The Development And Characterization Of High-value Products From Squid Viscera

In this study,the combination of biological separation technology was used for the comprehensive utilization of squid viscera to simultaneously produce chondroitin sulfate,peptone,refined squid oil and squid ointment without producing waste,thus achieving the high value utilization of squid viscera.(1)The separation and purification of CS from squid cartilage were studied by using alkaline-extraction,enzymatic hydrolysis and alcohol precipitation methods.The optimal alkali-extraction conditions were determined as follows:temperature 50?,alkaline concentration 2.80%,solid-to-liquid ratio 1:8,extraction time 4.20 h.Under these conditions,the yield of crude CS was 41.38%.The optimal enzymatic hydrolysis conditions were determined as follows:trypsin dosage 2.70%,pH 8.20,temperature 50?,time 3.40 h.Under these conditions,the CS and protein contents were 79.82%and 5.85%,respectively.The optimal alcohol precipitation conditions were determined as follows:sodium chloride dosage 2.50%,pH 6.60,ethanol concentration 70%.Under these conditions,the CS purity and yield were 92.19%and 23.76%,respectively.(2)The protein and lipid contents of squid viscera were determined to be 24.8%and 25.3%,respectively.So the viscera after extracting oil can be used as alternative source for peptone production.The optimal enzymatic hydrolysis conditions for peptone production were determined as follows:trypsin dosage 0.36%,pH 8.20,temperature 45?.Under these conditions,the yield of squid-soluble peptone was 21.86%,along with 3.1%of amino nitrogen and 14.7%of total nitrogen.The essential amino acid content of squid-soluble peptone was 34%,and the total amount of glutamic acid,lysine and phenylalanine that need for microbial growth was about 21%.Results of bacteria-growth curves show that squid-soluble peptone could be used as good nitrogen source for the cell growth of Escherichia coli and Lactobacillus.(3)The key process of the refined squid oil was optimized by alkali refining deacidification and sublevel decolorization by active clay.The optimal conditions for alkali refining deacidification were determined as follows:sodium hydroxide concentration 26°Be,temperature 54?,time 26 min.The optimal sublevel deacidification conditions were determined as follows:activated clay dosage 3.70%,appending proportion 3:2:1,temperature 88?,time 60 min.Under these conditions,the acid value of squid oil was reduced to 0.75mg/g,along with light yellow and crystalline appearance.The contents of polyunsaturated fatty acids,EPA and DHA were 38.91%,12.56%and 16.32%,respectively.(4)The visceral residue obtained from peptone production process was used for squid ointment production under steam cooking conditions,and its mouldproof conditions were investigated.The optimal conditions for the preparation of single antibacterial layer were determined as follows:agar content 2%,thickness 3 cm,sodium chloride dosage 5%,sodium benzoate dosage 0.30%,pH 3,dumping temperature 55?.Under these conditions,squid ointment could avoid mold contamination for 18 days.The optimal conditions for the preparation of compound antibacterial layer were determined as follows:agar content 2%,thickness 3 cm,the upper-lower layer ratio 5:1,sodi'um benzoate dosage 0.20%,sodium chloride dosage 4%,pH 3.50,dumping temperature of lower layer 80°C.Under these conditions,squid ointment could avoid mold contamination for 95 days.