What Does Snap Freezing Mean?

Snap freezing is the process of freezing something extremely quickly. It is sometimes called flash freezing and is used primarily in food applications or medical or science applications, such as freezing tissue samples. The way in which something is frozen extremely quickly is to expose it to sustained, extreme cold with no variance in temperature.

Temperatures

Water freezes at 32 degrees Fahrenheit (or 0 degrees Celsius). As soon as a food is frozen, any bacteria present in the food stops growing, which is the primary reason to freeze foods -- to keep bacteria at bay for longer periods of time. While ideal freezer temperatures may be between 10 below 0 Fahrenheit to 0 Fahrenheit, snap freezing employs much colder temperatures. Snap freezing can employ temperatures of negative 200 degrees Fahrenheit or colder.

Crystallization

Food is made primarily of water. When food is frozen slowly, crystals form. Crystals are frozen structures. The creation of crystals involves a molecular rearrangement. The rearrangement tends to separate the water from the food. It also tends to change the molecular structure of the food. While very fast freezing also causes molecular changes, the changes are fewer. Snap freezing reduces the process of slow-growing ice crystals, leaving the frozen items more closely resembling their structure prior to freezing.

Benefits

There are many benefits of snap freezing. From a manufacturer's point of view, it reduces time, once a food product is made. More important, when the food is reheated, it is less likely to have pooled water or an undesirable texture due to crystallization in a slow-freeze process. In science applications, snap freezing distorts the tissues being frozen less than slow freezing because it avoids the crystallization process.

Marketing Claims

Marketing claims about snap freezing abound. Many of them are true. Primarily, it avoids water separation upon reheating and it does a better job of preserving texture. Other claims are difficult to verify. The assertion by many, for example, that snap frozen foods are more nutritious and healthier is questionable. The speed at which something is frozen effects the arrangement of molecules but it doesn't add or remove them. If a food item contains vitamins, after it is frozen, it will contain frozen vitamins. When reconstituted, it will presumably still contain vitamins. The loftier of marketing claims fail to explain how a food would become less nutritious if frozen slowly.