Quick-Frozen Vegetables

Vegetable quick-freezing is a processing method for preserving vegetables in a low-temperature quick-freezing method. After pre-frozen vegetables are frozen at -30 ～ -35 ℃ or lower, they are packed in plastic bags, boxes or other containers, or after being frozen, then stored at -18 ℃ In order to inhibit the growth and reproduction of microorganisms and enzyme activity, so that vegetables can be preserved for a long time.

Freezing process and its principle When the moisture in vegetables decreases from the initial temperature to a freezing point below 0 ° C, it changes from a liquid state to a solid state, that is, it freezes. As the temperature decreases, the ice crystals increase, and the vegetables harden and become frozen. The freezing point of vegetables varies according to their type. Most vegetables start to freeze at a temperature of about -1 ° C. When the temperature continues to decrease to about -5 ° C, 70 to 80% of its water freezes, and the vegetables become harder. That is, at a temperature of -1 to -5 ° C, a large amount of ice crystals are formed, which is referred to as the largest ice crystal formation stage. If the temperature is further reduced to -30 to -35 ° C, the freezing process is completed. At different temperatures, the moisture in vegetables has a corresponding freezing rate. Therefore, in order to completely freeze the moisture in vegetables, the temperature must be lowered to the eutectic point, that is, the temperature at which the freezing rate of moisture reaches 100%.

Vegetable quick-freezing process In the vegetable quick-freezing process, the steps of selecting raw materials, cleaning, peeling, cutting, and blanching are basically the same as that of dried vegetables and vegetable storage. After the vegetables are blanched, they should be cooled and rinsed with fresh water in a timely manner, and then rapidly frozen using a blast freezing method or a fluidized bed freezing method at a low temperature of -30 to -35 ° C. Packing is made of polyethylene plastic bag or plastic box. It is divided into two types: pre-freezing packaging and post-freezing packaging. Generally, dry packaging is used.