Suan Cai Starter Culture Preparation And Its Flavour Components Analysis

Suan Cai is our country’s traditional fermented food. This study was carried out from the perspective of the industrialized production of Suan Cai. In this thesis the lactic acid bacteria (LAB) in natural fermented Suan Cai were isolated and identified, and the inoculated fermentation conditions were optimized, and the freeze-drying media of Suan Cai starter culture was obtained using Response Surface Methodology (RSM). The conclusions were as follows:1.48strains of LAB were isolated from14kinds of different natural fermented Suan Cai using morphology, Physiology and biochemistry methods.3Lactococcus and45Lactobacillus. The PCR-DGGE analysis of the9typical strains showed7of them was Lactobacillus plantarum.2. Two single factor experiments and one orthogonal experiment were designed to optimize inoculated Suan Cai fermentation conditions based on sensory evaluation.3best samples:Sample4,5and7were obtained for the subsequent tests. The optimum fermentation conditions were:inoculum size8%, stuff and water ratio is1:1, the strains ratio was:Leuconostoc mesenteroides:Lactobacillus plantarum:Lactobacillus casei2:1:1, starter culture media is skim milk, salinity1%(to the stuff), temperature25℃and fermentation period is2months.3. HPLC was used to investigate organic acid in3samples and the control Suan Cai. The results indicated that there was no distinction in component and content of organic acid between3samples and the natural product, whereas oxalic acid in sample4was lower than the others while other organic acids were higher, and the succinic acid was as the same as the natural product. The conclusion was coincident with the sensory evaluation results.4. The sample4’s volatility components was analyzed using SPME-GC-MS. The components in sample4were similar to the natural product, contained almost all characteristic flavor substances of traditional Suan Cai, but fewer amounts of volatility compounds were detected in LAB inoculated Suan Cai.5. The freeze-drying protectant of Suan Cai starter culture was obtained using Response Surface Methodology. The optimized media includes:trehalose1.67%. glycerol0.57%. sorbitol2%. maltodextrin1%and skim milk10.7%.