传统起子(酵头)的微生物分析及其对馒头品质的影响(英文)

馒头是一种中国主要的发酵食品。传统方法制作馒头是用酵头发酵的,酵头也叫起子、面肥。本文主要研究酵头的微生物组成以及对馒头品质的影响。采用平板划线法对12个酵头进行乳酸菌、酵母菌计数和分离。分离得到的菌种用生物梅里埃的Vitek-32系统进行自动鉴定。通过感官评价和(TPA)质地剖面分析分析来比较酵头发酵馒头和工厂化生产馒头的品质差别。12个酵头的乳酸菌计数的均数为8．11g CFU/g,酵母菌计数的均数为7．7 1g CFU/g。干燥的酵头的酵母菌计数(8．21g CFU/g)显著高于湿酵头(7．21g CFU/g,p＜0．05)。分离得到的3株酵母都为Saccharomyces cerevisiae(啤酒酵母),3株细菌分别为Bacillus cereus(蜡样芽胞杆菌),Acinetobacter lwoffii(鲁氏不动杆菌),Brevibacillus brevis(短小芽胞杆菌)。在酵头发酵馒头面团过程中,随时间延长pH降低,酵母菌和乳酸菌计数增加。与工厂化生产的馒头比较,酵头发酵馒头有较好的内部结构,相对较差的气味,而在感官评价的总分上与工厂化生产的馒头没有显著的差别。TPA分析的结果表明酵头发酵馒头在以下几个指标上显著高于其中一种工厂化生产的馒头(p＜0．05):硬度、胶性,咀嚼性,凝聚性,粘附性。总的来说,TPA分析结果表明酵头发酵馒头有着较好的食用品质。

Microbial Analysis of Traditional Starter Culture (Jiaotou) and Its Influence on the Quality of Chinese Steamed Bread

Chinese steamed bread (CSB) is a kind of Chinese traditional fermented staple food. It is traditionally fermented by Jiaotou, which is the starter culture of CSB. This study was to determine the microbial characteristics of Jiaotou and its influence on CSB quality. In this paper, lactic acid bacteria (LAB) and yeasts counts in 12 Jiaotou samples were enumerated and separated by plate method. The isolated strains were identified by BioMerieu Vitek-32 system. The qualities of Jiaotou fermented CSB and that of commercially produced ones were compared by sensory analysis and texture profile analysis (TPA). The average LAB counts of Jiaotou were 8.1 lg CFU/g, while the average yeasts counts were slightly lower (7.7 lg CFU/g). The yeasts counts of dry Jiaotou (8.2 lg CFU/g) were significantly higher than wet Jiaotou (7.2 lg CFU/g, p＜0.05). The isolated yeasts were identified as Saccharomyces cerevisiae, and three strains of bacteria were identified as Bacillus cereus, Brevibacillus brevis and Acinetobacter lwoffii, respectively. During dough fermentation, Jiaotou made the dough pH go down with the LAB but the yeasts counts increase.With better interior structure but inferior odor, the general sensory scores of Jiaotou fermented CSB were not significantly different to those of commercial ones. The TPA results indicated that Jiaotou fermented CSB was significantly superior to some kind of commercial CSB in hardness, gumminess, chewiness, cohesiveness and adhesiveness (p ＜ 0.05). In general, Jiaotou fermented CSB showed better eating quality indicated by parameters of TPA.