苋菜梗腌制过程细菌群落变化及风味的研究

Study on bacterial community changes and its flavor components of pickled amaranth stem

采用16S rDNA基因克隆文库结合GC-MS分析等方法,对腌制苋菜梗体系的细菌多样性、品质变化和腌制成熟时的挥发性风味物质进行分析。结果表明,腌制苋菜梗开始时(即腌制第0d)其优势菌群为乳杆菌属、片球菌属和魏斯氏菌属,第10d优势菌群为乳杆菌属和产碱杆菌属,到腌制中后期细菌群落组成基本稳定,其中产碱杆菌属、拟杆菌属和梭菌属为优势菌群。苋菜梗腌制过程中,pH、亚硝酸盐含量和细菌总数均先上升后下降,至腌制结束时分别为5.28、4.0mg/kg和数量级107cfu/mL。利用GC-MS分析方法测定了腌制苋菜梗卤汁中的挥发性风味成分,发现其主体风味成分为醇类、酸类和烷烃类,其中醇类物质占19.5%、酸类占15.9%和烷烃类占14.6%,相对含量较高的挥发性组分有2-丁醇、乙醇、己烷和乙醛。

The microbial community diversity,the related characters and its flavor components were investigated during fermentation process of pickled amaranth stem using 16S rDNA clone library and GC-MS analysis methods. Results showed that Lactobacillu,Pediococcus and Weissella in the pickling system were the predominant microbial communities at the earlier phase. After 10d of fermentation,the dominant population had changed to be Lactobacillu and Alcaligenes. In the later stage of pickling process,the community system was stable,and Alcaligenes,Bacteroides and Clostridium were major species. Meanwhile,the pH value,nitrite concentration and the total population of bacteria of pickled amaranth stem increased at the first phase,then decreased and finally reached the values of 5.28,4.0mg/kg and 1.0×107cfu/mL,respectively. The GC-MS analysis was used to identify the volatile flavor compositions in pickled amaranth stem. Results showed that the main volatile components in pickled amaranth stem products were alcohols,organic acids and alkanes. They account for 19.5%,15.9% and 14.6%,respectively. Volatile compounds with relatively high contents were 2-butyl alcohol,ethanol,hexane and acetaldehyde,respectively.