCESSING

OF FROZEN PACK GREEN ASPARAGUS

Thesis

Submitted to the faculty of the Michigan State
College of Agriculture and Applied Sci-
ence in partial fulfillment of the
requirements for the degree

of Master of Science

by
Clare H. Bundle

1959

TREK“;

II
III

IV

VI
VII

VIII

PRELIMINARY STUDIES ON PROCESSING

OF FROZEN PACK GREEN ASPARAGUS

Table of Contents I

Introduction

Review of Literature
Materials and Methods
Presentation of Data
Discussion

Summary

Bibliography

Acknowledgements

121490

Page

12
15
18
19

25

Introduction

The consumption of fresh, canned and frozen green vegetables has
increased markedly in the United States during the past decade. This
is particularly true with asparagus where a decided shift from the
bleached or white to the more nutritious green asparagus has taken
place. In 1958, 112,800 acres of asparagus were harvested in the
United States, which was nearly 4000 acres more than was harvested in
1957, and 10,000 acres more than the average for the 1927 to 1956 period
(4). The increase in acreage in Michigan is even more striking than the
totals for the entire country. In 1921 only 1000 acres were reported
for the state, but by 1958 the acreage of bearing asparagus had increased
to 2100 acres (4).

This increase in production of asparagus has not lead to a marked
increase in the consumption of fresh asparagus. According to figures
released by the United States Department of Commerce, the per capita
consumption of canned asparagus increased from 0.48 pounds in 1922 to
0.90 pounds in 1927. The per capita consumption of fresh asparagus
increased only from 0.40 pounds in 1922 to 0.70 pounds in 1927. Much
of this increase has been in the production of frozen pack asparagus.

In 1957, 6,259,474 pounds of asparagus were frozen, of which 1,087,724
pounds were packed in the western states and 5,171,750 pounds in the
eastern states (5). This would indicate the trend toward freezing green
asparagus rather than white.

In the future it is reasonable to expect a great deal more asparagus
will be processed in this manner. Commercial methods for processing
fruits have been more or less standardized. This in general is not
true with vegetables and particularly asparagus, which, due to its high

water and protein content, presents some of the most difficult problems

-2;

in freezing preservation of all the vegetables frozen packed. This
undoubtedly accounts for some of the undesirable packs of frozen pack
asparagus on the market.

With the rapid rise of the locker-storage movement in the middle
western states and the possibilities of small home freezing units in
the future.it is reasonable to expect a demand for authentic process-
ing directions for the locker patrons and the users of small home
equipment.

The purpose of this investigation is to determine methods of
blanching, packing, freezing, storing and the selection of suitable
containers for the production of a satisfactory frozen pack green

asparagus.

- 5 _
Review of Literature

A number of investigations have been reported on methods for
freezing preservation of green asparagus and closely associated
problems. Cruess (10) states that all of the leading varieties are
apparently about equal in suitability for freezing storage for the
principal varieties vary little in flavor or texture.

Crist and Dye (9) found green asparagus, whether fed fresh, freshly
cooked, or canned, where fed in proper amounts, contains sufficient
vitamin A to give healthy grown in albino rats. This was not true in
the case of bleached asparagus. They concluded from their experiments
that the vitamin A content of plant tissue is associated with its
greenness. Culpepper and Moon (11) in their investigations found that
the canned product was richer and more pleasing to the taste at the tip
than at any point below. The flavor and richness did not vary greatly
at the tip in stalks of differing heights, but there was considerable
variation at the base. They also determined that in stalks 4, 8, 18,
and 56 inches tall, the amount of material per stalk which would make
a desirable food product appeared to be greatest in the 18 inch stalks.

Cruess (10) comments on the fact that asparagus collapses markedly
on freezing and thawing and, therefore, is not particularly attractive
in appearance. If quick—frozen, it differs but slightly after cooking
from cooked fresh asparagus in flavor, color, appearance, or firmness.

Joslyn and Marsh (25) found blanched vegetables, as a rule, increase
in weight upon thawing if frozen in brine. The weight increased with
increase in the rate of freezing. Unblanched as well as blanched

vegetables, packed without brine, decreased in weight. They also noted

- 4 _

that blanching the asparagus had but little effect on the rate of
temperature change, whether packed without liquid, plain, or in brine.
They also found that, of the vegetables tested, loss in weight (due to
blanching) was greatest for asparagus. Joslyn (21) in other investigations
found the drained weights of vegetables depend upon the kind of vegetable
and the packing treatment. Loss in weight was greatest for asparagus

and spinach. His experiments showed an increase in the loss of weight

due to blanching and that blanching in acid tends to toughen vegetables.
Cruess (10) suggests that since steam removes less of the water soluble
materials than does water, possibly it should be recommended in preference
to boiling water for vegetables to be packed without liquid.

Plagge (29) recommends blanching asparagus in boiling water for two
minutes, Wiegand (55) two to three minutes in boiling water, and
Tressler and Evers (52) suggests that asparagus be scalded in boiling
water for two to three minutes. Carlton (8) recommends blanching in
boiling water, small stalks three and one-half minutes, large stalks
four and one-half minutes. The above investigators did not give any
data supporting their recommendations.

Cruess (10) says there is slightly less shrinkage of the asparagus
packed in a two per cent salt brine, and that there is practically no
difference in appearance or texture between the dry-packed and brine-
packed products-after cooking the thawed products. Investigations of
Joslyn and Marsh (25) showed that the addition of brine to vegetables,
to be preserved by freezing, markedly decreased the degree of breakdown
in texture. Wiegand (55) reported that vacuumizing was not necessary
in all cases, especially where syrups or brines were used in connection

with the packing of the fruit or vegetable. Tressler and Evers (52)

_ 5 -

citing Diehl, Pentzer, Berry and Asbury, say that airtight or non—
airtight containers may be used with brine pack, but the former is
preferred. However, with dry pack, airtight containers are desired.
The use of unlacquered metal containers is feasible, but asparagus
sometimes darkens, due apparently to the rusted condition of the cans
caused by concentration of the brine in freezing. Also there is
evidence that darkening may arise from other causes in the field.
Cruess (10) reports that asparagus sometimes absorbs off flavors and
deteriorates in flavor in loose containers, and recommends that air—
tight containers be used. Carlton (8) also states a preference for
airtight containers and suggests that where tin containers are used they
be lacquer lined. He also preferred straight side wall containers for
the easy removal of the frozen products.

Joslyn and Marsh (25) found, with the possible exception of asparagus,
increasing the rate of freezing by using solid carbon dioxide does not
appreciably improve the texture of frozen fruits and vegetables which
they examined. Woodroof (54), (55) found that fruits and vegetables
frozen quickly have a firmer texture after thawing than the same product
frozen more slowly. This desired type of freezing was found to be most
economically carried out by the "immersion” method of freezing. He also
found that very low temperatures (--1050 F.) produced objectionable effects.
such as alteration in colors. Diehl (1) reports that temperatures nearing
-100 F. or lower are unnecessary for satisfactory commercial preservation
of most fruits and vegetables. He found some exceptions to this rule,
with asparagus, the fresh quality of which seemed to be best retained

by rapid freezing at—20o F. or below. Morris and Barker (28) also found

- 5 _

that rapid freezing at-20° F. was helpful in the production of a
satisfactory asparagus product. Diehl and Berry (15) working on
freezing of fruits and vegetables found that,when packed in brine and
frozen at -20° F. or below, asparagus kept its fresh flavor, color, and
appearance more nearly intact. Fellers, Young, Isham and Clague (17)
state that, "Freezing of asparagus dees not cause a loss in the vitamin
C content." Fitzgerald (20) says, and Barker and Morris in England
state, that freezing affected the permeability of both asparagus and
peas, so that solutes leached into the cooking water more readily than
from fresh unfrozen vegetables; this increase of permeability was
greater the slower the rate of freezing. Fellers, Esselen and Fitzgerald
(15) found quick-frozen vegetables to retain a slightly higher percent-
age of vitamin B, and 132 (G) than canned vegetables, although both types
of food products are good sources of these two water-soluble vitamins.
Diehl and Berry (15) reported a temperature of 15° F. seemed to be
the upper limit and most suitable for storing frozen products. They
found that a storage temperature of 20° F. might be unsuitable from a
physiological rather than a microbiological standpoint. Carlton (8)
states vegetables stored at 10° F. have shown a loss in vitamin 0,
increasing rapidly at 15° F. The deterioration is attended by a loss
of color. Investigators (1) found as a result of tests that for most

horticultural products, 15° F. or below is best for long-time storage.

- 7 -

Materials and Methods

Asparagus of the Mary Washington variety grown on the Experiment
Station plots at East Lansing, Michigan, was used throughout the experi-
ment, This l2+year old bed is being carried on as a fertilizer experi—
ment, this being the ninth crop harvested. The bed is located on soil
ranging from sandy loam to a clay loam.

The asparagus was taken from cuttings beginning May 19th and
extending through June 14th. Only tip cuts were used, varying in
length (none exceeding six inches) to fit the type of container. A11
asparagus used conformed to U. S. No. 1 grade ranging from three-eighths
to three-fourths of an inch in diameter.

The asparagus was out early in the morning, graded immediately and
washed in four to six changes of tap water, depending on the amount of
sand adhering to the stalks. The leaf scales were removed from the first
few lots but this proved impractical and detracted from the appearance
of the product.

After washing, the asparagus was placed in a muslin sugar sack
liner and submerged in an enamel lined tub of hot (1800 F.) water for
five minutes, excepting those lots in which the blanching temperature
and time was varied. The tub was of sufficient capacity (15 gals.) to
maintain a temperature within one degree. This limited variation was
maintained by regulating the flow of live steam into the water through
a steam jet. After blanching, the asparagus was submerged quickly in
running tap water for 10 minutes which reduced the temperature to 55° -
57° F. After draining, the asparagus was packed, butts first, into
No. 2 C-enamel lined tin cans, except those lots in which the types of

containers were varied. Two per cent (by weight) salt solution

- 3 _

(cooled to 56°-40° F.) was added to cover the asparagus with the
exception of those lots in which the packing method was varied. Head
space, one-ninth of the volume of the container, was left to provide

for expansion during freezing. The cans were sealed airtight in a hand
sealing machine. The samples were frozen in a General Electric
commercial condensing unit, type CM (ice cream storage cabinets) at

-20° F. for six to eight hours. Those lots used in determining suitable
freezing temperatures were subjected to different temperatures. The ice
cream cabinets used were of sufficient capacity (20 gals.) to accommodate
the rate of heat transfer from the small number of lots put in the cabinet
at any one time. The frozen product was then placed in a cold storage
room at 0° F. until sampling. Those lots used in storage temperature
investigations were held at various temperatures in the ice cream
cabinets.

Cooking tests were made on all lots at the end of four months and
again at eight months. Samples for the cooking tests were taken from
the 0° F. storage and placed in ordinary cold storage, at 40° F., 48
hours before cooking. The samples were taken to the cooking laboratory
and given a standard cook by a competent technician. A color chart
reading was made on each lot before cooking, using "A Dictionary of
Color" by Merz and Paul as a color guide. The thawed asparagus was
drained, a 500-gram sample taken and placed in five cups of boiling
water to which was added six grams of salt and the whole allowed to cook
seven minutes, after coming to a boil. No lid was used on the three-
quart white enamel sauce pan. At the end of seven minutes the asparagus

was drained and samples were placed before a panel of five Judges. The

judges scored each lot according to the score sheet found on the following

- 9 -

page. Processing treatment of each lot was unknown to the judges and,
after a first practice sampling, no discussion or comparison of ideas
was permitted .

The judges’ scores for each factor were totalled and averaged, the
sample receiving the highest numerical score, under the column "General
Rating", being given first preference as described in the presentation of
data in the following section.

This experiment was divided into six divisions, each varying in one
’treatment; otherwise, each lot was handled as has already been desired.z

Data will be presented according to the treatments listed.

I. Blanching Procedure:

 

Temperature of Water Length of Blanch

W11- in Minutes
Untreated 0
160 5
160 5
160 10
180 1
180 5
180 5
204 1/2
204 l
204 5

204 5

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II. Freezing Tests:

Temperature of Freezing
(degrees Fahrenheit)

10
O
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-20
III. Storage Temperature Tests:

Temperature of Storage
(degrees Fahrenheit)

15
10
0
IV. Asparagus packed in two per cent salt brine in various types
of containers:
Unwaxed "Sealright" containers (straight side walls)
Unwaxed "Sealright" containers (sloping side walls)
Waxed paper tubs (snap cover)
Waxed "Nestyle Sealright" container (1 pt.)
Squat quart unwaxed paper container
"Nestyle Sealright" waxed paper container (1 pt. — asparagus
cut in one-inch lengths)
No. 2 C-enamel lined tin can (asparagus cut in one-inch sections)
V. Asparagus soaked one-half hour in two per cent salt brine before
packing dry in various types of containers:
Unwaxed "Sealright" container (straight side wall)
Unwaxed "Sealright" container (sloping side wall)

Waxed paper tubs (snap cover)

- 11 _

"Nestyle Sealright" waxed paper container (1 pt.)
Squat quart unwaxed paper container
Cellophane bag
Cottage cheese unwaxed paper container
No. 2 C-enamel lined tin can
VI. Asparagus packed dry in various containers:
No. 2 C-enamel lined tin can
Commercially frozen (rectangular paper container)

Commercially canned

- 12 -
Presentation of Data

The Effects of Blanching on Frozen Pack Asparagus:

Numerous authorities have shown that blanching of non-acid
vegetables previous to the freezing process is essential to bring out
the color and to inhibit enzymatic activity in the finished frozen
products. In the investigations here reported, the color of the
asparagus, before cooking varied only slightly, ranging from L 4 to
L 10, Plate 21 (Merz and Paul's "A Dictionary of Color"). This was
true of the various treatments to which the asparagus was subjected.

The color of the cooked product resembled that of the fresh very closely
except that the commercially canned asparagus was a yellowish green,
-and the comercially frozen a brownish green, after cooking.

The apparent limpness of the asparagus, due to leakage, was
slightly more noticeable after eight months storage than at four
months, but little difference was detectable among the various treatments.

Increasing the length of time and the temperature of the blanching
up to 2040 F. for five minutes, decreased the intensity of the aroma and
increased its desirability as is shown in columns 4 and 5 in Table I.

Noticeable differences in color desirability, general appearance,
texture, and tenderness, columns 6, 7, 8 and 9 in Table I, did not
conform to any particular blanching treatment.

The intensity of the flavor varied slightly, increasing with a
decrease in temperature and length of blanch given the asparagus, as
shown in column 10 in Table I. The desirability of the flavor, however,
showed an increase as the blanching treatment was increased up to 2040 F.

for five minutes, as shown in column 11 in Table I.

-15-

The asparagus which received a blanch of 204° F. for five minutes
was given the highest general rating. The commercial packs of canned
and frozen separagus were placed down in the general rating with the

underblanched treatments, as shown by the various items in Table I.

Effects of Freezing Temperatures on Frozen Pack Asparagus:

In the freezing tests, asparagus frozen at 10° F., 0° F., -10° F.,
or —20° F. did not show any appreciable differences after cooking when
rated by the judges, as is shown in Table II. That asparagus frozen at
100 F. was given a slightly higher rating than other lots might indicate
that temperatureaas low as -20° F. are not necessary. However, before
definite conclusions may be drawn, further tests should be conducted at
the various freezing temperatures. All lots were rated much more

desirable than either the commercially canned or frozen samples.

Effects of Storage Temperatures on Frozen Pack Asparagus:

In these investigations asparagus frozen at —20° F. and stored at
0° F. or 10° F. did not show any consistent differences in'the final
cooking tests, as indicated in Table III. The lot stored at 15° F.
was given a low general rating at the end of four months storage, but
due to mechanical difficulties in the refrigeration unit the lot was
lost before a second test at the end of the eight months could be given.
It was thought that this temperature might have proved too high for
storage for long periods. However, all lots were rated considerably
better than either the commercially frozen or canned lots, as shown by
Table III. Before any definite conclusions may be drawn, further storage

tests at each of the temperatures should be made.

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_ 14 -

Results of Different Types of Packs in Various Types of Containers:

In these investigations asparagus packed in two per cent salt brine
was much superior to asparagus soaked one—half hour in two per cent
salt brine and then packed dry, or than that packed dry without any
previous flavoring. This is evident by the general ratings given in
Tables IV, V and VI. The flavor of brine pack proved to be much superior
to the other packs, including the commercially frozen and canned lots.

It is evident that when a brine pack is used the effects of various types
of containers are reduced markedly.

Unwaxed paper containers when filled with brine did not furnish
a desirable type of carton, due to soaking of the paper, resulting in
a lack of support. Paper containers with snap covers did not prove
satisfactory when brine was used, as the expansion due to freezing
stretched the side walls and loosened the Covers. Containers with
sloping side walls proved difficult to pack, lacking fullness at the
large end; therefore the capacity of the container was not used to its
fullest extent.

The lot of asparagus packed in the cellophane wrap showed signs
of considerable desiccation and the asparagus possessed a peculiar flavor
imparted by the wrapper.

When asparagus was packed dry, the superiority of airtight or near-
airtight containers was clearly evident, as shown in Table V. Also the
ratings given these lots (those packed dry in airtight or near-airtight
containers) were higher than that of the commercially frozen lot, as

shown in Table VI.

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_ 15 -

Discussion

In view of the fact that asparagus for these experiments was
taken from fertilizer test plots, one might possibly question the
homogeneity of the chemical composition of the lots. Investigations
on the effect of freezing on the vitamin C and A content of green
asparagus by Fellers, Young, Isham and Clague (17) show that variation
in the amount of potash and nitrogen used in fertilization did not
appreciably affect the vitamin C and A content. The antiscorbutic
ratings showed asparagus receiving high nitrogen fertilization was
slightly better than that from a normal completely fertilized plot, the
latter being somewhat better than asparagus grown under high potash
fertilization.

It is commonly thought that asparagus becomes tougher as the
cutting season progresses. MacGillivray (27) has shown that toughness
of the stalks may occur at the beginning of the season as well as near
the end or vice versa. He also found that the toughness of the sections
of the asparagus did not correlate with the advance of the season. He
did find a correlation between the number of days it took to produce
a seven-inch spear and the toughness of the stalks, and that as the
spears increased in diameter there was a very slight increase in
toughness. The asparagus used in these investigations was comparatively
uniform in quality throughout the season.

Bisson, Jones and Robbins (7) experiments showed that asparagus
deteriorates in quality soon after harvest due to the loss in reducing
substances and total sugars, also an increase in fiber under ordinary

room temperatures. To avoid these types of deterioration, the asparagus

_ 16 _

used in this experiment was out early in the morning, washed, graded,
and trimmed immediately and then placed in cold storage at 52° F. until
it was frozen in the low temperature cabinets, which in no case exceeded
five hours.

In blanching studies, it was found that lots slightly under-
blanched did not lose or vary in color. But with a decrease in blanching
time and temperature the intensity and undesirability of the aroma
increased greatly and also the desirability of the flavor decreased.
These results indicate an incomplete inactivation of the catalase and
ascorbic acid oxidase enzymes. These results follow very closely similar
results of Joslyn, Bedford and Marsh (22) with artichoke hearts.

Since the highest blanching temperature and the longest blanching
time at that temperature used in these studies gave the best quality
product, it is reasonable to assume that the upper limits for both
temperature and time may not have been reached. Furthermore, the low
blanching temperature employed in commercial canning operations (180° F.
for 5 minutes) used in the freezing, storage, pack and container studies,
may lead to misinterpretations of the data from these phases of the
investigation.

Experiments conducted on desirable freezing temperatures did not
indicate that severe temperatures of -20° F. or lower are necessary
for freezing asparagus. These results do not conform entirely with
those of Diehl (1), Carlton (8), Diehl and Berry (15) and Morris and
Barker (28). Woodroof (54) , (as) pointed out that where the heat
transfer is rapid, temperatures below 0° F. have no practical added

value.

The results obtained in this study would indicate a justification

_ 17 _

of Woodroof's conclusion; however, further experiments should be
carried out before definite conclusions are drawn.

Results of this experiment show that storage temperaturssof 0° F.-
10° F. are entirely satisfactory for a storage period of at least eight
months. It appears that a storage temperature of 15° F. is too high.
(The flavor and aroma developed an off condition.) These results are in
agreement with those of Carlton (8) and Diehl and Berry (15). Through
mechanical difficulties this lot was lost before an eight months sampling
could be made. Further investigations should be made before reaching
definite conclusions.

It is evident that containers with sloping side walls are very
unsatisfactory for packing asparagus tips as it is difficult to fill
the large end of the container, resulting in a loss in storage space.
Enamel lined cans sealed airtight gave the most satisfactory pack since
dehydration (due to low humidity in the storage room) was prevented.
However, they offer objections as there is a loss in storage space with
this type of container.

Unwaxed cartons also gave poor results due to dehydration and lack
of support when the brine pack was used.

A two per cent salt brine added to cover the asparagus in the
containers gave the most desirable product in all types of containers
used. This type of pack improved the quality of the asparagus consider—
ably when non-airtight containers were used. These results are in accord
with work of Diehl and Berry (15) and Tressler and Evers (52).

No apparent quality was added to the pack when the asparagus was
soaked one-half hour in two per cent salt brine, drained and then packed

dry, over that of asparagus packed dry without previous soaking.

_ 13 -
Summary

Studies on the blanching, freezing, storing and packing (types
of packs and containers) of frozen pack green asparagus are reported.

Blanching temperature of 204° F. for five minutes gave the
most satisfactory product. Lower temperatures or shorter blanching
periods at the above temperature gave a much less desirable pack.

Freezing temperatures of 10° F., 0° F., —1o° F. and —2o° F.did
not vary consistently. No temperature showed any advantage over the
other. The asparagus was frozen satisfactorily in low temperature
ice cream cabinets.

The asparagus stored at 0° F. and 10° F. showed no significant
differences at the end of four or eight months. At the end of four
months an off flavor and strong odor were present in the lot stored
at 15° F.

Containers with sloping side walls and unwaxed paper containers
were found wholly unsatisfactory for packing asparagus tips. Enamel
lined tin cans were found to be the most satisfactory containers.

This was particularly true with dry packed asparagus. Waxed paper
containers with tight covers compare very well with airtight cans
when brine was used. Cellophane bags proved to be unsatisfactory.

A two per cent (by weight) salt brine was found to be superior in
quality to a dry pack, or to a pack in which the asparagus was soaked
one-half hour in a two per cent salt brine before packing dry. No
difference in quality was apparent between the last two packs mentioned.

The above data show certain inconsistencies which should be checked
by further studies before definite recommendations for the handling of frozen

pack asparagus can be formulated.

 

1.

5.

7.

8.

9.

10.

- 19 -
Bibliography

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5:109. 1955.

Quick-Freezing of Asparagus. Ice and Refrigeration
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Western Canner and Packer Yearbook
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Birdseye, C. and Fitzgerald, G. A. - History and Importance of
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Bisson, C. S., Jones, H. A., and Robbins, W. W. - Factors
Influencing the Quality of Fresh Asparagus After It Is
Harvested. Calif. Agr. Exp. Sta. Bul. No. 410, 1926.

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Crist, J. W. and Dye, M. - The Association of Vitamin A With
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Cruess, W. V. — Commercial Fruit and Vegetable Products, pp. 688-

715. 1958. McGraw-Hill Publishing Co., N. Y.

I
r
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_ 20 -

Culpepper, C. W. and Moon, H. H. — Composition of the Developing
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Diehl, H. C. - A Physiological View of Freezing Preservation.
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Diehl, H. C. and Berry, J. A. — The Temperature Factor In the
Freezing Preservation of Fruits and Vegetables. Proc.
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Fellers, C. R. ~ The Effect of Processing on Vitamins In Fruits
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on the Vitamin C and A Content of Asparagus. Proc. Amer.
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Fenton, Faith andTressler, D. K. — Losses of Vitamin C During
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- 21 _

Fisher, A. R. - Progress in the Quick Freezing Methods.
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Joslyn, M. A. - Preservation of Fruits and Vegetables by
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1950.

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in Frozen Vegetables - Artichoke Hearts. Quick Frozen

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1955.

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revue- "

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“3.1-7: e"

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- 22 -

Plagge, H. H. - Preservation of Fruits and Vegetables in
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Tanner, F. H. and Oglesby, E. W. - Influence of Temperature on
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Food Res. 1:481-495, 1956.

In.» '

Tressler, D. K. - Preventing Changes in Stored Frozen Foods. 1

_. 071'

Food Indust. 5:410, 1955.

Tressler, D. K. and Evers, C. F. - The Freezing Preservation of

l‘ <

Fruits, Fruit Juices and Vegetables. The Avi. Publ. Co.

 

“DPT." .Tr.

New York, 1956.

Wiegand, E. H. - Experimental Results on the Preservation of
Fruits and Vegetables by Freezing. Oreg. Agr. Exp. Sta.
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Woodroof, J. G. - Microscopic Studies of Frozen Fruits and
Vegetables. Ga. Agr. Exp. Sta. Bul. 201, 1958.

Woodroof, J. G. - Comparing Methods of Freezing Fruits and
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Hort. Sci. 28:507-509, 1951.

- 25 -

Acknowledgements

I wish to express my appreciation to H. L. Seaton of the
Horticultural Department for suggestions and advice on the

organization of this manuscript.

The writer is indebted to Miss Ruth Griswold of the Home
Economics Department for conducting cooking tests, and suggestions

for a palatibility grading chart.

To the judges who assisted in judging and scoring the samples

during the cooking tests.

To the General Electric Company for providing machinery and

funds to make these investigations possible.

 

 

 

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