Dairy Ingredients in Dairy Food Processing 431(39 ° F) and holding (also called aging or rip-
ening) the base. This allows for a portion of
the fat to crystallize and for reorganization of
emulsifi ers at the fat interface (Eisner,
Wildmoser et al., 2005 ). During freezing, the
mix is aerated while water is frozen and
scraped off the sides of the heat exchanger
by the dasher. A portion of the liquid milk fat
is also crystallized. The resulting product is
a mixture of air bubbles with agglomerated
fat on portions of the air bubble surface. The
source of fat in a frozen dessert can affect its
sensory properties. Milk fat contains a large
variation in fatty acids, so there is a large
melting range and a combination of liquid
and crystalline fat during freezing, which
contributes to its unique structure develop-
ment (Goff, 2009 ).Sources of Fat
Fresh sweet cream and fresh milk. Whole
milk may be used primarily as a source of
serum. There is no doubt that sweet cream is
the best source of fat for ice cream because
of its desirable fl avor, convenience of han-
dling, and good whipping characteristics.
Fresh cream is judged by fl avor, titratable
acidity, and microbial count. The developed
acidity should be low, and the cream should
have been carefully handled prior to pas-
teurization to prevent the development of
hydrolytic rancidity, which is due to free
fatty acids from the partial hydrolysis of but-
terfat. Proper heat treatment, an essential
phase for the preparation of cream for freez-
ing, consists of heating cream at 76.7 ° C
(170 ° F) for 20 minutes, or at 82.2 ° C (180 ° F)
for 10 minutes, or at 87.8 ° C (190 ° F) for 5
minutes. This treatment not only inactivates
the lipase enzyme naturally present in milk,
but also destroys 95% to 99% of the bacteria
present.
Frozen cream. Cream is commonly
stored in a frozen state to offset its short shelf
life and the high price of sweet cream during
certain seasons. When storing frozen creamsolids, sherbet has a coarser, icier texture
than ice cream. Like soft - serve ice cream, it
relies on carbohydrate - based gums for a
smooth mouth feel.
Frozen novelties are a highly variable
segment of the dessert market that include
products in bar form on sticks, chocolate -
covered bars, ice cream between wafers or
cookies and ice cream in cones. Particularly
important characteristics are the ability to
form the product into the appropriate shape;
apply the coating, cookie, or wafer and have
it adhere; and control moisture transfer to or
from the ice cream to the other components.
The ice cream or other frozen dairy base in
novelties is generally highly stabilized with
gums. Novelties are portion controlled
because they are usually individually pack-
aged within a box to provide stability to the
product. A recent trend is to provide 100 -
calorie products and low - fat or nonfat or
sugar - free novelty varieties. The 100 - calorie
products can be achieved by reducing the
serving size. For reduced - fat and reduced -
sugar products, because novelties are a
multiple - component system, sensory differ-
ences from full fat or full sugar counterparts
can be partially masked with the other com-
ponents so that satisfactory sensory charac-
teristics can be experienced.
Purpose of Dairy Ingredients in
Frozen Desserts
Fat
Fat contributes to fl avor in frozen products,
but more importantly, it contributes to texture,
foam stability, and melt - down in the mouth.
Prior to freezing, ice cream mix is blended,
pasteurized, and homogenized. The heat
during pasteurization fully melts crystalline
fat, and homogenization creates smaller fat
globules which allow protein and emulsifi ers
to form new surface interactions with the
greatly increased fat surface area. The next
step of dessert mix handling is cooling to 4 ° C