云南泡梨中乳酸菌的分离鉴定及其应用

【背景】泡梨是云南省常见的一种腌渍水果,在云南加工食用已经有一百多年的历史,因其味道酸甜可口、风味独特而深受人们喜爱,而目前对泡梨中微生物种群的系统分析和发酵原理的研究尚未见报道。【目的】研究乳酸菌在云南泡梨中的分布及应用,阐明乳酸菌种类对泡梨发酵中风味物质的影响。【方法】从云南省4个不同地区采集12份泡梨样品,经菌落菌体形态、生理生化特性和16SrRNA基因序列分析进行菌种分离与鉴定。利用分离的乳酸菌为菌种进行泡梨的制备,采用GC-MS技术对人工接种的复合乳酸菌发酵与自然发酵泡梨进行风味物质的分析与感官评价。【结果】分离鉴定出79株植物乳杆菌(Lactobacillus plantarum)、 3株类植物乳杆菌(Lactobacillus paraplantarum)、1株戊糖乳杆菌(Lactobacillus pentosus)、1株干酪乳杆菌(Lactobacillus casei)、2株副干酪乳杆菌(Lactobacillus paracasei)和1株短乳杆菌(Lactobacillus brevis),植物乳杆菌为泡梨发酵中的优势菌。将分离所得乳酸菌用于泡梨制备的结果表明,乳酸菌使泡梨的发酵时间缩短5d且品质更优,分析其中的风味物质发现接种乳酸菌发酵泡梨风味物质更丰富,其中酯类和醇类远多于自然发酵泡梨。【结论】云南泡梨中含有丰富的乳酸菌,选用分离出的优势乳酸菌作为复合乳酸菌用于泡梨发酵获得色泽、口感更好的泡梨,且发酵周期更短,风味物质更丰富。该研究对泡梨制备工艺和进一步标准化生产均具有重要意义。

Isolation, identification and application of lactic acid bacteria from Yunnan pickled pear

Background] Pickled pear is a popular pickled fruit in Yunnan Province with delicious taste and unique flavor. It has been eating in Yunnan for more than 100 years. However, the systematic analysis of the microbial population in this product and the study of the fermentation mechanism are still lack. Objective] The purpose of this study was to analyze the distribution of lactic acid bacteria in pickled pears, and to elucidate the effects of lactic acid bacteria on flavor substances in pear fermentation. Methods] Lactic acid bacterial strains were isolated from twelve samples of pickled pears collected from four different regions of Yunnan Province. Bacterial strains were identified by colony morphology, physiological and biochemical characteristics and 16S rRNA gene sequence analysis. The isolated lactic acid bacteria were used in pickled pears preparation and the resulting products were evaluated by sensory evaluation and flavor substances analyses by GC-MS. Results] Altogether, 79 strains of Lactobacillus plantarum, 3 strains of Lactobacillus paraplantarum, 1 strain of Lactobacillus pentosus, 1 strain of Lactobacillus casei, 2 strains of Lactobacillus paracasei and 1 strain of Lactobacillus brevis were isolated from pickled pear samples, with Lactobacillus plantarum being the dominant strain in pickled pears. Using isolated strains in the pickled pear fermentation, the product got better flavor and shorter process time than natural fermentation about 5 days. The composition of flavor substances analyses showed that in lactic acid bacteria fermented pears, ester and alcohol were much more abundant than those in natural fermented pears. Conclusion] Lactic acid bacteria are abundant in Yunnan pickled pear. Using these bacteria in pickled pear fermentation could produce picked pear with better color and taste, more abundant flavor substances, in shorter time. This study confers great significance for the improvement and standardized preparation of Yunnan pickled pears producing.