Yeast Immobilization And Application In Beer Fermantation

Immobilized cell technology is a new biotechnology that fixed free cell into limited field with chemistry or physical method in order to keep the activity of cell and allow it can be used repeatedly.This paper mainly discusses the synthesis method of chitosan-alginate sodium hydrogel, chitosan-polyvinyl alcohol hydrogel and chitosan-methylacrylic acid hydrogel. In order to find out the suitable immobilized carrier for beer production,the characteristic of these carriers,embeding Saccharomyces cerevisial to brewing beer and determining flavor substance of beer by gas chromatograph/mass spectrometer are studied.This paper also discusses the effects of alginate sodium concentration, chitosan concentration, immobilized time, mulching film time on hardness of chitosan-alginate sodium.The result shows that the optimization technical conditions of chitosan-alginate sodium hydrogel: alginate sodium concentration 3%, immobilized time 2h,chitosan concentration 0．5%, mulching film time 30min.The tolerance immersion and immobilized conditions of carrier are studied. The data suggests that embeding 0．4mL yeast suspendsions is advantageous to brewing beer and chitosan-alginate sodium can take continus fermentation.The study of the effects of ratio of chitosan and polyvinyl alcohol, amount of acetic acid, glutaraldehyde concentration, formaldehyde concentration on hardness of chitosan-polyvinyl alcohol illumiated the optimization technical conditions of chitosan-polyvinyl alcohol hydrogel: ratio of chitosan and polyvinyl alcohol 6, amount of acetic acid 6mL, glutaraldehyde concentration 4%, formaldehyde concentration 5%. The infrared spectrum, SEM, immobilized Saccharomyces cerevisial conditions and the growth kinetic curve of beer yeast imply that immobilized carrier has good tolerance immersion and well biocompatibility.The optimization experiment shows that the optimization technical conditions of chitosan-methylacrylic acid hydrogel: amount of methylacrylic acid(30%) 8mL, amount of ammonium ceric nitrate(3mmol/L) 0．2mL, amount of glutaraldehyde (2%)2mL, reaction temperature 35℃. The infrared spectrum, SEM, immobilized Saccharomyces cerevisial conditions and the growth kinetic curve of beer yeast show that immobilized carrier has good tolerance immersion, but velocity of fermentation is slower than free yeast.Comparing the flavor substance of beer made by three immobilized Saccharomyces cerevisial carrier, the result shows that Chitosan-alginate sodium is superior in beer fermentation.