Improvement of High Vitamin B_(12) Thua nao by Mixed Cultures of Soybean Oligosaccharide and the Use of Bacteria and Yeasts

摘要

The traditional production of "Thua nao" involves predominantly Bacillus spp. fermentation on soybean substrates. It is a high protein fermented food with ammonia smell but without vitamin B_(12) content. Based on soybean fermented sources and oligosaccharide (raffinose) utilizing capability, three potent microbial isolates with different characteristics to improve Thua-nao fermentation have been selected. They are ahigh proteoly tic Bacillus amyloliquefaciens, a high vitamin B_(12) producing Klebsiella sp.KB2 and a pleasant aroma contributing yeast, Candida sp. KB 1. Cocultures fermentation of Bacillus sp. B4 and Klebsiella sp. KB2 could improve the quality of Thua-nao by enhancing more soluble protein and vitamin B_(12) contents in the fermented soybean up to 91.43 μg/100gdw as nine times higher than control fermentation inoculated with Klebsiella sp. KB2 alone. Furthermore, the local Thua-nao isolate, Candida sp. KB1 could significantly decrease the strong ammonia smell without interference on the vitamin B_(12) content of the product.