| During the processing penaeus vannamei boone, it will produced a large number of processing wastes, which contained amounts of chitin. But most of processing wastes are directly discarded and aren’t fully utilized, which not only causes a waste of resources, but also brings serious pollution to environment. Chitosan is a production from the deacetylation of chitin, due to its natural nontoxic and numerous features. Chitosan has been widely used in many areas and the demand is constantly increasing, which becomes a key point today.In this experiment, processing wastes of penaeus vannamei boone was used as raw materials, crude chitin was produced from removing protein with enzymatic method and lactic acid decalcifying with ultrasonic-assisted method, then chitosan was prepared by deacetylation of crude chitin and drying process. Through the optimum of processing conditions, the better method of preparing chitosan from penaeus vannamei boone processing wastes was got. Main content and results of this study are as follows:(1) Processing wastes of penaeus vannamei boone was used as raw materials, the technological conditions of removing protein with enzyme method was studied.Processing wastes of Penaeus vannamei boone was used as raw materials, protein hydrolysis degree as indicator. Through single factors test, the effect of different proteases, enzyme dosage, reaction temperature, hydrolysis time and p H on enzymolysis effect was studied, based on the single factors test results, enzymolysis conditions was optimized with orthogonal test, the more suitable deproteinization process conditions was gained: suitable of protease was neutral protease, p H was 8, hydrolysis time was 5h, enzymolysis temperature was 45℃, enzyme dosage was 3000u/g, solid-liquid ratio was 1:10.(2) The samples of deproteinization processing was used as raw materials, the technological conditions of using lactic acid to remove calcium with ultrasonic-assisted method was studied.The samples of deproteinization processing by decalcifying processing, ash content was used as indicator. The effect of lactic acid concentration, reaction time, liquid-solid ratio and ultrasound time on decalcification was studied through single factors test, combined on the single factors test results, the condition of ultrasonic-assisted to decalcify was optimized with response surface analysis method, the better technology conditions: lactic acid concentration was 11.5%, reaction time was 95 min, liquid-solid was 26:1.Under these conditions, the measured value of the sample ash content was(0.35±0.05)g/100 g, the actual test value and the model prediction value were consistent, which showed that the model can better predict changes in ash content of chitin. Then the sample of deproteinization and decalcification by bleaching, the crude chitin was gained.(3) The technological conditions of deacetylation from coarse chitin to prepare the chitosan were studied.Chitin of homemade was used as raw materials, in ethanol soaking, and ultrasonic auxiliary conditions to remove acetyl with alkali method, high deacetylation degree chitosan was gained. Through single factors test, the effects of alkali liquor concentration, liquid-solid ratio, reaction time, ultrasound time and ethanol content on deacelation degree was studied. In this condition, the better condition of deacetylation with response surface analysis method was determined: alkali liquor concentration was 52.7%, reaction time was 7.9h, liquid-solid ratio was 29.8:1.Under these conditions, the measured value of the chitosan deacetylation degree was(71.60 ± 0.35)%, the actual test value and the model prediction value were consistent, which showed that the model can better predict changes in deacelation degree of chitosan.In conclusion, the key technology on chitosan preparation from processing wastes of penaeus vannamei boone was studied in this paper, the theoretical basis and technical support to achieve the high value of processing wastes of penaeus vannamei boone was provided. |
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