Application Study On The Predigestion Of Sargassum Thunbergii Powder By Zymin

Sargassum thunbergii powder was widely used as a component of the feed inaquaculture, but its application was limited for the low effective utilization. In order toimprove the utilization rate and promote the breeding benefit, the methods of digestiveprocessing by adopting enzyme preparation were studied in this topic.The applications of enzyme preparation in the digestive processing of Sargassumthunbergii powder were comprehensively researched in this paper. Firstly, the best roleconditions of the single enzymes on Sargassum thunbergii powder were studied. The threenon-starch polysaccharide enzymes, such as cellulase, xylanase, β-glucanase, middletemperature amylase and litmusless protease played main role in anti-nutrients, while themiddle temperature amylase and litmusless protease mainly acted in nutrients. Theresearch results of this part were as follows.（1）The single factor experiment and the orthogonal experiment of exogenousnon-starch polysaccharide enzymes decomposing Sargassum thunbergii powder showedas follows. Firstly, the optimum doses of cellulase was40U/g, and the increment ofglucose can be as high as2.064mg/g based on its optimum application conditions,including temperature as40℃, pH as6.5and time as60min. Secondly, the optimumdoses of xylanase was confirmed as40U/g, and its increment of glucose can be as high as2.590mg/g based on the optimum conditions, including temperature as45℃, pH as6andtime as40min. Finally, the optimum doses of β-glucanase was also40U/g, and itsincrement of glucose can be as high as2.237mg/g based on its optimum use conditions,including temperature as50℃, pH as6, time as60min.（2）The single factor and orthogonal experiment were implemented to sargassumthunbergii powder used the endogenous middle temperature amylase and litmuslessprotease, and the results were as follows. Firstly, the optimum doses of middle temperatureamylase was40U/g, and its optimum use conditions were temperature as40℃, pH as6,time as60min, then its increment of glucose can be as high as2.329mg/g. Secondly, the optimum doses of litmusless protease was80U/g, and its optimum use conditions weretemperature as55℃, pH as7, time as100min, then the increment of protein and itshydrolysate can be as high as15.015mg/g.Based on foregoing study, mixed enzymolysis research was carried out, whichincluded the non-starch polysaccharide enzyme combined acted with middle temperatureamylase and litmusless protease respectively. The aim of mixed enzymolysis research wasto compare the decomposition of nutrient substance by temperature amylase and neutralamylase before and after the cell wall of sargassum thunbergii destroyed by cellulose andxylanase. According to the results of the study, the composite enzyme was designed whichhas comprehensive catabolism to decompose anti-nutrients and nutrients of Sargassumthunbergii powder.（1）The experimental results of mixed enzymolysis contained two parts. For onething, in the case of the best economic usage added, temperature as45℃, pH as6andtime as60min, the increment of glucose produced by mix enzymolysis was17.9%higherthan single enzyme experiment. For another thing, in the case of the best economic usageadded, temperature as55℃, pH as7and time as100min, the increment of hydrolysateproduced by mix enzymolysis was13.8%higher than single enzyme experiment. Theresults showed that mixed enzymolysis was beneficial to increase the utilization rate ofnutrients in sargassum thunbergii cells.（2）The research of conditions optimized for composite enzyme showed that theoptimum role conditions was temperature as50℃～55℃, pH as6.5and time as180minwhen the doses of mixed enzymolysis substrate was1ml/g, substrate concentration was10%～20%. Moreover, the enzymolysis effect was still fine when the substrateconcentration was30%.