Study On Food Made Of Channel Catfish Skin

As export requirement of Channel catfish is increasing, fish skin is producing year by year. The utilization ratio of fish skin is very low so far. Channel catfish skin is selected as the raw material in this thesis, studying fish skin food production technology.The fishy smell is removed by 60.0g·L-1 black tea for 120.0 minutes, then soaked in the alkali solution to improve the brittleness of the fish skin.On the basis of single factor tests, a quadratic regression orthogonal design and response surface analysis were adopted.The optimum soaking conditions: concentration of sodium hydroxide 1.06g·L-1, soaking time of sodium hydroxide 15.4 minutes, concentration of sodium bicarbonate 31.0g·L-1 and soaking time of sodium bicarbonate 63.2 minutes and predicted value of breaking force was 902g.The denatured temperature of fish skin protein is 46℃.The fish skin in microwave power 492W for 15s can be aging. It was found that the capability of effects of factor on the breaking force: microwave power﹥drying oven time﹥microwave time. The optimum conditions were composed by follows: drying oven time 20 minutes, microwave power 683W, microwave time 30s. The variance analysis showed that the breaking force was significantly influenced by the drying oven time, microwave power and microwave time. The result of the variance analysis was the same as the range analysis. The moisture absorption isotherms of brittle fish skin that ranged from 10℃to 40℃showed a reverse S shape. With the increasing of the temperature, the equilibrium moisture content decrease in the certain aw.With the increasing of the aw,the equilibrium moisture content increase in the temperature to a certainty. The brittle fish skin can be preserved for 2 years in the PVC packing bag whose moisture permeability≤0.13g/(m2·24h) at 35℃.Water-swollen rate of fish skin increased as concentration and soaking time of sodium hydroxide increased. Meanwhile, as the soaking temperature increased water-swollen rate first increased then decreased. And the results of L9(33) orthogonal experiment turned out an optimum condition were the fish skin soaked in 1.0 g·L-1 sodium hydroxide for 150 minutes in 35℃.By the premise of guarantee of quality safety, brittleness is the main evaluation index of water-swollen fish skin. And brittleness is influenced by boiling mode and cooling processes. Optimum conditions are that 85℃water bath boils 45s then soaked 3 minutes in ice water. Shelf life is also a considered factor. Fish skin soaked in 1.0% sodium diacetate combined with vacuum pack can be preserved 16 days in 4℃.