Continuous Secondary Fermentation Of The Beer With Immobilized Yeast

In this paper, the beech wood chips were used as the carrier for immobilizingthe yeast in packed-bed reactor. Through measuring the amount of yeast on thecarrier, to select the immobilized carrier; to optimize the condition of theimmobilized yeast process, and adjust the performance of the yeast in the reactorduring the fermentation; To compare the flavor substances and amino acids fromtraditional fermentation and continuous secondary fermentation by GC and HPLCrespectively.The results as follows:1. The beech wood chip and the porous ceramic are used as yeast carriers, thesetwo kinds of carriers were compared by immobilized effect, and the beer fromcontinuous secondary fermentation by these two kind of carriers compared witheach other. The results were as follows: the immobilized yeast of beech wood chipswas31.2%/g higher than porous ceramics, the diacetyl and acetaldehyde of beerfrom the beech wood chips immobilized yeast are lower than the porous ceramics’.2. Through measuring the amount of yeast on the carrier in different time-temperature, to study on the immobilized mechanism thermodynamic of the carrier.The results were as follows: the gibbs free energy (ΔG0) and activation energy (Eact)were-37.4KJ and-4.50KJ respectively. the yeast adsorption on Beech wood chip ismultilayer adsorption, the gibbs free energy (ΔG0) and activation energy (Eact) arelow which shows that yeast of carriers are the nature of physical adsorption, Andequilibrium of the adsorption develops rapidly. Cell-carrier and the cell-to-cellinteraction are a mild endothermic process.3. Through measuring the amount of yeast on the carrier to select the bestconcentration of the yeast. To discuss the kinetics of Adsorption，and take them intothe Langmuir and Freundlich isotherms to have an optimized analysis. Because ofthe results of the experiment are very similar to the theoretical curve of theLangmuir and Freundlich isotherms, Regression coefficient R2were0.998å'Œ0.948respectively. As a dynamic experimental result, the yeast on carrier’s adsorptionmay base on a simple surface adsorption.4. The immobilized yeast amount of different growth stages (delay, logarithmicphase and stationary phase and decline phase) are different from each other,however, considering the Yeast activity, we choose yeast of the stationary phase. 5. The orthogonal test was optimized that the best concentration to immobilizeyeast is5x106cell/mL, the rate of fill is90%, the immobilized time is10h.6. To compare the flavor substances and amino acids from traditionalfermentation and continuous secondary fermentation, The results as follows: thediacetyl and acetaldehyde of beer from continuous secondary fermentation arehigher than traditional fermentation0.036mg/L and4.589mg/L. the13kinds ofamino acids from continuous secondary fermentation, Tyrosine, valine, methionine,tryptophan and phenylalanine were lower than traditional fermentation13.1%,7.5%,31%,2.2%,29.5%respectively.Above all, The beech wood chip is better than the porous ceramic which areused as yeast carriers, its immobilized methods is physical adsorption of the surface,at the same time, flavor substance of beer were in the scope of threshold values, itcan be used as the carriers to immobilize the yeasts of the continuous secondaryfermentation.