【作者】 付晓红；

【导师】 李正国；

【作者基本信息】 重庆大学 ， 微生物学， 2009， 硕士

【摘要】 榨菜是中国特产,与欧洲酸黄瓜、西德甜酸甘蓝一起被誉为世界三大名腌菜,深受世界人们的喜爱。近年来,酱腌菜朝着“低盐、健康、绿色”的方向发展,已在生产工艺改进、新产品研制等方面开展了大量的研究工作,使榨菜的生产工艺日趋成熟,产品也不断更新,对产品质量控制发挥了重要作用。微生物的发酵在榨菜腌制过程中具有十分重要的作用,了解榨菜腌制中的微生物发酵类型是有效控制发酵进程的基础。目前,仅杨珺等通过传统微生物培养法,对四川榨菜后熟期间的微生物种类进行了一定的分析,但各腌制时期的微生物群落的变化规律仍不明确。本研究以涪陵榨菜为原料,结合传统分离培养方法和分子生物学方法(DGGE),初步探明两种腌制工艺榨菜发酵不同时期的菌相组成及微生物菌系的消长变化规律,确定了榨菜发酵体系中的主要微生物及其性能,以及不同发酵时期的菌种种类及比例。在此基础上,研究接种微生物对榨菜品质及发酵特性的影响,为多菌种榨菜发酵剂的研制提供理论参考。本研究旨在通过对多菌种发酵剂的研究和使用,提高榨菜品质,简化加工工艺,缩短榨菜加工周期,为榨菜加工的现代化探索路径。研究结论如下:①榨菜基本完成后熟转化过程中随着乳酸类细菌的发酵,乳酸累积,pH值一路降低,而细菌和酵母数量的变化呈现先增加后降低的趋势,至25-30 d左右达到峰值。这反应微生物的生命活动与榨菜腌制成熟有密切联系。传统的分离纯化培养方法从盐脱水和风脱水两种腌制工艺中分离的微生物纯培养形态学及生理生化分析显示,盐脱水和风脱水榨菜中主要优势微生物一致,乳杆菌属(Lactobacillus)、鲁氏酵母(Saccharomyces rouxii)是两种腌制过程中的最主要优势菌群,同时风脱水还分离到盐杆菌、气球菌两株高耐盐性菌,并发现风脱水榨菜微生物多样性明显低于盐脱水榨菜中的微生物。②榨菜腌制过程中细菌16S rRNA V3区间的序列与现有的数据库中的细菌序列有很高的相似性,都在97%以上,对分离得到的21条优势条带测序结果显示,优势细菌主要属于肠膜明串珠菌(Leuconostoc citreum)、猎隼乳酸菌(Lactobacillus sakei)和乳酸乳球菌(Lactococcus lactis subsp. Lactis),同时,混淆威斯菌和不可培养菌在图谱显现出较高的荧光强度。③接种发酵榨菜产品在风味、色泽、香气等方面表现出与自然发酵产品相似的感官指标,无明显差异,但接种发酵能够使榨菜亚硝酸盐的含量得到明显的降低。表明,接种发酵对榨菜风味、品质无明显影响,但加快榨菜风味的形成,缩短了榨菜的生产周期,降低了产品的成本,同时提高榨菜产品的安全性。更多还原

【Abstract】 Pickled of mustard tuber (Brassica juncea var. tsatsai) is the Chinese special product cultivated locally, which has been recognized as one of the most famous pickling vegetables in the world. For the past years, sauerkraut has head for the“low-salt, healthy, green”. Many researches have been done for updating the crafts and producing new variety of products, so the crafts optimized and the products presented more variety gradually. The modified crafts have simplified the process, and play an important role in the quality control of products.The fermentation process of microorganism is important for the pickling of Brassica juncea. To make clear microbial fermented type in the period of pickling is the basic for controlling the crafts process. Now, Yang et. al, has analyzed the category of microorganism in after ripening time of Szechwan preserved vegetable. However, the variational regulation of microflora is indefinite in different periods.In this research, Fuling Brassica juncea was chosed as experimental object. combined culture-dependent and culture-independent methods ( DGGE ) , the composition and the variational regulation of the different periods and different crafts were proved up primaryly, the principal microorganism and the function were determined, and the proportion of strain in different periods have also been researched. Moreover, the research of the reflection of inoculating microorganism on the quality and fermentated characteristic, provided theoretical and technical support for the the research of starter cultures. Depending on the research and use of starter culture, this article provide theoretical basis for development of suitable preparatory methods for enhancing quality of products, simplifying the crafts, and shortting the fermentation process.The main results were as follows:①Following the fermentation process, the characters of Brassica juncea have changed correspondly. The pH of the Brassica juncea decreased during fermentation, while the increase of lactic acid. The total microorganism experienced a course of growth crest-time, then stabilizated gradually, and get to the peak value at about 25-30 d during fermentation process. This reflects that the close relationship of vital movement of microorganism and the mature of Brassica juncea.By the traditional culture method, the results of pure cultured morphology and physiology and biochemistry display that the main microorganism are the same, Lactobacillus and Saccharomyces rouxii are the main dominant flora in the immediate fermentation and the dehydration in air. Besides, the two saline tolerance strains of Halobacteria and Aerococcus were isolated only from the dehydration in air. We discovered the biodiversity of the dehydration in air is lower than that of the immediate fermentation.②These 16S rDNA sequences exhibited more than 97% identity compared with sequences present in the databases. Twenty-one dominant bands from DGGE bands were sequenced, The result showed that the intense bands were the Leuconostoc citreum、Lactobacillus sakei and Lactococcus lactis subsp. Lactis, simultaneously, W. confuse and uncultured eubacteria were also found in DGGE profiles.③The inoculated fermentated products has the similar oranoleptic indicator with the wild fermentated products, and the variety isn’t obviouse. However, the content of nitrite has reduced obviously in the inoculated fermentated products. It indicate that starter culture does not influence on the flavor and the quality of Brassica juncea, but speeds up the formation of flavor, shortens the period of production, cuts down the cost, and rises the security of the Brassica juncea products.更多还原