Introduce freshness estimate function into cooling system of foods.

To find a freshness estimate expression, an experiment on storage of tuna was made and the following results were obtained: 1) ratio of weight to initial weight (yield) was greatly influenced by conditions of humidity and velocity of air; 2) K value was not influenced by conditions of air velocity under 95-75% humidity and 0-1 m/s air velocity; 3) change of colour was influenced by conditions of humidity and air velocity. So using the weight of evaporated water in tuna as a function, a relative expression for humidity and air velocity was found for preventing weight loss in tuna.