Research On The Protein Utilization And Fish Oil Extraction Technology Using Tilapia Processing Byproducts

Our country is rich in fishery resources，and the huge annual output of tilapiaand other freshwater fish result in a large number of byproducts．The utilizationform of these byproducts is single，typically underutilized and abandoned．Thisstudy intends to use the main byproducts of tilapia（fish heads，fish bones，skin，meat and offal） as raw material，conduct protein utilization and fish oil extractiontechnology research of tilapia byproducts，and achieve efficient use of tilapia meatand byproducts．Tilapia meat and byproducts was hydrolyzed by using flavourzyme，papain，neutral protease，alkaline protease．The effect of temperature，amounts of enzyme，initial pH，liquid-solid ratio，enzymatic time on the hydrolysis degree was studied，and the best hydrolysis process of four enzymes for tilapia meat and byproductswas identified by orthogonal experiments．The hydrolysis conditions when thedegree of hydrolysis of papain for meat and byproducts is highest were as follows：temperature60℃，enzyme dosage0.6%，liquid-solid ratio of3.5：1，time5h，thehydrolysis degree was26.86%； temperature60℃， enzyme dosage1.1%，liquid-solid ratio of5.5：1，time5h，the hydrolysis degree was26.76%．Antioxidant activity，hypotensive activity and amino acid composition analysisof tilapia meat and byproducts’ enzymolysis liquid was studied．The change ofantioxidant activity with hydrolysis time was performed，and papain enzymolysisliquid under optimal hydrolysis time was selected for ACE（angiotensin convertingenzyme）inhibitory activity assay and free amino acid analysis．The results showedthat：enzymolysis liquid has a stronger antioxidant activity when hydrolysis timeof papain was2h，then ACE inhibition rates of meat and byproducts’ papainenzymolysis liquid were71.69%and74.14%，indicating that both have relativelystrong ACE inhibition activity；The amount of essential amino acids in byproductenzymolysis liquid was obviously higher than that of tilapia meat enzymolysisliquid；The amount of sodium alginate added to tilapia meat and byproducts enzymolysis liquid was determined at1.2%and0.8%by spray dryingmicroencapsulation using enzymolysis liquid， and the embedding rate ofmicrocapsules reached about90%．Fish oil was extracted using tilapia offal．The effect of pH，hydrolysistemperature，salting time，salting temperature and amount of salt on the extractionrate of fish oil was studied，and the optimum extraction process of fish oil wasdetermined by orthogonal experiment：pH7.5，hydrolysis temperature65℃，salting temperature60℃，24%of the amount of KNO3，salting time2min，then theextraction rate of fish oil was57.19%．A two-step process was used for fish oildeacidification，decolorization and deodorization．After refining，the viscous fishoil has a lighter color，becomes clear and transparent，and acid value，peroxidevalue and moisture and volatile matter content decrease．...