Ice Cream Shelf-Life
The most frequently occurring textural defect in ice cream is the development of a coarse, icy texture. Iciness is also the primary limitation to the shelf life of ice cream and probably also accounts for countless lost sales through customer dissatisfaction with quality. There is no answer to the question "What is the shelf-life of ice cream?", it depends entirely on its conditions of storage. It might be one year, or it might be two weeks or less. Although the source of and the contributing factors to the problem of icincess are well known, it is also one of the defects about which I am most often asked.
Processor's have known for a long time how to prevent iciness and the answer is still the same: formulate the ice cream properly to begin with, freeze the ice cream quickly in a well-maintained barrel freezer, harden the ice cream rapidly, and avoid as much as possible temperature fluctuations during storage and distribution. Ice crystals need to be numerous and of small, uniform size so they are not detected when eaten. It is heat shock, large temperature fluctuations, which is the greatest culprit to the loss of these small, uniform ice crystal size distributions and resulting coarse, icy texture. Perhaps it is time another message was added to the prevention of iciness and that is to educate the retailer's and the consumer about the causes of iciness and preventative action to maintain a smooth-textured ice cream.
Before we begin looking specifically at shelf-life, you need to re-acquaint yourself with the freezing aspects of ice cream manufacturing, the structure of ice crystals in ice cream, and the theoretical aspects of the freezing process.