Starch is added to frozen foods for similar reasons as fresh, refrigerated or canned foods. It helps to thicken the food, provides stability at low temperatures, and controls the flow characteristics of the food. However, freezing can cause other components of the food system, like fruit tissue, to release water, which increases the need for starch to absorb the excess water. Frozen dinners and fruit pie fillings are cooked, cooled, packaged, and then quickly frozen. Freezing food adds an additional level of stability requirements compared to other forms of distribution.
Frozen foods use starch for thickening, low-temperature stability, and control of the food’s texture. Freezing can make other components in the food, such as fruit tissue, release water, increasing the demand for water entrainment by the starch. Frozen foods undergo repeated temperature cycling during transit, which can cause retrogradation, leading to gelling, graininess, opacity, and syneresis. Reheating can partially reverse these defects, but the original texture may not be fully restored. Thaw-and-serve foods require the greatest freeze-thaw stability. Monosubstituted starch is used for these products because even crosslinked waxy maize starch becomes opaque and gels. Pregelatinized starches may be used to reduce heating and cooling costs.
Starch is added to frozen battered foods to help them stick together better and absorb less oil during frying. It also makes them crispier when reheated in the oven or microwave. Oxidized starches are used to improve adhesion, by forming strong bonds with proteins on the surface of the food. High-amylose starches and flours are preferred for achieving crispiness. Processed high-amylose starch is also used to make breading crispier. Researchers have used monosubstituted starch to make microwave frozen bakery products crispier. Waxy maize starch is used in frozen tofu to maintain its texture.