Aging of the Mix
The time of 4 h or greater at 2–4 C is recommended for aging
following mix processing prior to freezing. Aging is performed
in insulated or refrigerated storage tanks, silos, etc. or in singlewalled
tanks in chilled rooms, where valves and pipeline can
also be kept cold. Aging allows hydration of milk proteins and
stabilizers (some viscosity increase occurs during the aging
period), crystallization of the fat globules, and a membrane
rearrangement to produce a smoother texture and betterquality
product. Nonaged mix exhibits a low viscosity, is very
wet at extrusion from the dynamic freezer, and exhibits variable
whipping abilities. The appropriate ratio of solid–liquid
fat must be attained at this stage, a function of temperature and
the triglyceride composition of the fat used, as a partially
crystalline emulsion is needed for partial coalescence in the
whipping and freezing step. Emulsifiers generally displace milk
proteins from the fat surface during the aging period. The
whipping qualities of the mix are usually improved with
aging. Mix temperatures should be maintained as low as possible
without freezing.