Application of Industry:
Quick frozen foods quickly is the largest ice crystals generated by its area , when the average temperature reaches -18 ℃ sometimes rapid freezing method . A wide variety of foods will change in the freezing process, such as physical changes ( volume , thermal conductivity , specific heat, dry consumption changes ) , chemical changes ( protein denaturation, discoloration , etc. ) , changes in tissue and biological and microbiological of change. Is characterized by rapid freezing of food to maximize their food original color, flavor and nutritional value . That is, in the freezing process must ensure that these various changes occurring foods maximum reversibility.
Rapid freezing food has the following advantages :
1. avoiding the generation of large ice crystals in the cells between.
2. reducing the water outside the cell analysis, less drip loss during thawing Internal.
3. tissue concentrates solutes and food organizations , colloids , and time of various components in contact with each other significantly shortened , condensed down to the lowest level of harm.
4. the food quickly reduce the temperature to the activity of microbial growth under favorable resist microbial growth and the biochemical reactions.
5. a short residence time in the frozen food equipment , help improve equipment utilization and continuity of production.
Most of the food at temperatures down to -1 ℃ frozen at the start , most of the ice is generated between -1 ℃ ~ -5 ℃, this stage is called the maximum ice crystal formation stage. Quick Freeze can make at this stage freeze time is greatly reduced , with the fastest speed you can exclude this part of the heat , which is important to improve the quality of frozen foods.
Quick-freezing -35 ℃ (+2 ℃ / -2 ° C)