The raw materials for frozen foods include whatever is to be frozen, e.g. fish, chicken, green beans, pizza. In most cases, the food is specifically cultivated or adapted for freezing. In the case of frozen desserts such as cakes and pies or entrees such as meat loaf and gravy, the recipe must be tested and altered so that it freezes well. Large companies will order optimum ingredients according to standards they have established during their product testing. For example the noodles used in a frozen pasta entree may be ordered in bulk from a distributor that makes them in a certain specified width or viscosity or flour content according to the precise need of the frozen food manufacturer. In this respect, ingredients in a frozen meal may differ from what a home cook would buy at the supermarket. But in general, frozen foods do not require a host of extra ingredients such as preservatives. Added ingredients are most frequently thickeners and stabilizers such as starch, xanthan gum, and carrageenan. These help retain the desired texture of the food after thawing. Recipes for foods destined for the freezer may also do better with the addition of a sauce or glaze, because this protects the food from dehydration when it is passed under the freezing air blast. Vegetables or fruits destined for freezing may also be picked at a different time than they would be if they were to be sold fresh, because they need to be at optimal tenderness.
The freezing equipment is typically made from stainless steel and other metals. The gas used for freezing is most commonly ammonia. Freon is used in some systems, though because it breaks down the ozone layer, ammonia is more environmentally sound. Cryogenic freezing uses liquid nitrogen.