RELATIONSHIP OF INTERNAL TJMPERATURE
REACHED AND MAINTAINED BY VEGETABLES D73 NG BLANCHING
TO QUALITY RETENTION DURING FROZEN STORAGE

by

Jean Carstensen
h

A THESIS
(Submitted to the School of Graduate Studies of Hichigan
State College of Agriculture and Applied Science
In partial fulfillment of the requirements
for the degree of
Master of Science

Department of Foods and Nutrition
School of Home Economics

1950

 

 

 

 

 

ACKNO'. .‘LEDGXL'N T

The writer would like to express her
sincere appreciation for the expert and
sympathetic guidance of Dr. Pauline Paul.

She would also like to express her
gratitude for the efforts of the judging
panel, Olive Batcher, Haura Bean, Katherine
Gaffner, Ruth Ingalls and Anna Nae Redder.
Without their cooperation this study would

have been impossible.

f’ftri.? a2=)_
i 27,,

 

TABLE OF CONTENTS

Introduction IO...O.I00......5....OOOIOCOOOOICOIOOIIDO
RGViev, of Literature 0.0.0.0090390000.00....JIOOCOICOO

Relation of blanching to enzymes and keeping
qualities of frozen vegetables...................
Enzyme activity.
Effect of heat.
Index of adequate blanching.
Tune-temperature requirements.
Variation with length of storage.
Nature of enzymes
Early work.
Recent work.
Enzyme characteristics of different parts of
the plant.

Loss of Ascorbic Acid with blanching.............
Effect of freezing.
Extent of loss during blanching.

Blanching medium.................................
Effect of blanching on texture...................
Procedure.............................................
History of vegetables............................

Preparation for freezer storage..................
Blanching.
Hater.
Stemn.
Cooling and packaging.
Freezing and storage.
Temperature records.

Chemical and physical tests......................
Ascorbic acid.
Total solids.
Enzyme test.
Texture.

OI‘ganCleptiC testOOIOOOOOI'OOIIIQUOICOOOOOOOOOII.

13

15
16
18
18

 

Discussion of results................................ 23

Temperature reached during blanching............ 23
Increase with time.
Variation with size.
Variation in temperature of medium.
Difference in vegetables.

Palatability scores............................. 28

Broccoli.

General appearance.

Color.

Flavor.

Odor.

Texture.‘

General conclusions.
Cauliflower.

General appearance.

Color.

Flavor.

Odor.

Texture.

General conclusions.

Analysis of variance of the scores.............. l0
Broccoli.
Cauliflower.

Objective tests................................. Hi
Ascorbic acid determinations.
Broccoli.
Cauliflower.
Total solids.
Enzyme test.
Penetrometcr readings of texture.
Cauliflower.
Broccoli.

Smary and ConCluSions‘ooo‘oon.coco-coonooo-ooocoulloo 56

 

 

 

 

Graph

Table

NO‘UL-F‘UJN

 

FIGURES AND TABLES

Average Internal Temperature Reached by Broccoli
wring BlanchingIOIIOOOIIOOOOOOIIIOOOIODICOOOIOOI

Average Internal Temperature Reached by
cauliflower Du-ring BlanChingo o o O o o o o o o o o a o o o o o o o c 27

Mean Scores for Treatments - Broccoli............ 33
Mean Scores for Treatments - Cauliflower......... 39
Analysis of Variance - F Value................... Q3
Ascorbic Acid Content - Mg/lOO Gram (Wet Basis).. A6
Percent of Total Solids...-...................... i8

Peroxidase Blanching Test........................ 51

Comparison of Penetrometer Readings and Texture
Scores-Broccoli-0.0.0.0000.0DD-OOIIOOOIOOOCII... SLI-

Comparison of Penetrometer Readings and Texture
Scores - Cauliflower............................. 5

 

 

 

 

 

 

 

INTRODUCTION

Blanching vegetables prior to freezing refers to .
heating the individual pieces with boiling water or live
steam for a specified period of time. It is now established
as an essential practice in the preparation of vegetables
for preservation by freezing.

Evidence has indicated that the following benefits are
derived from blanching: 1.) partial or complete inactivation
of the enzymes, which of themselves or in conjunction with
air, cause poor texture, aroma and flavor during freezing
storage, 2.) wilting of the product so it can be more easily
packed, 3.) expulsion of gases that may promote oxidation,
L.) brightening or setting the green, yellow or red colors
in vegetables, 5.) washing and practically complete
sterilization of the fresh product and 6.) dissolving some
of the undesirable flavors in certain vegetables.

The heating that occurs in blanching, however, often
causes profound modification in texture and reduction in
the amount of aroma, flavor and soluble nutrients in
vegetables.

Therefore, there haVe been many studies conducted in
an attempt to develop blanching procedures which would

1

 

 

 

 

 

 

insure the advantages derived through heating, but which

would result in a minimum of the undesirable changes.
Attempts have been made to see what variations in blanching
practices would result in products of the highest quality.

The main objective of this series of experiments was
to determine the effect of the internal temperature reached
and maintained by broccoli and cauliflower during the

blanching process on the quality at Various intervals during

subsequent frozen storage. Different mediums and time

intervals for blanching were used to produce variation in

the internal temperature.

 

 

 

 

 

 

REVIEH OF LITERATURE

Although all investigators agree that blanching is
necessary in the preparation of vegetables for freezing,
there is much difference of oninion concerning the best
temperature, period of exposure and medium to be used in
blanching. Probably most of this difference of opinion
can be traced to the different objectives of the respective
investigators.

Relation of Blanching to Enzymes and
Keeping Quality of Frozen Vegetables

Enzyme Activity

 

Effect 23 Eggt. In the early investigations in the
field, most of the attention was paid to the relationship
of heating and enzymatic inactivation to keeping quality of
vegetables during frozen storage. As early as 1929, Kohman
(a?) pointed out that cooking vegetables enough for serving
stopped respiratory processes and preserved the flavor of
the vegetable in freezing storage. Joslyn (hO) was also
among the first to report that Certain vegetables heated
through blanching and packed in brine were successfully
preserved by freezing, but similar samples not scalded

deteriorated in appearance and flavor. At this time, he

3

 

 

 

 

 

attributed this deterioration to the action of certain

ripening enzymes, which low temperatures retarded but did
not entirely inhibit. Woodroof (87) observed that although
freezing greatly reduced most biological action, it did not
entirely prevent respiration processes that resulted in loss
of fresh flavor, aroma and color. At this time, he predicted
the possibilities of preliminary scalding or blanching of the
raw product as a solution to the problem of enzymatic
inactivation. Tressler (77) stated that vegetables blanched
and quick-frozen were found to retain their fresh flavor
even when stored for long periods of time.

lgggg 2f adeguate blanching. Following these early
reports, there were numerous studies conducted to determine
what enzyme could be used as an index of adequate enzyme
inactivation. Diehl (28) indicated that there was a definite
correlation between heat penetration and catalase activity.
He suggested that scalding sufficiently to destroy catalase
would prevent enzyme deterioration. Later, Tressler et a1.
(81) agreed with these findings.

Smart and Brunstetter (72, 73) found that when scalding
resulted in the practically complete destruction of catalase,
satisfactory packs of lima beans, spinach and kale could be
expected.

However, Alrighi, et a1. (3) stated that it was

necessary to heat at a higher temperature than that required
L

 

 

 

 

 

 

attributed this deterioration to the action of certain

ripening enzymes, which low temperatures retarded but did
not entirely inhibit. Woodroof (87) observed that although
freezing greatly reduced most biological action, it did not
entirely prevent respiration processes that resulted in loss
of fresh flavor, aroma and color. At this time, he predicted
the possibilities of preliminary scalding or blanching of the
raw product as a solution to the problem of enzymatic
inactivation. Tressler (77) stated that vegetables blanched
and quick-frozen were found to retain their fresh flavor
even when stored for long periods of time.

gnggg g: adequate blanching. Following these early
reports, there were numerous studies conducted to determine
what enzyme could be used as an index of adequate enzyme
inactivation. Diehl (28) indicated that there was a definite
correlation between heat penetration and catalase activity.
He suggested that scalding sufficiently to destroy catalase
would prevent enzyme deterioration. Later, Tressler et a1.
(81) agreed with these findings.

Smart and Brunstetter (72, 73) found that when scalding
resulted in the practically complete destruction of catalase,
satisfactory packs of lima beans, spinach and kale could be
expected.

However, Alrighi, et al. (3) stated that it was

necessary to heat at a higher temperature than that required

a

 

 

 

   

 

to inactivate the catalase to insure a product of good

quality. Joslyn (#2) concluded that in general, if the
scalding treatment was not sufficient to inactivate the
catalase and peroxidase, frozen vegetables would develop
off-flavor. Conversely, processed samples off in flavor,
contained active enzymes. 0f the two, peroxidase more
closely paralleled the off-flavor formation than did
catalase.

Bedford and Joslyn (7) found that in frozen green beans
the catalase activity and acetaldehyde content decreased as
the quality of the product improved, but they were not a
reliable index of flavor retention. The ascorbic acid
oxidase activity closely paralleled that of catalase. They
maintained that peroxidase activity would serve as a better
index of quality than would catalase activity.

Joslyn and Harsh (Ah) determined the correlation between
catalase inactivation and flavor retention to discover
whether complete inactivation of peroxidase and ascorbase
and phenolase was necessary. They observed that even though
vegetables gave a positive catalase and peroxidase test,
they retained flavor and texture for short storage periods.
It was difficult to correlate the qualitative enzyme tests
with keeping quality over short periods of time. However,
quantitative data on enzyme activity indicated that complete
inactivation of both peroxidase and catalase was obtained

in samples judged to be best in flavor for certain vegetables.
:

I

 

 

 

 

 

 

Kertesz, Dearborn and Mack (ab) concluded that the

most desirable duration of time for blanching peas was
established by a determination of the catalase activity in
the vegetable. Heating required to inactivate the catalase
also inactivated the ascorbic acid oxidase.

In l9h0, Diehl (21) studied the quantitative relation
between the activity of phosphotase enzyme and the retention
of quality of asparagus during freezing.

In very recent years, there have been further studies
to substantiate the findings of these earlier investigators.
Masure selected peroxidase as his index of adequate blanchr
ing (56). Cruess and Smith (18) in an examination of
frozen fruits and Vegetables on retail markets in central
California used peroxidase and catalase enzyme tests to
check on adequacy of blanching. The authors believed that
blanching should be long enough to inactivate the peroxidase
enzymes. In their estimation, it was not enough to merely
inactivate catalase by blanching.

Campbell (12) recommended catalase test for peas. In
his experience, peas exhibiting a negative test for catalase
activity never exhibited abnormal color when properly stored.

In the latest available report, Fitzgerald (33) stated
that enzyme catalase, which he considered the chief offender
in poor quality in storage, could be inactivated at a lower
temperature than enzymes such as peroxidase. However, in
the case of green beans and asparagus, inactivation of the
latter enzyme was exceptionally important.

6

 

Time—Temperature requirements. Following and concurrent

with.the work determining what enzyme could be used as an
indication of adequate blanching, there were many studies on
the time and temperature of blanching needed to inactivate
these enzymes and maintain the quality of frozen vegetables.
The earlier investigators recommended longer periods of
blanching than are now being used, either because of their
anxiety to completely inhibit all enzyme activity in the
vegetable or for some other objective. Recently, more
emphasis has been placed on determination of the extent of
inactivation required.

Joslyn (MB) found that blanching peas, string beans and
asparagus for sixty seconds in steam made possible flavor
retention during freezing storage for more than one year.

Diehl (20) stated that at low blanching temperatures,
(200°, 180° and 160° F. ) even for comparatively long periods
of time, the catalase in peas was not inactivated, with
subsequent deterioration in color and flavor, even at 0° F.
storage. However, negative tests were consistently obtained
with exposure as short as thirty seconds at boiling temper-
ature.

Smart and Brunstetter (72) found that scalding for two
minutes at 212° F. or twelve minutes at 190° F. would
inactivate the catalase enzyme of lima beans.

Joslyn and Harsh (uh) said that there was considerable
difference in flavor and odor in ranges of blanching

7

 

tenmperature from 1680—1710, from 1760-18;0 and from 1900—

2120 F. Samples of spinach and peas blanched in the lowest
range were of poor color, odor and flavor after two year's
storage. Those blanched at temperatures over 188° F. were
satisfactory in color and flavor. Later work with green
beans, (Bedford and Joslyn, 7) Substantiated these findings.
Green beans blanched below 80° C. developed undesirable
odors, flavors and color during storage. Between 850-900 C.,
there was best retention of quality. Above 95° 0. most of
the samples lost their string bean flavor.

Arighi, et a1., (3) obtained a satisfactory product by
scalding peas for two minutes at 800-900 C. This was at a
higher temperature than that required to inactivate catalase.
Peas blanched for various periods of time at lower temper-
atures were all found to be undesirable in color, odor and
flavor.

Investigators have not overlooked the objectionable
changes caused by overblanching. (3, 8, l9, h3, 72, 86, 88)
Overblanching caused cooked odors and flavors and mushy
textura.not usually associated with frozen vegetables. These
increased as the temperatures increased.

There seems to be a critical temperature range below
which the formation of off-flavor is not entirely inhibited
and the color is not "set". Above that temperature, there
is a loss of fresh flavor, formation of a cooked flavor, and
softening of texture. The temperature apparently is different

8

\ IA--~ c. ““2... .

 

 

 

 

for' different vegetables, increasing with the intended

storage periods.

Variation EEEB length 2: storage. Variation of the
enzyme inactivation and the length of storage was mentioned
by Joslyn (42). He stated that complete inactivation of the
peroxidase was not necessary for storage of three to seven
months at 0° F., but most of the initial activity must be
destroyed. Masure (56) also mentioned the possibility of
blanching in relation to length of time the product was to
be held in freezer storage.

The results of Woodroof's work (88) showed that the
quality of vegetables considered to be underblanched could
be maintained for a short period - three months in this case.
After this, there was a rather rapid loss of quality, and at
six and nine months, the vegetables that were adequately
blanched were higher in quality.

(Nature 22 Enzymes

Most of the blanching procedures were introduced before
there was much information available as to the nature of the
enzymes involved, the substrates acted on, and the products
formed. There were some early studies on enzymes themselves,
but it has only been in comparatively recent times that
extensive investigations have been conducted.

@2311 £233. Typical of the early work was that of
Kohman (A?) Who believed that changes in flavor during
freezing were brought about by a process of anaerobic respir-

9

 

 

 

atiLui and more directly by resoiratory enzymes. They based

this on the fact that during freezing, macerated vegetable
tissues act as a barrier to the penetration of oxygen to
the sound tissues underneath, which then undergo anaerobic
respiration. This view was not entirely in agreement with'
Tressler (77), who stated that most enzymatic changes in
foods Were both oxidative and hydrolytic in nature.

Joslyn and Marsh (A3) agreed with both of these invest-
igators. They said that the chemical changes in flavor and
color were due to oxidation, largely arising through the
oxidizing enzymes, and changes in flavor were due to anaerobic
respiration and other causes. In 1938, Joslyn (kl) pointed
out that enzymes had been found to be unaffected by exposure
to 10West temperatures investigated (liOOO below 0° F.) and
many of them were extremely active. He claimed that enzymes
must be inhibited by preventing the necessary combination
between all constituents of the enzyme-substrate system or
by destroying one or more of the components of the enzyme by
heat. Lineweaver (52) concluded that a study of the energy
of activation of enzyme reaction should make it possible to
predict the nature of major changes during storage. Diehl
(21) ascertained the stability of proteins present in peas
under freezing storage conditions. He found various reactions,
some varieties of peas showing protein decomposition and
others protein stability under the same storage conditions.
He considered the possibility of development of undesirable

10

 

 

 

 

 

 

flavors as being due to changes in the fatty constituents

of peas.

Recent work. However, not until 1942, did Balls (h)

 

conduct investigations into what actually happens to enzymes
during blanching and freezing. He believed that all enzymes
are proteins and consequently the problems of destroying
enzymes by heat and the effect of heat upon proteins were

the same. Heat denaturation and inactivation of the protein
occurs when foodstuffs are blanched. However, Balls also
pointed out that protein denaturation is not always permanent
and the protein may revert on cooling to its native state.
This would account for the reactivation of peroxidase
discovered by many investigators. (8, 22, 71, 88)

Balls (4) and Proctor (68) both remarked that although
catalase and peroxidase tests were commonly used for adequacy
of blanching tests, these two enzymes were not necessarily
those that caused the development of undesirable changes
during frozen storage. These are merely indicators and not
necessarily the actual damaging enzymes. Balls pointed out
that in normal vegetable tissue, the enzyme system is extremely
complex and that the undesirable colors, odors and flavors
may be due to any disruption and accumulation of intermediate
products in the long chain of biological oxidation. He.
concluded that total destruction of enzymes is usually not
practical nor for ordinary purposes is it necessary. This
is in agreement with Diehl, et a1., (22) who, in 1936: said

11

 

thaj; recovery of enzymatic factors in peas after scalding

was 110t industrially important.

In l9h3, Phaff and Joslyn (o3) emphasized the necessity
for selection of the proper indicator for an enzyme test.
Indicators of enzyme activity differ in their specificity,
ease of oxidation and other properties. Since the relative
peroxidase activity toward indicators varies with vegetables,
there must be discriminate application of peroxidase reagents
in testing for adequacy of blanching. Joslyn (AB) said it
was necessary to select proper indicators for particular
vegetables tested. Not only did the relative activity of
the peroxidase of a particular vegetable tissue vary with
the indicator used, but the apparent ease of thermal
inactivation of the enzyme. Only reagents giving a strong
positive reaction in unblanched tissues and a negative
reaction in tissues blanched sufficiently for flavor
retention are suitable.

Another comparatively recent investigation is that of
Rosoff's and Cruess' (71). It was mainly a study of the
peroxidase and ascorbic acid oxidase in cauliflower. They
found that purified ascorbic acid oxidase and freshly expressed
cauliflower juice catalyzed the oxidation of ascorbic acid
by molecular oxygen and by hydrogen peroxide.

Some studies have shown that different parts of single
vegetables have different enzyme characteristics, Which must

12

 

'be cxxrne in.mind when making blanching tests. Hergentime

(inf) said peroxidase activity of baby lima beans was quite
strong in the skin, but weak:in the cotyledon, while the
catalase reaction of the cotyledon was strong.

Phaff (63) said that peroxidase was the most active in
those portions of the tissues where respiratory and other
metabolic processes were greatest.

Rosoff and Cruess (71) found that peroxidase in cauli-
flower was mostly concentrated in vascular layers, in the

pidermal layer beneath the skin and in the flower buds.
The parenehyma had comparatively little peroxidase activity.
Loss of Ascorbic Acid with Blanching

There have also been many'studies to determine the loss
of nutrients during blanching. The vitamin C content has
been most often used as a or terion of nutritive value of
vegetables. It is the most easily destroyed and if retained,
probably indicates that the other vitamins also are present.
Effect 2: freezing

Apparently freezing in itself does not adversely affect
the ascorbic acid content of vegetables, if the vegetable
has been sufficiently blanched. (3, 25, 28, 75, 85, 88)
However, if the vegetables have not been previously blanched
sufficiently to inactivate the ascorbic acid oxidase, there
will be considerable loss of ascorbic acid due to the
action of this e zyme. (27, S7, 39, h5, h6, SS, 57, 76)

13

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Extent of loss during blanching

‘Most investigators have found that in the blanching
process preparatory to freezing loss of ascorbic acid may
occur. Fellers (29) said that the loss may often be as
much as 50% in peas and lima beans. Later workers found
smaller losses. Tressler, et al., (81) found that loss of
vitamin c during blanching in itself resulted in 103 less,
and during the whole processing the total loss was
approximately 303. These closely approximated the results
of Fenton and Tressler (31) who found a 383 loss in peas-due
to blanching, chilling and packaging.

Batchelder, et al., (6) made an extensive study of the
effects of blanching on vitamin C. Although they found that
there was no loss of ascorbic acid during scalding and
freezing of asparagus, peas retained only 75% of their
ascorbic acid and broccoli retained approximately 50$ and
70¢,with water and steam scalding respectively. Todhunter
and Robbins (76) showed that the process of scalding peas
in boiling water for one minute and cooling in water caused
a loss of 30-373 of the ascorbic acid present in the fresh
state.

Farrell and Fellers (28) found a 33¢ loss in ascorbic
acid in fresh green beans due to blanching. Gleim, et a1.,
(35) studied the effect of blanching on asparagus and
Spinach. In general, the spinach lost a greater percentage
(63$) than did aSparagus (Ski). With cauliflower, Kaloyereas

1
la

 

U+5) found that blanching in boiling water for 2% minutes

resulted in an 18.3% loss of ascorbic acid.

As the period of blanching is increased, there is
greater loss of ascorbic acid, probably due to the leaching
of the vitamins into the blanching medium. (1, A6, 39, 55,
59, 82)

Most of the reports in literature have been on the
losses occurring during commercial freezing. Phillips and
Fenton (6h) indicated that the same trends were witnessed in
home freezing. They found that blanching beans in boiling
water for two minutes resulted in loss of 13% of the ascorbic
acid. The total loss of the vitamin during freezing procedure
was about 20%. Retzer,et al., (69) indicated that the loss
in the freezing preparation of cauliflower was 18% or 19%,
for steam and hot water blanch respectively.

Blanching Medium

Some investigators have stated that the medium used has
no effect on the subsequent quality of the frozen vegetable.
They claimed there was no marked difference whether steam or

.hot water was used. (19)

It is generally agreed that boiling water scalding
destroys the natural enzymes present in vegetables more
rapidly than does steam blanching. Steam blanching, there-
fore, requires a longer period of time than does water
scalding. (6, 2);, 38, 69)

Some workers have claimed though that in hot water

15

 

 

 

blaxuihing more of the nutrients are leached into the medium

than into steam. iI."ner<:i‘.')'.r‘e, steam blanchinr is to be
preferred even though it requires a longer period of time.
(8, 11, 27, 37, 61, 81, 86, 88)

Some workers have found various results for different
vegetables. Thus Batchelder, et al., (6) found no signifi-
cant differences in palatability and ascorbic acid retention
between water-scalded and steam-scalded frozen asparagus. On
the other hand, peas that had been water—scalded retained
more natural flavor and ascorbic acid during storage than
did the steam-scalded samples. Steam scalding of broccoli
gave a more palatable product with higher ascorbic acid
retention than did water scalding.

The work of Retzer, et a1., (69) indicates a possible
relationship between the divergent opinions. They found that
immediately after blanching, the stemn—blanched cauliflower
contained a significantly larger amount of ascorbic acid
than that blanched in hot water. However the steam blanched
product lost a larger amount of ascorbic acid during the
cooling process. Results indicated there was no significant
difference between the two methods when cooling was also
taken into consideration.

Effect of Blanching on Texture

Worth noting is a special study conducted at Ohio State
University to show if the type of blanching was an important
factor in the tenderness of frozen beans. (2) Here they

16

 

,0

 

 

used a texture-meter, which read the pounds of pressure

required to pass through an 30 gram sample of green beans.
They found that blanching in steam produced a much more
tender product than blanching in boiling water. There was
an apparent correlation between readings on the texture-
meter and organoleptic scores.

Lee (51) has found the tenderometer prominent as an
instrument to be used for the determination of the quality
of raw peas. Jenkins and Lee (38) used the same instrument
and found that it had decided advantages in indicating the

tenderness or quality of asparagus.

17

 

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fire

          

PZOCCD"HE

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history of Vegetables
The broccoli and cauliflower were nurchased from the
college food service denartment, After delivery, the un-

trimmed heads were packed loosely into crates and held at a

O F. until reacv for use.

0

temperature of aufiroxinately h
Since the vegetables were received in large quantities, it
was necessary to hold some of them for one or two days before
they could be used. Broccoli and cauliflower, used as fresh
control samoles during the study, were purchased from the
local market.

In preparation for freezing and cooking, the broccoli
was cut into h% - 5% inch lengths and trimmed to remove the
attached leaves. The smaller inner leaves were not removed
but the leaves extending beyond the head were cut back. The
stalks were split and soaked in salt water for approximately
one half hour to insure removal of adhering bugs and worms.
The cauliflower heads were trimmed, thoroughly washed and
separated into flowerlets.

" .3.

Preparation for Freezer storage

Blanching

 

Hater. The samples of vegetables to be blanched in hot
water were weighed, placed in a galvanized wire basket and
immersed in an enamel kettle containing boiling water.

18

'LhL—r

 

 

 

 

Enough of the vegetable was blanched at one time to fill two

packages for frozen storage-—6SO grams of broccoli or 800
grams of cauliflower. Three gallons of boiling water were
used for these amounts. The broccoli was blanched for lg. 3
and 5 minute intervals in the hot water; the cauliflower for 2,
4 and 6 minute intervals. The water returned to boiling
temperature in the 5 minute blanch period for the broccoli,
and in the 4 minute blanch period for the cauliflower.

.§E§E§° The samples to be blanched by steam were placed
on a wire franc, which was supported on an iron rack approx-
imately two inches above the boiling water. Only enough
broccoli or cauliflower to fill one package for freezer
storage was blanched at one time. The samples of vegetables
were distributed as evenly as possible over the wire frame,
to facilitate the circulation of steam around eace piece.

The broccoli was blanched for 25, 5 and 7 minutes, and the
cauliflower for 3, 6 and 8 minutes in steam.
Cooling and packaging

Immediately after blanching, the vegetables were cooled
in cold running tap water. 'After draining, the vegetables
were removed from the basket, placed on towels to remove excess
water, and packed in pliofilm bags, which were protected by
cardboard boxes. These bags were sealed with a rubber band
and the packages were placed in a quick-freezing unit.
Ereezing and storage

After a minimum of twenty-four hours in the freezing

unit, the frozen vegetables were transferred to freezer

l9

 

storage, either at the local locker plant or in a SGOTaOe

cabinet in the laboratory. The vegetables were held for
1%, 3 and h months in storage, when they were removed for
sampling.
Temperature records

The temperature reached internally by the samples of
vegetables during blanching and cooling was determined by
means of a potentiometer. Copper-constanten thermocouples
were inserted 1) into the blanching or cooling medium, 2)
into the base of a com,aratively larger or medium-sized stalk
or flowerlet and 3) into a comparatively small stalk or
flowerlet. The extremes in size were selected so as to
give a representative picture of the range in internal temp-
eratures reached by vegetables during blanching. The temp-
eratures reached in these respective places were recorded on
a revolving drum inside the potentiometer. Later, these
charts were removed, and the final temperatures read and
recorded.

Chemical and Physical Tests

Ascorbic Aggg

Samples of fresh, fresh cooked, blanched, blanched and
stored, and cooked frozen vegetables were tested for ascorbic
acid content. In all tests, care was taken to maintain the
proportion of stem to flower that would be typical of the
vegetables prepared for serving. The method of determination
was that of Loeffler and Ponting. (53)

2O

 

 

 

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v) . ..... MM”, u-AIVWHLWT‘.‘

HWhQIfiAQE

 

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Total Solids

Total solids were determined using a semi-automatic
moisture testerl. These tests were run concurrently with
ascorbic acid determinations and on the same samples.
Samples were selected to get a representative portion of
stems and flowers. These vegetables were finely cut up,
weighed and placed in the moisture tester for two hours or
until half hour reading checked within 0.05%. This never
required more than two and one half hours.-

Enzyme Test

The qualitative test for peroxidase developed at the
Western Regional Laboratory was used. (83) Tests were made
on the samples immediately after blanching and at the end of
the final storage period.

Texture

Samples of freshly blanched and cooked frozen vegetables
from one replication in each test period were tested for
texture using a penetrometer2. Representative stalks and
flowerlets were selected for sampling. These samples were
Dlaced on a cork on the penetromcter platform, with the cut
surface of the vegetable resting on the cork. The texture
was measured by the depth, which a cone-shaped piece of metal
would penetrate into the uncut side of the stem in two

seconds. The total load using the cone was 150 grams,

 

1. Brabender Moisture Tester
2. Micrometer Adjustment Penetrometer

21

 

‘

fie. :31. z

 

 

(needle bar, h7.§ grams, and cone, 102.5 grams). The two

second penetration thee was selected because it would be
comparable to the almost instantaneous penetration experien-
ced in biting. Three readings on three different stems were
recorded.

Organoloptic Test

The cooked vegetables, at the different testing periods,
were judged for palatability by a panel of five judges. The
judges were all members of the Foods and Nutrition Department.

The test periods were at the beginning of the study and,
at the end of one and one half months, three and four months
of frozen storage. Three replications were conducted at each
testing period.

The following palatability factors were judged: 1.)
appearance, 2.) color, 3.) flavor, h.) odor and S.) texture.
The general conclusion score was the judge's over-all reaction
to the vegetable, and not an average of the other factors.
The score cards also showed whether the product was accept-
able or unacceptable on the basis of palatability. The
judges were asked to record any comments they had on any
particular product.

A sample of the score—card used in the study is shown

on page i in the Appendix.

22

 

 

a“. ittVr¢1rIPVIuv (1.1mm: LPN).

.3.“ *0. *1! .I I

 

 

 

DISCUSSIO‘ OF RESULTS

L

Temperatures Reached During Blanching

The average results of the potentiometer for each blanchr
ing treatment are presented in Figures 1 and 2 on pages 26
and 27. A complete set of recordings is included in the
Appendix on pages 11 and 111.
Increase with 31mg.

The records of the potentiometer showed that as the
blanching time increased, the internal temperature reached
by the vegetable also increased. The longer the time was
extended, the closer the values for the internal temperature
and the final medium temperature coincided. With the longest
periods of time used, both in steam and hot water blanching,
the temperatures of the vegetable and the medium were at or
very near the boiling point of water. The recordings from
the potentiometer showed the internal temperature gradually
increased from the time the vegetable was immersed in the
medium until it was removed or until it had reached 2120 F.
Variation Kipp gigg.

Within the time intervals, the temperatures reached
by the smaller and larger pieces of the same vegetable varied.
The smaller pieces approached or reached the temperature of

23

u

 

 

H. u,. ,. IL!

 

‘1 ii It .1

 

 

J

the blanching medium more often and more quickly shah the

larger pieces. The difference between the internal temp-
eratures of the large and small sizes diminished with increase
in blanching time. With longer times, the smaller pieces
reached the temnerature of the medium and the temperature

rise was stopped; whereas, the larger pieces still had not .
completed the climb before they were removed from the medium.

Variation in temeerature 23 medium

' T'D‘EJE‘

 

 

“he.

The recordings also indicated that the medium used
caused some variation in internal temperatures reached.

The vegetables blanched in steam required a longer time to
reach similar internal temperatures than those blanched in
hot water. This can be traced to the differences in the
range of temperature of the medium, itself. As indicated
by the graph, the range in temperature of the water was
very slight. Addition of the cold vegetables did cause a
slight drop in the temnerature of the water. During the
longer blanching periods, the temperature returned to the
boiling point.

The addition of the vegetable to the steam caused a
sharp decline in the temperature of the medium. The return
to the boiling point was much more gradual and took a longer
period of time. No matter how quickly the vegetables were
hmnersed into the steam, considerable steam escaped into X
the room before the cover could be replaced on the blanching t
container. This and the addition of the cold vegetables were R

21L

 

the causes of the drop in temperature of the steam.
Difference in Kgggtables

Both broccoli and cauliflower followed the same trends,
as indicated above. The differences in blanching times
selected probably account for the differences in the internal

temperatures reached.

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27

 

 

 

Palatability Scores

Broccoli
The mean scores for the broccoli in each test period
are presented in Table l on page 33.

General Appearance. With short storage periods (1% and

 

3 months), the general appearance of the broccoli blanched
for the shortest period of time and to the lowest internal
temperature was preferred over those blanched for longer
intervals. As the blanching time and the internal temp-
erature increased, there was some loss in color and texture
changes that were detrimental to the general appearance of
the vegetable. However, with the four month storage period,
although the trend still held for the steam-blanched samples,
the scores for the t ree water-blanched samples were closer
together and not much preference was indicated.

The scores sh wed that tiere was not much deterioration
in general appearance of frozen broccoli during short
storage periods.

The general appearance of the hot water blanched
vegetables seemed to be preferred over those vegetables
blanched by steam. This was especially true of the longest
blanching periods.

Throughout the study, the cooked frozen vegetables were
compared to freshly cooked vegetables. This was done in
two ways: 1.) Comparison with freshly cooked vefetables from
the same lot as the frozen samples at the beginning of the

28

 

 

 

 

n'

, Hfinrnir nun. TV... .. i M...

ll

E
1 ‘

     

study and 2.) compcrison with fresn vegetables purchased and
cooked at each testing period during the study.

With the exception of the seven-minute steam treatment,
frozen broccoli compared favorably_with the general appearance
of the freshly cooked vegetable from the same lot. The
setting of the green color during the blanching period acts
as a factor in preserving a good appearance. The fresh g
broccoli, purchased and cooked during the stuoy and used as ;
a control, was a different structural appearance and not of
equal fresh quality wit: the broccoli frozen for storage at
the beginning of the study. The general appearance of
frozen broccoli was rated higher than the fresh broccoli
purchased during the winter months of the study.

legg. Since color probably was one of the largest

factors used as a criterion in Judging general appearance,

 

many of the same trends were observed in the ratings.

The lowest scores Occurred in the ratings of the color
of the vegetable blanched for the longest period of time in
both media. Long blanching periods produced undesirable
changes in color, turning the color to an almost olive
green in the case of the broccoli blanched for seven minutes
in steam to an internal temperature of 2120 F. The low score
given to the five-minute steam-blanched vegetable during the
four month storage testing period, can be traced to a
prejudice of one of the Judges against this sample.

29

 

 

 

 

 

Storage for four months had little affect on color.
Most of the samples maintained approximately the same score
throughout the storage periods.

Hot water blanching was better for producing desirable
cdlor than was steam blanching.

The color of the frozen vegetable rated hiéher than the
celer‘ of fresh broccoli purchased during the winter months
from the local market.

Flavor. The flavor of the broccoli blanched for 1%
minutes in hot water to an internal temperature of 180.50 F.
was judged the highest during all storage periods. The mean
scores which this sample received were closest in value to
the mean score given the fresh broccoli at the beginning of
the study. For short storage periods, longer blanching
periods do not appear to be necessary for flavor retention.

The hot water blanch was more desirable than the steam
blanch for maintaining the flavor. The longer time intervals
used in the steam-blanching could be responsible for greater
loss in flavor.

Storage for this short period of time had little effect
on flavor. The vegetables blanched to an internal temperature
closely approaching that of boiling water lost more of their
flavor during storage than the vegetables blanched to a
lower temperature.

By their scores, the judges indicated a preference for
the flavor of frozen broccoli over the vegetable purchased

30

 

 

 

 

 

and cooked as a control during the study. Again, it must

be remembered that the structural characteristics of the
broccoli were different except for the last storage period.
The stalks and clusters of buds were comparatively smaller
and different in appearance.

gggg. The shortest blanching period in hot water seemed
to be best for preserving desirable odors. The greatest drop
in odor ratings during storage occurred in the 22 minute
steam blanched sample. Results of enzymatic tests showed
that the peroxidase enzyme was not inactivated in this sample.
Longer storage periods might show an even greater decline in
the scores given odor. Storage seemed to have little effect
on the odor of the other samples.

The palatability scores for odor indicate that the odor
of hot water blanched vegetables was preferred to steam
blanched broccoli. None of the scores for odor compared to
the scores given to the freshly cooked samples at the begin-
ning of the study. However, the odor was rated higher than
the vegetables purchased during the study.

Texture. Throughout the study, the broccoli blanched
to the lowest internal temperature generally rated higher
than did the broccoli blanched to higher internal temperatures.
Although the cooking times were shortened for the vegetables
that were blanched for the longer times, the variation in
texture was still noticeable.

Storage had little effect on texture scores. Most of

31

If“ "“"

 

 

 

 

the vegetables maintained approximately the same texture

scores during the entire study.

whether the vegetable was blanched in hot water or
steam produced little difference in the scoring results.

In comparison to freshly cooked broccoli, the texture
of frozen cooked broccoli was either equal or slightly beIOW.
Freezing apparently did cause some modification in texture
desirability.

General Conclusions. The scores given under general
conclusions were a reflection of he trends witnessed in the
judging of the other factors. For short storage periods, the
broccoli blanched in hot water for one and one half minutes
was preferred consistently over the other samples.

Scores given to broccoli blanched in hot water were on
the whole, higher than scores given to comparable samples
blanched b7 steam.

Storage had little effect on the scores given to the
vegetables, with the exception of broccoli, blanched in steam
for 5 minutes. A prejudice by one of the judges lowered
the mean score considerably at the h month storage period.

The frozen broccoli did not rate as high as the fresh
broccoli judged at the beginniig of the study. However, it

rated higher than fresh broccoli purchased from the local

market during the winter months.

firaauf.~_’lw-.__(::_:i;." b

.-....

 

 

 

   

 

Table 1

Mean Scores for Treatments — Broccoli

 

Kean Scores Fresh Broccoli - Before Freezing
Gen'l Color Odor Flavor Texture Gen'l

 

 

 

Appear. Concl.
g.9 6.1 5.9 5.6 5.6 5.7
Treatment Av.int. Gen'l Color Odor Flavor Texture Gen'l
temp. Appear. Concl.

 

1% months storage

 

 

Fresh(control) h.3 h.7 L.6 “.0 4.g t g
Blanched & Frozen
Hot water OF. *
1% minutes 130.5 5.? 0.1 5.6 5.h 5.1 5.h
3 minutes 200.3 6.0 5.9 S.h 5.0 5.0 5.1
5 minutes 203.8 5.0 “.h 5.3 5.2 5.0 L.9
Stems
2% minutes 137.0 5.h 5.5 .1 5.0 5.3 5.0
5 minutes q0.31.0 5.3 3.4 W.L 5.0 4.9 5.0
7 minutes 212.0 H.2 L.2 M.7 H.3 L.2 fl.2
3 months storage
Fresh(control) 1.6 b.C ),g “.1 3.9 h.l
Blanched E Frozen
Hot water
1% minutes 190.5 {.0 6.1 5.5 5.5 5.1 5,5
3 minutes 200.3 “.d s.7 §.: 6.3 h.9 5.3
5 minutes 208.8 1.9 5.5 h.8 5.2 ”,0 5.1
Steam
2% minutes 137.0 5.5 5.6 h.0 3. h.8 6,1
5 minutes 2031.0 5. 3.8 5,2 5,1. 73,2 5,3
7 minutes 212.0 h.~ h.3 h.6 L.7 h.§ h.6
h months storage
Fresh(control) h.9 5.5 G,1 5,3 g,g _,o
Blanched & Frozen
Hot water
1% minutes 180.5 5.7 6.1 5.5 5.7 h.9 5.L
3 minutes 200.3 6.0 6.2 h.9 h.s A, 3,6
5 minutes 208.8 5.3 5.9 5.h h,9 h,Z 1,9
Steam
2% minutes 187.0 5.3 5.3 h.5 ).3 5.1 5.1
5 minutes 20h.0 h.8 h.6 h.0 h.h L.O h.1
7 minutes 212.0 5.1 h.8 h.h L.5 h.é 1.5

 

33

 

 

 

Cauliflower
The mean scores for cauliflower in each test period are
preserved in Table 2 on page 39,

General Appearance. The scores of cauliflower displayed

 

different trends than did broccoli. The medium blanching
period was consistently favored over the long and short
periods for both steam and hot water. The internal temp—
erature of the cauliflower was related to the blanching
time, showing a low, medium or high value with a short,
medium or long blanching period. Both short and long
blanching periods seemed to produce deleterious changes in
the general appearance of the cauliflower. The four minute
hot water blanch for cauliflower to an internal temperature
of 208.00 F. rated the hinhest, when general appearance was
concerned.

Using steam or hot water apparently produced little
difference in the mean scores for comparative blanching
periods. Nor did storage for the length of time used in
this study produce undesirable changes in general appearance.

In general, frozen cauliflower did not rate as high as
freshly cooked cauliflower. This applied both to the fresh
cauliflower cooked at the beginning of the study and to
that purchased from the local market during the study.

Color. As with broccoli, the color of cauliflower
apparently was the important factor in judging general

appearance. As the scores for general appearance varied,

3h

 

 

 

 

 

 

 

so did the scores for color. In most cases, the scores
varied less than O.h from the scores given general annearance.
The same conclusions about the mean scores can be given, as
those given above under general appearance.

Before cooking, several of the frozen samoles disnlayed
a pink discoloration. This was esoecially noticeable in the
cauliflower blanched for three minutes in steam. The ninkish
tinge was not noticeable in the cooked nroduct.

ngg. The scores given odor pivoted around the medium
blanching period and medium internal temperature. The long

blanching period, using both steam and hot water, nroduced a

 

noticeable lack of distinctive odor. In the Short blanching
periods, the odor was not as pleasing as those samnles that
had been blanched to the medium internal temperature. ”i
Whether steam or hot water was used, there were little 3‘
differences in the range of mean scores between the two
blanching methods .
Host of the samples deteriorated in odor quality with
storage. The greatest dron was w tnessed in the mean scores
of the 6 minute steam sample at the four month storage
period.
In general, the odor of freshly cooked cauliflower Was
better than that of the frozen samples.
Flavor. At the 1% month and 3 month storage testing
periods, the judges indicated by their scores that there
was a preference for the flavor of the cauliflower blanched in

35

 

'I
‘0 '$-..

 

hot water or for the 6 minute steam interval. At the
four-momth storage testing period, the mean scores of all
the samples were closer together and considerable lower

than the previous storage periods. This was especially

true of the water blanched samples. While for short storage

periods, water blanching seemed to insure better flavor

"Fl 31'

retention, longer storage seemed to equalize the scores for

o .p‘J.

the two blanching methods. The results indicated that long

a“ ...u.:- a... - wh-u.

blanching periods are not desirable for flavor retention.

'.

Worth noting was the rather erratic behavior of the 3
minute steam blanched vegetable. For the first two storage
periods, the mean score rated the lowest among the samples.
At the four month storage period, it was rated better than
several of the other samples. During the three month storage
testing period, at two out of the three replications, the
judges graded this product as being unacceptable. At the
four month storage period, it was again rated acceptable.
This was the only sample that gave a positive enzymatic
test, and the erratic behavior could be attributed to
unpredictable enzymatic activity.

Of the factors judged for palatability, the scores for
flavor were the lowest. Apparently, preparation for freezing
and frozen storage altered flavor more than any of the other
factors. This was indicated by comrarison with the scores
for flavor of the freshly cooked vegetable. The flavor of

the freshly cooked vegetable was consistently rated consider-

/

3o

 

 

 

 

 

 

 

ably higher than the frozen vegetable.

Texture. Texture scores indicated a different trend

 

than the scores for the other factors. Vegetables blanched

for the shortest period of time and to the lowest internal

temperature in either medium were judged higher than vegetables

blanched for a longer period of time. Although cooking time

was adjusted to allow for difference in blanching time, the

resulting scores indicated that there were still differences

in texture with the different blanching treatments. The
shorter blanching period gave a somewhat firmer cooked
product, which apparently was preferred by most of the
judges.

Storage affected the texture of the vegetable blanched
to a higher internal temperature more than it did the low
internal temperature samoles. Uhile texture scores for the
vegetables blanched for a short time tended to remain high
throughout the storage periods, the texture scores for the
medium.and long blanching period deteriorated in storage.

In comparison to the fresh vegetables scored at the
beginning of the study: texture scores of frozen products

were considerably lower. The scores also rated lower than

the scores for the freshly cooked cauliflower purchased from

the local market during the winter months of the study.

_general Conclusions. During the first two storage

periods, the water-blanched sam les and the sample blanched

in steam for the six minute time interval were judged to be

37

 

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9

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4‘1".

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'of better over-all quality than the vegetables blanched in
steam.for longer or shorter periods of time. However, by
the end of the study, blanching treatment caused small
differences in the judges' ratings. Storage, apparently,
tended to equalize any differences present early in the
storage. This was also noticeable in the ratings between

steam and hot water methods of blanching. Early in the study,

 

water blanched samples were judged better than steam-blanched
8am9163. This difference, also, decreased with storage. i

JUdgeS preferred freshly cooked cauliflower to frozen r
cauliflower. This preference was more noticeable as the

length of storage increased.

38

 

 

 

 

Table 2

Mean Scores for Treatments - Cauliflower

 

Mean Scores Fresh Cauliflower - Before Freezing

 

 

 

 

 

 

 

 

Gen'l Color Odor Flavor Texture Gen'l
Appear. Concl.
5.7 5.7 5’06 507 6.2 5.6
Treatment Av.int. Gen'l Color Odor Flavor Texture Gen'l
temp. Appear. Concl.
l%-months storage
Fresh(control) h.7 h.7 h.5 h.9 5.2 h.7
Blanched & Frozen
Hot water OF.
2 minutes 1790+ h.5 8.3 h.5 L.2 5.0 h.1
h minutes 208.0 5.2 5.3 h.g h.5 .0 h.5
minutes 211.8 a.7 h.7 h. h.5 1.7 h.6
Steam
3 minutes _ 192.2 h.7 h.7 h.0 3.2 h-S fi.5
6 minutes 211.h .3 5.1 5.2 h.7 .3 ,.8
8 minutes 212.0 L.2 h.3 h.3 3.8 4.1 3.8
3 months storage
Fresh(control) 3.7 5.6 h.8 5.1 5.4 5.2
Blanched & Frozen
Hot water
2 minutes 179.h h.h h.6 h.7 h.8 5.2 h.5
1 minutes 208.0 _.3 5.h h.9 h.2 h.h h.h
minutes 211.8 b.8 h.9 h.1 h.2 h.6 L.3
Steam
3 minutes 192.2 h-Z h.0 3'8 .1 a.7 .3
minutes 211.h 5.0 5.0 h. i.0 h.1 i.1
8 minutes 212.0 L.2 2.2 h.0 3.5 h.0 3.7
h months storage
Fresh(control) u.9 b.8 L.3 5.0 5.0 h.9
Blanched & Frozen
Hot water
2 minutes 179.h .h.2 h40 .h.0 Jul. h.8 h40
1 minutes 208.0 5.5 5.5 h.8 3.8 h.h M.2
8 minutes 211.8 h.1 3.7 3.5 2.9 .8 3.h
Steam
3 minutes 192.2 h.8 h.7 h.3 3.8 h.5 h.0
6 minutes 211.2 2.9 2.5 3.5 3.b 2.2 3.7
8 minutes 212. h.2 3.9 3.fi 3. h.l 3.0

 

.41 __._.M
p.
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Analysis of Variance of the Scores

The scores for color, flavor, texture and general
conclusions were analyzed statistically to determine whether
the variation was due to treatment, storage or replication
or to interaction between these three factors. Table 3 on
page A3 gives a summary of the analysis.

Broccoli

Calculations showed that replication caused little
difference in the scores of the broccoli. In the case of
the ratings of general conclusions, replication was not
accountable for any of the variation.

The variation attributable to treatment was highly
significant for all scoring factors considered. The previous
discussion of the mean scores of the different scoring
factors, has indicated that the judges showed a preference
for samples blanched by hot water for a short period of
time. .As the blanching time increased, the scores generally
decreased. The preference for hot water blanching over
steam blanching would also result in a high F value due to
treatment.

In the case of flavor and general conclusions, analysis
of variance showed that storage caused some of the variation
between scorings. Flavor either remained approximately the
same or decreased in quality with length of frozen storage.

The interaction between storage and treatment was
significant for the color of broccoli. The figures indicate

ho

 

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the lack of uniformity between the response of color to

different treatments with storage. The greatest variation
was observed in the steam-blanched samples. The color of
the samples stemn blanched for 2% minutes and 5 minutes
showed a drop in value, whereas the values for the other
samples remained approximately the same throurhout the
entire storage period.

The interaction between storame and replication was
highly significant for flavor, texture and reneral conclu-
sions. Apparently the judges reacted differently to samples
presented at the first replication after a comparatively long
time away from judging, than they did to subsequent judgings.
This significant figure is rather difficult to trace,
especially since the F values due to storage and replication
are both 10v.

Cauliflower

Replication was not a statistically significant cause
for variation in color, flavor, texture and general conclu-
sions scores.

Treatment caused highly significant variations in color
and texture, and significant variation in flavor. The
discussion of the mean scores for color indicated that
medium blanching periods in both steam and hot water insured
better color in the frozen product than did the long or
short blanching periods. On the other hand, the shortest

blanching periods were the most desirable for texture

quality.
hl

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2-:

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92'

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Treatment did not produce as great a variation in the
flavor scores as it did for color and texture. Kean scores
indicated that low and high internal temperatures at the
completion of the blanching period in steam were not desir-
able for flavor retention. In th water-blanched samples,

the variation was not as obvious.

{fl}... .
Storage produced hirhly significant variation in texture F
scores. With storage, scores for texture decreased in value i
and this was reflected in the high F values for this factor. 3
The interaction between storage and treatment was ’

significant for the texture of the cauliflower. This figure
indicates the lack of uniformity in the response of the
different treatment to storage. Storage had a more dele-
terious effect on the texture of the medium and long blanched

samples than it did on the short blanched samples.

In the author‘s opinion, the lack of any significant

 

figures under general conclusions, reflects the over-all
response to frozen cauliflower. hediocre scores indicated
that it probably is not a too satisfactory vegetable for

freezing.

 

 

Table 3

Analysis of Variance - F Values

 

 

 

.~ .115"

 

Source Color Flavor Texture General
Conclusigng

Broccoli

Treatment 22 . 57* 3 . 07-;:--::- br. 28-;:~::- 7 . 07-::-::-

' Storage .lh 3.85% .21 3.78%

Replication .35 .31 '6% .09

T x s a.57v .23 .70 1.28

T X R 2.97 1.31 1.21 1.00

S X R .Oh ..Sh*% 7.21%* 3.28%
Cauliflower

Treatment 5.31*£ 3.0hfi 7.17%% 2.66

Storage l.8§ 3.30 8.83%» 2.63

Replication 2.2a 3.00 .25 3.30

T x s 1.03 1.76 2.50% 1.36

T x R 1.uo .Ig; 1.16 .Le

S X R l.h0 .50 1.00 .93

 

ha Significant
Significant

at 11 level
at SK level

 

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Objective Tests

Ascorbic Acid determinations
_______._.____ _____.__...____
Broccoli. The results of the ascorbic acid determina-

tions are presented in Table A on page he. The results

indicated that there are general trends in ascorbic acid

content with different treatments. Occasional discrepancies

in the general pattern were probably caused by errors in
sampling.
Tests immediately after blanching showed that consider-

able ascorbic acid was lost during the blanching process.

The longer the blanching was continued, the greater was the
loss of ascorbic acid. Storage tended to nullify these
differences. During storage, ascorbic acid was lost at a
greater rate in the samples blanched to a low internal
temperature and for a short period of time. The low value
for the 3 minute hot water blanch at the four month storage
period was probably due to an error in smnpling. At the four
month storage period, the ascorbic acid values for all treat-
ments were much closer together.

The blanching process caused a greater loss in ascorbic
acid than subsequent frozen storage. Freezing tended to
maintain the high ascorbic acid content of the fresh vegetable.
However, it must be remembered that this was only a four month
study. Longer storage might result in greater changes,
especially in the samples blanched to a low internal temp-

erature.

1:11

 

 

 

 

 

Steam blanching seemed to be slightly better for
maintaining the ascorbic acid content of the fresh vegetable
than did hot water blanching. However, the difference was
not great enough to clearly indicate that one medium should
be rated higher than the other.

The values for the cooked samples are included in the
Appendix on page iv.

Cauliflower

The results of the ascorbic acid determination for
cauliflower are presented in Table h on page A6. The
extremes in internal temperature reached by the vegetable
were not conducive for maintenance of the ascorbic acid
content of the fresh samples. Throughout the entire study,
the medium blanching period in both steam and hot water
resulted in higher ascorbic acid content.

The ascorbic acid content for the hot water blanched
samples was consistently higher than for comparable steam-
blanchcd samples. Storage for four months did not materially
decrease the ascorbic acid content of the A minute hot water
sample. Samples from the short and long blanching treatment
lost considerable ascorbic acid during storage.

The ascorbic acid values for the cooked samples are

included in the Appendix on page iv.

12-5

 

 

 

 

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Ascorbic Acid Content - Mg/lOO Gram.(flet Basis)

 

Table 8

 

 

 

 

 

 

Treatment Av.int. Av. Freshly Frozen Frozen Frozen
temp. raw blanched l%-mo. 3 mo. 8 mo.
Broccoli
Hot Water
1% minutes 180.5 102.88 87.75 83.00 85.00 70.33
3 minutes 200.3 102.‘8 77.75 82.00 8.83 80.50
5 minutes 208.8 102.8' 72.00 72.67 2,33 61,33
Steam
2% minutes 187.0 102.88 89.50 10 .0 3 8 2
5 minutes 208.0 102.88 73.50 8i.87 8.8% 72.3%
7 minutes 212.0 102.88 k7.00 68.17 63.33 Zh.33
Cauliflower
Hot Water
2 minutes 17 .h SS.O§ hh.15 85.20 hh,60 81.0
h minutes 20 .0 55.05 85.30 80.80 88.90 87.30
minutes 211.8 55.05 7.40 35.00 38.80 33.20
Steam -
minutes 192.2 55.05 82.80 28.80 35.0 17.20
minutes 211.h 55.05 hh.lO 53.30 36.2 37.h0
8 minutes 212.0 55.05 39.80 82.90 29.80 27.20

as

 

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Total solids

 

The results of the tests for total solids are presented
in Table 5 on page hB. The percentage of total solids in
the raw samples were higher than in the blanched or frozen
samples. Additional water apparently diffused into the
tissues of the vegetable during blanching and for equivalent
weights of vegetable this resulted in lower values for the

.1.

total solids in he frozen vegetables. Concurrent with this
was the leaching of certain soluble solids into the cooking
water.

Treatment and storage had very little effect on the total
solid content. host of the variation probably resulted from
sampling techniques. In sampling, efforts were made to
include the frosted part of the frozen vegetable, but it was
difficult to accurately gauge how much should be included
with each piece of frozen vegetable. This resulted in
differences in total solids va ues.

The values for the cooked solids are included in Appendix

on page iv.

 

 

 

 

Table 5

Percent of Total Solids

 

 

 

 

 

 

Treatment Av.int. Av. Freshly Frozen Frozen Frozen
temp. raw blanched l%-mo.. 3 mo. hjmo.
Broccoli
Hot Water p
1% minutes 180.5 10.19 9.30 .03 9.31 8.31
3 minutes 200.3 10.19 8.88 .10 7.80 8.%3
5 minutes 208.8 10.19 7.8 8.10 7.79 7. 0
Steam 6
2% minutes 187.0 10.19 7.00 8.81 8.9? 3.20
5 minutes 20h.0 10.19 7.9? 7.85 8.5% .3
7 minutes 212.0 10.19 8.21 7.39 8.15 9.17
Cauliflower
Hot Water 9
2 minutes 179.8 10.02 8.87 8.01 8.38 8.78
minutes 208.0 10.02 8.28 6.03 7'73 '55
minutes 211.8 10.02 8.18 8.7 8.;O 7.
Steam ,
minutes 192.2 10.02 $.58 Z.g5 8.%g 2082
minutes 211.8 10.02 {.92 . 0 7.1 7.79
8 minutes 212.0 10.02 0.04 7.28 7. 9 .
88

 

    
    
 

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Enzpne tests

 

The results of the enzyme tests are presented in Table
6 on page 51. In evaluating these results, it should be
remembered that the test used for the presence of peroxidase
enzyme is simply a qualitative one and, like all enzyme
tests, has its limitations.

The results for broccoli and cauliflower were the same.
With both vegetables, the short blanching period in steam
was insufficient to inactivate the peroxidase enzyme. The
internal temperatures of the steam blanched samples for the
shortest period of time were not as low as the internal
temperatures for the water-blanched samples for the shortest
period of time. Some other factor beside temperature seemed
to operate to make the water blanching more effective than
steam in inactivating peroxidase during short blanching
periods.

The results of the test at the close of the study were
the same as at the beginning.

The presence of peroxidase activity in broccoli blanched
for two and a half minutes in steam did not seem to result
in detrimental effects on palatability factors or ascorbic
acid retention for short storage periods. At the four
month storage period, the ascorbic acid content of this
sample had drOpped considerably in comparison to other
samples. If the storage were continued, the effect of the
presence of this peroxidase enzyme might result in more
noticeable effects.

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Study of the ascorbic acid values and palatability

scores for cauliflower showed that with storage, the sample
with the positive enzyme activity had lower values than the
other samples. In many cases, the lowest values were

dis la ed by the 3 minute steer blanched sample.
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Table 8

Peroxidase Blanching Test

 

Vegetable and

Average himediately

At close of

 

 

 

treatment internal after blanching storage period
til-2%.) .
Cauliflower
Raw Positive Positive
Hot water blanched
2 minutes 177-d Negative Negative
1 minutes 218.0 Hegative Negative
5 minutes 311.8 Negative Negative
Steam blanched
minutes 192.2 Positive Positive
6 minutes fill.h Negative Negative
8 minutes 313.0 Negative Negative
Broccoli
Raw Positive Positive
Hot water blanched
1% minutes 130.; Negative Negative
3 minutes 200.3 Negative Negative
5 minutes 233.8 Negative Negative
Steam blanched
2% minutes 187.0 Positive Positive
5 minutes 208.0 Negative Negative
7 minutes 212.0 Negative Negative

 

 

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ngetrometer readings of texture

This was an exeloratory investigation to determine
whether the nenetrometer had any nlace in testing the
texture of cooked frozen vegetables, and whether the read-
ings would comoare with nalatability scores for texture.
The results are nresented in Tables 7 and 8 on pages Ed
and 55.

First, it should be nointed out that penetrometer
readings were taken at only one of the three replications
at each test period. The average reading and mean texture
scores for this particular reelication are nresented in the
table. The average score for all the renlieations in that
particular test eeriod are also included, but it should be
remembered that the average nenetrometer scores cannot be
justifiably compared to these values.

Cauliflower. The penetrometer scores, as Well as the
texture scores, varied with the treatments. The longer the
vegetables were blanched in either the hot.water or the
steam, the higher the nenetrometer readings became. Possibly,
the contact with heat and moisture softened the cell walls
in the vegetable to such an extent that the vegetables became
comparatively softer. The penetration of the cone of the
penetrometer Was a measure of the firmness or body of the
vegetable.

The general trend indicated the lower values in
penetrometer readings were associated with higher average

52

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palatability scores of texture. A? arent v the judges

d .1;

preferred a more firm vegetable.

The blanching nedium.used seemed to have little effect
on the penetrometer readings for conoarative blanching times.
The time of exnosure and internal tenterature reached seemed
to be the detennining factor in variations in readings.

The decli.e in texture scores with sterote was not
reflected in the nenetr meter readings.

The correlation coefficient between the texture scores

and the jenetr meter readings was detelmined. The value was

’ O

y below the value of the 5g signifi-

Q

-.k§3. This was slifht
cance level. (. 55)

More extensive investigation is recommended before the
penetrometer can be used as a testinr instrument for deter-
mining texture quality in frozen-vegetables.

Broccoli. The behavior of the broccoli under the
penetration cone was more erratic than that of cauliflower.
Penetrometer readings of tie freshly blanched samnles showed
that the values did vary with tr,atnent. it the first test
period, techniques for working with the nenetrometer had not
been sufficiently develoned, so the readings were not very
satisfactory.

The correlation coefficient of the nenetrometer values

(I

and the texture scores at the _our—month neriod was -.lh92,

This was not statistica 1y significant.

 

 
 

Table 7

Comparison of Penetrometer Readings

and Texture Scores - Broccoli

 

 

 

 

 

Treatment Av.int. Av. a range Score for Av.texture
tgmn. of readings same sample score
7,._ 1/10 mm
Freshly blanched
Hot water
1% minutes 190.5 8.3 (§—TO)
3 minutes 200.3 3.0 (7-17)
5 minutes 208.8 1%.? (13—19)
Steam
2% minutes 187.0 7.7 (5—11)
5 minutes 20H.0 8.3 (7-11)
7 minutes 212.0 20.0 (10—23)
1% months storage
Hot water ,
1% minutes 180.5 120.3(120-130) 5.0 3.1
3 minutes 200.3 132.0(120—1 8) S.h 5.0
5 minutes 208.8 127.7(101-116) 3.0 5.0
Steam
2% minutes 187.0 111.7(109-112) 5.5 §.3
5 minutes 20h.0 102.7 (90-118) 6.3 i.9
7 minutes 212.0 123.7(107-138) h.5 h.
h months storage
Hot water
1% minutes 180.5 73.3 (57—76) L.8 h.9
3 minutes 200.3 109.0 (92-121) 5.0 h.z
5 minutes 208.8 103.7 (99-111) 3.8 u.
Steam
2% minutes 187.0 90.3 (70-103) 5.3 5.2
5 minutes 20M.0 115.3(105—126) h-B u.1
7 minutes 212.0 117.0(102-131) h.8 h.5

 

 

Table 8

Comoarison of Penetrometer Readings
and Texture Scores - Cauliflower

 

 

 

 

 

 

 

Treatment Av.int. Av. & range Score for the Av.texaure
tgmp. of readings smue sample score
F. 1 7‘) 1Y1 #
Freshly blanched
Hot water /
2 minutes 17Q.h-10.7 (13-22)
h minutes 200.0 §§.3 (3n-37)
minutes 211. 8 44.7 (3w-Sl)
Steam
minutes 192 2 11.3 (9-13)
0 minutes 211.h 9.3 (EQ-EF)
8 minutes 212.0 h9.0 (bk-9;)
1f:months
IIOt Va'ater r" F, {.2
2 minutes 179.h 93.3 (72-‘17) 3-2 9-0
minutes 208.0 120.3(123-132) [3.0 E.o
minutes 211.8 12.1-8.3(132-198) n8 1.?

Steam h v
minutes 192.2 89.3 (09-103) 17.3 .
minutes 211.2; 112.3 (93-137) ‘7-2 153

8 minutes 2 .2 .0 venue-loo) 1.2..2 I--1
3 months
Hot water i
2 minutes 179.h 8;. 7 (“0 121) v.0 f'fi
minutes 208.0 97. 3 (92-100) {0} ‘fi'“
minutes 211.8 11;.0. 3(110-176) 1.0

Steam
minutes 192.2 90. 7 (63‘100) L.8 %'1
minutes 211.24. :99. 7(110-12J) 1:40 1,00

8 minutes 212.0 8. 3(128“ )6) 3‘3 L. i_
h months
Hot water , 1; .8
2 minutes 179-9 80' 7 (02—96) [.5 fi.h
b minutes 208°C 113' 0(139 11?) 1I43 3-8
6 minutes 211.8 130.7( 20 13'J) ‘“

Stem ' 0
minutes 192.2 83- 0 (S7 107) %°§ fi,g
minutes 11. h 121 0(109"131) i‘3 H.1

8 minutes 212.0 151- 3(120‘170) ' ' _ii

 

 

SS

 

 

 

 

 

SCKLAR: AID COHCLUJIOIS

This study was conducted to determine the effect of the
internal temnerature reached and Jaintaincd by broccoli and
cauliflower during the blanching rrocess on the quality at
various intervals during subsequent frozen storage. The
vegetables were blanched in hot water or steam for different
time intervals. Records wer nade of the internal temnerature
of the broccoli and cauliflower during the different blanch-
ing procedures. At various intervals in frozen storage the
vegetables wcr removed from storage and tested for Luality.
A judging 7anel scored nalatability, and objective tests
were conducted on ascorbic acid, texture and total solids.

Jhen different blanching periods were used, there was
a difference in the internal temneratures reached by the
vegetable. As the blanching time increased, the interna
temperature reached by the vegetable also increased. Lhen
the longest neriod of time was used, both in steam.and hot
water blanching, the temperature of the vegetable and medium
were at or very near the boiling noint of water.

Results of nalatability Scores and ascorbic acid
determinations indicated that for broccoli a short blanching
time (1% minutes in water, 2% minutes in steam) and a low

n for

internal temperature (130.5 and 1717.00 -.) were best

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quality retention of broccoli over short storage periods.

Blanehinfi in hot water was more satisfactory than blanching
in steam.

Frozen broccoli retained much of the quality of the
fresh product during storage. It rated hither in nalatabil—
ity scores than fre°h broccoli nurehased durinc the winter
months of the stud? from the local market.

The results of the stud" indicate that cauliflower
blanched four minutes in hot water or six minutes in steam
to an internal tennerature of 203.00 F. and 211.h° F.
resnectiVely produced the most satisfactory nroduet in
frozen storage over short nerioas of time. Longer or
shorter blanchinr tines resulted in lower quality retention.
Under blanching resulted in undesirable flavor and odor,
probably due to ensffiatic activity. Over blanchin: nroduced
loss in odor and flavor. The product also became soggy.

For short storage neriods, hot water was the better
blanching medium. However, at the end of four months, results
indicated little difference in the quality of cauliflower
blanched by either hot water or steam.

Freezing cauliflower was not as satisfactory for
quality retention as was freezing broccoli. The frozen
cauliflower rated lower in nalatability scores than the
fresh veeetable scored at the beginning of the study and at
the different testing eeriods.

57

 

Exnloratory investigations on

the use of the penetro-
meter in testing texture in frozen vegetables showed a
general relationshie between tenetrometer readings and

palatability scores of texture. U thin limits, the lower

the nenetrometer readings, the higher the texture score.

However, more work is recommended before the penetrometer

readings can be used as

a criterion for evaluation of
texture.

58

U

10.

ll.

 

__ xff/‘W'IXIj
_L..:

.1 4.4,.)

r) . 1L1“... .

L LAVA

Adan, 3n :1 1‘11 I", C., and Stanworth, J. Chan-(363
Occurring During the Blanchin; of fegetables. J. doe.
Chem. Ind. 01, (l _ 2) 7o _ 99

Anon. Green Beans. ,uick Frozen Foods 10, (19L?)
- .4 Fly .
110. l, ;)l~_)1‘:_.

Alrighi, A. L., Joslyn, I. A., and Zarsh, G. L. Enzyme
Activity in Frozen Vegettbles. Ind. Eng. Chem. 23,
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Balls, A. K. 'h.e 1% te of Enzvnes in Processed Foods.
. . 4. V .~
Fruit Products J 2211? , 33—3).

Barnes, 3., Tressler, D. K. s.nd Fenton,F. Effe ct of
Different Cooking Cethods on the Fit. C Content of Quick
Frozen Broccoli. Food Research 8, (19.”3), l3—'30.
Batcheldcr, 3. L., Kirknn trick, I. 3., Stein, K. 3., and
harron, I. K. Jffeet of 3caldi115 Iethods of lualit' of
Three home-grown Vegetables. J. hone Econ. 39: (l/-7)!
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Bedford, C. L. and Joslyn, h. A. 3nz.,me Acti vitv in
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751‘7580

Bellinger, F. and Kethley T. F., Frozen Food Research
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Birdseye, C. The uicL—lreezln’ of Pcrisha ole Foods.
Ice and Refrig. 78, (l)?fi ) 7-; i

.‘ thre ;uiek Frozen Vegetables Stand Today.
Food Ind. 3, (1?. )1), —13-
Brown, K. D. Proper Blanehing is sures Good Results.

“ H ‘ ll‘
;uic1: Frozen Foods 6, (lyhhj, 170. a, 10-5+

Campbell, Horace..)olor Deterioration in Peas#3uring
Freezing Storage. guiek Frozen Foods 12, (leQ), Ho. 7,
129-132.

 

 

 

 

18.

19.

211.

25.

 

. Undcsirable Color Change in Frozen Peas
Stored at Sufficiently Low Temreratures. Food Research

2, (1937). 55-37.

Carlton, H. Home Freuaration of Fruits and Vegetables
for the Freezer Locker. Tenn. Exn. Sta. Bul. 108,
(1939), 1-11-

Clar, J. E. Preservation of Food Eroduets b7 Freezing.
N. J. Agric. ix Sta. Cir. Mel, (19fi3).

Crafts, A. S. 5on0 Effects of Blanehing. Food Ind. 16,
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Cox, H. J. and Fae Lasters, I. K. Lierosco ic Studies

of Tissue of Frozen Fruits and Vegetables. Food Research
1 r1

7, (lead), 13p-13a.

Cruess, 3. V. and Smith, I. 3. Better Blanehing Needed.
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Vegetables. ‘uic: Frozen Foods 9, (l9ho), No. S,

50- o7

Diehl, H. C. Progress Re ort on Frozen Pack. Ice and
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. Freezing Preservation and Frozen P9 ck
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. Camebell, E., and Ber.y, J. A. Freezing
of Aldennan Peas. Food Research 1, (1930), 01—71.

. Dingle, 11., andB rry, J. A. Enzymes
Can Cause Off-Flavors Sven Jhen Feeds are Frozen. Food
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Bunker, C. F., Fellers, C. 3., and Fitzgerald, G. 1.
Stability of Vit. C in Sweet Corn to Shir hing, Freezing
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Evers D. F. Frozen wood Industry. Ind. fins. Chem.
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Farrell, K. T. Vitamins Tested in Freezing, Dehydrating
and Canning. Huick Frozen Foods 5, (10i3), No. 11,
flip-'15, IO. 12’ 210

 

. and Fellers, C. 3. Vitamin Content of
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'06

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oul. no. 332, (lyJU).

Fcnton. F. Nutris

t ti e of guick Frozen Foods.
Refrig. nng. £2, (1911

u
I l
, 1 0—112.

- and Tressler, D. K. Losses of Vitmain C
During Commercial Freezing, Defrostinn, and Cooking of
7 - _r ‘ I 1 ’
Frosted Peas. Food Research 3, (1936), 409—410.

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ghy You Freeze it That Jay. Food Ind. 22,

(19505; £31—eo5.

and Fellers, C. R. Carotene and Ascorbic
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120.

Gleim, 3. G., Eressler, D. F., Fenton, F., Ascorbic
Acid, Thiamine, Riboflavin and Carotene Content of
Asparagus and Soinach in the Fresh, Stored and Frozen
States. Food Research 9, (l9hh), h7l-490.

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Greaves, V. D. and Boggs

, M u. irends in Freezin'
Preservation of Foods. J.

o S
Home Coon. 37: (19%;), 23-26.

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as an Index of Quality of Fresh Asraragus. Food Research
/ //

5. (19h0), 1o1-1oo.

,and Tressler, D. K. and Fitzgerald, G. A.
Vitamin C Content of Vegetables, VIII Frozen Peas.
Food Research 3, (1933), 133‘1M0-

Joslyn, M. A. Preservation of Fruits and Vegetables by
Freezing Storage. Calif. an. Sta. Circ. 320, (1930)-

. Certain Technological isvects of Preservation
by Freezing. guick Frozen Foods 1, (193o), No. 2, 10—13.

s1
T

 

. Inzyme Activity, Index of iuality in
arogeo Vegetables. Food Ind. 18, (1916), 1204-1310,
133d.-

and Marsh, G. L. Changes Occurring During
Freezing and Thawing of Fruits and Vegetables. Calif.
Agr'l. Ex“. Sta. Bul. 351, (1933).

and . Blanching Vegetables for
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Kaloyereas, S. A. The Effect of Various hethods of
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. Preservation of Iutritive Values of Foods
. ._ . .. .. . .. , v”) 0
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Lampett, L. F., Baker, L. C. and Parkinson, T. T.,
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Lee, F. A. The Influence of Smnoling on the Accuracy
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Lineweaver, T. T. Jhe Energy of Activation of Enzyme
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.. v f.

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Loeffler, H. J. and Ponting: J. D. Ascorbic Acid,
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L:

-

Magoon, C. A., Keeping 3uality as Related to the
o u , . r) 1
Distribution Problem. Ice and Refrig. o0, (1931),

39-t1-

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mahoney, C. 1., Sallis, 3. F., Hunter, H. 1., and 5
‘1 .I- ~ \ ~ - . a

acctt, L. A. Vitamin Content 01 Ieas, Effect of Freezing, %§g
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CSL- -QE 7 .3*~,‘

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(191:), 3.: 371, 333. "9'

u n u . . . fiu‘
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No. e. 130. ”"“'

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311.

I)!
9 G+s

. The Effect of ?reaaration for Freezing,
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. Four Lessons for Refrigerated Loclcer Patrons

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(1993): 1)l-2

 

 

 

 

 

 

70-

71.

f)
t—o

73.

74.

7S.

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Rosoff, Harold D ,
| |
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-7 I

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Tressler, D. X., hack, 9. L, Jenkins, R. R. and King,
C. G. Vitamin C in Vegetables. VII. Lina Beans.
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'f I‘
.1. ’ L}. Q.

fiheeler, Katherine and Tressler, D. K. ”lit uzin C
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Internal Temperature Reached and Time Heintained
by Broccoli During Blenching
Treatment OF OF OF Time OF
medium. small minutes large minutes cooled
piece niece media
1% minutes 206-208 200 160 60- 0
206-208 176 1Z0 58-68
206-208 176 1 0 56-66
3 minutes 206-210 210 202 58-66
206-210 210 208 62-70
206-210 208 161
206-210 208 172 56-71
5 minutes 206-212 212 206 52-5h
206-212 212 206 5h-56
206-212 212 208 52-52
208-212 212 210 54
2% minutes 1 196—190 180 138 Sh-GB
2 166-206 202 188 20-32
E 178-210 206 172 66-68
1 166-206 176 178 50-58
5 166-208 200 182 60-62
5 minutes 1 156-212 212 208 1/1 5b-56
2 161-212 212 212 3/6 52-56
166-210 208 202 56-70
i 120-208 178 18 58-60
5 132-208 202 178 58-62
7 minutes 1 160-212 212 212 2-1/6 56-58
2 160-212 212 212 1-3/6 6-58
P 160-212 212 - 212 1-1/2 56-62
1 158-212 212 212 2-3/1 56
5 151-212 212 212 1-3/t 56-58

 

 

 

 

 

 

Internal Temperature Reached and Time Maintained
by Cauliflower During Blanching

 

 

 

 

Treatment or OF Time 0F Time OF
medium small minutes large minutes cooled
piece piece media
Hot Water 7
2 minutes 1 206-208 181 166 18
2 20L-206 188 156 38-88
3 206-208 208 1 178 50-62
h minutes 1 206-212 208 202 56-56
2 206-212 212 1-1/8 206 58-60
3 206-212 212 3/8 208 51-86
6 minutes 1 208-212 212 1-1/2 212 1-1/2 58-62
2 206-212 212 3-1/8 210 52-5
P 206-212 212 1 212 . 3/6 52-5
1 208-212 212 1-1/2 212 1-1/2 58-62
Steam
3 minutes 1 166-210 202 1 1 56-60
2 160-208 186 168 56-58
P 161-210 200 176 54-56
1 loo-210 172 188 51-56
g 161-210 202 200 52-5%
162-212 210 176 -5
7 166-210 206 202 5 -60
6 minutes 1 166-210 210 1-1/2 208 1/2 5 -58
2 186-212 212 2-3/h 212 2-3/h 5 -60
i 160-212 212 212 58-60
160-212 212 2 212 58-62
5 162-212 212 2-3/1 212 2—3/1 58-62
8 minutes 1 156-212 212 5 212 8-1/2 60-66
2 168-212 212 /f 212 3-3/1 58-62
3 158-212 212 8-1 1 212 3-1/2 60-62
1 168-212 212 u-l/u 212 1-1/8 60-62
5 168-212 212 1 212 1-3/1 60-62

 

 

 

 

 

Ascorbic Acid and Total Solids - Cooked Samnles

 

Treatment 1% months

3 months

Qimonths
solids liquids solids liquids solids liquids

 

Broccoli
Hot Tater

 

 

 

1% minutes 10.75% 3.18 36.50 30.6 19.00 18.10
7.171% 1.10 8.51 1.61 7.07 1.75
3 minutes 35.13 8.75 33.63 23.50 35.75 8.10
8.20 1.75 8.52 1.36 8.71 1.51
5 minutes 30.75 7.38 11.25 7.10 16.75 8.85
7.18 1.21 8.73 1.25 7.18 1.20
Steam ,
2% minutes 13.03 7.23 11.38 18.30 12.88 18.10
7.71 1.15 8.30 1.16 7.87 1.61
5 minutes 37.38 8. 5 11.50 16.30 13.13 12.80
8.10 1.11 7.01 1.57 8.18 1.51
7 minutes 33.25 1.25 37.75 23.50 18.25 13.15
7.52 2.10 8.72 1.1 8.18 1.11
Cauliflower
Hot Water
2 minutes 28.88 6.60 20.38 5.38 17.67 1.70
6.75 1.10 7.37 1.21 7.30 1.22
1 minutes 28.21 6.17 11.01 6.16 37.38 5.57
7.81 1.00 7.70 1.11 7.05 1.37
6 minutes 15.75 2.72 13.63 3.71 13.63 3.51
6.78 .85 7.56 1.02 7.68 1.12
Steam
3 minutes 11.57 1.72 12.07 1.71 28.63 3.18
7.27 1.20 8.1 1.36 6.58 1.15
6 minutes 35.71 2.80 25.6 1.78 20.07 1.18
6.01 .77 6.71 1.13 7.21 .22
8 minutes 28.63 5.05 12.88 3.68 18.38 2.13
6.71 .72 .30 1.00 7.21 1.03
- Ascorbic acid mg/lOO gm.
xw Total solids - percentage
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