Study On Improving The Modification Of Low Germination Rate Barley By Using Geotrichum Candidau

Barley was the major raw material used for beer brewing and it was also quite a most important part of the cost. Domestic barley had inferior characterwastics in both germination rate and malt modification. Improving the solubility of low germination rate malt by using Geotrichum candidau microorganism-malting was studied in this paper.Five strains of Geotrichum candida with high extracellular hydrolase were inoculated in the malting process. The results showed that all the strains mentioned above were beneficial to the solubility of malt, especially the degradation of endosperm cell wall. G. candidum JN-4 was chosen as the best for microorganwasm-malting. The optimiziation of condition for spore production was studied. The optimum condition were: the medium was 5 oP wort, the initial pH was 5.5, the spores of inoculation concentration was 2 %, the volume of medium was 50 mL in 250 mL flask, the shaking speed was 200 r/min at 30℃and the culture time was 40 h. The spore yield has been reached 5×108/mL.The changes of fungi contamination during mlating processe were studied. The amount of all fungi increased during the steeping and germination stage, with its maximum on the fianl day of germination, and partly decreased to a certain level at baking stage. Adding Geotrichum candida in malting could change the composition of fungi communities. The mechanism of microorganism-malting was preliminary studied as follows: Geotrichum candida was adsorbed to barley surface firstly due to its high inoculation concentration. Then Geotrichum candida increased rapidly and occupied the barley surface. As a consequence, the growth of other microorganisms was inhibited. During germinating stage, Geotrichum candida penetrated barley surface with its mycelium, which increased penetrability of barley and helped degradation of endosperm cell wall.The microorganism-malting technique had been applied to domestic barley Ganpi-3 which had low germination rate. It was showed that the optimal inoculation concentration of Geotrichum candida spore was 104/g dry barley in the first steeping water at 20℃. Long steeping technology was as follows: 5 hours of water steeping, 10 hours of air rest, 3 hours of water steeping, 6 hours of air rest and 1 hour of water steeping.Calefactive germinationg technology: 14℃24 h,16℃24 h,18℃24 h,20℃24 h and kilning technology: 30℃5 h,45℃5 h,50℃4 h ,60℃6 h,70℃2 h,83℃3 h were adopt. The process could obviously promote effect of Geotrichum candida on barley and especially f/c extract difference, viscosity and 36.4 % which were the index reflecting the degradation of barley endosperm cell wall.Compared with the control,they decreased by 10.0 % , 22.4 % and 36.4 % respectively.