罗非鱼(Tilapia)鱼皮提取明胶的工艺优化

The Extraction Process of Gelatin from Tilapia Fish Skin

以罗非鱼(Tilapia)鱼皮为原料,分别用碱法、酸法、酶法进行前处理,对3种方法的提取效果进行比较,筛选出最佳水解方法为酶法。优化了酶法处理后的漂白、熬胶工艺,获得鱼皮提取明胶的最佳工艺。结果显示,前处理采用0.2%的混合酶,调p H值至3.5,于40℃水浴中酶水解鱼皮1 h,用6%高锰酸钾溶液进行氧化漂白3 h,再用1.5%草酸溶液进行还原漂白45 min。控制p H值为5?6,分3次熬胶,每次分别将水浴加热升温至60℃、65℃、70℃,各加热2 h,过滤后将3次胶液合并,在真空度不低于500 mm Hg,温度不超过60℃的情况下浓缩至20%左右。然后在60℃的鼓风干燥箱干燥至明胶含水量14%以下,经粉碎机粉碎,即可得成品明胶。该工艺产品得率19.93%(湿基)、粘度13.1 m Pa·s、凝胶强度1034.3 g/cm2。

Due to the rapid development of Tilapia exportation in China, a large number of fish processing by-products have been generated which are rich in collagen. Proper extraction of the collagen from the by-products could help alleviate environmental pollutions as well as improve the added value of the fish processing by-products. In this study we used Tilapia skin as the material and applied the orthogonal design and the single factor test to exam the efficiency of alkali method, acid method and enzyme method in the pretreatment of Tilapia skin, according to the skin yield, viscosity and gel strength. Through a set of experiments we first identified the best method among the three and then optimized the bleaching and extraction process, and at last we made a discussion about this study to provide guidance on the gelatin production using fish skin. The results showed that the enzyme method was the best for gelatin extraction. The process was as below：the fish skin was treated with 0.2%mixed enzyme solution at pH 3.5, and underwent enzymatic hydrolysis at 40℃ for 1 h;the skin was then blanched with 6%potassium permanganate solution for 3 h followed by further blanching with 1.5%oxalic acid solution for 45 min;the skin was then degelatinized at pH 5-6. The gelatin extraction process includes 3 heating steps：60℃for 2 h, 65℃ for 2 h, and 70℃ for 2 h before the final filtrated product was pooled. The filtrate was then concentrated to around 20%in the vacuum （≥500 mmHg） at the temperature ≤60℃. The concentrate was dried （water content〈14%） at 60℃ and the final gelatin product was obtained after crushing. The yield of gelatin was 19.93% （wet basis）, and the viscosity was 13.1 mPa·s, and the gel strength was 1034.3 g/cm^2.