Inoculated Fermented Tian Jin Dongcai And The Flavour Components

Tianjin dongcai is a traditional fermented vegetable produced from cabbage and garlic. The principle of fermentation is complex. The microbes from natural environment are considered to use nutrients in raw materials to produce acid and its special flavour. In this thesis, the lactic acid bacteria (LAB) in Tianjin dongcai were isolated and identified, and then the traditional and inoculated products were compared by means of instrumental and sensory analysis. The conclusions were as follows:1. The LAB in the initial period of fermentation was isolated and identified by physiological and biochemical criteria and sequencing of16S rDNA. The results were:DC1-1and DC3-7were Lactobacillus plantarum, DC3-3was Lactobacillus casei, DC2-5was Pediococcus acidilactici, DC4-1and DC4-5were Pediococcus pentosaceus and DC5-3was Leuconostoc mesenteroides.2. DC4-1was selected as an appropriated starter since it showed the best performance in MRS-broth with high level of garlic and salt concentration.3. An orthogonal experimental was designed and sequence of importance of different factors was temperature> inoculum size> salinity. Besides that, an ideal fermentation process was got, that is, temperature25℃, salinity10%and inoculum size4%.4. The sensory test showed that the inoculated dongcai was considered to complete fermentation in100days, and shorten the ripening period to more than1/2of spontaneous fermentation period.5. HPLC and amino acid analyzer were used to investigate organic acid and amino acid contained in products respectively. The result indicated that component of organic acid in inoculated product was same as spontaneous fermented dongcai, whereas oxalic acid in dongcai with starter was12%fewer than the other and lactic acid was about2.7times more than traditional.dongcai.13kinds of amino acids were detected in two types of product, and the total count in inoculated product was little fewer.6. Volatility component was analyzed using SPME-GC-MS. The components in inoculated dongcai were similar with the non-inoculated product, but less amounts of pungent compounds were detected in dongcai with LAB starter.