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UTHS

LQW T‘EME’JPERAWRE CONCENTRANGN
OF FRUiT AND VEQETABLE .GUII'SES

Thesis {or {he Beam 0% iv‘ 5.
MICHIGAN STATE SGLLEGE
Tlmmas A. Curfis
16350

This is to certify that the

thesis entitled
"Low Temperature Concentration

of Fruit and Vegetable Juices"

presented by

Thomas A . Curtis

has been accepted towards fulfillment
of the requirements for

M,S, degree in Agricultural
Engineering

W

Major professor

 

Date December 15, 1950

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LOW 'EHPZRATURE CKCLHTRATIOH OF 11RUIT

AND VLGLTABLE JUI‘ES

33’

PT."

i 1“”? ‘. rrzflr‘.‘ :1
J.-L tux-to A. Cu_.l.[.9

A THESIS
Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Agricultural Engineering

19

01
O

/1/'{ 6'7

ACIZE‘IO‘JILLDUL'EZBITES

The author wishes to exgress apprecia-
tion to Dr. halter M. Carleton and Professor
Arthur W. Farrall of the Department of Agri-
cultural Dngineering, William F. Robertson
of the Department of Horticulture and Dr.
Pauline Paul of the Department of Home Econ-
omics, Kichigan State College, for their many
helpful suggestions and guidance, Without

which this work would not have been possible.

Lev; mmmmruaz COR

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'\ ‘7 Yr' ”*1": .
JXMD Vuu.~.L:.p.LJ.u

By

TUOQAS A.

ABSTRACT OF THESIS

Submitted to the School of Graduate
State College
fulfillment of the

for the degree of

°r,-.f~r:1" “7‘71 C‘ "."h' "1
iuiolfl Or .JCILHCJJ‘

EXTRATION

CURTIS

OF FWUIT

JUICLS

Studies of Michigan

of Agriculture and Applied Science

requirements

Department of Agricultural Engineering

1950

LOK IJKLHAAJURL GU ZTTKAZIOT OF
“RUIT M IL JALDIALLZ JUICE
TM
.LJ

Thomas A. Curtis

*3

be frozen concentrated fruit juice industry is rela-
tively new. The reception of frozen concentrated orange
juice and later such juice cs as le .1 on, line, grapefruit,
grape, tangerine and others were so well received that a
whole new industry, both from a grower's standpoint and
equipnent manufacturer's standpoint, was born. Growers'
prices swelled to ten times that which they received be-
fore the advent of this industry. This price leveled off
at six times the original.

A whole new line of low temperature evaporators ap-
peared. Six equipment manufacturers placed new types of
evaporators on the market to handle the sudden deaand for
frozen concentrates. Basically, most of these evaporators
use refriveration sy stems either directly or indirect y
for both hea tin “ the incoming juice and coolin<g the outgo-
ing juice. Efficiencie s of these new evaiorators are much
higher than the old standard types. Research on the de-
velopment of concentration by freezing was stepped up with
new gains made.

The three main factors res:m:ns ible for the sudden
success of frozen concentrates include: (a) the overall
development of the frozen foods industry; (b) the de-

velopment of the cut-back method for making orange con-

centrate, and; (c) the development of low tenperature
evaporators and facilities for hauling and storing the
concentrates at 00F or lower.

It is felt that there would be a ready market for
any new highly palatable juice concentrate. For this
reason, juices that would conceivably make a highly
palatable concentrate were investigated with the hepe
of developing one or more juices or juice blends into
a highly palatable concentrate.

The main objectives of this investigation included:

1. To design and construct an improved apparatus

for the concentration at low temperatures of
fruit and vegetable juices; the treatment of
the juice to be similar to that which it would
receive on a comnercial basis.

2. To develOp or attenpt to develop a fruit or
vegetable juice or juices of high palatabili-
ty that would, if placed on the market, be re-
ceived with high consumer preference.

0. To determine which of these juices would warrant
further investigation as a frozen concentrate.

A low temperature concentration unit was designed
and built utilizing a refrigeration system and the in-
herent efficiencies of a refrigeration system. New de-
sign features included pulling the juice up a slope at a

slow velocity, and a water bath for carrying heat from

the condensing vapor to the low side of the refrigeration
system.

Of the juices unknown to the market as concentrates
plum, apple, celery and blueberry offered the most gromise
of being developed into a palatable concentrate. Italian
Purple and Japanese Red prune plums, Grimes, Jonathan,
Crab, Delicious and Spy apples, celery and blueberry juice
was investigated. I

The juices were all tasted and scored in preliminary
testing and tasted and scored in final testing with the
composition of the final tests depending upon the scores
of the preliminary testing.

Because of the small volume of samples, limited fa-
cilities, limited number of trained testers, and the large
number of samples, the results of these tests were neces-
sarily limited to determining which juices warranted
fur her investigation for beverage purposes.

A complete data log and heat transfer calculations
as well as an analysis of the system were included in this

investigation.

APPROVED:

 

 

I’M-{T I
Introduction . . . .
Review of Literature . .

Equipment New to the Industry .

HQTII
Statement of the Problem . .
Discussion of Objectives . .
The Juices Investigated . .
Juice Treatment . . .
Construction of Apparatus. .
View 1 of Apparatus. . .
View 2 of Apparatus. . .
How the System Works . .
Performance of the System. .
PH Chart . . . .

Colored Schematic View of System
Performance Data . . .

Results. . . . .

Score Sheet Used in Preliminary Testing

Score Sheet Used in Final Testing

Discussion of Results . .
Conclusions . . . .
Bibliography . . . .

Appendix . . . .

l7
17
20

25
28
29
50
52
53
54

38
4O
41
47
52

 

The frozen concentrated fruit and vegetable juice
industry is relatively new. Its start may be dated back
to 1931 when cold orange concentrate first appeared on
the market. The juice was delivered by milkmen and in
cardboard containers. The test marketing ended in de-
fault as the juice failed to hold up in storage either

e. The first

+4-
H:

with the processor or with the housew
real gains of the industry started in 1944 when Dr. L.
G. MacDowell, Director of Research for the Florida Citrus
Conmission, suggested that the commission overconcentrate
or nge juice under high vacuum and correSpondingly low
temperatures and add about 10 percent of the fresh juice
to bring the concentrate to the desired percent solids.
This became known as the cut-back method and was the
real start of the frozen concentrate juice industry.

Orange juice is the standard by which all other
juice concentrates will set their prices, production

0

totals, etc. Orange juice is firmly entrenched in the
housewife's menu. As orange juice is the yardstick for
other products, madam housewife is the yardstick for
orange juice. Her demand and the price she will pay,
governs the production of all juice concentrates.

The cut-back method of producing the orange con-
centrate will not prove satisfactory with all concen-

trates. While the orange concentrate has started a

whole host of other frozen concentrates, they are not all
prepared in the same manner. A good rule of thumb for
using the cut-back method could be to use the cut-back
method with any juice having a tart, strong flavor, such
that 10-20 percent when added to its concentrate will re-
store enough of the original flavor and aroma to favorably
compare to the original.

This rule would immediately take in all of the citric
juices and few of the other fruit juices, but practically
none of the vegetable juices. For example, apple juice
gives up much of its flavor, as do any of the juices, to
the water vapor that is drawn off the juice. These vola-
tile flavor compounds are in the form of esters and are
easily recovered by fractional distillation. The process
of recovering the flavor compounds by fractional distilla-
tion has only recently been practiced with considerable
success with apple and grape juice concentrates.

Orange juice, like so many other juices, is sensi-
tive to heat and the development of methods for concen-
tration at low temperatures was necessary. Grape juice
and tomato juice (7) are, however, not bothered by hot
pack or pasteurization temperatures and therefore will
probably never enjoy the success as a concentrate that
orange juice has had. Grape juice has had more success,
however, than that predicted by men in the field and will

always have a small corner in the frozen concentrate in-

dustry, because of its simplicity in preparation and de-
lightful flavor.

Since the advent of frozen concentrated orange juice,
new frozen concentrates have appeared on the market, nota-
bly lemon, lime, grapefruit, prune, coffee, chocolate drink,
tangerine, orange-grapefruit blend, and in limited quanti-
ties apple and cherry juice concentrate. Missing from the
list of juice concentrates are fruit juices such as fresh
plum, raspberry, blackberry, crab apple, currant, and blue-
berr*, and vegetable juices such as celery and tomato. All
of these mentioned have possibilities as a palatable frozen
concentrate.

Reception of the Product: Needless to say, orangacon-

 

centrate has been overwhelmingly received by the public. In
its first test marketing, gratifying results were received.
This occurred in a drugstore in Pittsburgh, Pennsylvania,
where the concentrate was sold for the freshly squeezed
juice (2?). Out of 200 customers, feeling that they were
drinking the freshly squeezed juice, only one suggested that
it did not quite taste like the fresh juice. The dime was
cheerfully refunded.

The growers in Florida were removed from certain dis-
astrous losses due to surplus orange crops. In 1945 the
grower was receiving thirty-five cents for a box of oranges,
while in 1947 this price had jumped to p3.50 per box. Natu-

rally the price leveled off, but not to anywhere near the

thirty-five cent level. The leveling off occurred at
around p2.oo per box with no danger of falling off. In
1947 through 1950 it was not surprising to hear about
major juice processors buying out whole groves at what
would formerly be termed fantastic prices. Growers were
selling what they had, then developing swamp lands into
more groves, selling these and so on. Anyone who owned
large groves were suddenly wealthc, more so than they
could have possibly dreamed.

If a palatable vegetable juice were to be exploited,
a tremendous educational program would have to be carried
on. he average person would have to be convinced that

he or she should drink the venetable 'uice as a bevera e
b

8
or as a breakfast juice. Nevertheless further investiga-
tion in this field is warranted by the:fact that there are
so many juices that would have a ready market if produced
with a high palatable flavor. The advantages of having

ready availability of vitamins in the concentrate cannot

be over-emphasized.

1'3"” T '1'" OF 7 IT". I" :1 f’T'T'fiT?

;;.'._J .LLJH H LJJ-LJL-V.‘LH

 

It is interesting to note that there are three major
factors responsible for the success of the frozen juice
concentrate industry. First and foremost it must be con-
ceded that any frozen product would not have a chance were

it not for the over-all general development of the frozen

foods industry. Second, the rapid development of equipment
and manufacturing methods for low temperature concentration
were of tremendous importance in allowing for the fast
success of the juice concentrate industry. For example,
production was increased from two million gallons in 1947
to twenty million in 1950 (estimated) for orange juice
alone. The fact that in most all grocery stores of average
size, there is a frozen foods cabinet for storing the
orange juice for sale, plus the fact that modern methods of
processing, handling and shipping at temperatures of zero
or lower, made such production increases possible. Third,
the develOpment of the ut—back method did away with any
flat, insipid juice that would result from concentration
by boiling, regardless of temperatires used. Rector (22
mentions the frozen food stimulus, surplus raw material,
demand for the concentrate from soft drink manufacturers,
wartime demand for a concentrate for EurOpe, preliminary
work on the.freeze drying of blood plasma, and the advance
nutritional knowledge, as being the six principal stimuli
leading to the creation of this product.

The process of cutting the over-concent°ated juice
with single strength juice is covered by a public service
patent. Neither the citrus commission nor the equipment
engineers could claim exclusive rights to the process due
to the part played by the United States Department of

Agriculture in its development. There is free availabil-

-5-

rerefore, to the patent which states in brief (10):

H.
d"
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(l) A process of producing a citrus fruit
juice concentrate capable of speedy
reconstruction by addition of water to
make a cold drink having a substantial
portion of the original aroma, flavor,
and palatibility of the citrus fruit,
comprising concentrating whole juice
of citrus fruit under vacuum to about
five-fold to eight-fold, then diluting
the concentrated juice with fresh, un-
concentrated whole juice of the same
citrus fruit to lower the concentration
to three-fold to four—fold, sealing
under vacuum and freezing.

(2) Applicable to all fruit juices.

(3) Free availability of the patent.

With each fruit or vegetable juice there is a differ-
ent problen. In the case of orange juice only 10 percent
of the fresh juice is necessary to restore enough of the
original flavor and aroma to pass the most critical taste
test. This means that the original juice is concentrated
to 590 Brix hen cut back to 420 Brix with fresh juice.
Unfortunately this process will not work with all juices.
Many contain most of their flavor and practically all of
their color either in or next to the skin; another group
such as apples must have their flavor compounds removed,
clarified, and concentrated, and their esters or flavor
compounds added to the concentrate; others such as blue-
berries must be heated to 1800, squeezed and allowed to
settle for three months without clarification before pro-

cessing, as clarification would ruin the flavor and remove

the natural flavor and aroma (15) as well as most of the

color; others such as grape and some apple varieties may
have sugar added, then be concentrated in order to arrive
at a high enough solids content without jelling or pre—
cipitation. The literature contains nothing on the low
temperature concentration of celery, carrot, beet, currant,
blueberry, raspberry, crab apple, apple blends nor as to
the exact nature of their flavor compounds, the amount of
heat that each will withstand without flavor damage, sug-
gested processing methods in preparing for concentration.
Perhaps most important of all, there is nothing in the
literature as to their desirability, from a taste stand—
point, as a fruit juice concentrate.

There is considerable res arch being conducted in
an attempt to develop an economically feasible method
for the recovery of the esters or flavor compounds which
are lost during any concentration by boiling, regardless
of the operating temperatures. hilleville and Eskew (17)
have devised a satisfactory method of ester recovery. The
juice distillate (containing the flavor compounds in the
form of esters) is heated under pressure; the pressure is
then suddenly released and the vapors fractionated and
concentrated so that the flmror is about 150times that in
the fresh juice. Such a method is now used commercially;
however, there is considerable room for improvement in
this method.

The United States Regional Laboratory at Philadel-

phia (9) developed an ester distillation process for re-
covering the esters from grape juice, and earlier a pro-
cess for the recovery of apple esters. Until recently,
grape and apple concentrates were practically unknown to
the market. They were previously concentrated and the
esters fractionated and returned to the concentrate for
the purpose of making fuller flavored preserves, jellies
and candies. However, the field of ester recovery has
Spread to that of the concentrate with the resulting pro-
duct difficult to differentiate from that of the original

juice, even by the most critical taste buds.

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The equipment that has aided the development of the
concentrate uses, for the most part, involves the use of
both sides of a refrigeration system. The high side (hot
gas) is used for heating the juice and the low side (cold
boiling liquid) is used to condense the water that has been
boiled off the juice. Kitchell (18) states that Joe Cross
of Mojonnier Brothers Equipment Company, after a thorough
study of the problem at hand, suggested using a refrigera-
tion system for simultaneous heating and cooling the orange
juice. It was imnediately tried and with considerable
success.

Using equipment that was originally intended to fill

a huge army demand for orange juice powder, the Florida

Citrus Commission was able to get into mass production
quickly, rather than wait for manufacture and delay in
giving the orders for new equipment to a private con-
cern. This all came about after the initial success of
test marketed frozen concentrated orange juice.

Cross (6) states that this new system requires no
steam or other sources of heat, operates at any tempera-
ture down to 40°F, gives multiple effect economy at single
temperatures, and delivers all water vapor as condensate.
In connection with low temperature concentration the
following steps must be rigidly followed; rapid handling
under sanitary conditions, thorough deaeration, hermetic
sealing in gas tight containers, and the juice must be
quickly frozen and stored at 00? or less. This may be
said about any unpasteurized food product which must be
expected to hold up under storage. The total time from
extraction to freezing in the can is now twenty minutes
for orange juice.

For over a century, designers had been looking for
a method of concentrating liquids in a closed vacuum
cycle, the heat given off in the condenser to be used in
boiling the incoming liquid. There is less than 2 per-
cent more heat in a pound of steam at 1000? than 60°F,
however, the volume at 60°F is 1208 cubic feet and any
vapor pump handling such a volume would lose far more

than 2 percent in friction; other losses combine to make

-10-

it more econmuical to use live steam rather than the re-
generative cycle. The high ratio of performance of a
refrigerating system, from the standpoint of heat, adapts
it perfectly to this service. It is easy for a refrigera-
ing machine to handle from three to five times the heat-

energy put into the motor driving it. Applied to a low
temperature system (5) using ammonia means that two pounds
of ammonia at 7.2 cubic feet is pumped instead of one
pound of steam at 1208 cubic feet.

After the adoption of the flojonnier system, several
other equipment manufacturers bruugh out their version
of low temperature concentration equipment. The most
notable of these is the Kelly-Howard concentrator, which
like most of the others, incorporates a refrigeration
sys em either directly or indirectly. The Kelly-Howard
concentrator (19) (now {noun as the Carrier-Howard) uses
hot water to provide heat for initial boiling, he original
heat being supplied by a hot well indirectly connected to
a refrigeration system. The vapor from this boiling is
pumped to the next effect and provides heat to continue
boiling the juice from which it just left and in the next
effect. In other words a step down vacuum system is used,
with a vacuum of 29.14, 29.44 and 29.64 inches of mercury
in each successive step.

Development of the hojonnier system has also stimu-

lated other manufacturers. Buflovak has now developed an

-11-

evaporator heated with low pressure steam which produces
a concentrate under practically the same temperature con-
ditions as those obtained in the ononnier and the Kelly-
_Howard evaporator. Rector (22) states that as far as can
be determined, the quality of the product produced in the
evaporatonsis identical.

The Stokes machinery Company has developed a process
of drying by sublimation which still has only limited use
in the field of low temperature concentration. The equip-
ment is high priced, likewise the maintenance; also they
have not developed a continuous system, although this is
the ultimate goal.

The National Research Corporation is the only firm
to switch from freeze drying orange juice to a powder to
the frozen concentrate with any success. This Corporation
placed their money on developing a powdered product for
consumer use. This investment proved to be a failure.
However, in the process they had developed a high capac-
ity low temperature evaporator of unique design such that
when the outstanding results of the first test marketing
of orange concentrate (using the cut-back method as well as
low temperature evaporation) reached Florida, the Corpora-
tion was able to start production in their evaporators on
a large scale and get into the market quickly. The Ration-
al Research Corporation must, therefore, be given credit as

being instrumental in the development of the present con-

centrate industry.

All of the aforementioned companies making low temper-
ature evaporators have applied for patents. Other than
basic claims, these patents are still pending at this writ-
i g. It must be remembered that the rapid progress in this
field is very new and that n w developments continually
turn'up. Knowledge of these developments is not always im-
mediately known.

Systems like the Kojonnier, Carrier-Howard and others
have several advantages over other types or older steam
type vacuum systems. These advantages (17) are: (a)high-
er economies; (b) less damage to flavors; (c) wide vari-
ation of operation temperatures; (d) flexibility of opera-
tion; (e) requires no source of heat, only electricity to
operate compressors, and; (f) delivers all water vapor as
condensate. y careful selection of refrigerants these
systems may be used for any juice concentrating over any
temperature range for any fruit or vegetable or sugar
solution. Cross (6) states that if this system were to be
compared to, say, a steam boiler multiple effect evaporator
handling an equal amount of evaporation, the energy input
to this system would be only a small part of energy re-
quired to produce steam in the boiler; fur her it would re-
quire a fifteen effect steam evaporator to acquire the same
efficiency.

The fact that all water vapor drawn from the juice being

-15-

processed is delivered as a condensate is important when

the esters or flavor compounds must be extracted from this
water and added to the concentrate. The condensate is also
used when concentrating certain pharmaceuticals, and alcohol
solutions or any solution that gives up important compounds
in its distillate.

The one process of concentrating juices at low temper-
atures that does away with cut-back methods, flavor losses
due to evaporation, etc., is concentration by freezing. A
commercially economical system of this type is the dream of
all processors. Ian“ investigators and many companies have
spent countless years and countless hundreds of thousands of
dollars attempting to develop a system of this type that
would be economically feasible. About the best systems to
come out of all of this research are described briefly from
what little information there is available.

Stahl Method (26): The Stahl method (on which

considerable current research is being con-

ducted) consists of either freezing the de-

aerated juice to a slush and then centrifug-

ing, or freezing to a solid cake and crushing

the frozen mass in an ice crusher and then

centrifuging. Several freezings and centri-

fugiigs are necessary to obtain the desired
concentration.

 

Noyes Process (4): The Eoyes process like
the Stahl method gives little indication
as to the type of equipment that is used.
The process is simply the freezing of the
juice and then by adding carefully con-
trolled heat uniformly, the water is re—
moved either by draining or siphoning.

 

The development of a suitable freezing concentration

system is important in that none of the flavor compounds
are removed during the concentration process. Kith:such

a system, over-concentration, ut-back methods, ester re-
covery from fractional distillation, etc., would be elimi-
nated.

Proponents of freezing concentration point out that
the latent heat of freezing water is only 80 calories,
while tlat of evaporation is 557 calories. This is true,
but such efficiency is not obtained in commercial practice
(29) because of the less direct use of energy in freezing
caused by the development of mechanical energy.

Of the two systems discussed above, it is difficult
to determine which w'll be fully developed on a commercial

basis. Little is known about the Stahl process, other

(—5

han a mention here and 'here in food engineering journals.

The author is more familiar with the Noyes process
because of a personal visit to the Cherry Growers Co-op,
Traverse City, Michigan, as well as perusal of the patents
covered by this process. It is felt that eventually a
commercially adaptable process will be developed and it is
the author's opinion that the Co-op is close to the solution,
if not already there.

Noyes' system is at present being used on a commercial
basis by the Co-op at Traverse City. There, the Co-op is
concentrating cherry and apple juice by freezing. This

process formerly required ten days. By tedious and time

-15-

consuming labor, they (the Co—op) have reduced this pro—
case for concentrating apple and cherry juice by freezing
to two days.

The Co-op is not producing concentrates at full ca-

'0

.5

city; a little more data on production costs, further

CO

developments in equipment, and a hook-up with a national
frozen foods firm such as Snow Crop, hinute Haid, Pasco,
etc., is all that is preventing ull capacity production
of this juice. They (the Co-op) believe that they can
Operate on a commercial scale with this system and still
undersell orange juice.

At this writing too much cannot be said about what
is going on at Traverse City. The Co-op has spent the
time and money required to develop this process and its
secrets are guarded accordingly.

From the patents (28), it may be concluded that the
juice is frozen into a solid mass. Carefully controlled
heat is then uniformly added and the concentrate is drained
off, leaving a practically pure ice crystal residue. This
is one step farther than.most investigators have carried
the freezing process and may well be the main part of the
Co-Op's system.

Dr. Pauline Paul (5) and others in the Home Economics
Dep rtment of Hichigan State College received some inter—
esting results from concentrating some Iichigan fruit juices

by freezi g. The juices were slush frozen and centrifuged.

A few of the interesting results included the fact that
the grape and raspberry concentrate was preferred over
the original juice, and that cherry juice was too tart
and that black raspberry was too flat for beverage pur-
poses. Tomato juices turned out weak in color, texture,

and flavor. .

-17-

PART II

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The definite objectives of this work were as follows:

1. To design and construct apparatus for the
concentration at low temperatures of fruit
and vegetable juices, such system to be
different in design from any other known
system. The treatment of the juice to be
similar to that which it would receive on
a commercial basis.

2. To develop or attempt to develop a fruit
or vegetable juice or juices of high
palatibility that would, if placed on
the market, be received with high con-
sumer preference.

0. To determine which of these juices would
warrant further investigation as a cold

beverage concentrate.

DISCUSSION or estcr vss

 

A discussion of the construction of the apparatus
appears later in this work. It is sufficient to say here
ptlat it vas important that the juices under investibation
be treated in a manner similar to that which they would
receive in a commercial plant. The results of the taste

panels are, herefore, of direct use to those people in

the juice processing industry. If the juices were to be
treated in any other manner, there would be delays by
commercial firms for the development of equipment to
handle any special treatments. As will be seen, the
juices were all processed in assanner similar to com-
mercial packs of similar juices. The principle of con-
centration is nothing new in that the juice is subjected
to a high vacuum, and a carefully controlled low heat
input. The low heat treatment during concentration pre-
vents any cooked flavor develOpment, or excess loss of
volatile flavor compounds in the condensate. In all
cases the vapor drawn from the juice was delivered as

a condensate with the thought that it could be frac-
tionated for study as a flavor improvement when added to
the concentrate.

The main opportunity confronting fruit and vegetable
growers in non citrus growing areas is for an attempt to
be made on the exploitation of juices from f°uit and
vegetables growinn in their own back yards. Vegetable
juices are known to contain certain essential vitamins
and minerals. However, it is hard to believe that he
housewife would purchase vegetable juices for her family
to drink as a beverage. There would always be a small
demand for a vegetable juice or a blend of vegetable
juices for their health giving 'ualities but not as a

beverage. From the standpoint of vitamins and minerals,

-19-

best root juices (23) are an almost perfect food, but

1

the juice contains a very distasteful earthy flavor
that so far has been impossible to remove.

A stock answer as to whether a person would drink
carrot, pea, spinach, cabbage, turnip, etc., as a bever-
age is "only a vegetarian sadist would drink such stuff";
it is felt that the demand would be so slight that in-
vestigation in such juices is not warranted.

Celery juice, on the other hand, does have certain
possibilities as a beverage, breakfast pickup or seasoner.
Slight as it may seem, there is a definite number of people
that would welcome a highly palatable, properly seasoned
celery juice, preferably in the frozen concentrate form
for convenience of handling and preservation of the highly
volatile flavor compounds inherent in the juice. For this
Treason, celery juice was the only vegetable juice investi-
gated in this work.

Tomato juice has possibilities as a cold concentrate,
but, like grape juice, it is not danaged by the temper-
ature of the hot pack. This juice separates on freezing
(7) and offers a faded color and flat taste to the con-
sumer. Concentration by freezing (3) offers approvimately
the same results. It is felt that exploitation of this
juice as a frozen concentrate would not yield the desired
results.

Apple concentrate will find a ready market as a frozen

concentrate, although, a good canned single strength pro-
duct has appeared recently on the market. It is felt by
the author that crab apple offers immense possibilities as
a booster for some of the more insipid juices inherent in
certain apple varieties.

Fruit juices such as strawberry, blackberry, peach,
pear, etc., were not investigated in that the inherent
qualities of these juices do not lend themselves readily
to desirable beverages. Juices with weak flat flavors
that would not conceivably receive attention as a concen-
trate were not considered in this work. Other juices such
as current and raSpberry were unobtainable at the time of

pperation.

retro JJTFTPS ’“T‘t‘vomrfi «run
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The juices investigated in this work included five
varieties of apple, two varieties of plum, celery and
blueberry. It was felt that of the juices unknown to the
market as a concentrate, those offered the greatest possi-
bilities.

The apple varieties included Northern Spy, Golden
Delicious, Grimes Golden, Jonathan and Crab. From this
work it was hoped that Crab Apple could be developed into
a booster for normal cider and definitely proven to improve
the flavor of juice from apples giving flat, watery, in-

sipid juice.

Plum juice, having a natural tart acid taste, was
investigated with the hope of developing it into a bever-
age, either by itself or in combination with other juices
such as apple, blueberry, etc.

Celery juice was investigated with the thought that
it could be developed into a beve age or at least a season-
er for dressings, soups, etc.

Blueberry was investigated with the thought that it
might be developed into a beverage because of its immense

popularity as a flavoring comp und in cakes, cookies, pies,

etc.

JUICE TRZATHEL

 

Spy, Delicious, Grimes and Jonathan: These apple
varieties were grated and pressed in a small 10 ton apple
press. Immediately after pressing the juice, pectinol was
added at a rate of 12 ounces per hundred gallons; this
amounting to 5.56 grams per gallon. The juice was allowed
to stand at room temperature for six hours, and then placed
in a cooler at 560? for 15 hours. At this time the clear
juice was siphoned from the precipitated pectin and im-
mediately concentrated. The juice was concentrated at 5
to l, with 75 percent of he water removed. The juices
were then stored at -2OOF until ready for taste tests.

Crab Apple: The juice from this apple is known to

 

contain high acid and an astringent taste. For this reason

the apples were stored for aporoximately 45 days after

picking. The temperature of storage was approximately
400?. After 45 days, the texture of the Crab Apples
was mealy and the acid content reduced. The Crab Apples
were grated, pressed and depectinized in a manner similar
to the other apple varieties. After concentration, pre-
cipitation occurred, and it was necessary to filter the
juice through a filter pad with diatomaceous earth added
to the juice. The juice was then stored at -200F. This
juice had a high acid flavor and had a tendency to pucker
the mouth; nevertheless, it was a typical apple flavor.
Plum: Two varieties of prune plum were investigated;
the processing before concentration being the same. The
two plum varieties were an Italian Purple Prune Plum and
a Japanese Red Plum. The plums were washed and pitted
from the raw state. The halves were placed in an open
steam jacketed kettle and quickly heated to 1600?. The
plums were slowly stirred with as little mashing as possi-
ble. Four and one half ounces of rapid—flo filter aid
(diatomaceous earth, type 1) was added to each peck of
plums processed. The plums were then placed in a nylon
bag and pressed at 500 p.s.i. on a horizonal hydraulic
press. The resulting juice was clear, of deep color, and
very astringent to the taste. Pectinol A was added at a

rate of one pound per 100 gallons of juice, and allowed

to set at 70°? for six hours, and for 15 hours at 56oF.

The clear juice was then siphoned off, concentrated and
stored at -soor.

Celery: Celery was washed and cut into six inch
strips and steam blanched for five minutes. The celery
was Lasediately immersed in cold water and passed through
a screw impeller type of tomato juice extractor and filter-
ed through a juice cloth. The juice was salted to .25
percent by weight (15). The color was light green and had
a slight cooked, weak flavor.

Blueberry Juice: Tressler, et.al, (15) suggest the

 

storing of blueberry juice for two months after heating

to 1800?. At the time of this investigation, time did

not permit the storage of the juice. Therefore, a quicker
method of processing before concentration was attempted.
The berries were heated to lBOOF in an open steam jacketed
kettle. They were then passed through a screw impeller
type of tomato juice extractor. The juice was first stored
at 560F for seven days wi h no apparent settling. The
juice was then frozen solid, thawed and again allowed to
set for seven days, still with no apparent settling. The
juice was again heated to lSOOF and a cellulose mash was
added. The juice was then hand squeezed through juice

cloth. The resultinr liquid was of high color and flavor

Q I
yet thin enough for the concentration process; the cellu-
lose mash absorbing most of the sludge and mucilaginous

matter inherent in the juice. The soluble solids of the

juice was doubled (from 14 to 28 percent) and the juice
immediately became too thick for further concentration.
The juice had a flat week flavor with high staining
preperties and had a thick undesirable texture. Storage
of the juice may be the only answer in preparation for
beverage purposes, as clarification removes some of the
flavor.

The original solids and final solids of the juices

investigated are listed as follows:

 

Original Final
Juice Solids Solids
Spy Apples 11.2% 44.9%
Delicious Apples 11.1% 44.6%
Jonathan Apples 11.5% 45.8%
Grimes Apples ll. % 46.8fl
Purple Plum 15.9% 49.0%
Red Plum 10.2% 41.0%
Celery 4.1g 20.0%
Blueberry 14.0% 28.0%

1 . ,4! .
Crao apples 14-0» 42. p

COKSTRJCT‘IOH 0F APPARATJS

 

It was decided that a refri5eration cycle w uld be
used as a heat source and in turn as a cooling source
for deliverin5 the vapor as a condensate. This type of
system would offer hi5h economy, easily controlled heat,
flexibility for Operation (any wall plug) and flexibil—
ity of construction, i.e., any te n.3erature ra an5e, any
pressures, by proper selection of refri5erant. The equip-
ment, for ex3eri imental purposes, namely a compressor, ex-
pansion valve and copper tubin5, was easily obtained. The
previously mentioned factors were all considered in choos-
in5 and desi5nin5 the equipment in order to hold down the
cost.

The equipment for the juice cycle had to be either
stainless steel or block tin tubin5. A combination of
both was used; stainless steel tubing in which to boil
the juice an d a coil of block tin tubin5 in which to con-
dense the vapor. A slopin5 double tube effect was con-
sidered as the most economical both from cost and con-
struction details. The sloping effect takes advantage of
a natural pump, i.e., the 'acuum punp pulls the juice up
the tube at a much slower velocity than that of a downward
slope. his fact results in less surface area (lower cost)
for heat transfer and 5reater armo nt of water removed per
effect or pas sa5o than a downx.ard slepe or vertical shell

and tube effect. From the previous discussion, it can

~26-

readily be seen that such a design would have definite
commercial advanta5es.
A water bath was chosen as a carrier of heat between

he cold boiling refrigerant and the condensing vapor.
This removed the necessity and expense of usin5 a material
that would not effect the flavor of he condensate nor
react unfavorably with the refrigerant. The cons ruction
of such an evaporator would also entail considerable cost
and remove any flexibility of the system in that one could
not be disassembled without dismantlin5 the other. By
keepin5 the tw systems separate, separate metals (copper
for the refri5erant, block tin tubin5 for the condensate)
were used, construction details were relatively simple,
and the cost comp ratively low. One main advanta5e of
such an evaporator is the lar5e temperature differential
that could be used. This lar5e temperature differential
allows for less equipment cost in that the same amount of
neat may be transferred for less surface area than a
system using a smaller temperature differential. This
fact is highly desirable for experimental purposes. How-
ever, a commercial system would probably do away with the
carrier, combine the two systems, use a smaller temperature
differential and moreaheat transfer area and consequently
more cost. The reader may ask why, and this is easily
answered in that such commercial systems would obtain.more

efficiency with refrigeration equipment using smaller

-27-

temperature differentials, which, in the long run, would
counteract the extra expense involved in construction and
use of greater transfer areas. By combining the two
systems, a commercial system would also take advantage of
a higher overall heat transfer coefficient due to the heat
being transferred directly from a boiling liquid to a con-
densing vapor (16).

A Cenco-Hyvac vacuum pump was used. The pump uses a
115 volt one-eighth horsepower motor, V-Belt driven. The
pump was protected against excess moisture by the subcool-
ing of the condensate. This pump lowered the boiling point
of water to 85°F during operation of refrigeration system.
With the heat source shut off, the boiling point was low-
ered to 60°F. This phenomenon.may be explained thus: The
amount of water vapor coming out of the tube is such that
at any given time the boiling point will not fall below
85°F, the water vapor is so thick that such lowering is
impossible. Then the heat is shut off and vapor ceases to
pour out of the evaporator tube, the pump draws off the
vapor immediately above the juice, thereby lowering the
boiling point of that solution. The system is leakproof
for all practical purposes, in that a vacuum of 27" of
mercury is maintained 24 hours after the drawing of the
vacuum. For this project this meant that the boiling
point of the original juice was lowered to 90°F. As the

juice became concentrated, the boiling point would rise,

-28...

 

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(due to the increase in solids), although the vapor
pressure above the juice would remain the same. For
example, a juice containing ll percent sugar would
boil at approximately 90°F on its first pass through
the system. On the last pass through the system and

a final concentrate of 44 percent sugar, the boiling
point would rise to lOSOF. This amount of vacuum and
correspondingly low boiling temperature was deemed low
enough to prevent any development of a cooked flavor

in the juices being investigated.

HOW THE SYSTEM WORKS

 

Juice Cycle: The original juice (point 1, fig. 2)

 

.(point ll, fig. 1) enters a long sloping tube (point 3,
fig. 1) and picks up heat from condensing refrigerant
gas. The boiling juice (under high vacuum) flows out of
the tube (point 2, fig. 1) and spills over into a four
liter suction flask (point 12, fig. 1). The vapor that
has been driven off the juice is drawn through the rubber
stopper and into a block tin condensing coil which is im-
mersed in a cold water bath (point 15, fig. 1). The
vapor condenses in this coil and flows out of the coil
and into another uction flask (point 14, fig. 1). The
vacuum is drawn off the top of this section flask (point
3, fig. 2) by the vacuum pump (point 15, fig. 1). The

condensing vapor gives up its heat to the cold water bath

which in turn gives up its heat to the cold boiling re-
frigerant.

Refrigeration Cycle: Hot high temperature freon

 

gas leaves the compressor (point 1, fig. 1) and enters
the double evaporator tube (point 2, fig. 1). This hot
gas than condenses as it gives up its heat to the boil-
ing juice within the tube. The hot high temperature
liquid leaves the evaporator tube (point 5, fig. 1) and
enters the liquid receiver (point 4, fig. 1). The hot
liquid then passes through a small silica gel drier
(point 5, ig. 2) and enters a thermostatic expansion
valve (point 5, fig. 1) where it is throttled into a
cold low pressure liquid before entering a copper coil
immersed in the cold water bath, which serves as an e-
vaporator for the refrigerant. The cold, low pressure
boiling refrigerant picks up heat from the cold water
(which is the same heat picked up from the condensing
juice vapor). The cold, low pressure gas is then drawn
off from the boiling refrigerant (point 4, fig. 2) and
compressed into a hot high pressure gas. This completes
the cycle.

The reader may follow the same cycles on the colored
schematic view (fig. 5, page ea). This sketch should
clearly illustrate some of the mechanics of the System,
i.e., the juice flowing up the long sloping tube, picking

up heat from the condensing gas. Also the form which the

-52-

coils take for the condensing vapor and the boiling re-
frigerant has been drawn to approximate their shape and
position in the water bath. The color scheme is illus-
trated by the key in the upper right hand corner of the

sketch and the cycles are easily followed:

PERFORMAECE OF THE SYSTEH

 

Operating conditions for each juice is approximately
the same. The only variance occurs when the temperature
of the incoming juice ranges considerably below its boil-
ing point. The initial temperature of the cold water bath
for each operation was the same, giving the same average
low pressure on the low side of the refrigeration system.
The average pressure of the high side is governed by the
boiling temperature and quantity of juice flowing up the
evaporator tube. The boiling temperature of the juice is
governed by the amount of vacuum drawn (constant) and
total soluble solids content of the juices being concen-
trated (variable). For all practical purposes the boil-
ing temperature of the juices in question may be considered
the same as they varied only a few degrees. From the PH
chart (page 55) it may be noticed that the amount of heat
available for boiling the juice is more than the heat
picked up in the low side. This fact sets up an inequality
which would.make this system unfeasible for long periods

of operation without a supplementary condenser on the high

-35-

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side. The difference would approach equality with smaller
temperature and pressure differentials. For experimental
purposes and short periods of operation (4 hours) this in-
equality does not interfere with the operation. The heat
difference shows up in the water bath as it receives more
heat from the condensing vapor than that which is picked
up by the refrigerant, consequently, there is a slow rise
in the temperature of the water bath. For short periods
of operation this is considered negligible. The rise in
temperature of the water bath means that the temperature
of the subcooled water vapor is higher. In the calcu—
lation of heat transfer area (see Appendix, page 4) extra
tube length provides for the heat inequality in that the
distillate is subcooled 40 degrees. For four hours of
operation the subcooling is reduced to 35 degrees which
is still appreciably lower than the boiling point of the
distillate and which still protects the vacuum pump from
drawing excess water vapor.

The unit volume of juice concentrated in all cases
was one gallon. To concentrate to 3 to 1 means that 75
percent of the total volume in the form of water must be
removed. Three fourths of one gallon is three quarts or
six pints which is six pounds. The rate of removal of
water from the juice is one twentie h of a pound per
minute or three pounds per hour. To concentrate one

gallon to 3 to l, theoretically, requires two hours of

actual operating time. Total time of operation averaged
two hours and forty minutes because of the time required
to transfer the partially concentrated juice to the origi-
nal flask for another pass through the system and because
of the inefficiencies of the system. Total passes through
the system for a concentrate of 5 to l averaged four, which
compares with a quadruple effect continuous evaporator.
Following is a data log on operating temperatures,
pressures, kilowatts used, pounds of vapor drawn off, etc.
Thermometers were placed in the stream of partially con-
centrated juice flowing out of the evaporator tube and in
the stream of distillate flowing out of the block tin tub-
ing. The vacuum drawn is read from tables corresponding
to the boiling point of the juice; far more accurate than
reading the type of gage used. A low pressure gage is
placed in the refrigeration cycle immediately before the
low side gas enters the compressor and a high pressure gage
at the liquid receiver. Temperatures of the refrigerant at
these various spots in the system come from a PH chart or
refrigerant tables. The kilowatts and pounds of vapor were“
measured directly with a watt meter and liquid measure re-

spectively.

-37-

PERFORMAICE DATA

 

R"WRIGLRATION CYCLE:

 

l. Condensing Pressure: Average condensing pressure and
temperature of freon gas = 215 psi abs. and l37OF.

2. Evaporator Pressure: Average pressure and temperature
of boiling freon = 35 psi abs. and 18°F.

JUICE CYCLE:

 

1. Average initial temperature of incoming juice = 60°F.

2. Vacuum and boiling temperature of juice = .7392 inches
of mercury and 95oF. (It must be remembered that the
vacuum is constant but that the boiling temperature of

the juice rises as it becomes concentrated; 95°F is
the average boiling temperature.)

OPERATION PERFOREANCE:
1. Average pounds of vapor drawn off of juice per hour =
.8 pounds.

2. Average kilowatt hours used per hour = .228.

3. Pounds of water removed per kilowatt hour 3 .8 8
3.5 lb. .228

4. Cost per pound of water removed (at 3¢ per kilowatt
hour) = 5 3 .86¢.
5.
5. Evaporator area for juice a 1.075 sq. ft.

6. Square feet of surface per lb. vapor per hour = 1.075 =
1.34. .8

7. Evaporator performance (1 kilowatt = 3413 BTU)

Performance . BTU Out ut - .8 x 1103 . 1.137.
ETU input .228 x 34l3

RESULTS

The juices were stored in one half pint containers
at —20°F until such time as they were ready for taste
tests. The length of storage varied from two and one
half months for the plum juice to three weeks for Spy
and Jonathan apple juice. The minimum for any juice was
three weeks with an average of seven weeks, which was
considered sufficient for any off flavor development due
to storage. Celery juice was the only juice to develop
off flavors. The off flavor development may have been
due to improper blanching, i.e., enough enzymes were
active at the time of storage to cause flavor deterio-
ation in storage. PrOper blanching may prevent such
off flavors.

There were some comments with regard to the celery
in that it was suggested that California varieties would
have produced a better juice. Remarks regarding the
flavor of the reconstituted juice was "bitter", "salty",
"metallic" and "completely unacceptable".

The general plan of attack was to conduct preliminary
’taste tests in order to determine which of the juices in-
vestigated would be preferred or which blends would give
promise of being developed into a highly palatable bever-
age. From the preliminary results, two beverages were made
up from the concentrates and single strength juices, their

composition depending on earlier individual scores.

-59-

In accordance with the suggestion of Eaten (l),
crackers and water were provided for removing the effects
of each sample before going on to the next sample. It
must be remembered that a large part of the people avail-
able for scoring the samples were unfamiliar with the
proper technique involved and that these people may have
had a tendency to give a high score. For this reason,

a majority of the testing was turned over to Dr. Pauline
Paul of the Department of Home Economics. A highly criti-
cal score was virtually assured, as well as having trained
personnel make the tests. Because of the large number of
samples tested, the score sheet (see page 40) was made as
elementary as practical. Concurrent with the testing in
the Home Economics Department, the author conducted taste
tests at the Department of Agricultural Engineering, using
the same score sheets and samples with the same basic in-
gredients. The results are combined in this work.

The tests were set up in groups with no one person
tasting more than nine samples on any given day. The
groups, composition, preferences and typical remarks
follow:

Group 1: Delicious, Jonathan, Crab, Grimes apple

juice and purple plum were set up with three samples

to each variety. Samples A, B, and C of each variety
were straight reconstituted juice, original juice,

and reconstituted juice plus l0 percent original

-40-

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SAL’IPLE SCORE SHEET USED IN PRE'II‘JI NAB TESTING

l.

2.

-41-

Which do you prefer?

A.

8.

Which one, if any, would you care to drink as
1".1‘J'V'i'1fl', '1“ L33’, .10 ’ I‘ H", A ' r30 1"".-.." {tr

SAMPLE SCORE SEET USED IN FINAL TEST

 

‘

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1-27~33

-42-

juice respectively. For the remainder of this work,

the reconstituted plus 10 percent of the original

juice Wlll be known as the cutback method or cutback

juice.

1. Jonathan and Crimes received high acceptabili—
ty ratings for both the original juice and the
cut-back juice. Typical couments included "typi-
cal apple flavor", "good taste", "lacks aroma but
has good taste". In both cases the straight re-
constituted rated last but received an acceptable
flavor score. Typical condents were "slightly
flat, lacks aroma",'hould be ver* good were it

not for the fact that the others were present

for comparison".

2. The straight reconstituted crab and purple
plum were preferred over the original juice and
the cut-back juice. However, the plum was un-
acceptable as a beverage in that it was highly
acid and astringent to the taste. Typical com-
ments included "too tart", "too uuch twang",
"too sour". The Crab Apple also received a high
acceptability score in the original juice form.

5. Delicious apple juice gave a poor, weak tast-
ing juice. The cut-back juice was preferred.
Typical comments were: "too watery", "weak",
"high aroma but flat taste".
Group 2: Three samples were set up with various apple
lends. Sample A contained 20 percent Crab, Spy,
Delicious, Jonathan, and Crimes. Sample B contained
50 percent Spy and 50 percent Delicious. Sample C
contained 40 percent Spy, 40 percent Delicious and
20 percent Crab. Straight reconstituted juice was
used throughout, lowering any flavor score.
Sample A: This sample received the highest pre-
ference score, but not as high overall score as
compared to some of the other juices. Typical

comments included "too much acid", "rather flat",
'lacking aroma", "undesirable residual taste".

-45-

Sample C: This sample ranked second to sample A.
Typical comments included "slightly acid", "lacks
aroma but has a sharp taste", ratner flat in
apple flavor", "needs something".

Sample B: This sample ranked very close to
Sample C. The presence of Crab Apple in the
other two was preferred. Typical comments

were: "weak", "flat", and 'some aroma".

Croup 5: This group consisted of plum, apple blends
made up from soores received previously on the indi-
vidual varieties. All of the juices in these blends
were made up from the concentrates. Sample A con-
tained 40 percent each of Delicious and Grimes and
20 percent purple plum. Sample D contained 40 per-
cent each of Spy, and Jonathan and 20 percent purple
plum. Sample C contained 75 percent Spy and 15 per-

cent each of plum and Crab Apple.

Sample B: This sample rated very high as compared
to the other two. Out of twenty tests it received

12 firsts, 8 seconds and O lasts. Typical comments

were: "could be stronger", "rather tart", "least
sharp", "distinctly superior", “desirable plum
flavor", "snappy apple and plum distinct".

Sample A: This sample rated second. It received
6 firsts, 8 seconds and 6 thirds out of twenty
scores. Typical comments were: "distinct plum
flavor", "a little sharp", "a most pleasing resi-
dual flavor", "most mellow".

Sample C: This sample rated last out of the three.
Out of twenty tests it received 4 firsts, 4 seconds,

and 14 thirds. Typical comments were: "too much
whang", "much too sharp", "too much acid, not 6-

nough flavor", "watery flavor, but leaves tart re-
Sidual taste".

Group 4: Each of the five apple varieties were blended

———-—-—$-——C

with purple plum at a ratio of five apple and one plum.

-44..

Only one blend was outstanding and this was the
Grimes-Plum blend. The score on this blend was
the highest of all the juices tested, and indi-
cations are that this juice definitely warrants
further investigation for beverage purposes, pre-
ferably in the frozen concentrate form for a year
around beverage.
Group 5: Celery juice was tested in the three
standard forms, that is, single strength, cut-
back and reconstituted. All were characterized
as strong, bitter, salty and completely unaccept-
able. A small minority of the testers suggested
that the juice may have possibilities as a seasoner
in soups, dressings or in combination with tomato
or other vegetable juices. Others suggested that
varieties from California or other sections of the
country may prove satisfactory for beverage or_
seasoning purposes.
Group 6: This group consisted of sweetened plum
and blueberry concentrates, tested for possibilities
as an ice cream sauce. The concentrates were made
up as follows:

#1 - 50 ml. purple plum concentrate

plus 50 ml. sirup A.

#2 - 50 ml. purple plum concentrate

H plus 50 ml. sirup B.

#5 - 50 ml. red plum concentrate

plus 50 ml. sirup B.

#4 - 50 ml. single strength purple
plum plus 50 ml. sirup B.

-45-

H

#5 - 100 ml. blueberry concentrate,
50 ml. sirup B, 5 ml. purple
plum concentrate.

Sirup A - 1 cup Sugar, 1 cup water
Sirup B - 5 cups sugar, 1 cup water

The testers preferred #4 and #5. The plum con-
centrates were all too tart. The blueberry con-
centrates were criticized by some as being rather
flat. Perhaps a larger amount of plum concen-
trates or a higher concentrate of blueberry would
improve it.
Group 7: This group consisted of two samples. They
were made up primarily from those individual varieties
receiving high scores and from those juices left in
stock. The scores are considered to be as good a
cross section of individual palates as practical.
There was a total of three and one half pints of each
sample. Total testers numbered fifty. They were
staff members and graduate students from the Depart-
ment of Agricultural Engineering, staff members and
students from the Department of Home Economics, and
staff members from the Department of Horticulture.
This was the final attempt to further develop a high-
ly palatable beverage of known composition and juice
treatment. The results speak for themselves.
The two samples were labeled A and B (see sample
score sheet, page 41). The composition of Sample A
was 35 percent Grimes, 26.4 percent Spy, 24.1 percent

Delicious, 9.3 percent Crab and 5.2 percent Jonathan.

These percentages are of the total solids in the final

-46-

sample represented by each variety. Of these per-
centages all of the Jonathan and 5 percent of Grimes
were original juice, thus making each sample similar
to a commercial cut-back juice. Sample 8 contained
52.5 percent Grimes, 24.7 percent Spy, 22.5 percent
Delicious, 8.9 percent purple plum, 6.8 percent sugar
sirup (testing 64 percent sugar), and 4.8 percent
Jonathan. The total soluble solids of these samples
tested was 12.8 percent. The PH of each was 5.54
giving an indication of rather high acid. Every
attempt was made to make the samples alike with the
exception of Crab Apple in one and plum in the other.
Examples of score sheets used in testing these
juices are attached on pages 40 and 41. The questions
on the preliminary score sheet were asked in an
attempt to get the tester to think critically before
scoring and to receive the comments and evaluations.
The questions on the final sheet were for straight
evaluation purposes. The information should be of
interest to those in the juice processing industry.
The results of the testing are tabulated as
follows:
1. Which do you prefer?
A - 57
B - 10
No choice - 5
2. §hic§2would you drink as a beverage?
x _

B - 6
Keither - 2

-47-

5. Which do you prefer over regular apple
Juice?
A - 18
B - 6
Both - 9
Same preference - 8
Neither - 8

DISCUSSIOE OF RESULTS

 

In attempting to evaluate the results of the taste
tests, it must be remembered that one type of reconsti-
tuted juice wasn't tried, i.e., a reconstituted juice
with its recovered esters added. Every attempt was made
to have the esters fractioned from the distillates. One
possibility existed and that was to use the ester recovery
apparatus owned by the Department of Horticulture at michi-
gan State College. However, ‘ue to circumstances beyond
anyone's control, the successful erection and operation of
the apparatus was not completed at the time of the taste
testing. Therefore, this type of juice, i.e., one with
the esters added back, was not scored with the others.

The practice of adding back esters from apple distillate
is being practiced commercially with candy, pastry manu-
facturers, makers of jams and jellies, etc.

The adding back of esters should generally raise the
score of the juice under investigation. The scores of the
juices in this work are, therefore, slightly lower than if

he juices contained the esters. The various blends re-

ceiving high acceptability ratings would, therefore, re-

-48-

ceive a higher score yet if the ester impregnation system
were used.

The volume of each variety of juice was not great,
one gallon being the average. From the number of varie-
ties, it can be seen that the possible combinations of
blends, in addition to the testing of each individual va-
riety, makes a large total number of samples. Thorough
discussions with men in the field of juice beverages helped
to narrow the total number of samples tested, thereby al-
lowing a greater number to take each test. Because of the
limited facilities, limited number of trained testers,
small volume of samples and the large number of samples,
the results of these tests must necessarily be limited to
determining which juices warrant further investigation for
beverage purposes.

In the preliminary taste tests it may be noted that
the reconstituted juice received low scores all along the
line. It is a well established fact that any beverage that
contains volatile flavor and aroma compounds imnediately
loses these components of flavor with the vapor drawn off,
the heaviest concentration being in the first 10—25 percent
of the vapor. The resulting juice is always flat to the
taste. The only juices that are actually preferred as a
concentrate are those with high original acid and tart-
ness. This was proven when both the Crab Apple and the

Plum were favored in the reconstituted form and again in

-49-

Dr. Paul's (5) work. Comuents all the way through the
testing included "flatness", and "lack’ng aroma" when-
eVer the straight concentrates were used. These comments
were missing in some of the cut-back juices and the ori-
ginal juices. This work clearly indicates that the cut-
back method is successful with most of the apple and plum
juice beverages.

Delicious apple juice should be used at a minimum
with apple blends and plum-apple blends. This juice gives
a desirable aroma and may be used in limited quantities
(preferably not more than 10 percent) for that purpose.
In larger quantities this juice leaves an undesirable re-
sidual taste in the mouth and adds practically nothing to
the desirability of the body of the juice.

Grimes, Jonathan, Spy and Delicious are varieties
normally used in making cider, depending on what is left
over from the market, number f packing house culls,
seconds, etc. There is no standard formula for making
cider. It varies from year to year, depending on sur-
pluses, culls, etc. Crab Apple is entirely new to the
cider industry in this country. In Europe there are
Special varieties of this apple grown for cider purposes
only. The results from this work indicate that this
apple has definite possibilities for adding high flavor
and aroma to apple blends either as a straight run juice

or as a concentrate. Difficulty may be encountered as

the juice precipitates upon concentration regardless of
depectinizing treatment. Continued filtration or siphon-
ing is required after concentration with this juice.

The two final beverages both show high promise of be-
ing adaptable for beverage purposes. The scores were much
higher and the beverages were much more warmly received
than those in the preliminary testing. This would, in part,
be due to the fact that the final beverages contained at
least 10 percent by solids of original juice, whereas the
juice blends in the preliminary testing were made from
straight run concentrates. Also, the final two beverages
were made up from combinations and blends receiving high
scores in the preliminary testing, which was the purpose
of such preliminary tests. A large majority preferred
Sample A over Sample 8. It is felt that this is due, in
part, to the confusion resulting from Question 5 on the
score sheet. This question asked, "which if any, do you
prefer over regular apple juice". Sample 8 had a definite
plum flavor and may have been down-graded accordingly be-
cause of the lack of natural apple flavor. The fact, how-
ever, that such a large percentage (95 percent) deemed
that they would at least drink one or the other as a
beverage was gratifying. Eighty—five percent liked the
beverage just as well as or better than regular apple
juice. This clearly indicates that either of these bever-

ages would be successful if placed on the consumer market

as a concentrate, using the cut-back method. It must be
remembered that these scores were given to juices two
months old and with only 10 percent of the original juice
present to give aroma and flavor.

Because of the large number of culls and seconds, in
the Delicious variety of apples, a good method of making
a palatable beverage using this juice would be highly re-
ceived by the industry. Samples using Crab Apple in vary-
ing amounts with the Delicious are preferred over the same
samples without the Crab Apple.

Freshgium juice contains acid in amounts of 1.8 per-
cent to 2.5 percent expressed as malic. This amount of
acid makes the juice unacceptable as a straight juice,
although the flavor and color of the juice lends itself
favorably to beverage purposes. For this reason plum was
blended with apple juice and the results indicate that a
blend of Grimes and plum offers an excellent chance of be-
coming a beverage with high consumer preference. This
beverage, along with several other blends, definitely
warrants further investigation by juice processors.

It is regrettable that time did not permit the further
concentration of blueberry juice. Storage of the juice for
two to three months is probably the one successful method
of removing the sludge and mucilaginous material inherent
in the juice. The juice was concentrated from 14 percent

to 28 percent solids when thickening occurred. Neverthe-

less, this concentrate when mixed with plum shows possi-

bilities as an acceptable ice cream sauce. However, the

cost of this juice will probably prohibit its successful

exploitation as a beverage or ice cream sauce.

1.

2.

5.

5.

CONCEUSIONS

 

Jonathan, Spy and Grimes apple juice give an accept-
able concentrate using the cut-back method.

Crab Apple juice is unstable in that the juice must
be filtered or siphoned off after concentration.
Straight purple or red plum juices (prune variety)
are unacceptable as beverages.

Cut-back apple juice of the Spy, Grimes, Jonathan
and Delicious varieties gives acceptable concen-
trates for blending purposes.

Concentration removes practically all of the aroma
commonly associated with apple juice.

Concentration improves the flavor of Crab Apple and
purple plum for blending purposes.

The presence of Crab Apple in proportions of 10 to

~20 percent improves the flavor of normal apple

juice blends.

The following blends, on the basis of scores re-
ceived in the taste tests of this work, definitely
warrant further investigation for beverage purposes:

1. 84% Grimes apple juice
16% Purple Plum

5.

20% Crab Apple
20% Grimes

20% Jonathan
20% Spy

20% Delicious

40% Spy
40% Jonathan
20% Purple Plum (sweetened to taste)

35%

26.4%

24.1%
9.5%

502;?)

52.5%
24.7%
22.5%
8.9%
6.8%
4.8%

Grimes

Spy
Delicious
Crab Apple
Jonathan

Grimes

Spy

Delicious

Purple Plum

Sugar (testing 84%)
Jonathan

7.

8.

9.

10.

ll.

12.

15.

14.

 

Eaten, materials for Removing Taste Effects in
Organoleptic Test, J. of Home Economics,
Jan. 1947.

Chemical Reactions Upon Freezing of Fruits and
Vegetables, Food Industries, 75-77, Feb.
1950.

Concentration of Juice from Michigan Fruit by
Freezing, Rich. Agr. Exp. Sta. Quart.
Bill. 29, n 4, 271-3, 1947.

Correspondence and visit to Cherry Growers Co-
op, Traverse City, Michigan, Aug. 1950.

Cross, J. A., Recompression Evaporation, Fruit
Prod. J., May 1948.

Cross, J. A., Revolutionary Evaporator Raises
Quality and Lowers Cost, Food Industries,
516, 1421, 1948.

Cruess, W. V., Comparison of Canned and Frozen
Tomato Juice, Quick Frozen Foods, 120,
OCt o 1948.

Cruess, W. V. and Rivera, W., Prune Juice Con-
centrate, Fruit Prod. J., 295, June 1949.

Eskew, R. K., Ester Recovery for Grape Juice,
Food Indus., 76, June 1950.

Frozen Concentrated Citrus Juice Covered by
Public Service Patent, Fruit Prod. J.,
195, march 1949.

Frozen Concentrated Citrus Juice, Food Ind.,
929-52, July 1949.

Heid, J. L., Frozen Concentrated Orange Juice,
Fruit Prod. J., 252—55, April 1949.

Joshlyn, Tressler and harsh, Fruits and Vege-
table Juices, Avi. Pub. Co., N.Y., 1959.

Kaufman, C. W. and Campbell, H. A., Some Funda—
mental Considerations in the Processing
of Frozen Orange Juice Concentrate, Food
Tech., 595-404, 1949.

15.

16.

17.

18.

19.

20.

21.

25.

24.

27.

28.

Kefford, J. F., Freezing Concentration of Fruit
Juices, FOOd Mfgo, 551-2, Aug. 1, 19490

McAdams, W. H., Heat Transmission, McGraw-hill
Pub. Co., E. Y., 250, 1942.

fiilleville and Eskew, Recovery of Volatile Apple
Flavors in Essence Form, Western Canner
and Packer, 51, Oct. 1946.

Mitchell, Terry, Refrigeration Cycle Replaces
Steam, Refrigeration Engineering, June
1948.

Few Kelly-Howard Concentrator, Quick Frozen
Foods, Aug. 1949.

Pederson, C. S. and Beattie, H. C., Concentra-
tion of Fruit Juices by Freezing, H. Y.
State Agr. Exp. Sta. Bul. 727:1-27, 1947.

Penner, S. 8., maximum Possible Rate of Evapora-
tion of Liquids, J. Phys. and Colloid
Chem., 567-75, Feb. 1948.

Rector, T. A., Frozen Concentrated Orange Juice--
Its Research Background, Refrigerating
Engineering, 249-55, April 1950.

Reid, C., Concentrated De-Esterified Beet Root
Juices, Fruit Prod. J., 268-85, may 1949.

Roy, R. T. and Russell, H. 3., Concentrated and
Then Quick Frozen Orange Juice Retains
Its Vitamin C, Food Indus., 1764-65, Dec.
1948.

Schwarz, H. W. and Penn, F. 2., Production of
Orange Juice and Orange Juice Powder,
Indus. and Eng. Chem. 958-44, hay 1948.

Stahl, Proc. Fla. State Hort. Soc. 1944, 45,
Rolzker, 9.3. Patent 2,448,802, Sept. 7,
1948.

The Goose That Laid the Golden Egg, Colliers, 57,
23.13.80 12, 1950.

'U. S. Patents covering the Noyes Process: 2,542,962;

2,595,498; 2,416,945; 2,419,909; 2,445,867.

VonLoesecke, Outlines of Food Technology, 62, Rein-
hold Pub. Corp., N. Y., 1949.

APPENDIX

 

DETERIINATION OF EQUIPMENT SIZE

Keeping in.mind that low cost and simple construction
was desirable, a system of small (as practical) capacity
was selected. A compressor of approximately one-half
horsepower figured to be satisfactory. The amount of water
boiled off per hour is governed by the size of the com-
pressor or heat input in the form of electrical power.

This type of system could easily have ten times the capaci-

ty, but the cost and size would be approximately as large.

ROTOR HORSEPOWER 0F COMPRESSOR

 

The size of the motor to operate the compressor was
calculated in the following manner (29):

1. Desired to remove 1/20 of a pound of water
per minute.

2. At 95°F, water requires (at a vacuum of
28.26" of Hg.) 1040.1 BTU's to change into
steam. Total load therefore is:

1040.1 x 60 = 5505 BTU's/hour or 55.1
20 BTUls/minute.

5. Condenser heat available per pound of re-
frigerant from the PH chart I 56 BTU's/1b.

pounds to circulate/min. - 56 - .985 lb/min.

4. Compressor work from PH chart = 14 BTU's/lb.
Total Compressor Work - .985 x 14 5 15.8 BTU's/min.

5. Theoretical Indicated Horsepower = 15.8 = .529
42.42

6.

Motor horsepower using a drive efficiency
of 98 percent, a compression efficiency of
80 percent and a mechanical efficiency of
82 percent =

M.H.P. - T.I.H.P. a -529 = .5125
5:5.xD;E;xc.E. .98x.80x.82

 

 

One-half horsepower motor was used.

CALCULATION OF HEAT TRANSFER AREAS

 

The condensing surface for the high side of
the refrigeration system consists of one-
half inch welded, type 504, 18 gage stainless
steel tubing. The juice flows up this tube
and accepts heat as the hot refrigerant gas
condenses. The length of tubing required
may be calculated as follows:

Q = UA(Tl-T2)K Q = Overall transfer of heat
which equals 5506 BTU's
(see item 2, page 1 of
appendix).

C1
II

Overall heat transfer co-
efficient equals 110 for
ya condensing vapor and
boiling liquid.

A = Total area required to
transmit total heat for
the given conditions -
5.1418xDL. Outside di-
ameter of pipe equals
.65 inches or .65/12 feet.

' Temperature of the con-
densing gas equals 157°F.

F3
[.4
I

T2: Temperature of the boil-
ing juice equals 95°F.

K = Fullness factor of pipe,
estimated at 2/5 full.

L = 5506 x 12 = 6.51 feet
-9 5. .6 overall
length used
was 7 feet

()1

3.

The surface for the evaporator of the refriger-
ation system consists of one half inch c0pper
tubing. After the proper length was calculated,
the tubing was wound into a coil and placed in
the upper part of the water bath assuring good
natural convection currents since cold water
will sink and warm water will rise (the condens-
ing water vapor coil was placed in the bottom
of the water bath). The length of tubing for
the*refrigeration evaporator surface was cal-
culated as follows:

Q I UA(Tl-T2) Q I Overall transfer of heat
which equals 2820 (see
H chart, page 55).

U = Overall heat transfer co-
efficient which equals 40
for a boiling liquid to a
liquid with non-agitation
(16).

A I Total area required to
transmit the total heat
for the conditions given
which equals 5.1418XDXL.
Outside diameter of pipe
6 uals one half inch or
1 24 Of fOOto

Tl: Temperature of the water
bath which equals 45°F.

T = Temperature of the boil-
ing refrigerant whic
equals 18oF. ‘

Q = Ux5.l418xDxL(Tl-Tg)

L I 2820 x 24 I 21.5 feet, overall length
40x5.1418xlx25 used was 22 feet.‘

The surface area required for the water vapor to
condense consisted of one half inch block tin
tubing. The tubing @fter length required was
calculated) was formed into a pyramidal shaped
coil and was allowed to rest in the lower part
of the water bath (see schematic drawing, page
54), thus assuring maximum natural convection
currents. The heat is given up to the water
bath by the vapor condensing in this tubing.

The water is warmed and rises to the cold re-

frigerant coil above it which accepts this
heat, the water simply being the carrier of
the heat from the condensing water vapor to
the boiling refrigerant. The length of tub-
ing required is calculated in the following
manner 3

Overall hourly trans-
fer of heat which equals
5506.1 (see item 2, page
1 of appendix).

Q. ' UA(T1"T2) Q.

U = Overall heat transfer co-
efficient Which equals
100 for a condensing vapor
to a liquid with no agi-
tation other than natural
convection currents.

A = Total area required to
transmit total heat for
the given conditions which
eqllals SolélBJCDXLo 011t-
side diameter of tubing
equals 1/24 of a foot.

Tl= Temperature of condensing
vapor which equals its
boiling temperature of
95°F, however, 75° was
used in the calculation
because it was desired
to subcool the condensate.

T2= Temperature of the water
bath which equals 45°F.

Q I Ux5.l518xDxLx(75-45)

L I 5506 x 24 I 7.9 feet
100x1x5.1418x52

The total 1ength.used was 10 feet of effective
length to assure protection for the vacuum pump.
The subcooling maintained a minimum amount of
vapor going into the pump. Total subcooling
amounted to 450 as the condensate was delivered
at 50°F.

The area used to boil the juice is the same area
used as a condensing surface for the hot refriger-
ant gas. To assure a proper amount of heat trans-

fer, the juice need only be throttled such that
the pressure of hot refirgerant gas remains con-
stant. This means that the same amount of re-
frigerant is being condensed that is being com-
pressed, which assures previously calculated heat
transfer (see PH chart, page 55). By forcing the
juice to flow up hill at a correspondingly slower
velocity than that of a downhill slope, less area
would be required to transfer the same amount of
heat to a given quantity of juice. This means that
for a given surface area, the same amount of water
will be driven off a smaller quantity of juice
which will deliver a higher concentrate. The a—
mount of water driven off the juice remains con-
stant as this is governed by the size of compressor
used, the amount of juice accepting the heat from
the hot gas is governed by its velocity over the
given area, boiling temperature, etc; all other
factors being constant, the velocity of the juice
is the main factor governing the amount of heat

it will accept for a given surface area.

 

 

 

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