When vegetables in the freezing center temperature must be within 30 minutes, from minus 1 degrees to minus 5 degrees, and then to minus 15 degrees below, where can reach or exceed the speed of frozen vegetables can be called quick-frozen vegetables.

　　Frozen vegetables from the production to the sale, its quality is good or not, mainly according to the initial quality and the final quality of affirmation. The initial quality is determined by P.P.P. And the final quality is determined by T.T.T., which reflects the relationship between how long a frozen food can be maintained and the temperature. The quality of frozen vegetables is good at first, but through each circulation process to people's hands, the final quality will change. The quality of the product also changes when it is frozen. The degree of change is mainly due to the temperature and the length of time it has been frozen. The lower the temperature, the smaller the mass change and the longer the freezing time. At the same temperature, the longer you refrigerate, the greater the change in quality, and the worse the final quality.

　　From 48 to 58, many experiments in the United States concluded that there was a relationship between the quality of frozen food and the temperature at which it was frozen. The relationship was called T.T.T. The quality of frozen vegetables comes from P.P.P. and T.T.T. Therefore, only with good raw materials and scientific methods for refrigeration, but also with good materials for packaging, can you get a very good frozen vegetables.