Shelf-Life Testing: Procedures and Prediction Methods

Abstract

The shelf life of a food can be defined as the time period within which the food is safe to consume and/or has an acceptable quality to consumers. Just like any other food, frozen foods deteriorate during storage by different modes or mechanisms, as summarized in table 19.1. Microbes usually are not a problem since they generally cannot grow at freezing temperatures unless subjected to extensive temperature abuse above the freezing point. Enzymes, which can cause flavor change (lipoxygenase) in nonblanched fruits and vegetables and accelerated deterioration reactions in meat and poultry (enzymes released following disruption to organelle membranes during precooking) are a big concern for frozen foods. Cell damage or protein and starch interactions during freezing cause drip and mushiness upon thawing. Discoloration could occur by nonenzymatic browning, bleaching, and freezer burn. Vitamin C loss is often a major concern for frozen vegetables. Physical changes, such as package ice formation, moisture loss, emulsion destabilization, and recrystallization of sugars and ice in frozen desserts are often accelerated by fluctuating temperatures.