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SUPPLEMENTARY
MATERIAL

. m BACK OF BOOK

CONSTRUCTION AND MANAGEMENT
OF
QUICK-FRLEZING UNIT
FOR
PRESERVING HOME PRODUCED FOODS

  

 

J
i ’ by

i i 4 . . nu”. L_ “4““ ‘7‘. ‘.-'.:'. incl.
m it: .. - . 1 - __ ' -
A ‘ . _

Paul Boyd Igggpson

 

A THESIS

Submitted to the Graduate School of Michigan
State College of Agriculture and Applied
Science in partial fulfilment of the
requirements for the degree of

 

MASTER OF SCIENCE

Department of Agricultural Engineering

1940

THESLS

 

TABLE OF CONTENTS

Acknowledgments . . . . .
Purpose of Problem . . .
Introductidn

Equipment and Procedure .

Part I - Construction of Freezer-Storage Unit

Part II - Management

Res‘flts . O O O O O O O O O O O O O O O O O

conCIqu-ons O O O O O O O O O O O O O O O 0

Literature Cited

’mb

i I}
lg "a

+13

'1

IO

Page

15
18
46
54
64

68

2.

ACKNOWLEDGMENTS

The author acknowledges helpful suggestions from
Professor H. H. Musselman and Assistant Professor D. E. Wiant
of the Department of Agricultural Engineering, and J. G. Duncan,
Assistant Bulletin Editor of Michigan State College.

Acknowledgment is due to the Kold-Hold Manufacturing
Company of Lansing, Michigan for furnishing the freezer plates,
condensing unit, expansion valve, heat exchanger, Freonslz, capper
tubing and other fittings and the installation of the forementioned

equipment in the cabinet.

5.

CONSTRUCTION AND MANAGEMENT OF QUICK-FREEZING UNIT

FOR HOME-PRODUCED FOODS

PURPOSE OF PROBLEM

The purpose of this problem was to make a study of the possi-
bility and practicability of freezing and storing the family food supply
at home in a home-constructed quick-freeze and storage plant.

INTRODUCTION

Freezing of fruits, vegetables and meats is rapidly becoming
a universal means of preserving the home food supply. Cold storage
locker plants are generally accepted as a modern and practical means of
food storage. However, at the present time, lockers are available to a
limited number of people. Most people are familiar with the advantages
of locker storages and frozen.foods and many have used this service, but
the inconvenience of going to the locker plant instead of the cellar for
the food has raised the question, "Why not freeze and store fruits, veg-
etables and meats at home?"

Why Freeze Foods?

For years people have been.devising new methods of preserving
perishable foods. Drying and smoking were used in the days of the early
settlers. Then came the process of pickling and canning meats, fruits
and vegetables. Efforts to find better methods of food preservation
brought about the cold-pack process and later the hot-pack process. With
the introduction of modern.refrigeration, freezing became popular. Can,
ning and freezing eliminate the dangers of food spoilage, but usually pro-
duce a marked change in the quality of fruits and vegetables as compared

with that of the fresh product. With canning, the change is due to the

4.

high‘temperature required for sterilization. With freezing it is re-»
lated to ice formation within the tissues.

Tressler (1) reports that, in general, freezing preserves the
food color, flavor and palatability of fresh fruits and vegetables better
than canning or any other method known to date.

Freezing also eliminates much of the drudgery and expense of
home canning, including long hours over a hot stove. Preserving food
products, such as meats, fruits and vegetables, by freezing is easier,
simpler and in practically every case results in a great saving of
time. For example, a 200-pound dressed hog can be cut and wrapped into
family sized packages and made ready for freezing in about three hours.
Compare this time with the day and a half or two days the housewife usu-
ally spends canning meat with a pressure cooker or other methods. When
properly prepared, frozen and stored, meats, fruits and vegetables are
superior to home-canned products.

fiapid Freezing Desirable

When water freezes, it tends to freeze as pure water and
other elements in the water are pushed aside. All foods contain.water;
when they are frozen, the elements that give color, flavor and food val-
ue to the juice are also pushed aside. Some of the changes are not re-.
versible.

Both Woolrich (2) and Earner (3) report that when a product
is frozen rapidly the colloidal gel or solution sets before much of the
water can separate from it.

Some investigators believe there is less damage to cell struc-

ture when the product is frozen quickly.

5.

Woolrich (2) reports the size of crystal depends upon the

length of time it takes the food product to pass through the crystal-

lization zone which is 51°F. - 25°F. The smaller the ice crystal,

the less damage to cell structure.

Warner (3) reports that quick-frozen meat, after thawing,

more nearly resenbles fresh meat.

The length of time required to freeze a given product de-

pends on the following factors:

8.

d.

e.

Temperature of the freezer.

Size and shape of the container - that is, a thin package
will freeze more quickly than a thick one, because heat
is conducted from a thin package to the freezing plates
much quicker than the heat from a thick package.
Material from.which the container is made. Various
properties exhibit different values of heat conduction.
For example, a metal container will conduct heat more
rapidly than a container made of paper or some other
fibrous product.

Nature of food being frozen. No two foods contain the
same amount of water, therefore, will require different
length of time for freezing.

The amount of food being frozen. A 4—pound package will

freeze faster than a 20-pound package.

As a result of rapid freezing, fresh meats, fruits, and veg-

etables retain their original cell structure, natural flavor and vitamin

content.

In many instances, the flavor and texture is improved; some

 

6.

hwestigators report that meat, especially, tastes better and is more
tender after freezing .
Freezing,and Storage Temperature

The temperature maintained in a freezer-storage cabinet de-
termines to a great extent the quality of food products when removed
from freezer. The length of time a product can be kept in a frozen
cmndition depends upon the temperature and its uniformity. An.excel-
lent product can be spoiled by imprOper temperature.

Diehl and Birdseye (4) report that freezing at or below and
maintaining a temperature of GOP. is of great importance. The best
and most recent practice is to freeze in an air temperature of about
~100F. They also report that vegetables in particular deteriorate if
held much above 00F. or several degrees lower and storage at 00F. or
higher.

Wiegand (6) also reports that temperatures ranging from —5°F.
to 45°F. are satisfactory freezing and storage temperatures for fruits
.and vegetables. He found that alternate thawing and freezing is con-
ciucive to mold growth ard.development of unpleasant flavors and should
'be guarded against.

Berry (7) has found that some yeast grow at O°F., which indi-

<iates that care must be exercised even at low temperatures.

Taylor (8) reports that products should be frozen as quickly
843 possible after harvesting. He also recommends 00F. as best for rapid

freezing. Above OOF. results in inefficiency, slower freezing and larger

ice crystals .

The committee on Foods (except milk) in the Food and Nutrition

 

 

7..

“Section, Americaanublic Health Association of which Donald K. Tress;
1er, Chairman (9) reports that pork becomes rancid sooner than beef.
Frozen pork can.be kept in good condition at 15°F. for only 2 months,
at 10°F. it keeps free from rancidity for about 5 months and becomes
very rancid thereafter. At 00F. pork will keep free from rancidity
for at least 8 months.

They also reported that fluctuating temperatures in cold
storage where meat and poultry are stored cause a rapid deterioration -
of the quality of the products because the fluctuations in temperature
speed up dessication and also accelerate crystal growth in the product
and consequently increase leakage when the product is thawed. The
recommendation of the committee is that frozen products be kept at a
uniform temperature not higher than 50F. and preferably at 00F. at all
times. At such temperatures practically all foods can be kept in
excellent condition for at least 8 months if they have been properly
prepared before packaging.

D. L. Augustine (10) reports that raw pork in commercial
quantities may be rendered safe so far as trichinosis is concerned by
either rapidly lowering the temperature to -0.4°F. (-18°c.) and hold-
ing the meat for at least 24 hours at that temperature.

Effggt of Freezinggon.Vitamins

Lease, Lease, Webber, and Steenbock (ll) have shown that
vitamin A is very rapidly lost from rancid meats; thus it seems that
frozen liver stored at higher temperatures, than from 10°F. to 15°F.
will slowly lose vitamin.A.

The committee on Foods of the Food and Nutrition Section,

American Public Health Association (9) reports that frozen foOds stored
at temperatures of 10°F. to 15°F. show a slow loss of quality (color,
flavor and vitamin C) but after a year's storage the product will still
be edible, provided it was packaged with sirup or sugar. Properly blanp
ched vegetables gradually lose their vitamin C content at temperatures
above 50°F.

According to Jenkins, Tressler, and Fitzgerald (12) snap beans
and spinach require even lower temperatures than 09F. if they are to
maintain a high vitamin C potency longer than four months.

Dunker (15) working with fresh sweet corn found that no loss
of vitamin C occurred in 54 days of storage at -25.5°F.

Fitzgerald (14) also found that freezing had little effect Upon
vitamin C. Vitamin C is an index of quality; most every factor that
detracts from quality also lessens vitamin C content of vegetables.

In a review of studies Plagge (5) reports that according to
Fellers there is no apparent loss of vitamin C content in the freezing
of peaches, blueberries, cranberries, blackberries, peas, lima beans,
sweet corn and asparagus, although losses were noted in grapes and
cherries.

Effects of Freezing on Bacteria, holds and Xegsta
It should be remembered that frozen foods are not sterile.

 

However, microbial action is slowed down considerably and many organ,
isms are killed at sub-zero temperatures.

Smart (15), in her experiments on frozen vegetables stored
from 5 to 7 months at -.O4OF., reported an average reduction of micro—

organisms of 97.5%.

 

9.

Diehl and Birdseye (4) report that fresh fruits and veg-
etables normally carry many thousands of spores of yeasts, molds and
bacteria that cause loss of quality and decay if the product is kept
at temperatures favorable to the organisms' growth. Cold retards the
growth of the organisms. Neither blanching nor freezing actually
sterilize the product. Some organisms survive freezing and some spoil-
age organisms exhibit slow growth at low temperatures; therefore, it
is important that frozen foods be stored at low temperatures and the
product be used very promptly after thawing.

Tressler (1) reports that growth of bacteria, yeasts, and
molds becomes negligible at about 15°F. on fruits and at about 10°F.
on'vegetables.

Warner (5) reports that at a temperature of 15°F. there ap-
pears to be no microbial action.

Products Need Protection from Oxidation

According to Warner (5), oxidation is very rapid at high or
normal room temperatures, is slow at 55°F. to 40°F., and still slower
at 0. However, there may be oxidation at 00F. and, therefore, some
protection from the air must be provided for the product being stored.

Waxed papers, waxed cartons, cellophane bags, are most
commonly used as wrappers and containers to keep products from.coming
in contact with the air.

Freezigg and Storing_at Hog;

Until recently most of the work with frozen foods has been

of a commercial nature. However, many of the commercial principles

can be applied to home freezing - especially those of handling and

 

 

 

Samples of paper commonly used for wrapping
meats for freezer storage.

10.

Fig. 2.

 

The home freezing and storage cabinet of F. W. Knowles,
manager of Northwest Baker Ice Machine 00;, Seattle,
Washington. Picture courtesy of State College of Wash.

 

Fag. 5.

Experimental freezer cabinet built by the
State College of Washington.

12.

 

15.

processing the food products. Owing to the expansion of rural elec-
trification and the improvement in mechanical refrigerating equipment,
even fast freezing can be done at home very easily.

Knowles (16), manager of the Northwest Baker Ice Machine
Company of Seattle, Washington, in 1957 tells of his experiment in
home freezing. He constructed an "ice cream type" cabinet, using
plywood and 4" cork insulation with a galvanized iron lining. He
used direct expansion coils with methyl chloride as a refrigerant and
lowered the temperature to -20°F. (Fig. 2). The freezing of meats,
fish, fruits, and vegetables was suCCessfully accomplished. The
products frozen.were prepared by Mrs. Knowles without any special equip-
ment, not even a thermometer for checking the blanching temperature
which indicates ordinary home methods prevailed. The economic possi-
bilities were exemplified in that butter was purchased at 20¢ a pound,
stored in the freezer and used when the price was 40¢ a pound.

Danna and Miller (17) of Pullman, Washington, in 1957 built
an experimental 00F. locker for farm use. In 1958 they exhibited at
the local fairs an "openrtop" type of cabinet (Fig. 5). In.July 1958,
they constructed on the Cox farm, an experimental 55°F. cold room and
GOP. locker box within. The cold room was 8 x 7 feet and 6 feet 6 in,
ches inside measurements. The 00F. box was built along'one side and had
a capacity of 42 cubic feet. Twelve inches of wood shavings provided
insulation in the walls and an additional six inches were used around
the "zero" box. For evaporators the "zero" box was lined with a 00p-
per pipe coil, the cold room had a finptype of coil. A 1/2 H.P. air-

cooled condensing unit provided refrigeration for both evaporators.

 

Fig. 4.

A commercial built freezer cabinet.

14.

 

 

15.

Power consumption on the Cox plant was computed to be from 56 - 78
K.W.H. per month. The equipment, excluding labor, cost approximately
$525.

At the present time there is being introduced to the public,
a few commercially built home freezers and storage cabinets and in all
probability most will be successful.

The home constructed freezing plant offers many possibilities
as to the different arrangements of installation. For example - farm—
ers or others who plan to construct a walk—in cooler could very easily
include a freezer-storage compartment. Again there are others who
would prefer to have a cabinet in their basement. A family in New York
State had their freezer-storage cabinet built so that the door opened
into their kitchen. A most convenient place, but probably not the most
economical from an Operating standpoint because most kitchens are usually
warmer than some other parts of the house.

Equipment and Procedure

The cabinet used in the test was made at the michigan State
College Agricultural Engineering Laboratory during the late summer and
fall of 1959. The cabinet stand and the plate supports were also made
in the Agricultural Engineering Laboratory.

The mechanical equipment consisted of:

5 - Kold-Hold hold-over plates 22" x 52"
l - Low Temperature Thermostatic expansion valve
1 - No. 2780-E Kold-Hold Heat Exchanger - Accumulator
7 lb. Freon 12
- Capper tubing and fittings
1 - 1/2 H.P. "Chieftan" compression unit with low

pressure switch.

16.

 

Fig. 5. Recording instruments used on freezer-storage cabinet
at Michigan State College.

 

17.

A Bristol recording thermometer was used to record the temperature
within the cabinet. This instrument was mounted on the right end of
the cabinet. The small tube was inserted into the cabinet through a
half-inch hole drilled in the end (Fig. 5). The position of the hole
was such that the thermometer tube came midway between the top and
bottom and about 2 inches from the rear of the cabinet.

Room temperature was recorded on a Taylor thermograph.

This instrument was placed on tOp of the cabinet.

A watt-hour meter was used to measure the amount of electric-
ity used. The original plan was to place the freezing unit in a walk—in
refrigerator on a dairy, farm, but this was not possible and the unit
was set up in the Agricultural Engineering Laboratory and has been oper-
ating continuously since January 27, 1940.

The principal products that have been frozen and stored have

been beef, pork, poultry, mutton and veal.

 

 

18.

PART I

CONSTRUCTION OF FREEZERPSTORAGE UNIT

Cabinethype

Two principal styles of cabinets predominate. First, the
top—door type of cabinet. This cabinet is simpler and probably easier
to construct. It has the advantage of being Operated more efficiently
because there is no tendency for cold air to leak out when the cabinet
lids are opened. However, the top-door type of cabinet has the dis-
advantage of inconvenience. That is, products stored within this type
of cabinet are likely to be piled on top of each other and when one
wants a definite article from the cabinet, it is necessary to take out
many more products than the one desired. Products could be sorted and
placed in.wire baskets for storage which would probably simplify loca-
ting the food desired.

The second type of cabinet is the side-door or vertical door
type. However, it may be well to point out two disadvantages as listed
by Danna and Miller (17).

First, when.the door is opened, cold air spills out and is
replaced by warm, moist air. The moisture collects as frost on the
evaporator.

Second, it is difficult to maintain door gaskets so as to
prevent air leakage. Sometimes frost will accumulate between the
' gaskets and cabinet, causing the door to freeze shut.

These disadvantages are not so serious as they may seem.

In regard to opening of doors, a freezer cabinet for home-use or-

19.

dinarily would not be opened more than once a day. As to gaskets,
there are available moisture-proof gaskets made and treated especially
for sub-zero conditions. This type of gasket was used on the cabinet
under test and during the four months it has been in Operation it has
not caused any trouble from freezing.
The advantages Of the side-door were enough to decide to
use that type of cabinet. The advantages were:
a. Convenience - a very desirable factor. Products
stored on shelves are more easily arranged in a
systematic order and it is much easier to find the
product one is looking for. Neither does the house-
wife have to "stand on her head" to remove packages
from the bottom of the freezer as is usually the
case with a top-door type of cabinet.
b. The side-door cabinet can utilize to the greatest
extent the many advantages Of the plate type of

evaporator which is discussed later in detail.

Size of the Cabinet
There are many things that have a part in determining the
size of the cabinet, some of which are:
The primary requisites are to have a cabinet that will
adequately and economically serve the needs of the family. A family
Of five persons requires enough storage capacity for about 250 pints

of vegetables, 250 quarts of fruit, and 800 pounds of meat.

20.

Table 1. Capacity of Freezer-Storage
for Family of Five

 

 

 

QuantitX*-_Kind '_f Cubic feet required 4g1__
250 pt. vegetables 4.55
250 qt. fruit 8.66
800 lb. meat 12.50
Total cubic feet 25.29

 

*Amounts recommended as an adequate diet for active people by Bureau
of Home Economics.

Table 1 shows that 25 cubic feet would be adequate for the
average family. Then it is probable that the freezer would not be
filled to maximum capacity at all times, and therefore, the cabinet
could be of about 20-25 cubic feet capacity. This size can be Opera-
ted by a 1/5 H.P. condensing unit under favorable conditions. A
cabinet larger than 25 cubic feet would probably require a % H.P.
condensing unit and this increases the cost.

Second, materials such as ply wood are made in standard
sizes and it is more economical to buy in these sizes. Therefore,
the cabinet dimensions were such that standard sizes could be used.

Third, it was decided to use the plate type of evaporator
of a standard size of 22 x 48 inches because it costs less accordingly
to buy a standard size plate. This places a minimum limit on the in-
side cabinet dimension. However, plates do not necessarily limit
dimensions except when using standard sizes, as they can be purchased
in almost any size at an additional cost. I

Fourth, to expedite moving the cabinet, the outside dimen-

sions were kept within usual doorway limits.

 

21.

Considering the various factors the cabinet was made
50% x 56 x 72 inches over all, which gave a capacity of 20.5 cubic
feet. See drawing 1 for detailed dimensions.
Proggrties of Insulating Materials
From a previous discussion it was found that a temperature
of 00F. to -10°F. should be maintained within the cabinet. To do this
it is necessary to provide adequate insulation and refrigeration. In—
sulation is one Of the principal parts of any refrigerating plant and
its economic choice is important. Originally the cabinet was constructed
to use in a walk-in cooler on a retail dairy farm. The temperature
Of the walk-in refrigerator was maintained at 40°F. This makes a tem-
perature difference Of 40°F., and according to the American Society
Refrigerating Engineers data book, about four inches Of cork is an
economical thickness; therefore, four inches of cork was used in the
construction of the cabinet.
There are three types of insulating materials, (a) the rigid
type as cork or Celotex; (b) the blanket type as Balsam Wool and (c)
the fill type as sawdust, Rock W001 and Zonolite. All types have good
insulating properties, but their use is determined by the type of struc-
ture in which they are to be used.
When selecting an insulating material for a freezer cabinet
one should consider the following properties:
a. Low conductivity. Conductivity as is practically
interpreted includes the heat that will pass through
the insulating material whether by conduction, ‘
radiation or convection. Conductivity is expressed

in the number of British Thermal units (B.t.u.'s) that

C.

d.

e.

f.

i.

22.

will pass through one square foot of one inch

of insulating material in one hour for each degree F.
The symbol commonly used is U or k.

Durable. Once insulation is in place, it should
remain there and resist decay, deterioration, and
other forms of breakdown.

Odorless. This is especially important in a case
where food products are to be stored.
Moisture-resistant. Efficiency of insulation de-
creases as the moisture content increases. For
low temperature conditions, it is especially im-
portant that the insulation be at its best. Some
types of insulation, such as sawdust and shavings,
are not so resistant to moisture and may prove
troublesome when used under sub-zero conditions.
Good handling characteristics. The insulation
should be one that can be easily applied to a par-
ticular job.

Structural strength. The rigid insulating materials add
to the structural strength, whereas the other types
do not.

Resistant to settling. Fill types of insulation,
unless installed with care, may settle and result
in air spaces, which are a source of heat leakage
and increase Operating expense.

Light in weight.

Fire resistant.

25.

Cork was selected for use in the wall of the cabinet be-
cause it has the above mentioned properties in that it has a low
conductivity value, good handling characteristics and most important,
it is odorless, offers structural strength and rigidity and is resis-
tant to moisture. Any rigid insulation, such as cork, can.be de-
pended upon not to settle.

Because moisture is harmful to all kinds of insulation,

a moisture-vapor seal was made in the wall of the cabinet. This was
an asphalt sealer and binder recommended by the Armstrong Cork
Company. Two coats of this paint were applied to the interior of the
outside wall. Besides providing a seal, it acted as a binder to hold
the cork after it was coated with an erection asphalt. A good rule
to follow is: "Seal the warm side of the insulation and ventilate
the cold side."

W

The function of the refrigerant is to act as a carrier
of heat. The gaseous refrigerant is compressed, cooled and conden-
sed to a liquid. This high pressure liquid, less much of its original
heat, is passed through an expansion valve. The high pressure liquid
passing to a low pressure, minus heat left in the condenser, vaporizes,
absorbs heat and changes to a vapor form, then is ready to repeat the
cycle. ;

Of the more common.kinds of refrigerants, such as ammonia
(NHs), sulphur dioxide (502), methyl chloride (03501) and dichloro-
difluromethane (0012F2)’ commonly known.as Freon-12 (others are

Freon 11 and Freon 21 and Freon 115) the latter was selected because

 

 

 

Fig. 6.

 

A typical freezing plate evaporator.

24.

 

Fig. 7.

A typical fin type of evaporator.

25.

 

26.

of its non-toxic properties. Freon liquid or vapor is not absorbed
by, and has no effect on, any materials being refrigerated, and the
vapor has no effect upon the odor, taste, color or structure of dairy
products, meats, or vegetables.

Freon refrigerants, as such, are the least toxic refriger-
ants that have been discovered, according to the Underwriters' Labora-
tories Reports MH-2256, MH-2575 and mH-2650. Freon is classed as being
non-combustible and noneinflammable.

A
a

Choice of Evapgrator

An evaporator is a device which holds the liquid refriger-
ant while it is boiling and thus absorbing heat from its surroundings.

Evaporators usually are of two forms-—a plain surface or a
finned surface. The finned surface types are usually limited to air
cooling conditions above 54°F. except in special cases where they are
fitted with automatic heating devices for defrosting. For sub-zero
conditions the plain type of evaporators are usually used. Plain
evaporators may be in the form of bare pipe coils or a plate. Fig-
ures 6 and 7 illustrate the difference in the various types of
evaporators.

The plain coil evaporator is the cheaper, but for a quick
freezing and storage cabinet the plate evaporator has enough advan-
tages in.that this type was preferred over the coils. Essentially
the plate is a coil arrangement enclosed within a flat, rectangular
metal case about 1 inch thick, 22 inches wide and 48 inches long.

The width and length are variable.
Plates are obtainable with or without a hold-over solue

tion. Figure 8 shows a section of an ice cream cabinet using plates

27.

 

(A)

Cutaway view - green portion indicates hold-over

solution in freezing plates.

Fig. 8.

28.

with a hold-over solution. The hold-over solution is a solution

that provides refrigeration similar to water ice, but, where ice

melts at 52°F., the hold-over or eutetic solution freezes and melts

at a lower temperature, previously determined in the manufacture of

o
the solution. -8 F. is the freezing and melting temperature of the

colution for protection of frozen products. Because of this property

of providing additional refrigeration in case of power failure, the

hold-over type of plate was desirable for frozen food storage.

Other advantages of plates are:

8..

C.

d.

Ease of installation; this simplifies construction
of a home freezing plant.

Economical use of space; the plates are thin, take up
little space and can be used as shelves and there-
fore adapted to the side-door type of cabinet.
Faster freezing is accomplished because the plate
provides more surface contact for the conduction of
heat, whereas coils provide only line contact. The
more evaporator area that can be brought in contact
with the package, the faster the product will become
frozen. As previously brought out, rapid freezing
is very desirable.

Ease and quickness of defrosting; to defrost the
plates it is a simple matter to take a wire brush
or a wide-blade putty knife and brush or scrape

the frost from the plates. This can be done in

a very few minutes, and in so doing the tempera-

29.

ture of the cabinet will need not vary more than
a few degrees. As pointed out previously, fluctua-
tion in temperatures or variations is undesirable,
and the refrigerating unit does not have to be shut
down or stopped.

e. More sanitary; the flat surface carlbe easily cleaned.

f. Excellent appearance.

r7.
‘1

50.

PROCEDURE - CABINET CONBTRUCTION

Bill of Material for cabinet

222222
12 pieces 2 x 4 x 6 Fir

2 " 5/4 x 4 x s w._Pine

2 " 5/4 x 6 x 8 "

l n 5/8 x 24 x 60 Fir plywood

s n 1/4 x 50 x 72 n n

l n 1/4 x 30 x 48 v n

5 n 5/4 x 56 x 72 n "
Hardware

2 pieces 3/4 x 5/4 x 1/8 x 6' - 4" angle iron

1 n 5/4 x 5/4 x 1/8 x 8' -4" n n
4 n 2 x 2 x 1/4 x 2' -6" n n
2 fl 2 x 2 x 1/4 x 5' -2" n u
2 fl 2 x 2 x 1/4 x 6' -2" n n

6 refrigerator hinges

2 " latches

1 Double strike

1 Gross 1-5/4 ~12 F.H. screws
12 Stove bolts 1/4 x l R.H.

Insulationl_paint, etc.

56 feet of gasket material

1 gal. asphalt binder and sealer
40 lbs. erection.asphalt
41 pieces corkboard 2" x 12" x 56"
1 qt. Valdura aluminum paint

1 qt. Gray paint

51.

 

Fig. 9. Completed experimental freezer-storage
cabinet - front view.

Fig. 10.

View of

cabinet and condensing unit.

52.

 

55.

The first step was to construct the frame, the details of
which are shown on drawing No. l. The frame was built of standard
two by fours. The center section, between the doores, is made as a
separate piece and is removable to facilitate installation or removal
of freezing plates.

The next step was to glue and nail the 5/4 plywood back in
place. Then the sides and ends were fastened in place with glue and
flat head screws. The 5/4 x 5% trim was glued and nailed in place on
the front of the cabinet. At this stage of construction the center
section was made and fitted in place. It was important that this
part be located in the exact center of the cabinet opening to avoid
making the doors of different sizes. Making and fitting the doors was
next in order, but they were not hung until after all the insulation
had been put in place and two coats of paint had been applied.

For protection against the harmful effects of air infiltra-
tion, the interior of the cabinet and doors were covered with two coats
of an asphalt primer and sealer recommended by the Armstrong Cork Com-
pany. The asphalt primer and sealer also provide a bond to which the
hot erection asphalt stuck.

The cork slabs were fitted to the walls in such a manner that
no two joints would overlap. The fitting was done first so that when the
job of permanently fastening the cork insulation was begun it could be
completed while the asphalt was hot. Each slab of cork was thoroughly
coated with a special odorless erection asphalt and pressed in position.
When the installation of the cork was completed, it was given-a coat

of hot asphalt to seal the joints and pores.

Fig. 11.

 

Freezing plate supports.

54.

55.

Next the 1/4 inch plywood liner was fitted and held in
place by L—shaped metal strips between the cork and frame. The back
liner was fitted last; this held the back edge of the sides and ends
in place. The metal strip was held in position by screws through the
door jamb.

The interior of the cabinet was given two coats of Valdura
Aluminum paint; the exterior was first given a sealer coat and two
coats of gray paint.

The final work on the cabinet was to install the hardware
and door gaskets and hang the doors. A specially prepared type of
gasket material for low-temperature was used. It was obtained from
the Jarrow Products Company of Chicago.

The freezer plate supports and the cabinet stand were made

of angle iron. See Fig. 11 and drawing No. 2 for further explanation.

56.

Table 2. Thermal Conductiviéy of Insulating Materials

 

 

 

(k - B.t.u. /in/ft /hr 01“)
Densigy
gaterial lb/ft _ K
' Alfol, flat 5.0 - 4.1 .25

Alfol, crumpled .24 .284
Balsam wool 2.2 - 5.8 .246 - .270
Cabots Quilt 5.4 - 4.6 .25 - .26
Celotex 15.2 - 14.8 .50 - .54
Cork 8.52 .285
Dry zero 1.0 - 2.0 .24 - .25
Masonite 15.0 .55
NuWood 15.0 .52
Palco (Redwood) Wool 5.0 .255
Redwood Fibre 6.72 .55
Rock Cork 15.6 .55
Temlock 15.0 .55
Kapok .875 .24
Shavings 8.74 .40
Sawdust 1.56 - 5.62 .57 - .60
Thermofelt 7.8 .28
Thermofill 26.0 .52
U. S. Mineral Wool 12.0 .26
WOOD

Virginia pine, across grain 54.5 .96

White pine, across grain 51.2 .78

Pitch pine, across grain - 1.05

Fir, across grain 54.1 .97

 

AOSOBOEO Ref. Data BOOk 1939‘40

57.
Computation 9f Heat Loss Throggh Walls

For all practical purposes, the heat losses through the wall
of the type of cabinet described in this report can be calculated from

the following equation:

 

K = l
.5 + x1 + x2 + .5
k1 1‘2

0
K = B.t.u. per square foot per hour per 1 F.

X, X2, etc. - Thickness of different materials in wall section
K, K2, etc. - Transmission coefficient of insulating materials
.5 a Commonly used as surface resistance value
Known.values.
a. Inside area of the cabinet : 46.8 square feet
b. Wall section, 5/4 a 1/4 plywood & 4n cork
0. Transmission coefficient - see Table 3
d. Temperature difference, maximum average
Cabinet temperature 00F.
Outside temperature (The average maximum July

0
”temperature is 81 )*

10 K = 1 = ___l‘____, 8 .061 B.t.u.
.5 4 i + 4 + .5 16.28

.28
2. B.t.u. per square foot per degree per 24 hours.

. .061 X 24 = 10464 B.t.u.

 

5. Total B.t.u. per degree = 1.464 x Area

1.464 x 47

8 6808 01‘ 69 B.t.u.

4. Maximum average outside a 810

Maximum average inside - 00
Temperature difference - 81U

 

*A.S.R.E. Data Book — 1939-40 p. 184

58.

Table 5. Specific and latent heat of various

 

 

 

 

food_products ‘_
Article Composition <§pecific Heat Latent Heat
Water Solid Above Below of Freezing
Freezing Freezing

Fruit

Berries (fresh) 86.5 15.5 .892 .46 124.5
Cantaloupes (whole) 45.0 55.0 .560 .555 65.0
Peaches (whole) 75.5 26.5 .788 .420 106.0
Pears, Watermelons 76.0 24.0 .808 .428 109.0
Meats

Beef (fresh) 68.0 52.0 .744 .404 98.0
Beef (fat) 51.0 49.0 ' .608 .555 75.5
Beef (lean) 72.0 28.0 .776 .416 102.0
Hams, Ribs (not brined)60.0 40.0 .680 .580 86.5
Shoulders “ “ 76.0 24.0 .808 .428 109.0
Livers 65.5 54.5 .724 .596 95.5
Lamb 58.0 42.0 .664 .574 85.5
Pork (edible portion) 60.0 40.0 .680 .580 86.5
Tenderloins, Butts, etc67.0 55.0 .756 .401 96.5
Veal 65.0 57.0 .704 .590 91.0
Fish

Fresh fish 70.0 50.0 .760 .410 101.0
Poultry ,

Poultry, dry picked 65.0 55.0 .720 .595 95.5
Poultry, scalded 75.0 25.0 .800 .425 108.0
Vegetables

ASparagus 94.0 . .952 .482 154.0
Carrots 85.0 .864 .449 119.5
Green beans 89.0 .91 - -
Broccoli 90.0 .95 - -

Trade Literature - Dole Refrigerating Company, Chicago

59.

Table 4. Approximate heat absorbed in lowering the temperature
of the water content of food products from 460°F. to -5°F.

 

 

Percentage Heat absorbed
Product of water per 1b. of
product
—— l__i .1. B;t.u.
Fish fillets 65 85 125 - 157
Shellfish, edible portion 79 87 149 — 165
Meat, edible portions 40 75 76 - 142
Poultry (dressed) 59 47 74 - 89
Vegetables, edible portion 67 95 150 - 174
Berries & fruit, edible portions 85 90 155 - 170

A.S.R.E. Reference Data Book, 1959-40

 

Fig. 12.

Typical condensing unit.

Fig. 15.

Condensing unit used on freezer
end View.

cabinet -

41.

 

42.

o
5. Normal heat leakage for 24 hours u 69 x 81 a 5,508 B.t.u.
6. Adding 10% for service load then the total load would be

(5508 x .10) + 5508 - 6,058 B.t.u.

Product Load

 

Computation of heat to be removed from product during the
process of freezing. Calculations are based on the assumption that 100
pounds of beef is placed in the freezer and all heat removed in 24 hours.

1. By Table 4 the specific heat and latent heat of beef are:

Specific heat above freezing _ .744

Specific heat below freezing - .404
Latent heat of freezing - 98.0

2. Heat to remove above freezing, assuming the meat will be
pre-cooled to about 60°F. 28°F. is used as the freezing
point of beef.

B.t.u. 3 lb. product x sp. heat x temperature difference

Latent heat = 100 X 9800 I 9800 B.t.u.

Heat removed from 280 to 00
= 100 I 0404 x 28 I 1151 B.t.u.

 

Total B.t.u. for 100 1b.
beef 15,511 B.t.u.

Determinigg the Size of Condensipg Ugit
The capacity of a condensing unit depends upon the amount of

 

refrigerant condensed per unit of time and therefore is dependent upon
such things as the piston.diSplacement, speed, efficiency, suction

pressure, condensing temperature, and super heat.

45.

Condensing units are manufactured in standard motor horse pow-
er size and manufacture B.t.u. per hour rating depending upon the re-
frigerant being used.

Then for all practical purposes if the operating temperatures,
refrigerant and the amount of B.t.u. to remove per hour is known, the
size of condensing unit in horsepower can be determined from manufacturers
Specifications.

Table 5 is typical of that found in.manufacturers literature.

Referring to the previous calculations it was found that -

Normal load ; 6,058
Product load = 15,511
Total 19,569 B.t.u. per 24 hrs.

Compressors are usually figured on a basis of 16 hours of
Operation out of 24; therefore, the condensing will have to remove
Ilg,§§g or 1,210 B.t.u. per hour
16 Referring to Table 5, a 1/5 H.P. compressor would be
required.
Note that over half of the 19,569 B.t.u. is product load
and the 1/5 H.P. condensing unit is necessary only when the calculated
load of products is being frozen. Certain management practices can
lighten this product load and these are discussed in'Part II - Management.
Computation of Plate Area
1. For low temperature conditions it is common practice to assume an
air temperature and plate temperature difference of 166 and a X.
factor for freezing plates of 2, which means that for each square

foot of plate surface as measured on both sides will absorb 2 B.t.u.

per degree per hour.

44.

2. At 160 temperature difference the B.t.u. absorbed per sq. ft. =
16° x 2 or 52 B.t.u. per sq. ft. per hour, one side.

.5. Square foot of plates = Hourly 105d
52 x 2 sides

 

 

1210 - 18.9 sq. ft.
2x52 '

4. Each plate was 22" x 52" which equals 7.95 sq. ft. one side

5. 18.9 + 7.95 = 2.58 or 5 plates required

The above mentioned calculations were based on the cabinet
described operating under average maximum room temperature of 81°F.
conditions instead of in a walk—in cooler for which it was designed.

By adding one more inch of cork the service load would be
reduced from 6,058 B.t.u. to 5,181 B.t.u. per 24 hours, a reduction of
877 B.t.u. per 24 hr. or 56.6 B.t.u. per hour.

Operating under these conditions the extra inch of insulation
would be advisable, but the following factors should be considered.
First, the cost, which would be about $4.50 for material provided the
cabinet dimensions remain the same. This cost is not excessive and
probably could easily be afforded. The other factor to consider is the
reduction of storage capacity of cabinet. Fortyaeight square feet is
equal to approximately 4 cubic feet or a reduction of about 20% of the
cabinet capacity. This is quite an item and in all probability would
be worth more to the user than what could be saved in Operating expense.
The cabinet could be made larger, which in this case, would have to be
done to accommodate the standard size freezing plates. Then the cost

would be more than $4.50 or approximately $12.

45.

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PART II

MANAGEMENT

The success of any home freezing and storage plant, whether
commercially built or a properly constructed home-built plant will
depend very largely upon the management. The introduction of frozen
foods is a wonderful achievement, but unless the public learns how to
select prOperly, process, freeze, store, and use frozen.meats, fruits
and vegetables an inferior product will result and freezing preserva-
tion.will be retarded from which it will take some time to recover.

Locgtion of gpme Freezing Unit

For efficient Operation, a freezer-storage plant should be
located in a cool, well-ventilated, and convenient place. The function
of a refrigerating machine is to remove heat from the refrigerated space
and dissipate this heat in the surrounding air around the condenser.

The warmer the outside air becomes, the more difficult it is for the
refrigerating machine to give up the heat removed from the cabinet and
the machine becomes less efficient. Good ventilation or air circulation
aids the machine in getting rid of the heat. TOO Often one sees conden-
sing units covered with some poorly ventilated cabinet. This adds to the
appearance, but decreases the circulation of air.

A convenient place of location of the plant is important
because of economical reasons. The more the plant is used, the more
profitable it becomes to the user. A simple example will illustrate
this point. Suppose it costs $20 a year to Operate the plant, and 100
pounds Of products pass in and out of the cabinet per year. The cost

in this case is 20 cents a pound for storage. Suppose an average sized

47.

family used 1,500 pounds of frozen products a year; then the cost would
be 1.5 cents per pound.

To use a freezer-storage cabinet efficiently one should plan
to take advantage of placing products in the cabinet when they are at
the peak of the season, when they are more delicious, most plentiful
and less expensive. During the year different products are used, mak—
ing room for those in season.

A suggested plan is shown in the calendar below.

January, February, March and April:

Beef, pork and other meats.

May:

Rhubarb, asparagus, and other early vegetables
and fruits.

June - July:

Early fruits and vegetables.

August:

Sweet corn, lima beans, snap beans, cherries,
raspberries and other fruits and vegetables -
chickens.

September, October:

Peaches, apricots and other fruits.

November, December:

Pork, beef, lamb and other meats.

ngration - Simple and Dependable
The actual operation of a home freezing plant is relatively

simple once it is installed.

48.

The most important thing is to be sure that the cabinet
temperature does not vary more than 50F. for any length of time.
Keeping a thermometer in the cabinet is a good plan. Of course,
the ideal arrangement, but expensive, would be to have a recording
thermometer.

A plant prOperly installed can be depended upon to give
satisfactory Operation. Power line failures are not a serious problem
because the utility companies are constructing better lines and giving
better service. Very seldom is electrical power interrupted for any
length of time in the rural areas.

Defrosting of the home freezer is simple when freezing
plates are used. A wire brush or a wide blade putty knife makes a
very useful tool to do the job. All that need be done is to give the
plates a good brushing or scraping. Ordinarily defrosting needs to be
done about once every two months. Of course this depends upon the
amount of moist air that enters the cabinet. Usually one can tell
from Observation when the frost needs to be removed.

It is well to remember that the accumulation of frost on
any freezing unit lowers the efficiency because frost is a rather
poor conductor of heat and therefore, it is desirable to defrost the
unit when needed.

The home freezing plant will give the same dependable ser-
vice the household refrigerator has been giving.

Differences in Kinds of Product and Method§_gf
Handligg
Some kinds and varieties of fruit, and vegetables are

.better adapted for freezing preservation than others.

49.

Strawberries, cherries, blueberries, raspberries and peaches
are a few of the more common kinds of fruits that have proven suitable
for freezing.

0f the vegetables, peas, lima beans, snap beans, asparagus,
spinach, broccoli, Swiss chard, cauliflower, and corn cut off the cob
have been most satisfactory kinds for freezing.

There appears to be a difference in the freezing quality of
different varieties within the same kind of product. Tressler (1)
rates the Eclipse peach, excellent; J. H. 8811, good; Late Alberta,
fair and the Carmen, very poor.

Tressler (1) also reports that a variety in one locality
may be desirable for freezing, while the same variety in another
locality may be undesirable for freezing. A possible eXplanation may
be the lack of uniformity in soil and climatic conditions.

Much work is being done by investigators in determining what
varieties of fruits and vegetables are suitable for freezing in differ-
ent localities. Timely information.regarding varieties adaptable for
freezing is best obtained from the Horticultural or Home Economics
Department of the State Agricultural College.

For best results it is essential to select fruit and veg-
etables that are in.their prime condition for immediate consumption.
Freezing does not improve the quality and texture of over—mature or
under—mature products.

Freezing fruits and vegetables within a few hours after
gathering is necessary if the original quality is to be maintained.

Harvesting the products in the morning and freezing them in the after-

50.

noon or sooner is desirable. At ordinary summer temperatures vegetables
change rapidly after harvesting. Sugar and moisture are lost rapidly
and vitamin C. may be partially destroyed by delay after harvesting.

If products must be held over to the next day they should
be placed under some form of refrigeration. Temperatures of 52°F. to
409F. greatly slows up the reapiration and enzymatic changes.

Freezing preservation is reasonably new to most peOple and
the method of processing vegetables and handling fruits differs some-
what from home canning methods. Usually freezing is much simpler and
quicker. Even though freezing is simple and quick the processing
procedure must not be neglected. Very often the tendency is for people
to blame the equipment rather than.the preparation or processing the
food product.

In brief, the method of handling vegetables is as follows:
After sorting, grading and washing the most important step is the
scalding or blanching. Blanching intensifies or brightens the color,
destroys many molds, yeasts and bacteria, makes packing easier by
softening the tissue and inactivates enzymatic activity. The last
is very important. After the blanching the vegetables are dipped
into a cold water bath to stop cooking action and cool the product.
Vegetables can be packed "straight" or in a weak salt brine.

Fruits require a different treatment. They are usually
sorted, graded and washed the same as the vegetables. Fruits do
not require blanching. Fruits are usually packed in a sirup solution
or plain sugar and some kinds of fruits can be successfully frozen
without either sugar or sirup.

Containers for fruits and vegetables that are to be stored

51.

_at 00F. should be as air-tight, moisture-proof and vapor-proof as
economically possible. Glass and tin cans satisfy the requirements

in regard to moisture proofness and air-tightness. With glass there
is a breakage problem unless care is exercised in filling the can.

Tin cans have been very satisfactory except carelessness may result
because peOple may confuse them with ordinary canned goods and they
are liable to be left out in an open room to thaw, then spoilage starts
very soon. The rectangular shaped, waxed carton with a moistureavapor
proof liner has proven depéndable and also utilizes the locker space
better than cylindrical containers. Containers having small openings
at the top or taper towards the tOp should be avoided because of the
difficulty in removing the products.

Meats are the simplest of the products to handle because
about all that needs to be done is to cut the meat in a family sized
piece and wrap it in a moisture-vapor proof paper. See sample, Fig-
ure 1. It is well to label the package as to content, weight and date.

Freezing of Products

Good management practices are - pre-cool the product, freeze
in small quantities and in small, flat, rectangular packages. Each
package being frozen should be in direct contact with the freezing
plates in order that freezing will be as rapid as possible.

The household refrigerator is suitable for pre-cooling
small amounts of product, whenever one is available, or in some
cases, cold water or ice may be used. Although it would not be
necessary to obtain ice especially for this purpose.

Refrigerating plants are designed to cool and freeze a

pre-determined load in a certain length of time; therefore, it would

52.

be better to distribute the load over a period of time other than

to introduce a large quantity of goods at one time. The introduction
of large quantity of warm product at one time is liable to cause the
temperature of the cabinet to rise more than it should. The tempera-
ture ought not to vary more than 40F. or 50F. Thirty to fifty pounds
would be considered a reasonable amount to freeze at a time. Sixty-
five pounds of meat was placed in.the freezer cabinet being tested
and the temperature did not vary more than 40F.

The smaller the package the faster it will freeze and for
practical purposes the package ought to be of a size that one package
would be enough for a meal. With the smaller, family size package,
there will be less waste because the product will be consumed and none
need be left over for other meals. This is important because frozen
foods tend to spoil after thawing quicker than fresh foods. However,
frozen foods can be kept for a few days under good refrigeration.

Vegetables deteriorate very rapidly after harvesting; there-
fore, to have a high quality product vegetables should be harvested,
cleaned, processed, and frozen as quickly as possible. Consequently
small quantities can be handled much easier and quicker. The same
would also hold true for fruits.

For best results, products should be spread over the free-
zing plates in a single layer if possible. After the products have
frozen the packages can be piled to make room for freezing additional
products.

Length of Storagg_Time

For practical purposes there are no advantages in extremely

55.

long storage periods, such as more than a year. The primary purpose
of a freezer storage is to carry products over to a time when they
cannot be obtained fresh. For example, vegetables and fruits could
be frozen in July or August and used during the winter months.

Most fruits and vegetables can be stored successfully for
a year. Most meats with few exceptions can be kept for about one

year, provided it is well wrapped and stored at a uniform tempera-

ture 0f 00F. or below. Pork turns rancid quicker than beef; fat
pork turns rancid quicker than lean pork, and it is advisable to
keep pork 39; longer than a months at 00F.
Care in Handlinngrozen Foods

Frozen foods should be regarded as perishable foods.
Because of the blanching and freezing treatment frozen foods are
more perishable than fresh foods. Although there has been a great
reduction in microorganisms, there are enough left to start spoilage
if and when the optimum temperature is reached for the organisms

growth. A general rule is to cook and consume frozen vegetables_iust

 

§L_soon a they have thawed - cook all veggtables before eating. Left-

 

 

 

overs when cooked immediately will keep for a short time under refrig-
eration.

Fruits are considered satisfactory for consumption in the
raw state. They may be eaten partially thawed or completely thawed.
A rule similar to the one used for vegetables could apply for fruits i
consumg frozen fruits g§_§ggg gg thgy have thawed. '

Frozen meats may be cooked as soon as they have thawed or

cuts such as steaks and chops may be cooked in the frozen state by

54.

starting the cooking at a low temperature. With larger pieces it may be
preferable to thaw before cooking. The method to use will depend on
personal likes and dislikes.

giggnlipgss is Necessary

Cleanliness about and in the freezing cabinet is just as im-
portant as cleanliness in the preparation and processing of food products.
Keeping the freezer clean and in a sanitary condition is a very good
form of insurance of preventing the deve10pment of any off-odors within
the freezer storage. Food from a clean and sanitary place is much more
appetizing than that from a less attractive place.

Tressler (18) says: "As yet, too little consideration has
been given to sanitation of locker plants, and, even in some instances,
to sanitary precautions in commercial food freezing plants. Unless
strict sanitary precautions are maintained in food plants, both during
the preparation of the food and its subsequent refrigeration, freezing
preservation will get a black eye from which it will take years to
recover. Spoiled frozen food is certain to make those who eat it ill,
and a few deaths from so-called "ptomaine" or botulinus poison will
come close to wrecking the grand and glorious prospects of the general
use of freezing preservation."

This statement should emphasize the importance of using
sanitary methods in the preparation of food products for the home

freezing plant.

 

The freezer-storage unit has been in operation since Jane
uary 29, 1940. It has been Operating in the Agricultural Engineering

laboratory at Michigan State College. The results are as follows:

Investment in Equipment

55.

The cost of the freezing plant at retail prices would be:

8..

b.

C.

Cabinet, complete
abinet stand
Freezing plates

Condensing Unit 1/2 H.P.
(Includes pressure switch)

Expansion valve, low temperature
Heat exchanger

Freon-12

Fittings, tubing, etc.

Total cost at retail prices

Operating_ Costg

$66.67
6.06

105.00

200.00*
15.00
20.00

7.00

5.00

$ 454.75

A kilowatt-hour meter was installed on February 8, 1940.

During the period from February 8 to February 16 the temperature of

O
the cabinet was —20 F. to -22°F. February 16 the temperature of the

cabinet was adjusted to -lO°F. and has been maintained at that tem-

perature since.

The power consumption record is shown in Table 6.

Table 6 shows that it requires 1.12 kw—hr. less to Operate

the cabinet at -10°F. than at —20 or -22°F.4

Operating at -10°F. the average consumption of electricity

was 5.25 kilowatt hours per day.

The cost of electricity varies within the state, depending

 

-_—

*Approximate cost of 1/2 H.P. condensing unit.

56.

Table 6. Kilowatt-hours required to operate home
freezer storage cabinet February 8, 1940 to
May 15, 1940.

 

 

 

Meter Kw—hr. Av.Kw—hr. Tempera-
Date Reading used per day ture of Remarks
__.___ cabinet
0
Feb. 3 7,972 -20 F. Meter installed
16 8,007 55 4.57 -220 Temperaturg adjus—
ted to —10 F.
21 8,025 16 5.20 -100
29 8,050 27 5.57 -10° Recording thermomet- '
er installed Feb. 29.
Mar. 4 8,065 15 5.25 -10°
11 8,084 21 5.00 -100
19 8,106 22 2.74 -100
27 8,128 22 2.74 —10°
Apr. 6 8,162 54 5.40 -100
22 8,214 52 5.25 -100
May 6 6,267 47 5.55 -10°

 

Av. Kw-hr./day Feb. 16 to May 6 e 5.25 Kw-hr.

on the amount of electricity used. Studies made by the Consumers Power
Company show that on three demonstration electrical farms, 1957-58, the
average yearly cost of electricity was 1.49, 2.105 and 2.648 cents per
kw-hr.

Using a value of 2 cents per kw-hr. the cost of operating the
freezer-storage cabinet would average approximately 6.5 cents per day.
At the 1.5 cent rate, the approximate daily cost would be 4.87 cents.
The Operating cost could also be decreased by raising the cabinet tem-
perature to 00F., but it would not be advisable to raise the temperature

above this point.

 

IMIDAY

MON

of Free zer-Storaga Cabinet

Typical charts shaving the temperature inside

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60.

Total Yearly;Costs
Total yearly cost includes depreciation, interest, taxes,
insurance, repairs and operating expenses. For equipment of this kind
15% of the investment is considered as overhead eXpense. Therefore,

15% of $454 would be $65.10 (Table 7).

Table 7. Estimated total_year1y cost of freezer-storage unit
Item Amount (dollar§l_

Overhead (15% of $454) $65.10
includes depreciation, interest
taxes, insurance, repairs and

 

miscellaneous
Operating @ 6,5 cents per day 25.72 ‘_
Total .1, $88.82 _w_

 

 

Qperatigg,Performance

Maintenance of a uniform temperature of GOP. or below in the
freezer-storage compartment is of primary importance in freezing preser-
vation of foods. The temperature in the cabinet has been maintained very
satisfactorily. Variations in temperature have not exceeded a plus or
minus two degrees except when the doors were Opened for placement or
removal of products and when power was off. Figures 14 and 15 illustrate
typical records of the cabinet temperature. Figure 16 illustrates the
corresponding temperature records of the room temperature.

For some unknown reason the electricity was disconnected
from 5:00 p.m. Wednesday, April 10 to 9:00 a.m. Friday, April 12, a
period of 42 hours. After the first 6 hours the-temperature was -5°F.,

after the next 6 hours the temperature was 00F. and during the next

0
50 hours the temperature rose only 10 resulting in a temperature of’+10°F.

 

’3

 

 
   

IOCNKSVI.‘, u v

  
     

-.€ mm 6 ‘9
w, ~qu 'W'd.’

 
   

Figure 17. Chart shoring the temperature of the freezer cabinet during the time
the power supply was disconnected

62.

”During the first 6 hours the temperature rose only 50 which indicates
there would be no particular harm done to product during short periods
of power failure (Figure 17).

After the freezing unit had been in operation for about 8
weeks some frost accumulation was noticed on the front center of the
top plate. Frost accumulation could have been caused by leaky door
jackets, opening and closing of the doors and leaving the doors ajar.
Because of the type of locking arrangement it was possible for anyone
attempting to open the cabinet door to release the catch just enough
to leave the door ajar. One shim was removed from the door strike and
a notice posted on the door requesting that the doors be kept tightly
closed. Since then the frost accumulation has been reduced considerably.

Products Frozen and Stored

Poultry, pork and beef have been frozen and stored in the
freezer—storage cabinet. Only a few hours are required to freeze meat.
Sixty-five pounds of beef varying in weight from 1% pound to 5 and 8
pound packages were completely frozen in about 8 or 9 hours. This time
was determined by observation of the place on the temperature chart when
the temperature leveled off to normal —lOOF. with the introduction of
this 65 pounds of meat the temperature did not vary more than 4°. An
average sized steak laid flat on the plates will freeze solid in about
one hour and twenty minutes. One hundred twenty-five pounds of choice
cuts of pork was the first amount of meat frozen. Unfortunately the
recording thermometer was not available when this meat was frozen.

Five chickens have been frozen, three were frozen whole and

two were cut into pieces for freezing.

 

....

Fig. 18.

 

Products stored in freezer-storage cabinet.

'65.

64.

The quality of the pork, beef and chickens at the time of
consumption was excellent. Freezing seems to improve the flavor and
tenderness of meat. Chicken in particular appeared to be more tender

than when eaten fresh.

Conclusions

 

This study shows that home produced foods can be frozen
and stored in a home-built cabinet.

Meats frozen and stored at 00F. or below are more palatable
than those canned by pressure cooker or preserved by other methods.
Investigations have shown that frozen fruits and vegetables are of
better quality and more nearly resemble the fresh fruit or vegetable
than canned products. Imagine being able to invite your friends in
for fresh strawberry Shortcake at Christmas. Blueberries, cherries
and peaches are other delicious fruits that can be enjoyed out of
season. This is but one example of the services derived from a home
freezing unit.

Labor saving is am important factor. The home freezing unit
can Contribute greatly to lightening the duties of the homemaker.
Meats especially can be preserved so much easier and quicker by freez-
ing than by canning. From experience it was found that a 200—pound
hog could be cut into family sized servings, wrapped, labeled and
ready for freezing in about three hours. Compare this time with one
and one-half or two days the housewife usually spends canning meat
by ordinary methods. This time did not include the rendering of the

lard or making sausage.

65.

The total cost Of owning a home freezing unit including de-
preciation, interest, repairs and operation would be approximately
$88 per year. Rental of the equivalent space, 20.5 cubic feet, from
a commercial locker plant would cost $59.40.* Assuming 1,500 pounds
of food products stored per year, the locker plant processing charges
would be approximately $25.25. Add this to $59.40 and the total is
$62.65. Comparing the two kinds of storage the cost per pound (for
1,500 pounds) would be 5.8 cents for the home freezer and 4.2 cents
for the commercial locker. The home freezer-storage is at the source
of SUpply and consumption thereby eliminating the inconvenience and
the expense of travel to and from the locker plant.

Home produced meat is much cheaper than that purchased from
the local market. By freezing his own.meat the farmer has a quality
of meat equal to or better than that he would purchase from the local
market. For example a saving of $12.46 may be made by freezing one hog
(See Table 8).

On that basis, the savings on two hogs would pay for the
Operating costs of a home freezing unit. The savings that could be
realized on a beef would be about $60 to $75.

The total yearly cost as calculated is higher than necessary
because the price Of the 1/2 H.P. condensing unit was used in calcula-
ting the yearly cost. A 1/5 H.P. condensing unit could be used and this
would decrease the amount of investment and interest. The cost Of Opera-
ting the 1/5 H.P. unit would be less than that Of operating the 1/2 H.P.
unit.

The economy Of a home freezing plant will depend upon the use

 

*Based on locker size 18 x 20 x 50 inches at the rate of $12 per year.

\

 

 

 

 

 

Table 8. Savings realized by preserving home produced
Dressed yield Retail price Purchase

Cut of meat <__per hog* per pound** ‘_price

(poundS)

Hams 53.1 $ .19 $ 6.50
Loins 26.7 .21 5.55
Bacon strip 21.4 .20 4.28
Picnic shoulder 20.4 .11 2.24
Boston butt 8.8 .19 1.67
Spare ribs 8.8 .12 1.06
Sausage trim 17.5 .08 1.58
Lard 24.0 .07 1.68
Hocks 5.7 .10 .57
Head & feet 18.5 .01 .18
TOTAL 182.5 <£24.51

Av. iive weight 254 $5.15/cwt*** titaos
SAVINGS ~e§l2.46

 

Brown, Geo. A. and Westveld, Amy.
Michigan.State College Ext. Bulletin 151, NOV. 1955, p. 15

The Home Meat Supply

*
** Prices obtained at local market April 16, 1940
***

Prices on Detroit Livestock Market April 16, 1940

66.

67.

made of it. For example, if 1,500 pounds of product can be frozen
and stored for 5.8 cents per pound, to freeze and store 500 pounds of
products the cost would be 17 cents per pound.

Additional farm income may be had by marketing frozen farm
products. For example, frozen poultry could be a specialty.

Home freezer-storage units can be adapted to various in-
stallations to accommodate different situations and individual require-
ments. The freezer fits in especially well with a walk-in cooler, thus
offering storage under controlled conditions throughout the year. No
longer would the farmer have to depend upon freezing weather to preserve
his fresh meat supply.

Although the present freezer-storage unit has performed satis-
factorily, it is believed that following suggestions or changes would be
advisable.

a. Simplification of cabinet by re-designing, making it
adaptable to either a rigid, blanket or fill insulation.

See drawing 5. . I

b. One door is recommended, simplifies construction and in
addition decreases the amount of heat leakage, amount of
gasket material and expensive hardware.

c. Suggested that the interior door stop be adjustable to pro-
vide a positive seal against the inside gasket.

d. Using one door the whole front section should be demountable

to facilitate installation of plates. This suggests that a

front section and door assembly could be commercially built

and marketed to farmers or others contemplating building a

home freezer-storage unit.

(l)

(5)

(5)

(7)

(8)

(9)

(10)

(11)

(12)

68.

LITERATURE CITED

Tressler, Donald K. and Evers, Clifford F. The Freezing
Preservation of Fruits4_Fruit Juicesi.and Veg:
etables. New York: The Avi Publishing Co., Inc.
1956, p. 46

 

Woolrich, W. R. Handbook of RefziggrationgEngingering;
New York: D. Van Nestrand Co., Inc., 1958, p. 570

Warner, K. F. Cold-Storage Lockegg for Preservigg Farm-
Cured Meats. Mimeograph copy. U. S. D. A. Bureau
of Animal Industry. A. H. D. No. 16 Revised, 1959.

Diehle, H. C. and Birdseye, Miriam. Storage of Fruits
and Vegetables in Community Freezer Lockers.
U.S.D.A. Miscellaneous Extension Publication 47,
October 1958, p. 8

Plagge, H. H. Fruits and Vegetables, Studies Relating
to Their Freezing and Storage. Ice and Refrigera-
tion. Vol. 94, March 1958, p. 220

Wiegand, E. H. Expgrimental Results on the Preservation
of Fruits and Vegetables by Freezing. Agriculture
Experiment Station Circular 122, Oregon.State
College, Corvallis, Oregon, May 1958.

Berry. J. A., Cold Tolerant migzggrgagisms and Engagn Rack.
Canner. Vol. 78:11 p. 15-14, 1954.

Taylor, R. B. Quick Freezing Fruits and Berries.
Quick Frozen Foods, Vol. 1, October 1958, p. 51

Public Health Aspects of Frozen Foods with Particular
_Ref§rence to_the Products Frozen in Cold Storagg
Lockers and Farm Freezegggv Mimeograph paper
U.S.D.A. Extension Service.

Augustine, D. L. Effects of Low Temperatures on Engysteg

Trichinella Spiralifi. American Journal of Hygiene,
Volume 17, May 1955, p. 697-710

Lease, E. J; Lease, J. G.; Weber, J; and Steenbock H.

Destruction.of Vitamin.A by Rancid Fat. Journal
of Nutrition. Volume 16, 1958, p. 571-585

Jenkins, R. R.; Tressler, D. K.; and Fitderald, G. A.

Vitamin C in Vegetableg. Storage Temperatures
fgr Frosted Vegetables. The British Association

of Engineering. Proceedings of General Conference on
Refrigeration, March 20, 1959

(15)

(14)

(15)

(16)

(17)

(18)

69.

Dunker, C. F.; Fellers, C. R.; and Fitzgerald, G. A.
Stability of Vitamin C in Sweet Corn to Shipping,
Freezing and Canninge, Food Research. Volume 2,
1957, p. 41.

Fitzgerald, G. A. Effects of Freezing;9n Vitamin 9 Content
of Vegetables. Refrigeration Engineering. Volume
57, January 1959, p. 55. -

Smart, Helen F. Types and Survival of Some Microorganisms
in Frozen:pack Peas. Beans and Sweet Corn Grown
in the East. Food Research, Volume 2, 1957, p. 515-
528.

Knowles, F. W. An Experiment in Home Freezing. Ice and
Refrigeration. Volume 92, January 1957, p. 57058

Danna, Homer J, and Miller R. N. The Farg Egeezing Plant
and How to Use it. State College of Washington,

Agricultural Extension.Bu11etin No. 249, April 1959.

Tressler, Donald K. What Freezing Preservation Means to *{~

the Earner, the Consumer and the Food industries.
Mimeograph copy, New York State Agricultural Experi-

ment Station.

3091910

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