Study On Enzymatic Hydrolysis Technology Of Tilapia Wastes

This paper aimed at producing fish protein from tilapia wastes through enzymatichydrolysis technique. The paper firstly studied different enzymatic hydrolysis conditions ofneutral enzyme, protamex, trypsin, flavourzyme and papain. Study showed that neutralprotease and protamex were both sensitive to temperature, and their optimum hydrolysistemperature were 45℃and 50℃, respectively; trypsin and flavourzyme were also sensitiveto temperature, and their optimum hydrolysis temperature were both around 50℃. In addition,papain had a good heat resistant quality, and its optimum hydrolysis temperature was 60℃.Furthermore, study investigated that the optimum content of neutral protease, protamex,trypsin and flavourzyme added into tilapia wastes were 0．3%, 0．3%, 0．3%, respectively, whilethe optimum content of papain was 0．6%; the optimum hydrolysis pH of five proteases wasall at 7．0; the optimum hydrolysis time of Papain was 1 hour, neutral enzyme was 3 hours, andthe rest of three proteases were all 4 hours; the optimum quality ratio between tilapia wastesand water of hydrolysis by the five proteases was 3:1．Secondly, taking the hydrolysis degree as the overall index in order to evaluate theseproteases, their hydrolysis ability were analyzed under their optimum condition. Resultsindicated that neutral protease was best among all the proteases, the hydrolysis degree ofwhich was up to 35．20%. In addition, the paper also established a sensory evaluation methodin order to evaluate the crude hydrolysates produced by different proteases and the resultshowed that flavor of the hydrolysate was much better when the tilapia wastes werehydrolyzed by flavor protease compared with papain.Protamex and trypsin were selected to perform the single enzymatic hydrolysis. Theprocess of enzymatic hydrolysis was optimized and the optimal conditions were obtainedthrough orthogonal test. The optimum hydrolysis condition of protamex were as follows:content of enzyme 0．7%, hydrolysis temperature 50℃, hydrolysis time 5 hour, pH value 7．0,quality ratio between tilapia wastes and water of hydrolysis 5:1 and degree of hydrolysis inthis condition was 34．81%. The optimum hydrolysis condition of trypsin were as follows:content of added enzyme 0．7%, hydrolysis temperature 50℃, hydrolysis time 5 hour, pHvalue 7．0, quality ratio between tilapia wastes and water of hydrolysis 5:1, and degree ofhydrolysis in this condition was 35．16%.The study further adopted a unique technique that used two different proteases at the same time, namely ensoprotease and exopeptidase, to react on Tilapia wastes in different manners.Result showed that the combination of neutral protease and flavor enzyme was much bettercompared with other protease combinations in terms of Tilapia wastes enzymatic hydrolysis.By means of a dual quadratic rotary combinative design scheme, a dynamic mathematicmodel that showed the connection between hydrolysis degree (Y) and enzyme ratio (X₁) ,hydrolysis temperature (X₂) as well as hydrolysis time (X₃) was designed. In order to obtainthe optimum condition for the enzymatic hydrolysis of Tilapia wastes, the study furtheroptimized the enzymatic hydrolysis process by means of Response Surface Analysismethodology. The optimum condition of Tilapia protein enzymatic hydrolysis was shown asfollows: ratio of neutralized protease to flavor protease 2．18:1, temperature 52．3℃, hydrolysistime 4．8h, and the maximum enzymatic hydrolysis degree of Tilapia wastes in this optimumcondition was up to 47．32%.