Dairy Ingredients in Dairy Food Processing 433Frozen condensed whole or skim milk.
Freezing condensed whole or skim milk is
a fairly expensive way to store solids; as
a result, they generally are not used. Evap-
orated canned milk also is not generally
used due to the mandatory sterilization
heat treatment required in its production,
which imparts a noticeable cooked fl avor
and carmelized color. Sweetened condensed
whole milk or skim milk are sometimes used
as a source of MSNF, providing 8.5% fat and
28% total milk solids. The added sugar (40%
to 44%) improves the keeping quality over
that of plain condensed milk. The sugar con-
centration makes the osmotic pressure of the
solution high enough to suppress the growth
of practically all microorganisms.
The titratable acidity test should be applied
to all condensed milk products. When diluted
to contain the same MSNF concentration as
skim milk, the titratable acidity should be
approximately that of fresh skim milk
(0.18%). Sweetened condensed products
have a cost disadvantage and are not very
popular in the ice cream industry. The freight
cost of shipping sugar in the form of sweet-
ened condensed milk is more than that of dry
bagged sugar.
Dry buttermilk and condensed butter-
milk. Sweet cream buttermilk is obtained
from churning cream that has not developed
noticeable acidity. Buttermilk has benefi cial
effects on the whipping ability of the mix due
to the inherent lecithin content. It also con-
tributes to a richness of fl avor. Dried butter-
milk lipids tend to deteriorate readily in
storage, so the typical shelf life is six to nine
months. Care must be taken to use only fresh
ingredients. The fat content of condensed dry
buttermilk is 3% to 4% and should be taken
into account when calculating the ice cream
mix.
Nonfat dry milk solids (NFDM). NFDM
is one of the most concentrated sources of
serum solids that is frequently used. Spray -
dried powder should have good fl avor andHowever, because of their low serum solids
content in contrast to the serum solids desired
in an ice cream mix, their use is limited.
Plain condensed skim milk. Plain con-
densed skim milk is the source of serum
solids that is used more frequently than any
other of the condensed products. Fresh con-
densed skim milk is easy and convenient to
use, has an excellent fl avor, and is readily
available. The composition varies from 25%
to 40% total or serum solids, depending on
the condensing operation and the distance the
product will be transported (higher solids
contents are less stable to transportation).
The concentrate is purchased on a basis of
the solids content. The heat treatment given
the fl uid skim milk is usually the same as the
regular pasteurizing range. The keeping
quality of condensed skim milk is better than
that of cream. It should be stored at 0 ° to
1.7 ° C (32 ° to 35 ° F) and used while fresh and
sweet (usually seven to 10 days).
Plain condensed whole milk. Plain con-
densed whole milk is concentrated approxi-
mately two and a half times and contains
about 8% fat and 20% serum solids.
Condensed whole milk is frequently used in
ice cream because it is a convenient source
of both serum solids and fat. Superheated
condensed skim or whole milk is made by
slowly heating the already condensed product
to a high temperature, usually in the range of
82.2 ° C (180 ° F). When done properly, con-
centrate has a much greater viscosity. When
used in the mix, it improves the whipping
ability and contributes a smooth texture.
Superheated condensed milk permits ice
cream manufacturing without stabilizers, and
may offer a marketing advantage for certain
consumers. Superheating increases the hydra-
tion capacity of the milk proteins, which bind
more free water. Accordingly, less water is
available to form ice crystals during freezing
and shelf life. The ice cream ’ s smooth texture
is maintained during its shelf life; thus,
superheating functions like a stabilizer.