What is frozen food?

Quick-frozen food, also known as quick-frozen food, is a kind of food produced by low temperature and rapid freezing. Quick-frozen food refers to the proper processing of raw materials, usually within 15 minutes, so that the temperature quickly passes through the temperature range of -1°C to -5°C (also known as the maximum ice crystal formation zone) within 30 minutes. Crystallization, and the storage and transportation temperature of food should be lower than -18 ℃. Food is quickly frozen in an ultra-low temperature environment, the tissue and cell structure will not change, and the activities of microorganisms and enzymes are temporarily inhibited, then sealed, vacuum-packed (to prevent dry consumption, oil consumption, oxidation, etc.), and finally placed at -18 ℃ Long-term storage in the following environment, the time is 300-600 days. Many people tend to confuse quick freezing and freezing, but in fact the two concepts are completely different.

Will the nutrients of quick-frozen food be "frozen"?

Meat is stored frozen at lower temperatures to better retain its nutritional content. In particular, the content of protein and minerals is basically unchanged. It can be said that compared with fresh meat, frozen meat does not have much loss in nutrition except for the worse taste. Compared with fresh fruits and vegetables, although frozen fruits and vegetables are inferior in taste, their nutritional value is not necessarily lower. This is because, from picking vegetables and fruits, through transportation, storage and other processes, nutrients are constantly being lost, while frozen fruits and vegetables are quickly frozen at -18°C once they are picked, and the respiration is almost stagnant. Activity is also inhibited, which is actually more conducive to nutrient retention. For transportation and storage, many vegetables are quick-frozen. There are many kinds of vegetables suitable for quick-freezing. If vegetables, leafy vegetables, stem vegetables, root vegetables, edible fungi, etc. The processing is done by pre-treatment by boiling, steaming or microwave.

An experiment comparing the nutrients of eggplant, kidney bean, garlic sprouts and cabbage under quick-frozen and normal temperature storage conditions found that in the early stage of storage, the vitamin C content of quick-frozen vegetables was lower than that of vegetables stored at room temperature, but with the increase of storage days , The vitamin C content of vegetables stored at room temperature decreases rapidly, and soon it is lower than that of quick-frozen vegetables.

How to Choose Frozen Foods

First, select quick-frozen foods whose freezing conditions are below -18°C. If the sales store does not have a freezer or the freezing temperature of the freezer cannot reach -18°C, the product quality cannot be guaranteed and should not be purchased. Pick the frozen food that is closest to the production date.

Pay attention to the production date. The closer the food is to the production date, the fresher the food and the less the loss of nutrients. If the quick-frozen food is not thawed during the production and transportation and storage process, there will be no water generation, so there will be no frost or even ice cubes. Frost and ice cubes will only be produced during repeated thawing, and the nutrition of the food will be damaged to varying degrees, so we should prefer frost-free and ice-free quick-frozen foods. Choose products with no damage to the packaging bag, complete frozen product form, no softening or sticking, no frost or little frost in the package, and natural color, no discoloration, and no dullness.