Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates generally to the provision
of a whipped milk product which is commonly known as a milk
shake. More particularly, the present invention relates to a
whipped product which can be ~rozen and subsequently thawed
to provide a product having the characteristics of a milk shake.
Milk shakes are a well known product which are made in
the home or sold by the food-serving industry, which includes
restaurants, ice cream parlors and fast-serve operations. The
milk shake is usually made by combining milk with ice cream and
a flavoring material to provide a mix and thereafter whipping
the mix to provide a milk shake having some overrun.
In the food-serving industry it is relatively time con-
suming to prepare individual milk shakes. Moreover, milk shakes
must often be prepared in advance in anticipation of peak husiness
during certain hours of operation. It is often difficult to
anticipate the correct number of milk: shakes which should be
prepared and wastage is incurred. In the home, preparation of
milk shakes requires the setting up of equipment, scooping of
ice cream, and availability of liquid milk.
It has been recognized that it would be desirable to
provide milk shakes in a frozen condition which could be thawed
to provide a product like that which is made by the conventional
method. However, conv~ntionally prepared milk shakes made by mix-
ing together ice cream and milk are not suitable for freezing
and subsequent thawing. Conventionally prepared milk shakes,
when frozen and subsequently thawed, lose their overrun and
break down into stratified layers of flavoring and milk. Various
attempts have been made to provide a milk shake suitable for
freezing but they have not resulted in products which are
sufficiently like the conventionally prepared milk shakes upon
thawing to be competitive or satisfactory to consumers.
Accordingly, the principal object of the present invention
is to provide a milk shake which is suitable for whipping and
freezing. It is another object of the present invention to pro-
vide a frozen milk shake which upon thawing is sufficiently like
conventionally prepar~d milk shakes to be satisfactory to con-
sumers. It is a further object of the present invention to
provide a method for making a milk shake which is suitable for
freezing and upon subsequent thawing provides a milk shake sub-
stantially similar to conventional milk shakes.
Generally, in accordance with the present invention, a
milk shake is provided from edible protein, fat, disaccharide
sugar, monosaccharide sugar, stabilizer, emulsifier and a poly-
hydric freezing point depressant. The milk shake contains suit-
able flavoring materials to provide a desired flavor. Prefer-
ably, the milk shake of the invention comprises dairy ingredients
selected from whole milk, skim milk, casein, sweetened con-
densed whole milk, condensed skim milk, skim milk powder, whole
milk powder and cream in such proportions as required to pro-
vide fat and protein in the ranges indicated below. The disaccha-
ride sugar and monosaccharide sugar are present in the mix at
a particular ratio and at levels within the ranges indicated
below. The polyhydric freezing point depressant is provided
at a level sufficient to establish an initial freezing point
of less than -4C and preferably within the range of from
about -~C to about -17C.
The components of the milk shake of the invention are
present at levels sufficient to provide a milk shake having the
ingredients indicated below in Table I within the indicated range:
T~BLE I
Ingredient Weight Percent
Protein 2.4-3.4
Fat
Disaccharide Sugar 4.0-6.0
~onosaccharide Sugar 5.0-9.0
Water 66 - 74
It is a further requirement for the milk shake of the
invention that the ratio of monosaccharide sugar to disaccharide
sugar in the mix be within the range of 1.2:1 to 1.6:1. When
dairy ingredients provide protein and fat, they also provide the
disaccharide sugar, lactose. In general, from about 3 to about
4 percent lactose is provided by the dairy ingredients. If
further disaccharide sugar is required, it is prefexred to use
sucrose to provide the balance of disaccharide sugar. A pre-
ferred monosaccharide sugar is dextrose.
The preferred fat source in the milk shake of the in-
vention is whole milk or cream. ~Iowever~ other fats derived from
vegetable and animal sources which are incorporated in ~illed
milks and whipped toppings can be used. In particular, partially
hardened vegetable oils which have physical properties substan-
tially similar to those of milk fat can be used.
The preferred protein source in the milk shake or the
invention is whole milk, skim milk and modified whey products.
However, imitation milk, containing a vegetable protein, can be
used.
The polyhydric fxeezing point depressant is used in the
milk shake of the invention to provide the milk shake with an
initial freezing point of -4C or less. During dynamic cooling
of the milk shake, latent heat is removed from water in the mix
and ice crystals are formed. A new freezing point is established
for the remaining solution since it has become more concentrated
in respect to the soluble constituents. The transfer of sensi-
ble heat from the unfrozen solution lowers the temperature to
a new freezing point and more water is converted into ice.
Thus, the freezing point of the liquid portion of the milk
shake is continually changing as water is ~rozen during the
freezing proce~s. It is an important feature of the present
invention that the milk shake have an initial freezing point
of -4~ or less. Such initial freezing point is substantially
lower than heretofore known mixes used to prepare frozen
whipped desserts, such as ice cream. As explained more fully
hereinafter, the temperature of the milk shake is reduced by
dynamic cooling to a temperature within the range of -7C to
-14C. This temperature range is below the temperature nor-
mally associated with dynamic cooling of ice cream mixes and
other frozen comestible mixes. The use of the polyhydric freez-
ing point depressant in the milk shake of the present invention
permits use of such lower temperatures and provides a semi-
frozen mix with desired level of overrun upon exit from a heat
exchanger used for dynamic cooling. Upon subsequent further
2n cooling of the semi-frozen mix a desirable crystal size, tex-
ture and mouth feel are imparted to the milk shake.
Suitable polyhydric freezing point depressants are
glycerin and propylene glycol. A parti¢ularly preferred
polyhydric freezing point depressant for reasons of flavor
is glycerin. As indicated, the polyhydric freezing point
depressant is used at a level sufficient to provide a milk
shake having an initial freezing point of -4C or less, pre-
ferably within the range of -4C and -17C. In general, the
freezing point depressant is used in the milk shake mix at a
level of from about 6 to about 9 percent by weight of the mix
to provide the desired initial freezing point.
The use of a polyhydric freezing point depressant in
accordance with the invention in combination with the use of
lower dynamic cooling temperatures greatly enhances the sta-
bility of the milk shake of the invention. Stability is an
expression of the ability of a fat-water emulsion, such as
the milk shake of the invention, to resist the de-emulsifying
effect of whipping and freezing. Stability depends not only
on a balance of ingredients, but on their state of dispersion
and interaction.
Due to the high level of moisture and low level of fat
in a milk shake, the foamed milk shake is inherentl~ unstable.
In accordance with the present invention, it has been found
that the interaction of the polyhydric freezing point depressant
with selected stabilizers and emulsifiers provides the milk shake
of the invention with sufficient stability to withstand the
whipping-freezing-thawing cycle and provide a milk shake with
the desirable foam, texture and body characteristics associated
with conventional milk shakes. Stability is dependent on emul-
sion (water-fat) stability, colloid (protein-gum stabilizer)
and the interaction between the emulsion and the colloid.
The milk shake mix is homogenized so as to reduce
- the fat to a fine degree of subdivision and a high degree of
dispersion. This results in providing a greatly e~panded
fat surface. The globules in the homogenized milk shake are
surrounded by an interfacial layer of protein which is com-
ple~ed with the stabilizing agents used in the invention.
It should be understood that the milk shake of the
present in~ention is a very high moisture, low fat product
compared to frozen dessert products which have been heretofore
known. While not wishing to be bound by any theory, it is
~elieved that the stability of the mil~ sha~e is xelated both
to the presence of the polyhydric freezing point depressant,
the stabilizer and the emulsifier, and to the particular method
for manufacture of the frozen milk shake, wherein lower than
usual dynamic cooling temperatures are used.
The stabilizing agents useful in the present invention
are any of the gums normally associated with the manufacture of
ice cream. Such gums include carboxymethylcellulose (CMC) in
the sodium salt form, carrageenan, sodium alginate, propylene
glycol alginates, locust bean gum and guar gum. It is preferred
to use a mixture of gums. It has been found that the use of a
particular mixture of gums is greatly preferred to provide the
highest level of stability. In this ~onnection, it is preferred
to use a mixture of sodium alginate, carboxymethylcellulose in
the sodium salt form and carrageenan. Preferably, the mixture
of gums contains sodium alginate a~ a level of 50 to 80 weight
percent, sodium carboxymethylcellulose at a level of 10 to 30
weight percent and carrageenan at a level of 10 to 30 weight
percent. The stabilizing agents are used in the milk shake at
a level of from about 0.05 to about 0.10 weight percent, pre-
ferably from about 0.06 to about 0.08 weight percent.
The emulsifier can be any monoester normally used as
an emulsifier in the preparation of frozen desserts. Particularly
useful are the monoester emulsifiers identified as propylene
glycol monostearate and glyceryl monosteara~e. It should be
understood that the reference to propylene glycol monostearate
and glyceryl monostearate is to the highly distilled commercial
products which contain at least about 90 percent of the mono-
ester. Also useful as an emulsifier in the present invention
are mixtures of propylene glycol monostearate and glyceryl
monostearate stabilized in the alpha crystalline form in
accordance with the teachings of United States Patent No.
3,453,116 to Freund and United States Patent No. 3,673,106
to Jonas et al~
A particularly preferred emulsifier for use in the
milk shakes of the invention is propylene glycol monostearate.
It has been found that for chocolate flavored milk shakes, pro-
pylene glycol monostearate enhances the ability of the milk
shake to prevent syneresis upon thawing and to prevent separ-
ation of chocolate color during the thawing cycle. Moreover,
it has been determined that propylene glycol monostearate
provides an emulsion which is more compatible with the colloid
system (protein-gum stabilizers) of the invention. This en-
hanced compatibility results in ice retention, slower melting
and more even melting.
In the method of manufacture of the ~rozen milk shake,
whole milk, imitation milk or filled milk~ is added to a
jacketed kettle equipped with agitating means. Any remaining
portion of dry sugar which is to be used is added to the
kettle~ The remaining non-~olatile fluid ingredients, in-
cluding the polyhydric freezing point depressant, are added
to the kettle and the mix is pasteurized under suitable time
temperature conditions. A suitable condition for pasteurization
is to heat the mix to 160F for 30 minutes. After pasteurization,
the mix is maintained at a temperature of from about 60C to
about 82C until the mix is homogenized.
It is sometimes preferred to hydrate the emulsifier
prior to adding the emulsifier to the remaining ingredients.
In this connection, the emulsifier is heated to a temperature
sufficient to melt the emulsifier and hot water is thereafter
added to the emulsifier in a jacketed mixing kettle. The
à~
hydrated emulsifier is then fed to the main mixing kettle by
means of a metering pump. Salt and a vitamin-mineral premix,
if used~ are then added to the mix in the kettle.
The remaining dry ingredients including, the stabilizing
agent and a portion of any dry sugar used, are mixed with non-
volatile dry, powderedt flavoring materials and are combined
with the mix in the main kettle.
While the mix is maintained at an elevated temperature
of from about 60C-82C the mix is pumped in a closed loop to
thoroughly disperse all of the ingredients in the mix. There-
after the mix is homogenized single stage at a pressure of from
about 500 to about 2,000 psig.
The mix is then preferably pre-cooled to a temperature
in the range of about ~C-16C prior to whipping and cooling
the mix. The pre-cooling is desirable to lessen the cooling
load on the heat exchanger used for dynamic cooling. Just
prior to introducing the pre-cooled mix to the heat exchanger,
any volatile flavoring materials to be used are added.
The mix is then dynamically cooled in the heat exchanger
to a temperature of less than -7~ while a gas is injected into
the mix at a level sufficient to generate from about 50 to about
100 percent overrun. Any suitable heat exchanger can be used.
The heat exchanger- is preferably a scraped wall heat exchanger
provided with an inlet whereby an inert gas can be injected
into the mix as it is being cooled. A conventional ice cream
freezer is suitable for dynamic cooling of the mix. In this
connection, it is not usual to lower the temperature of ice
cream mixes and other related frozen dessert products to a temper-
ature less than about -5~C by use of an ice cream freezer.
In the method of the present invention, it is desirable
that less than about 80 percent of the water present in the
milk shake mix be frozen during passage of the milk shake mix
through the freezer. Preferably, from about 55 percent to
about 80 percent of the water is frozen during passage of the
milk shake mix through the freeæer.
It is known that fast freezing of ice cream mixes under
dynamic conditions induce the formation of small ice crystals
, which is a prerequisite for a smooth texture ice cream. However,
it is not the intention of the fast cooling step under dynamic
conditions of the present invention to provide small ice crystals.
In fact, it is preferred that a relatively small portion of the
water of the milk shake mi~ be frozen during the cooling step
in the ice cream freezer. The melt down characteristics of the
ice cream and the melt down characteristics of the milk shake of
the present invention are totally different. Furthermore, sub-
sequent freezing of the milk shake of the present invention
after the intial dynamic cooling step results in a product
which upon subsequent thawing has the desired characteristi~s
of a conventional milk shake. There is no similarity between
thawed ice cream and conventional milk shake. It is believed
that the ice crystal structure of the ice cream and the frozen
milk shake of the present invention are entirely different.
The use of the polyhydric freezing point depressant in the
milk shake mix of the present invention permits the use of low
dynamic cooling temperatures without attaining a significant
freezing of the water present in the milk shake mix during the
dynamic cooling step.
The following Examples illustrate various features of
the present invention but are intended to in no way limit the
scope of the invention which is defined in the appended
claims~
EXAMPLE I
A chocolate milk shake mix having the following ingre-
dients at the indicated levels was prepared:
INGREDIENT WEIGHT PERCENT
Homogenized Whole Milk 72.6
Sweetened Condensed Whole Milk
(Butter fat 8.5~, Non-Fat Milk
Solids 20g6, Water 29.5% !
Sucrose 42%) 2.6
Cream (about 38% butterfat) 3.0
Glycerin 7.6
Dextrose 7.1
Emulsifier (Hydrated) 3.9
Water 3.5
PGMS .14
Glycerol
Monostearate .18
Sodium Stearoyl-
2-lactylate .08
Stabilizers .07
Sodium alginate .o5OO
CMS .01%
Carrageenan .01%
Cocoa 2.4
Vitamin-Mineral Mix .23
Malt Powder .20
Salt .16
Artificial Flavors .11
Water .10
The homogenized whole milk at a temperature of 1.7C is
added to a jacketed kettle equipped with scraper blades. The
milk is heated to a temperature of (46-49C) with agitation
and two thirds of the dextrose is added. The cocoa is slowly
added and is dispersed over a 15 minute hold period. The
- 10 -
L~
sweetened condensed whole milk is added slowly with agita-
tion and the temperature of the mixture in the kettle is
allowed to rise to 54-57C. The glycerin is then added fol-
lowed by addition of the cream.
In a separate jacketed, scraper equipped ke-ttle, the
emulsifiers ar~ hydrated. The propylene glycol monostearate
(PGMS), glycerol monostearate (GMS) and sodium stereroyl-2-
lactylate are blended. The blend is slowly added to hot water
(49C) in the kettle with agitation. The mixture is heated to
77C and held for 15 minutes with agitation. The emulsifier
mixture is then slowly cooled with agitation to a temperature
of 15-21C. After cooling, the hydrated emulsifier may be
held for daily use.
An amount of the hydrated emulsifier sufficient to
provide the indicated level of emulsifier is added to the
batch in the kettle with agitation.
In a separate blender, one sixth of the dextrose,
sodium alginate, carboxymethyl c~llulose, carrageenan and malt
powder are blended. This dry blend is added to the heated (54C)
batch from the kettle by means of a powder funnel system with
recirculation and agitation. Recirculation is continued until
the dry ingredients are completely dispersed. Thereafter, the
salt is added and the temperature of the batch in the kettle
is raised to (71C) with agitation. The batch is held in the
kettle at 71C for 30 minutes to pasteurize the batch.
Five minutes after pasteurization is completed,
vitamin-mineral mixture is added to the batch. The vitamin-
mineral mixture is combined with one sixth of the dextrose
which serves as a carrier and insures good dispersion~
-- 11 --
~3~
After pasteurization, the batch is homogenized at
1,000-1,500 psig, single stage, at a minimum temperature of
150F to provide a milk shake mix. The homogenized milk shake
mix is cooled to a temperature of 10-16C. A liquid mixture
of the artificial flavors and water is prepared. Just prior
to dynamic cooling of the milk shake mix, the liquid mixture
of artificial flavors is added to the milk shake mix.
The milk shake mix is introduced into a conventional
ice cream freezer at a temperature of 10C. During passage of
the milk shake mix through the freezer, the temperature of the
mix is reduced to -10C and air is injected into the milk shake
mix at a level sufficient to provide 75 percent overrun. At
the time of exiting from the dynamic cooling step about 40-60
percent of the water present in the milk shake mix is frozen.
260 ml samples of the milk shake mix is stored in a freezer
at a temperature of -29C for a period of ~-2 days. At this
temperature 100 percent of the water in the milk shake is fro~en.
Samples of the milk shake are removed from the freezer
and stored for 30 days at -12.aoC after which they are equili-
brated at 21C for 24 hours to determine phase separation
(stability). Containers of the samples were opened and the ex-
tent of syneresis and color separation are measured. The
syneresis as determined by the extent of an aqueous layer which
formed is 113 ml (43.5 percent). The samples also demonstrated
a high degree of color separation. The percentage of unmelted
iceas afunction of thaw-time was zero at 2 hours.
EXAMPLE II
A chocolate milk shake mix was prepared in accordance
with the formulation and method of Example I with the exception
- 12 -
that PGMS was used as the sole emulsifier. The PGMS was added
directly to the batch in the kettle prior to pasteurization heat
treatment of the batch.
260 ml samples of the milk shake are removed from a
freezer (-29C) and stored for 30 days at (-12C), after which
they are equilibrated at (21C) for 24 hours to deter~ne phase
separation. The syneresis as determined by the extent of free
water is 99 ml (38 percent~. These samples indicated absolutely
no degree of color change. The percentage of unmelted ice as
a function of thaw-time was zero at 3.5 hours.
