You will find in real life that the color of the food in the freezer sometimes changes. What is the reason? Why does the color change occur when refrigerating and keeping fresh in the freezer? Many people probably don't know what is going on. Today, the price of the freezer is here to give you a brief explanation. During the freezing process of frozen food in the freezer, in addition to the discoloration caused by refrigerant leakage, all other discoloration that occurs at room temperature will occur during the long-term freezing process of the freezer, but the progress is very slow.
(1) Discoloration of fat:
As mentioned above, fatty fish such as hairtail and sardines will undergo oxidative rancidity due to fat oxidation during the freezing process of the kitchen reach in freezer. In severe cases, they will become sticky, produce peculiar smells, and lose the commercial value of food.
(2) Discoloration of vegetables:
The surface of plant cells has a cell wall with cellulose as the main component, which has no elasticity. When plant cells are frozen in the freezer, the cell walls will burst. Under the action of oxidase, fruit and vegetable foods are prone to browning. Therefore, the raw materials are generally blanched before quick-frozen vegetables to passivate the peroxidase, so that the quick-frozen vegetables will not change color in the frozen storage. If the blanching temperature and time are not enough, the inactivation of peroxidase will be incomplete, and the green vegetables will turn yellow-brown during the freezing process; if the blanching time is too long, the green vegetables will also become yellow-brown, this is because the vegetables The leaves contain chlorophyll and are green. When the chlorophyll becomes pheophytin, the leaves will lose green and become yellowish-brown. Acidic conditions will promote this change. Vegetables are blanched in hot water for too long, and the organic acids in the vegetables dissolve into the water to make them acidic water, which will promote the above-mentioned discoloration reaction. Therefore, the correct control of the temperature and time of vegetable blanching is an important link to ensure that the quick-frozen vegetables in the freezer do not change color in the frozen storage.