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Masters Theses 1911 - February 2014
Dissertations and Theses
1933
A study of ice cream high in fat content
John Harold Brockschmidt
University of Massachusetts Amherst
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A STUDY OF
ICE CREAM HIGH IN FAT CONTENT
BY
JOHN HAROLD BROCKSCHMIDT
THESIS
SUBMITTED FOR THE DEGREE OF
MASTER OF SCIENCE
AT
MASSACHUSETTS STATE COLLEGE
AMHERST, MASSACHUSETTS
JUNE
1933
ACKNOWLEDGEMENTS
The writer wishes to take this opportunity to thank the Dairy and Ice Cream Machinery
and Supplies Association for the Fellowship which
made this work possible.
Deep appreciation and thanks are due
Professor J. H. Frandsen who proposed the problem, gave helpful suggestions, and arranged for
needed equipment and supplies.
Acknowledgement is made to Professor
M. J. Mack for permission to continue work on
a problem of similar nature started by him.
The
writer wishes to thank him for his generous
assistance in outlining the problem, and for
valuable suggestions and criticisms as the work
progressed.
He wishes to thank Professor W. S.
Mueller for his cooperation and suggestions, and
Mr. H. G. Lindquist for his assistance in judging
the ice cream.
INTRODUCTION
High fat ice cream in the past has been manufactured mainly for a select trade and for use in fancy
molds.
The people buying it were willing to pay an ad-
ditional sum for a higher quality product.
Perhaps for
this reason high fat ice cream has been considered more
of a luxury than a product to be consumed regularly as
a refreshing food.
It seems now, however, with the prevailing low
prices of butt erf at that the general trend is toward ice
cream higher in fat content.
This is particularly true
in New England where a specialized type of business has
developed for manufacture and sale of ice cream containing 18 to 20 per cent butterfat, or more in some instances.
Small dealers who operate the popular roadside
stores are responsible mainly for the introduction of
this new quality product as a regular item of sale.
Usu-
ally these dealers do not prepare their own mix, but buy
a prepared rich basic mix from creameries, milk plants,
and even ice cream plants which make a specialty of selling ice cream mix to smaller dealers.
At the present
time, even the largest manufacturers handle the product.
They sell either the mix or the high fat ice cream, de-
- 2 -
pending upon the facilities of the small dealers.
In order to illustrate the complexity of the
problem of an adequate fat content in ice cream, the following factors enumerated by Sommer
(l)
serve very well.
They are:
1.
The effect of fat on the quality of ice cream.
2.
Cost.
3.
The effect of richness on the amount of ice cream
consumed.
4.
The effect of the fat content on the caloric value and nutritive ratio of the product.
5.
The consumer's preference.
The optimum percentage of butterfat to incorpo-
rate in an ice cream mix always has been a debatable
question.
It is not only one of individual, local, or
sectional preference but also one of economic importance.
The economic problem offers the greatest obstacle to an
ice cream manufacturer for a higher fat content since
butterfat by volume usually is the most costly single
ingredient of the mix.
However, if the tendency is toward
higher fat ice cream, then the manufacturer must meet the
issue in some manner and raise the fat standard.
Butterfat gives to ice cream a characteristic
richness and mellowness of flavor and smoothness of texture.
The desirable qualities are difficult to obtain
- 3 -
with any other ingredients or by any manufacturing process.
It is reasonable to assume that there is a limit
to the amount of butterfat which can be incorporated into ice cream and still maintain a progressively better
product.
Just what this limit is will vary with indi-
vidual preference.
The advocates of a low fat standard contend
that more ice cream will be consumed if the fat content
is low.
It is argued that ice cream with a low percent-
age of fat has a greater cooling effect and that such ice
cream is a more nearly "balanced" food.
It is argued
that high fat ice cream is, "Too low in its protein content
in comparison with the energy giving constituents fat and
sugar (l)
Those who favor a high fat standard emphasize
the high caloric value of ice cream high in fat content.
They claim that since people do not subsist on an ice
cream diet alone a "balanced" product is not essential.
Furthermore, they contend that more high fat ice cream
will be consumed because it tastes richer and is smoother
in texture.
It is not the purpose of this problem, however,
to recommend any particular fat standard, but rather to
- 4 -
study the problems connected with the manufacture of ice
cream high in fat content.
The methods of processing
and amounts of ingredients that produced the high fat
ice cream having the smoothest texture and least resist-
ant body will be recommended for commercial use.
Ice cream with a fat content of 18 per cent or
higher is defined as high fat ice cream in this study.
All experimental data are limited to this range
— the
majority of the trials being conducted with ice creams
containing 18 and 20 per cent fat.
The object of the problem is to determine the
following in regard to high fat ice cream:
1.
The optimum serum solids ration to fat and
total solids.
2.
The optimum percentage of gelatin.
3.
The optimum homogenization pressures.
4.
A method of incorporation of butter into high
fat mixes.
5.
The optimum:
a.
Brine cut-off temperature.
b.
Drawing temperature.
c.
Overrun or yield.
d.
Serving temperature.
- 5 -
REVIEW OF LITERATURE
A review of the literature disclosed a wealth
of data on the subject of butterfat in ice cream, but
very little of it bore a direct relation to the specific
problem of high fat ice cream.
Generally speaking, the
material dealt with the effects of butterfat on the properties of ice cream and ice cream mixes in which the fat con-
tent was varied from 4 to as high as 25 per cent.
There
could be found no published exhaustive study of high fat
ice cream.
The great variation in personal opinion of the
investigators regarding an optimum fat standard for ice
cream is of interest.
There was some discrepancy as to
what fat percentage constituted high fat ice cream.
A
review of the literature did not suggest a basis for
developing this problem because so little conclusive work
has been reported on ice cream high in fat content.
The
available literature, however, served to emphasize the
conflict of opinion pertaining to butterfat in ice cream,
particularly to high fat ice cream.
Williams (2), in a study of consumer preference
for different proportions of fat in ice cream, found that
of a total of 316 sales 82 per cent were of ice cream
- 6 -
containing 18 per cent fat, 10. 4 per cent of ice cream
containing 15 per cent fat, and 7.6 per cent of the sales
in which the purchasers favored ice cream containing 12
per cent fat.
He concluded that the fat content does not
seem to have a great effect on the quantity of ice cream
consumed.
A test with two grades of ice cream showed that
the average adult person consumed 1.2 pints of 10 per cent
and 1.12 pints of 15 per cent ice cream when given all he
would eat.
Lucas and others (3) studied ice cream containing 8 to 14 per cent fat.
They found that the addition of
each 2 per cent of fat above 8 per cent increased the
score for flavor of the ice cream approximately
3
points
and raised the score for body and texture approximately
2 points.
Increases in fat slightly shortened the time
required to attain maximum overrun.
The average maxi-
mum overrun, however, was reduced by approximately 10
per cent for each 2 per cent increase in fat.
They con-
cluded that increases in fat acted as a deterrent to
overrun.
Resistance of the ice cream to melting was in-
creased with the fat content.
Since the fat limit was
14 per cent in this study, only an indication is given
of what might occur in higher fat ice cream in regard
- 7 -
to the effect of butterfat on flavor, overrun, and melt-
ing resistance.
Fisher (4)
,
however, studied the influence of
butterfat and serum solids on the flavor, body, and texture
of ice cream by a series of trials in which the per cent
of butterfat was varied from 6 to 20 per cent.
He con-
cluded that as the percentage of butterfat is increased to
12 per cent there is a great improvement In flavor.
The
improvement in flavor continues from 12 to 16 per cent,
but is much less marked, while above 16 per cent.
"There
is a tendency to get too rich a taste for a good many
people".
He failed to observe any material improvement
in body and texture until at least 16 per cent butterfat
was present.
Williams (5) advocated the adoption by manu-
facturers of two grades of ice cream, one having a ratio
of milk solids not fat to fat of about 10 to 12 and the
other a ratio of about 6 to 16, respectively.
He believes
that people prefer ice cream with a high fat content and
a low percentage of serum solids.
Bierman (6), in a study of the effect of composition on dipping losses, concluded that a high fat content in ice cream decreases the dipping losses.
He found
- 8 -
that a high milk solids not fat to fat ratio increased the
dipping losses.
From this standpoint a high fat content
in ice cream would be desirable.
Washburn
(7)
contended that the composition of
high fat ice cream is such that it is too high in total
calories in proportion to the muscle building nutrients.
He concluded that a fair fat standard based upon the needs
of the people eating the ice cream would be comparatively
low, say 8 to 10 per cent.
Holdaway and Reynolds
(8)
found that in plain
ice cream the presence of fat increased the power to re-
sist melting.
As the percentage of fat increased the ice
cream became softer.
The fact that fat produces a smoother texture
is shown by Brainerd (9) in microscopic examinations of
the structure of ice creams containing various percentages
of fat.
The results of the study showed clearly that ice
cream containing 20 per cent fat was smoother than that
containing 10 per cent, i.e., the ice crystals were smaller.
Baer (10) showed that the body and texture of ice
cream improved with increases in the percentage of fat.
Dahlberg (11), in a microscopic investigation
of the structure of ice cream and its relation to texture,
found that milk fat mechanically prevented the growth of
- 9 -
ice crystals by limiting the area in which the ice
crystal
could grow.
Mixes containing no fat were coarse and icy.
A mix containing 12 per cent fat and 10 per cent serum
solids made a very smooth ice cream.
It contained fewer i
crystals than the mixtures containing either milk fat
or
serum solids alone.
These facts indicated that a correct
balance of the milk constituents is more essential for a
smoother texture than the total quantity of either fat or
serum solids.
Ambrose (12) studied the relation of the percentage of butt erf at to flavor, body, and texture of ice
cream.
He stated that within certain limits there is a
complimentary value in the relation of the proportion of
milk solids not fat to fat in producing a good quality
ice cream.
More specifically, when the proportion of milk
solids not fat is sufficient, an increased percentage of
butterfat acts very much the same as increased milk solids
not fat in producing smoother texture, greater resistance
to melting, and a more desirable body.
He stated, how-
ever, that there is an upper limit beyond which an in-
crease in the butterfat content, seemingly, does not im-
prove the quality of ice cream, but that a higher per-
centage of butterfat produces a richer flavor.
- 10 -
Nelson and Reid (13) studied ice creams in which
the fat was varied from
4.
to 25 per cent.
They showed
that with increased amounts of fat the specific gravity
of the mixes decreased and viscosity increased.
The low-
est yields were obtained with the 20 and 25 per cent fat
mixes, but the average overruns obtained varied only 7 per
cent.
The rate of melting decreased with increased per-
centages of fat.
appeared foamy.
After melting, the rich ice creams
The fat content appeared to have no ef-
fect upon the hardness of the ice creams.
They found that
ice creams with 14 per cent or more of fat gave a pro-
nounced butterfat after-taste and a coating of grease in
the mouth, both of which were considered objectionable.
From their experimental data they concluded, "A mixture
containing 10 per cent fat appears to result in the most
desirable ice cream".
Contrary to this there is the statement of
Walker (14), "Place the slogan, 'Keep Up the Quality',
constantly before you.
Never let the butterfat in your
fancy ice cream drop below 16 per cent fatj 18 to 20
per cent, with the solids properly balanced, makes the
most delicious and best selling ice cream for desserts".
- 11 -
EXPERIMENTAL PROCEDURE
It was necessary at the start of the problem to
narrow the range of butterfat percentages under consideration so that a reasonably complete study of the problem
could be made.
Accordingly, mixes containing 18 to
24.
per cent fat were prepared, frozen, and Judged in order
to observe the effect of the fat content on the flavor,
body, and texture of the ice creams.
Of the four ice
creams, those which contained 18 and 20 per cent fat,
respectively, were judged as being most satisfactory.
Therefore, the experimental work was conducted with 18
and 20 per cent fat ice creams only.
The problem was divided into six parts.
Mixes
were prepared according to definite procedures which will
be discussed in connection with the experimental results
obtained with each part.
Fresh cream was used to supply the fat in all
mixes except those in the part in which the effect of
different sources of fat was studied.
In this part, un-
salted butter testing 81 per cent fat, plastic cream testing 80 per cent fat, and frozen cream testing 40 per cent
fat, were used to supply the fat in the mixes.
Powdered
skim milk (95.6 per cent solids) and skim milk furnished
- 12 -
the added milk solids not fat.
were heated to 110° - 120° F.
The cream and skim milk
The powdered skim milk,
gelatin, (Bloom strength 225), and sugar were then added.
All mixes were pasteurized at 155° F. and homogenized at
the pasteurization temperature.
The mixes were cooled to
45° F. over a surface cooler and aged for 24 hours at 40° F.
before freezing.
The percentage of fat in the finished mix was
determined either by the Mojonnier method or with the Minnesota reagent.
The percentage of total solids was deter-
mined by the Mojonnier method.
m
Viscosity readings were made with 100 c.c. samples of each mix after aging 24 hours, using the McMichael
viscosimeter.
Readings were taken at 20° C. with a No. 30
wire and disc bob.
14-. 9
r.p.ra.
The cup was rotated at the rate of
No attempt was made to reduce the samples to
their respective basic viscosities but a standard procedure for obtaining samples was adopted.
The mixes were
agitated one-half minute before sampling and again agitated incident to raising the temperature to 20°
C,
thereby giving comparative readings for all batches.
All
readings are stated in degrees M.
The fat globules and clumps were measured with
an ocular micrometer disc standardized with the micro-
- 13 -
scope so adjusted that each of the smallest divisions
represented 0.63 microns.
One c.c. of the mix was di-
luted with 99 c.c. of distilled water.
One drop of this
dilution was mounted on a hanging drop slide.
Two freezers were used for the freezing process,
one a 4.0-quart brine freezer and the other a 1-gallon ex-
perimental brine freezer.
The data obtained with the ex-
perimental freezer were checked with the 40-quart freezer.
Overrun and temperature readings were taken at one-minute
intervals starting at the end of the second minute.
Two pint samples of each ice cream were drawn
at approximately 85 per cent overrun and hardened at 0°
to -5° F. before judging for flavor, body, and texture.
One pint sample was used for the melting trials.
sample was placed on a wire screen (mesh
inch) and exposed to room temperature.
5
Each
wires to the
The drippings were
collected in 250 c.c. graduated cylinders.
Comparative
data on the appearance of the melting ice creams on the
screen and the character and amount of drippings were
recorded.
-
u
-
COMPARISON OF ICE CREAMS CONTAINING DIFFERENT
PERCENTAGES OF BUTTERFAT
A preliminary study of Ice creams containing
different percentages of fat was undertaken principally
to serve as an introduction to the subject matter to
follow.
The study is intended to show that the respective
temperatures to which ice creams of different fat content
are frozen is of more importance in obtaining overrun than
the difference in fat content.
Furthermore, it is in-
tended to show that whipping ability is neither sacri-
ficed nor consistently improved by incorporating relatively
high percentages of fat into ice cream mixes.
Mixes containing 15 per cent sugar; 0.4 per cent
gelatin; 12, 16, 20, and
24.
per cent fat; and 10, 8.5,
7, and 6 per cent serum solids respectively were prepared.
Each mix was divided into two parts.
All the mixes in the
first part were frozen to 25.3° F. (except the mix containing 24 per cent fat which became so stiff in the
freezer that the temperature was raised to 26.2° F.).
The
mixes in the second part were frozen to different temperatures as indicated in Graph No. II.
Graphs
I
and II show the effect of variation
in freezing temperatures on the whipping ability of Ice
- 15 -
cream mixes containing different percentages of fat.
When
the freezing temperature remained constant, increasing the
percentage of fat decreased the rate of whipping (Graph
No. I)
.
However, the mix containing 12 per cent fat
whipped more slowly after 115 per cent overrun was reached.
The mixes containing 16 and 20 per cent fat reached the
highest maximum overrun.
Both the 20 and 24 per cent fat
mixes became entirely too stiff in the freezer with the
freezing temperatures used.
This probably explains the
slow rate of whipping and low maximum overrun obtained
with these two mixes.
By increasing the freezing temperature pro-
gressively with each increase in fat content, an entirely
different whipping picture was obtained (Graph No. II).
The rate of whipping of the mixes increased with increased
percentages of fat.
Above 85 per cent overrun, however,
the ice cream containing 24 per cent fat became too stiff
in the freezer and the rate of whipping decreased.
The
ice cream containing 20 per cent fat attained the great-
est maximum overrun while the ice cream containing 12 per
cent fat attained the lowest maximum overrun.
In both
series there was an initial lag in the rate of whipping
with increasing percentages of fat.
- 16 -
The data show that differences in the rate of
whipping and maximum overrun obtained with identical series
of mixes are caused by the relative stiffness to which the
ice creams are frozen.
There was no consistent difference
in the whipping ability of mixes containing different per-
centages of fat, providing the ice creams were frozen to
the same stiffness in the freezer.
Sommer (15) obtained
similar results with mixes of different fat content when
all factors other than fat content remained constant.
In freezing ice creams which are high in fat content, a relatively high freezing temperature was found to
be necessary in order to eliminate excessive stiffness of
the ice cream in the freezer.
In the case of ice creams
containing 20 per cent fat, a brine cut-off temperature
of 26.6 to 26.8° F. was found to give satisfactory stiff-
ness to the ice cream when drawn at 85 to 90 per cent
overrun.
Viscosity and fat globule clumping increased
with increased percentages of fat.
However, since the
percentage of serum solids and the homogenization pressure
varied with each mix, no direct comparison can be made.
Melting resistance of the ice creams increased
with increased percentages of fat.
- 17 -
Table 1.
Influence of Varying Percentages of Fat on
Viscosity and Fat Globule Clumping.
Per Per Cent
Cent Serum
Homogenization Viscosity
Fat
Solids
Pressure
°M
12
10
2500 - 1000
83
Average
No. of
Average
Size of
Clumps
microns
Clumps
Per Field
~
No Clumping
16
8.5
2000 - 500
110
12
20
7
1000 - 500
186
17
3.2
x 5.0
24
6
800 - 300
348
23
6.3
x 9.5
.63 x 1.3
Due to the increased melting resistance of the high
fat ice creams relatively high serving temperatures were
found to be desirable.
Low temperatures (less than 12° F.)
caused the ice creams to be tough or "chewy" and too resist-
ant to melting in the mouth.
When the serving temperature
was raised to 16 to 20° F. the ice creams lost this characteristic toughness and melted more smoothly and readily in
the mouth.
The flavor of the ice cream was more pronounced
at the higher serving temperatures.
- 18 -
INFLUENCE OF HOMOGENIZATION AT DIFFERENT PRESSURES
ON ICE CREAMS HIGH IN FAT CONTENT
Table 2. contains a summary of the results secured with the homogenization pressures most frequently-
used in the study.
Higher pressures were tried but the
viscosity of the high fat mixes homogenized in excess of
3000 pounds pressure was such that proper cooling of the
mixes over the surface cooler was impossible.
Table 2.
The Relation of Homogenization Pressure to
Viscosity and Fat Globule Clumping.
Average
Per
Viscosity
No. of
Homogenization
Cent
Clumps
of Mix
Pressure
Fat
Per Field
in
Mix Lbs. per Sq.In.
°M
18
73
5
1.9 x 3.2
1.3
163
10
7.0 x 8.2
1.9
85
8
2.5 x 3.1
1.3
200
13
5.6 x 6.3
0.63
105
3
.63x 1.3
1.9
1000
119
10
6.3 x 8.2
1.3
1000 - 500
117
6
3.8 x 5.0
1.3
1500
132
8
8.2 x 12.6
2.5
1500 - 500
127
6
4-4 x 5.0
0.63
1000 - 500
1500 - Single
1500 - 500
2500
20
Average
Average
Size of
Size of Individual
Globules
Clumps
microns
microns
800 - 300
- 19 -
From the start of the problem it was evident
that low homogenization pressures were necessary in
processing high fat mixes.
Reid and Russell (16) like-
wise found that as the butterfat content in ice cream increased, the optimum homogenization pressure decreased.
Too high pressures resulted in extremely viscous
mixes while too low pressures or no pressue resulted in
churning of the mixes in the freezer.
The optimum pres-
sures were found to be somewhere in the range of 500 to
3000 pounds.
Therefore, the homogenization pressures in
Table 2 were taken as being representative of possible
pressures or combinations of pressures which would give
satisfactory results.
Double- stage homogenization resulted in less
viscous mixes.
Fat globule clumping was less pronounced,
both in number and size of clumps.
Single-stage homoge-
nization at 2500 pounds pressure with 18 per cent fat
mixes and 1500 pounds with 20 per cent mixes gave entirely
too high viscosities.
However, as soon as the second
stage was introduced the viscosity of the mixes decreased
and the mixes readily flowed over the surface cooler.
Similarly, Dahle and Martin (17), Judkins (18), Turnbow
and Nielson (19), and Reid (20), reported less fat globule
- 20 -
clumping and lower viscosities when double-stage homoge-
nization was used with mixes containing lower percentages
of fat.
Graph No. Ill shows the comparative effect of
single and double-stage homogenization on the rate of whipping.
In all cases double-stage homogenization increased
the rate of whipping of high fat mixes.
The maximum over-
run that could be obtained was increased with the intro-
duction of the second stage.
As the pressue of both
single and double stage homogenization increased there was
a decided tendency towards increased stiffness of the ice
cream in the freezer.
This possibly accounts for the de-
creased maximum overrun obtained with the higher pressures.
Figures 1 and 2 show the effect of single and
double stage homogenization on the melting resistance of
ice creams containing 18 and 20 per cent fat, respectively.
By referring to figures 1 and 2 it can be seen
that double-stage homogenization decreased the melting
resistance of the ice cream.
As the pressure increased,
the melting resistance increased.
Single-stage homoge-
nization, in most cases, caused the ice creams to be
entirely too resistant to melting.
In both groups the
lower double-stage homogenization pressures gave the most
- 21 -
Figure 1.
The effect of single and double stage homogeni-
zation on the melting resistance of ice cream containing 18 per cent fat, 7 per cent serum solids, 15 per
cent sugar, and 0.4 per cent gelatin.
1
1000
- 500
2—1500
3
single
1500 - 500
A— -2500
5
2000 - 500
single
- 22 -
The effect of single and double stage horaogenization on the melting resistance of ice cream contain-
ing 20 per cent fat, 7 per cent serum solids, 15 per
cent sugar, and
1
800 - 300
2
0.4-
per cent gelatin.
3—1000
1000 single
- 500
U—1500
5—1500
- single
- 500
- 23 -
satisfactory results.
Numbers 2, 4, and
5
(Figure 1)
appeared curdled on the screen and were too' resistant to
melting.
There was very little difference in the vis-
cosity of the mixes or in the melting of 1 and 3.
In
figure 2, No. 1 melted faster and more evenly than the
other samples, but the mix lacked the body and character
of a high fat mix.
Double- 3 tage homogenization at 1000 -
500 pounds pressure gave good results from the standpoint
of viscosity, melting resistance, and rate of whipping.
As the homogenization pressure increased, the
ice creams became smoother in texture but were tough and
too firm in body.
The ice creams which were processed by
double-stage homogenization were smoother in texture.
These ice creams melted more readily in the mouth.
Low
pressures resulted in a weak body and a tendency towards
coarseness.
Medium homogenization pressures gave optimum results from the standpoint of viscosity, whipping ability,
melting resistance, and body and texture.
It is not
possible to recommend any specific homogenization pressure
which will give equal results with all high fat mixes
under all manufacturing conditions.
This study indicates,
however, that there is, in processing mixes high in fat
- 2A -
content, a narrow range of homogenization pressures that
can be successfully used.
The following summary may be
drawn of the homogenization pressures which gave most
practical results for 18 and 20 per cent fat mixes.
Mixes Containing 18 Per Cent Fat
1500 - single
Minimum
2000 - single
or
1500 - 500
Optimum
2500 - single
Maximum
Mixes Containing 20 Per Cent Fat
1000 - single
Minimum
1500 - single
or
1000 - 500
Optimum
2000 - single
Maximum
It should be noted that double-stage homoge-
nization is preferable.
- 25 -
THE EFFECT OF VARYING PERCENTAGES OF SERUM
SOLIDS ON ICE CREAMS HIGH IN FAT CONTENT
Mixes were prepared containing 18 and 20 per
cent fat, 15 per cent sugar, 0.3 per cent gelatin, and
varying percentages of serum solids.
The mixes were proc-
essed by double-stage homogenization at 1000 - 500 pounds
pressure.
Mixes referred to as having no added serum
solids are mixes, the serum solids of which were obtained
solely from the serum solids naturally present in the
cream and skim milk used.
When the percentage of serum
solids is indicated in the discussion, the additional
serum solids were obtained from powdered skim milk.
The results of this study show that added serum
solids are desirable in high fat ice cream in order to obtain a smooth texture and firm body.
of serum solids to fat must be low.
However, the ratio
The following dis-
cussion of the data proves this statement to be true.
Viscosity of the high fat mixes, in general, did
not increase with increasing percentages of serum solids.
In the case of ice cream containing 10 per cent fat, Lucas
and Roberts (21) found that each 2 per cent increase in
per
serum solids increased the viscosity of the mixes 25
cent.
There was, however, an inverse relationship be-
- 26 -
tween the percentage of serum solids and the degree of
fat globule clumping and the subsequent effect on the vis-
cosity of high fat mixes.
Table 3 illustrates this point.
The viscosity of the mixes containing no added serum solids
were lower than the viscosity of the mixes to which serum
solids were added (see Table 3).
As the percentage of
added serum solids increased, the degree of fat globule
clumping decreased, which was accompanied by lower viscosity.
Similarly, Dahle (22) found that the lower the serum
solids to fat ratio in mixes containing lower percentages
of fat, the greater was the tendency for fat clumping.
Table 3.
Influence of Varying Percentages of Serum Solids
Ojfl
Average No.
of Clumps
Per Field
Average
Size of
Clumps
6.0 no added
39
7
3.1 x 5.0
7.0
69
13
5.7 x 6.9
7.5
53
10
3.1 x 5.0
8.0
46
6
1.9 x 2.5
5.8 no added
54
10
3.8 x U»U
6.5
97
15
8.2 x 9.5
7.0
85
11
4-.
8.0
79
A
Per
Cent
Fat
Per Cent
Serum
Solids
Viscosity
IS
20
.
U x 5.0
2.5 x 3.2
Sommer (l) found that the percentage of serum
solids in the mix has no pronounced effect on the whip-
ping ability of mixes of average commercial composition,
but there is a tendency for the whipping to be slightly
slower with increased percentages of serum solids.
also proved to be true in high fat mixes.
This
Graph No. IV
shows that as the percentage of serum solids increased
there was a tendency towards slower whipping.
The effect
is not pronounced until the percentage of serum solids
reached 8 per cent.
All the mixes attained the same maxi-
mum overrun.
Figures 3 and A show the effect of added serum
solids on the rate of melting of ice cream high in fat
content.
There is no consistent rate of melting.
There
is, however, a general trend toward an increased rate of
The
melting with increased percentages of serum solids.
reason for the deviation of samples from the trend is
attributed to the difficulty experienced in controlling
the rate of whipping of the ice creams.
The slower melt-
ing ice creams were foamy and curdled on the screen
foaminess indicating higher overrun.
— the
As the percentage
of serum solids was increased, the leakage of serum de-
creased.
Serum leakage was always present when the sample
containing no added serum solids were allowed to melt.
- 28 -
The effect of varied percentage of serum solids
on the melting resistance of ice cream containing 18
per cent fat.
1
No added
2
3
7.0 per cent
8.0 per cent
A
9.0 per cent
- 29 -
Figure
4..
The effect of varied percentages of serum solids
on the melting resistance of ice cream containing 20
per cent fat.
1
No added
2
3—7.0
6.5 per cent
per cent
4
3.0 per cent
- 30 -
There was no leakage of serum in the ice creams containing 7 per cent or more of serum solids.
In all cases the samples having a low melting
resistance and melting without foaminess and curdling were
judged best.
Sample No.
2 in
in Figure A are examples.
Figure 3 and sample No.
3
Both show low melting resist-
ance and absence of curdling and foaminess.
When judged
they were placed first in their respective groups.
The optimum percentage of serum solids to incorporate in high fat ice cream was found to be 6.5 to
7.0 per cent in 20 per cent fat ice creams and 7 to 7.5
in 18 per cent ice creams.
Less than 6.5 per cent serum
solids gave a slightly coarse texture and weak body.
More
than 7.5 per cent serum solids in the case of 18 per cent
fat ice creams and 7.0 per cent serum solids in ice cream
containing 20 per cent fat produced a decidedly objectionable heavy, soggy body.
- 31 -
THE RELATION OF THE PERCENTAGE OF GELATIN TO
THE BODY, TEXTURE AND MELTING RESISTANCE
OF ICE CREAM HIGH IN FAT CONTENT
Dahlberg, Carpenter, and Henlng (23) found that
ice creams containing 16 per cent fat and over were im-
proved but slightly by the use of gelatin.
In lower fat
ice creams the rate of melting decreased with increased
percentages of gelatin, but in many cases the ice creams
without gelatin melted most slowly.
The results obtained
by these investigators were not in complete agreement with
those obtained in this study.
The writer found that gela-
tin is just as essential in high fat ice cream as in low
fat ice cream.
Without exception, the ice creams con-
taining 0.0, 0.1, and 0.2 per cent gelatin respectively
were coarse in texture and weak in body.
The ice cream
containing 0.5 per cent gelatin was very smooth in texture, but was heavy and soggy in body.
One would expect,
therefore, that between 0.3 and 0.4 per cent gelatin
would give optimum results in securing a favorable body
and texture in high fat ice cream.
true.
This was found to be
The ice cream containing 0.4 per cent gelatin was
and
judged as being best from the standpoint of body
gave a nearly perfect texture.
- 32 -
Figure
5.
The effect of varied percentages of gelatin on
the melting resistance of ice cream containing 20 per
cent fat.
1
0.0 per cent
2
3
0.3 per cent
0.2 per cent
4
5
— -0.5
0.4 per cent
per cent
- 33 -
Figure
statement.
5
further substantiates the foregoing
The rate of melting increased as the per-
centage of gelatin was increased to
0.4 P er cent.
ple No. 5 containing 0.5 per cent gelatin
melted
Sam-
more
slowly than No. 3 and No. 4, but more quickly than
No.
1 and No. 2.
The fact that the sample containing no
gelatin melted most slowly is in agreement with results
obtained by Dahlberg, Carpenter, and Hening.
However,
the fact that the rate of melting of high fat ice cream
increased as the per cent of gelatin increased (up to
0.4 per cent) does not agree with their work with lower
fat ice creams.
The character of the melting and particularly
the drippings of the various ice creams offered a possible explanation of this interesting characteristic of
high fat ice cream.
It was noted upon inspection of
the drippings that leakiness of serum was invariably
obtained when ice creams containing less than 0.3 per
cent gelatin were allowed to melt.
mained on the screen.
The fat portion re-
When the ice creams containing
0.3 to 0.5 per cent gelatin melted there was no leakage
of serum.
The character of the drippings was more nearly
like that of the original unfrozen mix.
- 34 -
Graph No. V. shows the effect of increased
percentages of gelatin on the rate of whipping of high
fat ice cream.
As the percentage of gelatin increased,
the rate of whipping in general slightly decreased.
(In all the mixes prepared)
.
The viscosity increased
as the percentage of gelatin increased.
- 35 -
INFLUENCE OF SOURCE OF FAT ON ICE
CREAM HIGH IN FAT CONTENT
During the months of low milk production, fat
in ice cream often is obtained from sources other than
sweet cream.
Butter, butter oil, frozen cream, and
plastic cream are used to supply either a part or all of
the fat during this period of low milk production.
Ex-
cessive fat clumping, increased viscosity, and slow whipping are often experienced when these substitutes are in-
corporated into mixes.
The degree of intensity of these
difficulties increases as the fat percentage of the mix
is increased.
The effect is particularly pronounced in
high fat ice cream.
This study was undertaken to determine the
effect of the source of fat on the properties of high
fat ice cream.
A study was made of methods of intro-
duction of butter into high fat mixes.
The effects of
adding egg yolk and lecithin to high fat butter mixes
were noted.
Mixes containing 18 per cent fat, 8 per cent
serum solids, 15 per cent sugar and 0.35 per cent gelatin were prepared.
The fat in the mixes was obtained
and
from fresh cream, frozen cream, plastic cream,
butter, respectively.
The mixes were frozen and the ice
cream judged for the effect of the source of fat on flavor, body, and texture.
The effect of the fat sources
on the properties of the mixes was noted.
The viscosity of the mixes containing sweet
cream and frozen cream was lowest.
Excessive fat clumping
and a comparatively high viscosity were noted when the fat
of the mix was obtained from butter or plastic cream.
Graph No. VI. shows the effect of the various
sources of fat on the whipping ability of the mix.
Fro-
zen cream, butter, and plastic cream decreased the rate
of whipping as compared to the whipping ability of the
mix in which the fat was obtained from fresh cream.
There
is a marked decrease in the maximum overrun that could be
obtained in the mix, the fat of which was furnished by
plastic cream.
The decrease in whipping ability of mixes
due to the use of butter is shown by Dahle (22)
Whi taker (24), and Caulfield and Martin (25).
Similarly,
Mack (26) found that mixes made from frozen cream whipped
more slowly than those made from fresh cream.
The ice creams melted uniformly, but that made
from butter showed a curdled condition.
The most desirable ice creams were obtained
- 37 -
when fresh cream and frozen cream were used to supply the
fat.
Butter, and to a less extent plastic cream, imparted
an old storage flavor to the ice cream.
Because of the
high concentration of fat in rich ice cream it is best to
use only the highest quality raw products.
If butter or
frozen cream are to be used, they should be reasonably
fresh and clean flavored.
In order to insure a good
whipping mix and high quality ice cream, butter, plastic
cream, or frozen cream should not be used as the entire
source of fat.
- 38 -
A STUDY OF RECONSTITUTED CREAM FROM BUTTER AS A
SOURCE OF FAT IN ICE CREAM HIGH IN FAT CONTENT
Mixes containing 20 per cent fat, 7 per cent
serum solids, 15 per cent sugar, and O.A per cent gelatin were prepared.
The fat was obtained from fresh cream,
reconstituted cream, and butter.
Egg yolk and soy bean
lecithin were added to two of the mixes.
Table No. U
contains the detailed composition of each mix.
Reconstituted cream was made by heating together to 145° F. the necessary amounts of butter and
skim milk for each mix and homogenizing the mixture at
1000 pounds pressure.
The resulting emulsion was then
combined with the skim milk powder, sugar, and gelatin.
This mixture was pasteurized at 155° F. and homogenized
at 1000 - 500 pounds pressure, using double stage homogenization.
The mixes were cooled to
4-5°
F. and aged 24
hours before freezing.
From Table 4 it can be seen that emulsifying
the butter with skim milk by homogenization before adding
to the mix reduced viscosity and fat globule clumping.
The untreated butter mix was entirely too viscous to
cool properly.
Fat globule clumping and also the vis-
cosity were reduced by emulsifying the butter.
It Is
- 39 -
interesting to note in this connection that the extent of
fat globule clumping and viscosity of the fresh cream mix
was higher than values obtained when reconstituted cream
supplied the fat.
When fresh cream was introduced into a
mix in which one-half of the fat was obtained from reconstituted cream, fat globule clumping and viscosity increased.
Both powdered egg yolk and lecithin increased
the viscosity and fat globule clumping of such mixes.
Lecithin had a more pronounced effect than did egg yolk
in this respect.
Table 4.
The Effect of Cream, Butter, and Reconstituted
Cream on Viscosity and Fat Globule Clumping
of Mixes High in Fat Content.
No. of
Clumps
Average
Size of
Clumps
Per Field
microns
Average
Mix
No.
Source of Fat
in Mixes
Viscosity
om
1
Fresh Cream
2
Butter
3
Reconstituted Cream
4
5
6
i Fresh Cream
\ Reconstituted Cream
Same as No. 4 plus
0.5 per cent Powdered
Egg Yolk
Same as No. 4- plus
0.25 per cent Soy
Bean Lecithin
195
64
%
(No. 26 wire)
133
21
3.1 x 5.0
30
11.3 x 13.9
5
1*3 x 2.5
w
15
2 .5
224-
22
3.2 x 4.4
295
26
4-4 x 5.6
x 3.2
.
.
,
- AO -
Graph No. VII shows the influence of egg yolk,
lecithin, and reconstituted cream on the whipping ability
of mixes high in fat content (see batches
1, 2, and 3).
The fat in these mixes was obtained from fresh cream,
butter, and reconstituted cream, respectively.
Both but-
ter and reconstituted cream decreased whipping ability;
the latter had the greater effect.
the fat in Mix No.
4.
By securing one-half
with fat from fresh cream, a decided
improvement in whipping ability was noted.
In fact, this
mix showed practically the same rate of whipping as the
fresh cream mix.
However, after 120 per cent overrun
was reached the rate of whipping decreased.
Egg yolk increased the rate of whipping of mixes
in which one-half of the fat was obtained from fresh cream
and one-half from reconstituted cream.
The mixes con-
taining egg yolk, however, whipped more slowly for the
first few minutes than the plain mix.
This characteris-
tic initial lag in whipping, as caused by egg yolk, was
observed in low fat mixes by Button (27)
Lecithin, when added to a mix high in fat content, was found to decrease the rate of whipping.
4, 5, and 6 on Graph No. VII should be compared.
Mixes
Mix
No. 6 containing lecithin shows a consistent lag in the
- 41 -
rate of whipping of 2 to 3i minutes when compared with
mix No. 4 which contained neither egg yolk nor lecithin.
Caulfield and Martin (25) found soy bean lecithin a deterrent to whipping ability.
lecithin repressed overrun.
Button (27) found that egg
It should be noted that these
investigators worked with mixes low in fat content.
Reconstituted cream decreased the melting resistance of the ice cream.
The effect was particularly
noticeable in the ice cream containing no other source of
fat.
The ice cream was completely melted in three hours
while the butter sample had barely started to melt at the
end of this period.
Fresh cream, when used to replace
half the fat in the ice cream, decreased the rate of melting.
Egg yolk and lecithin had little effect on the rate
of melting.
There was very little difference in body and
texture of the ice creams in this series.
Reconstituted
cream, however, tended to make the ice creams softer and
melt more quickly in the mouth.
There was no outstanding
difference in flavor except in the ice cream, the fat
of which was obtained from cream or partly from cream.
Since the butter used was not of the highest quality, the
improvement in flavor was pronounced when cream was the
-
-42
-
sole source of fat and very favorable when one-half cream
was used.
The data show clearly the benefits to be de-
rived from the use of reconstituted cream in high fat ice
cream.
They may be summarized as follows:
Reconstituted
cream effectively reduces the viscosity of mixes in which
butter is used as the source of fat.
The lower viscosity
facilitates prompt cooling to low temperatures.
Lower
viscosity aids in the ease of pumping and handling the
mix from the aging vat to the freezer.
The principal disadvantages are:
The added ex-
pense and labor involved in emulsifying the butter,
additional space for storage of the reconstituted cream,
and depressed whipping ability of the mix.
The latter,
however, is not serious since the effect is not marked
and, furthermore, the use of cream to supply part of the
fat restores the whipping ability of the mix to that of
a fresh cream mix.
- 43 -
SUMMARY AND CONCLUSIONS
1.
There was no consistent difference in the whipping ability of ice cream mixes containing differ-
ent percentages of fat.
When the freezing tempera-
ture remained constant, increasing the percentage
of fat decreased the rate of whipping.
By in-
creasing the freezing temperature progressively
with each increase in fat content (up to 20 per
cent) the rate of whipping of the mixes increased
with increased percentages of fat.
A relatively high freezing temperature was found
to be necessary in freezing ice creams high in fat
content in order to eliminate excessive stiffness
in the freezer.
A brine cut-off temperature of
26.A° F. in the case of 18 per cent fat ice cream
and 26.8° F. in the case of 20 per cent fat ice
cream gave drawing temperatures of 25.5° F. and
25.8° F. respectively, which assured ease of drawing of the ice cream.
2.
Relatively low homogenization pressures were
found to be necessary in processing ice cream mixes
high in fat content in order to eliminate excessive
-
viscosity.
u
-
Double-stage homogenization gave opti-
mum results from the standpoint of viscosity, whipping ability, melting resistance, body, and texture.
There was no one pressure which gave equal results
with all mixes.
The following range of homogeniza-
tion pressures, however, proved most satisfactory
under the conditions of the study.
Mixes Containing 18 Per Cent Fat
1500 - single
Minimum
2000 - single
or
1500 - 500
Optimum
2500 - single
Maximum
Mixes Containing 20 Per Cent Fat
1000 - single
1500
Minimum
- single
or
Optimum
1000 - 500
2000 - single
3.
Maximum
Added serum solids were found to be desirable
obtain a smooth
in high fat ice cream in order to
serum solids
texture and firm body. The ratio of
ratio of 7.5 per
to fat, however, must be low. A
fat, and 7.0 per
cent serum solids to 18 per cent
- 45 -
cent serum solids to 20 per cent fat gave the most
desirable body and texture.
4.
The rate of melting of high fat ice creams containing varying percentages of gelatin increased
with increased percentages (to 0.4 per cent) of
gelatin.
Ice creams containing 0.5 per cent gela-
tin melted more slowly than those which contained
0.4 per cent.
Ice creams containing no gelatin
had the greatest melting resistance.
The optimum percentage of gelatin to incorporate in high fat ice cream was found to be 0.3 to
0.4 per cent.
Less than 0.3 per cent gelatin
caused the ice creams to be coarse in texture and
weak in body, while 0.5 per cent gelatin caused
the ice creams to be heavy and soggy in body.
5.
Because of the high concentration of fat in
rich ice cream, it was found advisable to use only
the highest quality of raw products.
Butter,
plastic cream, and frozen cream, when used as the
abili'
entire source of fat, decreased the whipping
cream.
ty and imparted off -flavors to the ice
In
fresh cream
order to eliminate these difficulties,
- 46 -
should be used to supply part of the fat in high
fat ice cream.
The viscosity of high fat mixes made from untreated butter was such that the mixes were entirely too viscous to cool readily over the surface
cooler*
Reconstituted cream made by emulsifying
butter with skim milk was found to reduce the
viscosity of the mixes.
The whipping ability of
mixes made with reconstituted cream was slightly
impaired, but by using fresh cream to supply part
of the fat in the mixes, normal whipping ability
was restored.
Dehydrated egg yolk improved the whipping ability of butter mixes.
Soy bean lecithin decreased
whipping ability.
Due to the increased melting resistance of the
high fat ice creams, relatively high serving
temperatures were found to be desirable.
The ice
cold
creams lost the characteristic toughness of
serving
ice creams (less than 12° F.) when the
these
temperature was raised to 16° - 20° F. At
the ice creams
higher temperatures the flavor of
was more pronounced.
A
r
-
4-6
a -
——
i
i
Influence of Percentage of Fat on
Rate of Whipping When the Freezing
Per Cent
pgr d;ent fat
Brine Off 25.
9.0
per Cent
Brine iff 26.2° F.
,_2/i.
i
Graph No
A
10
6
Time in Minutes
12
1L
- 4-6
b -
-
46
c -
T
nfluence of Single and Doubl Stage
Homogenization at Different Pressures on
the Rate of Whipping of Mixes High in Fat Content
e
per
Cent
Overrun
34©
-120
to
SO
•
500
single
1500
•r
1500
AO
5^0-
Composition of Mixes
15
-7
-20
4.
per
per
per
per
cent
cent
cent
cen
fai._
sugar
serum solids
gelatin
Graph No
10
6
Time in Minutes
12
III
-
Per
46 e
-
in on the
Cent
Overrun
Fat Content
w
tem-
per -©ent-feia-t^n
P er cent gelatin
T
1
peg-^ent-^e l at ln
per cent gelatin
p e r 9 e nt -gelatin
of Ingredients
cent fat
cent serum solids
sugar-
Graph WQ. V
12
Tiffie~in
Minute
1-4
-
4-6
f -
- 47 -
The following section includes freezing
data for the graphs referred to in experimental
results and other freezing data obtained during
the course of the study.
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LITERATURE CITED
1.
Sommer, H. H., 1932. Theory and Practice of Ice
Cream Making. Published by the author at Madison,
Wis.
2.
Williams, 0. C., and Campbell, G. R., 1923. Effect
of Composition on the Palatability of Ice Cream.
U.S.D.A. Dept. Bui. 1161.
3.
Lucas, P. S., Matsui, T., and Mook, D. E., 1930.
The Influence of Sugar and Butterfat on Quality
of Ice Cream. Mich. Agri. Exp. Sta. Special Bui.
No. 201.
4.
Fisher, R. C, 1924. Experimental Studies in Ice
Cream During the Past Year. Creamery and Milk
Plant Monthly. Vol. 13, No. 4.
5.
Williams, 0. E., 1926. Varying the Serum Solids
Ratio. The Ice Cream Trade Jour. Vol. 22, No. 12.
6.
Bierman, H. R., 1927. How the Composition of Ice
Cream Affects Dipping by the Dealer. Ice Cream
Trade Jour. Vol. 23, No. 2.
7.
Washburn, R. M. , 1921. What is a Fair Standard for
Ice Cream? Jour, of Dairy Science. Vol. 4,
No. 3.
8.
9.
Holdaway, C. W., and Reynolds, R. R., 1916. Effect
of Binders Upon the Melting and Hardness of Ice
Cream. Virginia Agr. Exp. Sta. Bui. 211.
Brainered, w . K., 1915. Smoothness and Keeping
Qualities in Ice Cream, as Affected by Solids.
Virginia Agr. Exp. Sta. Tech. Bui. 7.
10.
Baer, A. C, 1916. Ice Cream Making.
Exp. Sta. Bui. 262.
11.
Dahlberg, A. C, 1925. The Texture of Ice Cream.
N.Y. Agr. Exp. Sta. Tech. Bui. 111.
Wis. Agr.
- 70 -
12.
Ambrose, A. S., 1923. A Study of the Relation of
the Composition of the Mix to the Quality of the
Finished Ice Cream. Jour, of Dairy Science. Vol.
6, No. 5«
13.
Nelson, D. H., and Reid, H. E., 1924. The Effect
of the Different Percentages of Butterfat on the
Physical Properties of Ice Cream. Missouri Agr.
Exp. Sta. Res. Bui. 70.
14.
Walker, E. S., 1932. Fitting Fancy Ice Cream Into
the Production Program. Report of the Proc. of
the 32nd Annual Conv. of the Int. Ass*n. of Ice
Cream Mfgrs. Vol. 2.
15.
Sommer, H. H., 1927. What Factors Affect Whip?
The Ice Cream Trade Jour. Vol. 23, No. 8.
16.
Reid, W. H. E., and Russell, L. B. , 1930. The
Effect of Different Homogenization Processes on
the Physical Properties of an Ice Cream Mixture
and the Resulting Ice Cream When the Percentage
of Fat is Varied and the Solids Not Fat Remain
Constant. Missouri Agr. Exp. Sta. Res. Bui. 134.
17.
Dahle, C. D., and Martin, W. H., 1925. The Effect
of Methods of. Homogenization on the Quality of
Ice Cream. * Perm. State College Annual Report,
Bui. 196.
18.
Judkins, H. F. , 1928. Do You Homogenize Mix
Properly? The Ice Cream Trade Jour. Vol. 24,
No. 11.
19.
Turnbow, G. D., and Nielson, K. W., 1928. Viscosity
and the Ice Cream Mix. Ind. and Eng. Chemistry.
Vol. 20, No. 4.
20.
Reid, W. H. E., 1928. Homogenization:
on Physical Properties of Ice Cream.
Cream Review. Vol. 11, No. 6.
21.
Lucas, P. S., and Roberts, W. J., 1927. The Relation of Milk Solids Not Fat to Overrun and
Quality of Ice Cream. Mich. State College Tech.
Bui. 86.
Its Effect
The Ice
- 71 -
22.
Dahle, C. D., 1930. Fat Clumping in Ice Cream.
Ice Cream Field. Vol. 16, No. 4-.
23.
Dahlberg, A. C, Carpenter, D. C, and Hening, J.C.,
1928. Grading of Commercial Gelatin and Its Use
in the Manufacture of Ice Cream, II. Ind. and
Eng. Chemistry. Vol. 20, No. 5.
24.
Whi taker, R. , 1930. The Influence of the Use of
Butter on the Freezing Properties of Ice Cream
Mix. Jour, of Dairy Science. Vol. 13, No. 1.
25.
Canfield, W. J., and Martin, W. H. , 1929. How Butter
Affects Whipping. Ice Cream Trade Jour. Vol.
25, No. 9.
26.
Mack, M. J., 1930. Frozen Sweet Cream as an Ingredient in Ice Cream. Mass. Agr. Exp. Sta. Bui.
268.
27.
Button, F. C, 1930. Dried Egg Yolk's Freezing
Effect. Ice Cream Field. Vol. 16, No. 5.
This thesis has been read and approved by:
ifJ.
Date:
J/;