葡萄糖酸内酯豆腐生产过程中微生物的变化及豆腐中主要腐败菌的鉴定

分别对新鲜的和37℃/24h贮藏后的葡萄糖酸内酯豆腐(GDL豆腐)中最普遍的菌落进行分离、纯化,发现二者中的存在的主要微生物不同。新鲜的充填豆腐中以坚强芽孢杆菌(Bacillusfirmus)为代表的芽孢杆菌为主;在37℃存放24h以后的豆腐中以屎肠球菌(Enterococcusfaecium)为主。为确定这些腐败菌的来源,研究了豆腐制作过程中微生物的种类和数量的变化。实验结果表明,在GDL豆腐生产过程中,熟浆中微生物含量极少,但灌装后细菌总数急剧上升,保温成型(二次杀菌)不能使细菌总数呈下降一个对数单位。芽孢杆菌和屎肠球菌主要来源于大豆原料中,在GDL豆腐生产的各工序几乎都能检测到。经过清洗和不清洗的大豆样品,在85℃恒温水浴锅中保温15min,然后检测大豆中残存的耐热微生物。实验结果表明,在这两个样品中都含有少量的芽孢杆菌和大量的肠球菌,对大豆原料进行清洗可以显著降低耐热菌的残存量。

Isolation and Identification of Major Purified Bacteria in Glucono-Delta-Lactone (GDL) Tofu Processing

Isolation and identification of the major bacteria were performed on Glucono-Delta-Lactone (GDL) tofu from different aged lots. The dominant organisms were found to have changed from Bacillus spp. such as Bacillus firmus in fresh tofu to Enterococcus faecium in GDL tofu stored at 37℃ for 24h. Samples were taken during tofu′s processing, while plate counts and organisms′characteristics in each sample were assayed. The spoilage organisms Bacillus firmus and Enterococcus faecium are both found contaminated from the raw material soybean. Cleaning the soybean can reduce the total bacteria counts, especially ofh eatr esistantb acteria.