Study On Enzymatic Hydrolysis Technology Of Tilapia Wastes And Specific Spoilage Organism From Tilapia Wastes Enzymatic Hydrolysates

The Tilapia heels enzymatic solution preparation of compound flavoring base material for the purpose of experiment to investigate.Tilapia offal protein hydrolysis degree is a main index,comprehensive enzyme solution liquid sensory score,the total number of colonies and volatile basic nitrogen index,were treated with trypsin enzymolysis single,trypsin andflavourzyme enzyme subsection enzyme solution analysis of enzyme solution temperature,solid-liquid ratio,pH,and the amount of enzyme,enzymatic hydrolysis time and other factors have influence on the above indexes,and interview analysis method(RSM)to optimize enzymatic hydrolysis conditions of response.The results showed that the optimum conditions by response surface analysis that trypsin single enzyme solution: ph7.5,solid to liquid ratio of 1?2 and the enzyme solution of 55 degrees Celsius temperature,enzyme dosage was 0.4% and the time is 6 h,protein hydrolysis degree 21.6%(model predictive value was 22.2%).At this time the volatile base nitrogen and the total number of colonies respectively 17.1mg/d L,1.7 x 104cfu/ ml and comprehensive sensory evaluation was 3.25.Technics of enzyme hydrolysis of trypsin and flavourzyme enzyme trypsin temperature 55 degrees Celsius temperature,pH is 7.5,enzyme dosage is 0.2%;flavor enzyme temperature to 50 degrees Celsius temperature and pH 7.0,enzyme amount is 1.5%,solid-liquid ratio of 1?3,protein hydrolysis degree of 32.1%(model predictive value was 32.7%),integrated sensory score was 3.5.Through the calculation of the design expert 8.0.6 software,two model p value < 0.0001,the lack of fit test,P > 0.05 were not significant,indicating that the quadratic polynomial regression model is highly significant,model fitted with the actual situation is very good,forecast value and the actual value was not significantly different,indicating that using response surface methodology optimization of enzymatic hydrolysis conditions is feasible.Specific spoilage organism of Tilapia Wastes enzymatic hydrolysates during chilled storage was studied by PCR-DGGE and PCR-RFLP.Results indicated that Tilapia enzymatic hydrolysates spoilaged about 20 days at 4 ?,and the total number of bacteria increased during 0~12 days(8.71×102~8.13×107 cfu/g)gradually,became stable during 12~20 days.There were three types of bacteria by PCR-RFLP analysis of 16 S rRNA from 18 strains of bacteria selected randomly.Type one which dominated 61% of the total bacteria was highly similar with Pseudomonas.The maps of PCR-DGGE showed that the bacteria reduced gradually before spoilaged,and there was only one single band of bacteria at last.Sequencing analysis results of DGGE bands showed that there were three types of bacteria Pseudomonas sp.,Aeromonas and Acinetobacter in the Tilapia Wastes enzymatic hydrolysates,Pseudomonas fluorescens was the predominant bacteria when spoilaged,this conclusion was consistent with RFLP.