Study On The Technology Of Continuous Production Of Draft Beer By Immobilized Yeast

The study of using sodium alginate as carrier of the immobilized beer yeast cells.A technology of continuous beer fermentation by immobilized yeast cells were studied. Besides,the effects of the pore size and the pressure on membrane filtration of draft beer were also investigated.To provide the basis of theory and practice for applying the technique of immobilizing cells to the beer industrial production and improve the quality and flavor of pure draft beer has guiding significance. The main results includes:In sodium alginate as carrier preparation of immobilized yeast cells in the process of,this paper discusses the effects of sodium alginate concentration,calcium chloride concentration,immobilized time on hardness of hydrogel.The result shows that the optimization technical conditions of sodium alginate hydrogel:sodium alginate concentration2.5%,Ca2+concentration2%,immobilized time2h. The optimized conditions resulted in the hardness reach up to482.74g.The yeast cells immobilized in sodium alginate were applied to continnous beer fermentation. Through the study on the effects of fermentation temperature, flow, filling volume on Diacetyl production,the optimized processing conditions of continuous beer fermentation were obtained.Fermentative temperature being12℃,the flux being6L/h,and filling volume being60%resulted in the content of diacetyl decrease to0.085mg/L.The main physical and chemical indexes of beer produced by the technology of continuous fermentation applying immobilized yeast cells were determined.The results indicated that there is no significant difference between the beer produced by traditional technology and by new technology described above as far as the main physical and chemical indexes.The new technology had no effort on the quality and flavor of beer.The continuous beer afterfermentation was conducted for15days by immobilized yeast cells.The result indicated that the new technology was very stable.In beer filtration experiment, the effects of the pore size of membrane and the pressure on effects by filtration and fluid flux of draft beer were studied. The results show that:larger pore size caused highest beer flux in the initial phase and the flux then kept stable at 0.6-0.9kg/m2-h,the effects of pressure on beer flux became more evident under the condition of larger pore size and when the pressure exceeded certain value the flux tended to be stable.0.5μm (pore size) membrane suitable for practical production because of the cleaning more convenient.Membrane filtration could improve physical and chemical indexes of draft beer, especially on diacetyl, protein retention,to make pure draft beer tastes more pure and refreshing, flavor stability.