Shock freezing of food
The fastest freezing process currently provides shock. Similar to the fast frying of meat, a thin, deep-frozen layer is formed during shock-freezing, which prevents the escape of liquid from the foodstuffs. The ice crystals, which are considerably smaller than conventional freezing processes, considerably reduce the destruction of the cell membrane. There are now very good freezers in the trade. Unfortunately, the fewest consumers can afford such high-quality (expensive) devices.
Critical: frozen “menus”
Whilst fast-frozen vegetables are correspondingly fast compared to fresh vegetables, ready-made frozen foods, or entire frozen food, are far more critical.
These “complete menus” are created by food technicians and chemists in the laboratory. It is a good deal to make a ready-to-use product with several ingredients so that it looks, tastes and smells like a homemade dish, and all the ingredients used, such as meat, vegetables and potatoes – including different sauces – by later heating Can be cooked at the same time, without any individual ingredients boiled or halbroh. ”
This is possible only by means of a sophisticated technique, and by using a series of preservatives, colorants, aromas and flavor enhancers, as well as various binders and emulsifiers. With a food (food agent), these dishes certainly have nothing in common.
The main ingredient of most food is water. It always contains salts and other soluble substances such as carbohydrates and proteins. These allow the freezing of the tissue fluid to drop below ± 0 ° C, since only chemically pure water (without dissolved salts) freezes at 0 ° C.
The more dissolved substances are contained in the water, the more concentrated is the liquid and the lower the freezing point. The focus of ice crystal formation is in the temperature range between -0.5 ° C and -5 ° C (range of maximum crystal formation).
In the freezing of food, the liquid first freezes between the cells (cell gaps) because it is not so concentrated, i.e. not so rich in dissolved substances. However, due to the formation of ice, the concentration of the non-frozen solution increases in the cell spaces, so that a concentration gradient to the cell interior arises.
Since two differently concentrated solutions always have the tendency to compensate for the concentration difference (diffusion), the water diffuses from the cell interior into the cell interspaces.
Fast freezing is ideal
If the heat is quickly removed from the foodstuff and the area of ice crystal formation is quickly passed through:
- Makes uniform ice crystal formation in the cells and cell interstices.
- Fine-grained ice crystals are distributed uniformly in the food tissue.
- The diffusion of water from the cells into the cell interspaces is almost irrelevant.