The Study On The Comprehensive Utilization Of Brewer's Spent Grain

Brewer's spent grain(BSG) is the main by-product of brewing industry.The ratio of BSG and raw materials is about 31%. Many factories sold it asanimal feed, but some factory pull it as waste which causing pollution to theenvironment and resource waste. BSG is rich in dietary fiber and protein. It isa high quality dietary fiber source and protein source. This paper mainly studyon the comprehensive utilization of BSG. The optimum conditions ofextracting protein, insoluble dietary fiber(IDF) and soluble dietary fiber(SDF)was studied and cellulase produced by Trichoderma viride with solidfermentation was preliminarily studied.The optimum conditions of extracting protein from BSG was studied. Theoptimum enzymatic conditions of protease: the enzyme load is 2mL/100gdried BSG; the temperature of hydrolysis is 60℃; the pH of hydrolysis is 8．0;the time of hydrolysis is 5 hour; the proportion of liquid and solid is 12:1．Atthe optimum conditions, the extraction rate of protein could reach 63．61%.The optimum enzymatic conditions of cellulose: the temperature of hydrolysisis 55℃; the pH of hydrolysis is 5．5; the enzyme load is 1．2g/100g dried BSG;the time of hydrolysis is 4 hour. The extraction rate of protein was increased by 7．4% with protease and cellulose hydrolysis compared with only proteasehydrolysis. The total protein content of hydrolysate is 1106．4mg·(100mL)^-1 .The content of free amino acid is 267．4mg·(100mL)^-1 . The hydrolysate couldbe concentrated by nanofiltration membranes. After protease hydrolysis, IDFcould be extracted from solid waste by screening. The yield rate of IDF is56．7%. The water-holding capacity is 6．83 and the swelling capacity is6．0mL·g^-1 ; but it also has 8% protein.The extraction of SDF from brewer's spent grain by alkali and enzymewas also ,studied. The optimum conditions of extracting SDF from BSG byalkali: the temperature of extraction is 70℃; the concentration of NaOH is0．9%, the time of extraction is 80min; the proportion of liquid and solid is17:1．At the optimum conditions, the yield rate of SDF could reach 13．37%.The optimum conditions of extracting SDF from BSG by enzyme: thetemperature of hydrolysis is 55℃; the enzyme load is 10g/100g dried BSG;the time of hydrolysis is 5 hour; the pH of hydrolysis is 8．0; the proportion ofliquid and solid is 15:1．At the optimum conditions, the yield rate of SDFcould reach 4．71%. The yield of SDF extracted by alkali is higher than theyield of SDF extracted by enzyme; and the colour of SDF extracted by alkaliis deeper than the colour of SDF extracted by enzyme.Cellulase produced by Trichoderma viride with solid fermentation waspreliminarily studied. Trichoderma viride could ferment BSG and producecellulose during this process, but cellulose activity is low. The technology is suggested to further studied.