The Study And Production Of Anchovy Condiments And Antioxidant Peptides

Anchovies (Engraulis encrasicholus) are highly abundant in the Pacific Ocean andthe Atlantic Ocean. It was estimated that the annual catch of Yellow Sea and EastChina Sea was about500,000tons in these years. Previous research has shown thatanchovies are rich in essential amino acids and n-3fatty acids (FAs), such as EPA andDHA. A majority of anchovies are used for fish meal production and onlycomparatively small amounts are used for human consumption. A large amount ofanchovy by-products, which generally amount to50%of the weight of the fishmaterials, was generated in the process. Nowadays, the majority of anchovyby-products were discarded which caused waste and serious environmental problems.In the study, two kinds of anchovy condiments were studied by the methods oflow-salt solid-state fermentation and enzymatic fermentation with anchovyby-products. Then, biochemical parameters of two kinds of anchovy condiments wereanalyzed and antioxidant peptides were isolated and purified from one of anchovycondiments. In addition, its neuroprotective effect and immune activity were assessed.The results and conclusions are as follows:The conditions of making koji for two processes A and B were optimized by onefactor and the best conditions of making koji for processes A and B were: run water:80%,80%; the time of making koji:48h,36h; bean/bran＝3:1,3:1; inoculum:0.8%,0.6%. Based on the best conditions of making koji, the conditions of fermentationwere optimized. The highest amino nitrogen of7.50mg/mL and7.73mg/mL wereobtained under the condition of koji: brine (1:1.42,1;1.52), brine concentration(16.02%,16.30%) and the volume of back pouring (30.00%,23.15%) with RSMoptimization for sauce A and B, respectively. The results of chemical analysissuggested that amino nitrogen, degree of hydrolysis (DH), reducing sugar, DPPHradical-scavenging activity, total acidity and total amino acid in sauce B were higher than sauce A. Besides, volatile odorants analysis and sensory evaluation showed thatsauce B was superior to sauce A. This study demonstrated that, adding anchovy juicein the process of fermentation is a better way to product a fish sauce with good flavorand nutrition value.The enzymatic-pure liquid fermentation process was established and thefermentation conditions of anchovy enzymatic liquid were optimized by RSM. Thehighest amino nitrogen of7.35mg/mL was obtained under the condition of sterilizingtime (20min), loading volume (30%), fermentation temperature (35℃) and branaddition level (4.42%) with RSM optimization. The results of chemical analysissuggested that amino nitrogen, degree of hydrolysis, reducing sugar and total aminoacids increased, while total acidity decreased during fermentation. It could be inferredthat various components of anchovy enzymatic liquid were utilized and a lot of smallmolecule compounds with antioxidant activity were produced. Besides, the results ofvolatile odorants and sensory evaluation showed that no particularly unpleasant flavorwas found in the fish sauce. In conclusion, anchovy juice which was produced byenzymatic hydrolysis and fermentation was a new product with potential developmentand good market prospects.Two antioxidant peptides f2and f3were purified with methods of G-15gel column,DEAE sephadex FF anion exchange column and reversed-phase HPLC C18columnfrom anchovy juice. The molecular weight and amino acid composition of f3weredetermined. According to the results of molecular weight and amino acid composition,it could be speculated that f3was a novel antioxidant peptide. In addition, the sourcesof f2and f3were investigated and found that f2was obtained by the fermentationprocess and f3exist in anchovy enzymatic liquid, presumably obtained duringenzymatic hydrolysis. Besides, the neuroprotective effect of f3were assessed and theresults indicated that f3could significantly reduce glutamate-induced PC12celldamage and significantly increased cell survival.