Microbial Technology Utilization Of Penaeus Vannamei Boone Shrimp Head

The shrimp processing and consumption generate each year thousand tons ofsolid wastes. These wastes, which account for about45-48%by weight of rawmaterials, are a source of proteins, chitin, carotenoids, and minerals. Traditionally,shrimp chitin is extracted by chemical methods, while the use of corrosive chemicalagents such as strong acids or bases makes the process ecologically unacceptable.Alternative methods of enzymatic and microbiological have been reported. However,neither of them can remove the protein and ash of shrimp wastes concurrently.1) This study established a laboratory cleaner process of microbial fermentationof shrimp (Litopenaeus vannamei) head waste (SHW). In the process, Bacilluslicheniformis OPL-007(B.007) could grow in media containing SHW as sole carbonand nitrogen source, indicating that this bacteria could obtain its carbon and nitrogenrequirements directly from SHW. Finally, we got the rate of deproteinization (DP) anddemineralization (DM) were85.30%and97.10%, respectively.After Fermentation, this work determined the contents of active substances in thefermentation broth. The contents of total phenolic, polysaccharides, reducing sugar,free amino acids and organic acids of the fermentation broth were888.80,402.74,85.88,2061.79and5426.74mg/L, with8essential amino acids (EAA, with thecontent of1037.517mg/L) and6organic acids. Four kinds of enzymes, namelyproteases, chitin hydrolase,-amylases and lipases were also detected in thefermentation broth. The antioxidant activity of the culture supernatant was studied interms of the scavenging activity of DPPH radicals, reducing power and Fe2+chelatingability. It was found the fermentation broth by B.007showed a strong antioxidantcapacity. Taurine, as one of the most of non-protein amino acids, was proved to be thegreatest contribution to the antioxidant properties of fermentation broth by B.007.These results suggest that bio-deproteinization of SHW by B.007can be applied inthe production of chitin and functional foods.The2.5L fermentation broth by B.007was filtered and spray-dried, and10.142g shrimp protein powder was obtained. The protein powder was earthy yellow, with aflavor of shrimp. The contents of moisture, ash, protein and mineral elements were5.020%±0.211,19.811%±0.833,67.599%±1.693and7.570%. Particularly, four kinds of major elements (Na, K, Ca and Mg) and seven kinds of trace elements (suchas Fe, Cu, Zn) were founded in the shrimp protein powder, together with15kinds ofhydrolyzed amino acid (389.876mg/g), which included6essential amino acids(106.48mg/g),8non-essential amino acids and1non-protein amino acids, taurine(27.704mg/g).The shrimp protein powder was free of Salmonella, Staphylococcus aureus,Vibrio cholerae, Shigella, Bibrio parahemolyticus and other pathogenicmicroorganisms, and rich in Bacillus licheniformis, with the total colonies number of110000CFU/g.2) Successive cofermentation was applied to biologically extract chitin fromshrimp head waste in combination with the protease-producing bacterium, B.007andan acid-producing bacterium, Gluconobacter oxydans DSM-2003(G.2003). Whenthese bacteria were cultivated individually, B.007removed83.1%of the protein inthe absence of glucose and G.200393.7%of minerals from shrimp heads. When thewaste was first cofermented with B.007followed by G.2003(B--> G), the DP andDM removal efficiencies were87%and93.5%respectively at a chitin recovery of90.8%. The fermentation time in this study (96h) was almost half of the cultivatedcycle reported.In the co-fermentation broth8organic acids with a total amount of16g/L werefound. Major acids were lactic, formic and acetic acid, followed by gluconic, succinic,pyroglutaminc and propionic acid. In the cofermenation,3times more organic acidswere released than in the monofermentation of G.2003. The liquor fraction can beused either as a protein-amino acid supplement for human consumption or as ananimal feed.The antioxidant activity of the culture supernatant by B--> G was also studied interms of scavenging activity of DPPH radicals, reducing power and Fe2+chelatingability. It was found the fermentation broth by B--> G showed a much strongerantioxidant capacity than fermentation broth by B.007.Additionally, chitin with the highest quality, when compared with those of singlefermentation and chemical method, was obtained by the optimal strategy with methodof scanning electron microscopy (SEM). The cofermentation method employed in thisstudy offered the opportunity to preserve the exceptional qualities of chitin and itsderivatives, and additionally led to a liquor fraction rich in proteins, minerals and amino acids, which has the potential application in the production of functional foods.