Cultivation Of Chlorella Protothocoides In The Hydrolysate From Soy Sauce Residue Coupling Production Of Fish Protein Feed

Soy sauce residue is a by-product in the process of brewing soy sauce,which contains crude protein,carbohydrates and other nutrients.In this work,we prepare a hydrolysate by cellulase and alkaline protease hydrolyzing soy sauce residue.Chlorella protothecoides contain protein,which are widely used in food and protein feed.In this work,the hydrolysate of soy sauce cultivate Chlorella protothecoides and obtain fish feed.The main contents are as follows:(a)Cellulase and alkaline protease hydrolyzing soy sauce residue to prepare the hydrolyzate of soy sauce residueSurface response method optimize the hydrolysis conditions of cellulase hydrolyzed soy sauce residue.The material-liquid ratio,enzyme addition,p H,temperature,time and yield of reducing sugar were 1:10,1.6%,4.2,50?,113 min,and 7.06%respctively.Alkaline protease hydrolyzes soy sauce residue,on the basis of cellulase hydrolyzing soy sauce residue.The optimal hydrolysis conditions were that the p H was 8.0,and the temperature was 50?,and the enzyme addition was 2%,and the reaction time was 100 min.Comparing with the obtaining soy sauce residue hydrolysate and the Basal medium,the concentration of Na~+is a little high in the hydrolysate,and there is no significant difference in the concentration of K,Mg,Ca and other large elements,and the reducing sugar is slightly low,but the concentration of ammonium nitrogen is high.It has potential application to cultivate Chlorella protothecoides.(b)Optimization of the soy sauce residue hydrolysate cultivating Chlorella protothecoidesThe optimal dilution ratio of the soy sauce residue hydrolysate diluted by Basal medium were 6 times.The optimal concentration of optimized C,N and P sources were 15 g/L,1 g/L and 1.25 g/L respectively.Using glucose as the carbon source and soy sauce residue hydrolysate as the nitrogen source,the Chlorella protothecoides was cultivated for 264 h.Biomass and protein yield are 7.65 g/L and3.213 g/L respectively(c)Feasibility evaluation of soy sauce residue hydrolysate cultivating Chlorella protothecoides co-produced protein as fish feedThe crude protein,the crude oil,the carbohydrate and the crude fiber content of the Chlorella protothecoides were about 44%,33%,12%and 3.4%respectively.By analysing amino acid composition,methionine was the first restricted amino acid,EAAI>0.95.Microbial indicators and heavy metal content are within the allowable detection range specified in feed hygiene standards.The Chlorella protothecoides cultivated by soy sauce residue hydrolysate is suitable as a high-quality protein feed for fish.Intestinal crude enzyme extract of crucian carp and grass carp digest Chlorella protothecoides powder in vitro.It indicates that the intestinal crude enzyme extract of two freshwater fish have good digestive effect on Chlorella protothecoides powder.