Abstract:The fish scale of tilapia taken as the raw material, the orthogonal test design was adopted to study the pretreatment of the fish scale of tilapia by using alkali method, acid method, enzyme method, acid and saline method, and saline and alkaline method. Then the five optimized processes were compared and the gelatin extraction process was studied. The results showed that the enzyme method was the optimum extraction process of gelatin from tilapia fish scale. The process was as the following: pretreatment with 0. 2% acidic protease solution with pH adjusted to 3.5, enzymatic hydrolysis at 35 ℃ for 1h, then the fish scale was rinsed to pH 5~6 after being soaked for 4 h in 2% hydrochloric acid. The gelatin extraction process includes 3 heating steps,heating at 65 ℃ for 3 h, heating at 70 ℃ for 35 h and heating at 75 ℃ for 35 h, then the final product was filtrated and the filtrate was pooled.
