Abstract:

Glucoamylase and yeast were co-immobilized by adsorption-embedment method with polyvinyl alcohol (PVA)- sodium alginate as embedding materials and with diatomite or activated carbon or alumina as adsorbent. The results showed that the optimum ratio of PVA to sodium alginate is 9:1 and the best adsorbent is diatomite at the addition level of 0.6 g/20 ml. Moreover, the experimental results on the saccharification and fermentation performance of co-immobilized beads indicated that the optimum sorghum powder concentration, fermentation temperature, initial pH value and saccharification-fermentation time are 25%, 30 ℃, 5.0 and 7 d, respectively. Under the above conditions, the alcohol content is up to 11% (V/V). After the coimmobilized beads are continually used for 10 batches, their performances are still stable.

Key words: polyvinyl alcohol (PVA), sodium alginate, co-immobilization, adsorption-embedment method, diatomite