A very troublesome defect in ice cream since there appears to be no single cause or remedy. Defect shows up in hardened ice cream and manifests itself in reduced volume of ice cream in the container usually by pulling away from the top and/or sides of container. Structurally, it is caused by a loss of spherical air bubbles and formation of continuous air channels. Some factors believed associated with the defect are:
- Freezing and hardening at ultra low temperatures.
- Storage temperature. Both low and high appear to contribute.
- Excessive overruns.
- Pressure changes, for example, from altitude changes (lids popping when shipped to high altitudes, shrinkage when returned to low altitudes).
NOTE: Retailing: More so than other frozen products, ice cream requires constant, uninterrupted freezing cycle at low temperatures to avoid problems. Problems at retail level can arise from overfilling of display cabinet, heat from display lamps or door defrosters, hot air from incorrectly positioned circulation fans, displaying ice cream together with semi-frozen goods.