Study On Bioconversion Technology Of By-products Of Seafood Processing

China is not only a country with abundant types and quantities of seafood in the world,but also a big consumer of seafood.Seafood will leave some by-products after processing.Seafood is processed to leave some by-products,and some seafood processing by-products,such as fish head,fish bone remains,fins,and guts,produced during processing and manufacturing,account for approximately 40%-60% of the total seafood products.Data show that more than 70% of the world's seafood output is processed and sold,while China's 2019 processing proportion accounts for less than40% of the output,and the utilization rate of processing capacity is only 80%.Because of the short chain of seafood by-product processing industries,severe waste of resources,and low economic benefits,how these resources can be better utilized is an important research topic in modern seafood processing.In this study,protease and probiotics were used to biotransform by-products from yellow-fin tuna processing and blue-dotted mackerel processing,explore the optimum conditions of enzymatic hydrolysis,fermentation and bacterial-enzymatic co-transformation,effectively combine biotransformation technology and biological products research and development technology to explore the deodorization technology of seafood processing by-products.Biological product processes.The main research results are as follows:(1)Optimization of enzymatic conditions by neutral protease,flavourprotease,trypsin,papain were individually and orthogonally coupled with yellow fin tuna byproduct,blue dot magenta byproduct.The optimal enzymatic hydrolysis result was:pH of byproduct of yellow-fin tuna hydrolyzed by flavor protease was 7.5,feed-liquid ratio was 1:7,amount of enzymatic added was 8000u/g,time was 4h,and soluble protein conversion rate was 42.76%.The pH value of by-product from enzymatic hydrolysis of yellow-fin tuna by neutral protease is 6.5;the feed-liquid ratio is 1:7;the enzymatic dosage is 8000u/g;the time is 4h and the soluble protein conversion rate is33.14%.The optimum conditions for enzymatic hydrolysis of blue-dot mackerel by flavor protease are pH 7.5,feed-liquid ratio 1:9,amount of enzymatic added 8000 u/g,time 4 h and soluble protein conversion rate 33.75%.Neutral protease enzymatic blue dot magenta by-product pH was 7.5,with a feed to liquid ratio of 1:7,enzyme addition was 8000 u/g for 4 h,and the soluble protein conversion rate is 34.76%.(2)Through the screening and optimization of Lactobacillus bulgaricus,the optimal fermentation conditions of Lactobacillus bulgaricus were obtained.Streptococcus thermophilus and Yeast using yellow-fin tuna by-product and blue-dotted mackerel by-product as substrates.The optimum fermentation results are:Lactobacillus bulgaricus fermented yellow-fin tuna by-product material-liquid ratio 1:9,strain dosage 40%,fermentation days 4 d,protein conversion rate 29.35%;Streptococcus thermophilus fermented yellow-fin tuna by-product material-liquid ratio 1:7,strain dosage 40%,fermentation days 4 d,protein conversion rate 31.65%;yeast fermented yellow-fin tuna by-product material-liquid ratio 1:7,strain dosage40%,fermentation days 6 d,protein the conversion rate was 27.15%;by-product material-liquid ratio of Lactobacillus bulgaricus fermentation blue spot mackerel was1:7,strain dosage was 30%,fermentation days were 2 d,and protein conversion rate was 22.04%;by-product material-liquid ratio of fermentation mackerel by Streptococcus thermophilus was 1:7,strain dosage was 50%,fermentation days were4 d,protein conversion rate was 26.25%;by-product material-liquid ratio of Yeast fermentation blue spot mackerel was 1:9,strain dosage was 50%,fermentation days were 5 d,protein conversion 22.57%.(3)According to the results of single-bacteria and single-enzymatic screening,the optimum protease and strain were selected for bacterial-enzymatic combination,and the orthogonal optimization conditions for synergistic degradation of yellow-fin tuna by-product and blue-dotted mackerel by-product were as follows: 1:7 ratio of material to liquid of flavor protease and Lactobacillus bulgaricus to transform yellow-fin tuna by-product,8000 u/g amount of enzymatic added,40% amount of strain added and 3 days of inversion.The soluble protein conversion was42.97%.Neutral protease combined with Lactobacillus bulgaricus can transform yellow-fin tuna by-product with a feed-liquid ratio of 1:9,an enzymatic amount of9000 u/g,a bacterial amount of 30%,a transformation period of 4 d,and a soluble protein conversion rate of 39.84%.The conversion ratio of flavor protease and Streptococcus thermophilus to by-product of blue spot mackerel is 1:7,the amount of enzymes added is 8000 u/g,the amount of strains added is 20%,and the conversion rate of soluble protein is 36.32% for 3 days.Neutral protease combined with Streptococcus thermophilus transforms blue-dot mackerel by-product with a feed-liquid ratio of 1:7,an enzymatic amount of 9000 u/g,a strain addition of 40%,a transformation period of 5 days and a soluble protein conversion rate of 37.07%.(4)Through enzymatic hydrolysis,fermentation,bacterial enzymatic combined conversion process and bacterial enzyme combined with Maillard response,the odor can be effectively reduced.During the fermentation process,through the metabolism of probiotics,the odor substances of small molecules participate in the metabolism and synthesis to become smaller biological macromolecules or change the molecular structure under the action of protease to become smaller components,thus achieving the purpose of deodorization.By comparing the response values of W5 S to nitrogen oxides,W1 S to methane and W2 S to alcohols,we can see the deodorization effect of several sample solutions: bacteria enzyme combined with Maillard reaction solution >bacteria enzyme combined with Maillard reaction solution The results showed that the optimum fermentation conditions were as follows: syngenetic transformation liquid >enzymatic hydrolysate > fermentation liquid.