Method of making ice cream

Frozen desserts are prepared using, as an emulsifier, esters of elaidic acid with polyhydric alcohols selected from the group consisting of glycerol, propylene glycol, sorbitol and saccharose.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to frozen desserts prepared by using, as an 
emulsifier, elaidic acid esters of polyhydric alcohols selected from the 
group consisting of glycerol, propylene glycol, sorbitol and saccharose. 
2. Description of the Prior Art 
Various frozen desserts such as ice cream, ice cream of low fat content, 
ice milk, fruit sherbets, frozen custards and mellorine have been prepared 
by freezing homogenized oil-in-water emulsions each of which contains oil 
and fat, skim milk, saccharose, flavorings, water and an emulsifier. 
Monoglycerides of fatty acids have conventionally been used, as 
emulsifiers, in the preparation of various frozen desserts and have 
exerted very important effects on the production processes. 
When used as emulsifiers, the monoglycerides of fatty acids mainly function 
to improve foamability, to impart solidity and to improve the 
shape-retaining property of the frozen dessert. Illustrative 
monoglycerides of fatty acids conventionally used for these purposes 
include the monoglyceride of stearic acid, the monoglyceride of oleic acid 
and mixtures thereof. 
The reasons for the fact that the monoglyceride of stearic acid (glyceryl 
monostearate) and the monoglyceride of oleic acid (glyceryl monooleate) 
have been generally used for this purpose are that not only are the 
starting fatty acids for these glycerides available most easily, but also 
these glycerides have special advantages for such use. In brief, the 
monoglyceride of stearic acid has a strong emulsifying force and does not 
deteriorate the flavor and taste, and on the other hand, the monoglyceride 
of oleic acid can considerably improve the shape-retaining property. 
However, these glycerides have serious disadvantages, and thus they cannot 
be considered as the ultimate or best emulsifiers. Specifically, the 
monoglyceride of stearic acid has a very poor shape-retaining property, 
and the monoglyceride of oleic acid causes serious deterioration of the 
flavor and taste and it has the further disadvantage that it increases 
greatly the viscosity of the starting mixture for preparing the frozen 
dessert which is disadvantageous when the starting mixture is aged or 
digested. 
For this reason, stearic monoglyceride and oleic monoglyceride are mixed 
together for practical use. Even when the mixed composition is used, the 
deterioration of flavor and taste due to the oleic monoglyceride is not 
completely obviated. Accordingly, it is desired to decrease the amount of 
oleic monoglyceride used in the mixture from the standpoint of flavor and 
taste, but to increase it for improving other desired qualities or 
properties such as the shape-retaining property. In consideration of the 
contradictory requirements mentioned above, the practical mixing ratio of 
oleic monoglyceride to stearic monoglyceride is in the range of 20 to 30 
percent, based on the total weight of the mixture of the two 
monoglycerides. 
The amount of the emulsifier in a starting mixture for preparing ice cream 
in the most generally practiced process for making ice cream is from 0.20 
to 0.35% by weight, based on the total weight of the ice cream mix, so 
that the amount of oleic monoglyceride, based on the weight of the 
starting ice cream mix, is 0.04 to 0.12% by weight. 
Oleic monoglyceride affects seriously the flavor and the taste of the ice 
cream, even though the used amount thereof is so small. 
SUMMARY OF THE INVENTION 
We have discovered an emulsifier for ice cream which does not cause any 
flavor or taste problems and which has sufficient foamability and improved 
shape-retaining property. According to the invention, there is used, as an 
emulsifier for frozen dessert mixes, an elaidic acid ester of a polyhydric 
alcohol selected from the group consisting of elaidic monoglyceride, 
elaidic ester of propylene glycol, elaidic ester of sorbitol, elaidic 
ester of saccharose and mixtures thereof. Elaidic monoglyceride (glyceryl 
monoelaidate) is particularly preferred for the purposes of this 
invention. 
The elaidic ester of polyhydric alcohol which is used in the present 
invention can be easily prepared from elaidic acid and a polyhydric 
alcohol selected from the group consisting of glycerin, propylene glycol, 
sorbitol and saccharose by a synthesis method in which a portion of the 
hydroxyl groups in said polyhydric alcohol is esterified with the carboxyl 
group of said elaidic acid. It is preferred to use emulsifiers which are 
monoelaidic acid esters of the polyhydric alcohols. 
Elaidic acid per se is a well-known fatty acid. However, there have not 
been synthesized glyceride and other esters of polyhydric alcohols using 
this particular fatty acid. Moreover, these esters have not yet been used 
as emulsifiers. Accordingly, it is believed that elaidic esters of 
polyhydric alcohols are novel emulsifiers. Particularly, elaidic 
monoglyceride has improved foamability, shape-retaining property, flavor 
and taste and appropriate viscosity as compared to the conventionally used 
monoglycerides of stearic acid and oleic acid when any one of the 
latter-mentioned monoglycerides is used by itself. 
The emulsifier of the present invention is superior to the mixture of 
stearic monoglyceride and oleic monoglyceride heretofore used as an 
emulsifier. 
Elaidic acid is a fatty acid having 18 carbon atoms, the same as stearic 
acid and oleic acid, and it has one unsaturated bond, the same as oleic 
acid. However, the double bond of oleic acid is in cis form, whereas the 
double bond elaidic acid is in trans form. The differences in the physical 
properties of those acids are attributed to the aforementioned differences 
in the chemical structures thereof. The most characteristic difference is 
the difference of the melting points of the respective fatty acids. The 
melting points of the respective fatty acids are 69.6.degree. C. (stearic 
acid), 10.9.degree. to 11.5.degree. C. (oleic acid) and 44.8.degree. to 
45.5.degree. C. (elaidic acid). Monoglycerides of the respective fatty 
acids have the melting points of 81.degree. C. (monoglyceride of stearic 
acid), 35.degree. C. (monoglyceride of oleic acid) and 58.5.degree. to 
59.3.degree. C. (monoglyceride of elaidic acid), respectively. 
Elaidic acid can be first prepared by converting oleic acid by treatment 
with the oxides of nitrogen or certain other catalysts, including sulfur 
and selenium, especially nitrous acid gas or a nitrite and nitric acid. In 
this reaction, an equilibrium mixture is obtained containing about 
two-thirds elaidic acid and one-third oleic acid. Elaidic acid can be then 
isolated by re-crystallization from its alcohol or ether solution, or 
ether or benzene treatment of its lead salt to remove oleic acid. 
Thus obtained elaidic acid is then heated to 200.degree.-250.degree. C. 
with 1.0-1.5 equivalents of a polyhydric alcohol plus 0.1-2.0% of a 
catalyst such as lead salt or an alkaline compound such as sodium 
hydroxide. Water is removed continuously under a reduced pressure of 
40-300 mm. The resulting product is a mixture of partial esters of the 
polyhydric alcohol. In this esterification, it is recommended that the 
reaction mixture is blanketed with an inert gas such as nitrogen or 
hydrogen gas to protect from oxidation. The reaction is completed for 1 to 
4 hours. At the end of this time an equilibrium will have become 
established between the free alcohol in the mixture and the reaction 
product, making it impossible for further combination of the alcohol to 
take place. 
Thereafter, by the use of molecular distillation, technical grades 
containing 40 to 50% monoesters will give distillates of 90 to 97% 
monoesters. Three-stage, centrifugal, short-path distillation produces 
practically instantaneous removal of monoesters with limited 
decomposition. 
As will be understood from the foregoing description, the melting point of 
elaidic monoglyceride lies at an intermediate temperature between those of 
stearic monoglyceride and oleic monoglyceride. Elaidic monoglyceride is a 
novel emulsifier and is a high melting point ester of an unsaturated fatty 
acid. The melting point (58.5.degree. to 59.3.degree. C.) of elaidic 
monoglyceride is one of the important characteristics thereof. 
The melting point of elaidic monoglyceride is not as high as that 
(81.degree. C.) of stearic monoglyceride, so that the elaidic 
monoglyceride is easy to handle during the ice cream preparation steps on 
one hand; and on the other hand, it is higher than that (35.degree. C.) of 
oleic monoglyceride and also higher than human body temperature, so that 
the elaidic monoglyceride does not melt in the mouth cavity and hence does 
not considerably affect the taste of the ice cream. 
The emulsifier of the present invention is mixed with the starting mixture 
for preparing ice cream prior to the freezing of said starting mixture. 
The added amount of the emulsifier is, in general, in the range of 0.1 to 
0.5% by weight, preferably 0.20 to 0.35% by weight, based on the weight of 
the starting ice cream mix. 
The other ingredients of the starting frozen dessert mixture can be any of 
those approved by governmental authorities, such as the Food and Drug 
Administration in the United States of America, for preparing ice cream, 
mellorine, frozen custard, french ice cream, french custard ice cream, ice 
milk, fruit sherbets, etc. These other ingredients are well-known and the 
present invention does not pertain to any discovery concerning them. As is 
well known, such other ingredients comprise dairy ingredients, sweeteners, 
flavorings, caseinates, eggs or egg derivatives, stabilizers such as 
industrial gums, etc.

EXAMPLE 1 
Composition 
______________________________________ 
Material Parts (g) 
Ratio (% by weight) 
______________________________________ 
Fat (Milk Fat) 
160 8.0 
Sugar 300 15.0 
Skim Milk 200 10.0 
Stabilizer 5 0.25 
Emulsifier 5 0.25 
Water 1330 66.5 
Total 2000 100.0 
______________________________________ 
Elaidic monoglyceride according to the present invention was used as the 
emulsifier. For comparative examples, the same compositions were prepared 
except that in place of the elaidic monoglyceride, there were admixed, 
respectively, stearic monoglyceride, oleic monoglyceride, and a mixture of 
stearic monoglyceride and oleic monoglyceride. The thusly prepared 
compositions were processed in accordance with the conventional method to 
produce ice cream, and then the properties of the products were compared. 
The properties compared were viscosity and temperature of the starting ice 
cream mixture prior to being frozen, overrun, taste and shape-retaining 
property. The shape-retaining property was tested by a method wherein the 
solidified ice cream was placed on a net in a chamber maintained at 
30.degree. C. The duration of the time period starting immediately after 
the ice cream had been put into the chamber and terminating at the time 
when it began to drop through the net was measured. The measured time 
period is referred to as the dropping initiation time. 
The "dropped amount" was also determined by measuring the amounts of the 
ice cream that dropped through the net during each five minute time 
interval during the time period from 20 minutes and 45 minutes after the 
ice cream was put into the chamber. 
The test results are set forth in Table 1. Reference numerals (1) to (4) in 
Table 1 mean that the following emulsifiers Nos. (1) to (4) were used, 
respectively. 
(1) Elaidic Monoglyceride 
(2) Stearic Monoglyceride 
(3) Oleic Monoglyceride 
(4) Mixture of Stearic Monoglyceride and Oleic Monoglyceride (Mixing Ratio 
= 8:2) 
The whipping properties of the ice cream formulations was determined by 
measuring overrun by weight. Overrun is the amount of ice cream obtained 
in excess of the amount of mix used and is caused by whipping air into the 
mix. Percent overrun by weight is determined by the following formula: 
##EQU1## 
Table I 
______________________________________ 
Embo- 
diment 
of the 
Inven- 
Comparative 
tion Samples 
Test Item 
Emulsifier No. 
(1) (2) (3) (4) 
______________________________________ 
Temp. of Starting Mix. 
4.5 4.0 7.0 7.0 
(.degree. C) 
Viscosity of Starting Mix. 
500 400 5500 350 
(cps) 
Max. Overrun Value 
109.5 98.0 117.0 100.5 
Dropping Initiation Time 
32 min. 11 min. 38 min. 
18 min. 
34 sec. 38 sec. 15 sec. 
59 sec. 
Dropped Amount (%) 
(Elapsed Time) 
20 min. 0 15.0 0 0 
25 min. 0 30.0 0 14.5 
30 min. 0 44.0 0 28.5 
35 min. 4 58.0 0 42.5 
40 min. 14.5 70.0 5.0 57.0 
45 min. 25.5 -- 11.0 -- 
Flavor and Taste good good un- some- 
pleas- what 
ant un- 
pleas- 
ant 
______________________________________ 
EXAMPLE 2 
Composition 
______________________________________ 
Material Parts (g) 
Ratio (% by weight) 
______________________________________ 
Fat (Vegetable Oil) 
200 10.0 
Sugar 290 14.5 
Skim Milk 260 13.0 
Stabilizer 5 0.25 
Emulsifier 5 0.25 
Water 1240 62.0 
Total 2000 100.0 
______________________________________ 
As the emulsifiers, elaidic monoglyceride according to the present 
invention and, for the comparative examples, stearic monoglyceride, oleic 
monoglyceride, and a mixture of stearic monoglyceride and oleic 
monoglyceride were used. In accordance with the conventional method, lacto 
ice cream of high fat content were produced from the above-defined 
compositions, and the properties of the products were compared. 
The test items and methods for measuring the same are the same as in 
Example 1. 
Used Emulsifiers 
(1) Mixture of Elaidic Monoglyceride and Monoelaidic Ester of Sorbitol 
(Mixing Ratio = 9:1) 
(2) Stearic Monoglyceride 
(3) Oleic Monoglyceride 
(4) Mixture of Stearic Monoglyceride and Oleic Monoglyceride (Mixing Ratio 
= 8:2) 
The test results are shown in Table 2. 
Table 2 
______________________________________ 
Embo- 
diment 
of the 
Inven- Comparative 
tion Samples 
Test Item 
Emulsifier No. 
(1) (2) (3) (4) 
______________________________________ 
Temp. of Starting Mix. 
7.0 7.5 7.0 5.5 
(.degree. C) 
Viscosity of Starting Mix. 
875 875 2920 950 
(cps) 
Max. Overrun Value 
111.0 91.0 86.0 95.0 
Dropping Initiation Time 
43 min. 19 min. above 39 min. 
28 sec. 16 sec. 45 min. 
42 sec. 
Dropped Amount (%) 
(Elapsed Time) 
20 min. 0 1.0 0 0 
25 min. 0 11.0 0 0 
30 min. 0 22.0 0 0 
35 min. 0 45.0 0 0 
40 min. 0 51.0 0 0 
45 min. below 1 -- 0 7 
Flavor and Taste good good un- some- 
pleas- what 
ant un- 
pleas- 
ant 
______________________________________ 
EXAMPLE 3 
Composition 
______________________________________ 
Material Parts (g) 
Ratio (% by weight) 
______________________________________ 
Fat (Vegetable Oil) 
60 3.0 
Sugar 250 12.5 
Skim Milk 120 6.0 
Stabilizer 6.5 0.325 
Emulsifier 5.0 0.25 
Water 1588.5 77.925 
Total 2000.0 100.0 
______________________________________ 
As the emulsifiers, elaidic monoglyceride according to the present 
invention and, for comparative examples, stearic monoglyceride, oleic 
monoglyceride, and a mixture of stearic monoglyceride and oleic 
monoglyceride were used. In accordance with the conventional method, lacto 
ice creams of low fat content were produced from the above-defined 
compositions, and the properties of the products were compared. 
The test items and methods for measuring the same are the same as in 
Example 1. 
Used Emulsifiers 
(1) Mixture of Elaidic Monoglyceride and Elaidic Ester of saccharose 
(Mixing Ratio = 95:5) 
(2) Stearic Monoglyceride 
(3) Oleic Monoglyceride 
(4) Mixture of Stearic Monoglyceride and Oleic Monoglyceride (Mixing Ratio 
= 70:30) 
The test results are shown in Table 3. 
Table 3 
______________________________________ 
Embo- 
diment 
of the 
Inven- 
Comparative 
tion Samples 
Test Item 
Emulsifier No. 
(1) (2) (3) (4) 
______________________________________ 
Temp. of Starting Mix. 
8.0 7.0 7.0 5.5 
(.degree. C) 
Viscosity of Starting Mix. 
875 600 6400 690 
(cps) 
Max. Overrun Value 
121.0 101.0 100.0 115.0 
Dropping Initiation Time 
27 min. 12 min. 43 min. 
21 min. 
49 sec. 12 sec. 23 sec. 
1 sec. 
Dropped Amount (%) 
(Elapsed Time) 
20 min. 0 16.0 0 0 
25 min. 0 27.0 0 2.0 
30 min. 3.0 -- 0 17.0 
35 min. 10.0 52.0 0 26.0 
40 min. 15.0 62.0 0 37.5 
45 min. 21.0 -- below 1 
46.5 
Flavor and Taste 
good good un- some 
pleas- what 
ant un- 
pleas- 
ant 
______________________________________ 
EXAMPLE 4 
Composition 
______________________________________ 
Material Parts (g) 
Ratio (% by weight) 
______________________________________ 
Fat (Milk Fat) 
100 5.0 
(Vegetable Fat) 
60 3.0 
Sugar 300 15.0 
Skim Milk 200 10.0 
Stabilizer 5 0.25 
Emulsifier 5 0.25 
Water 1330 66.5 
Total 2000 100.0 
______________________________________ 
As the emulsifiers, elaidic monoglyceride according to the present 
invention and, for comparative examples, stearic monoglyceride, oleic 
monoglyceride, and a mixture of stearic monoglyceride and oleic 
monoglyceride were used. In accordance with the conventional method, soft 
ice creams were produced from the above-defined compositions, and the 
properties of the products were compared. 
The test for shape-retaining property is omitted, but the other test items 
and methods for measuring the same are the same as in Example 1. 
Used Emulsifiers 
(1) Mixture of Elaidic Monoglyceride and Elaidic Ester of Propylene Glycol 
(Mixing Ratio = 85:15) 
(2) Stearic Monoglyceride 
(3) Oleic Monoglyceride 
(4) Mixture of Stearic Monoglyceride and Oleic Monoglyceride (Mixing Ratio 
= 85:15) 
Test results are shown in Table 4. 
Table 4 
______________________________________ 
Embo- 
diment 
of the 
Inven- 
Comparative 
tion Samples 
Test Item 
Emulsion No. 
(1) (2) (3) (4) 
______________________________________ 
Temp. of Starting Mix. 
6.0 5.5 6.0 7.0 
(.degree. C) 
Viscosity of Starting Mix. 
450 475 6000 375 
(cps) 
Max. Overrun Value 
110.0 96.0 116.0 102.0 
Flavor and Taste 
good good un- some- 
pleas- what 
ant un- 
pleas- 
ant 
______________________________________ 
As will be apparent by comparing Examples 1 to 4, elaidic esters have 
improved properties in that they have stable foamabilities which are not 
badly affected by changes in the fats or oils used and changes in the 
amounts of the used fats or oils, and that they have superior 
shape-retaining properties in comparison with that exhibited by the 
mixtures of stearic monoglyceride and oleic monoglyceride.