| Salted chilli is a Chinese traditional chilli product,and the salt concentration reaches22%in the process of making chilli raw material.So.it is of great significance to screen Halotolerant Lactic Acid Bacteria which can grow and reproduce in salted chilli.In this study, two Halotolerant strains were successfully screened from salted chilli.and they were preliminarily identified and applied in salted chilli fermentation process. The results are as follows:In the preliminary screening,two strains of Halotolerant strains Ly-2and Ly-4which could grow normally in the condition of18%salt concentration were gained from the improved MRS culture medium, observation in the microscope shows that Ly-2is a cocci, Ly-4is a bacillus. Two strains are all G(+) bacteria, and the catalase experiment results were negative, morphological observation in culture medium shows that both their surfaces are smooth and they can produce soluble calcium circle. Ly-2is a facultative anaerobic cocci and Ly-4is a facultative anaerobic bacillus.In further step, had the screened strains for l6S rDNA sequence detection, the testing results were analyzed by phylogenetic tree method with the99%similarity species sequence, Ly-2was found to have the closest genetic relationship with Enterococcus, and Ly-4was closest to Lactobacillus. The results prove that Ly-2is a kind of Enterococcus, Ly-4is a kind of Lactic Acid Bacteria.The next step was researching on the growth curve of the Ly-2and Ly-4, Ly-2Enterococcus changed into the logarithmic phase in14hours,into the plateau after26hours, pH maintained around4at last. Ly-4Lactobacillus changed into the logarithmic phase after4hours, into the stable equilibrium phase after14hours, pH maintain at5.Adopted the uninoculated fermented liquid as the blank control,detecting six kinds of organic acid in fermented liquid of Ly-2and Ly-4included formic acid, tartaric acid, acetic acid, citric acid, lactic acid and oxalic acid with RP-HPLC. Qualitative and quantitative analysis of the results indicated that the largest amount of organic acid in fermented liquid is formic acid, Ly-2is better than Ly-4in the ability of producing lactic acid, and Ly-4Lactobacillus acid production rate is far behind the Ly-2Enterococcus. Seting0.01mol/L diammonium phosphate (100%) as mobile phase, flow rate was1mL/min, the uv detection wavelength was210nm, sample quantity was10microns, column temperature was30℃, chromatographic column was Promosil C18(5microns,4.6mm*250mm),with this detecting condition, two Halotolerant strains in the fermented liquid organic acid were effectively detected, and it also eliminated the influence on test results of uninoculated fermented liquid.Used Headspace Solid-phase micro-extraction (SPME) method to pretreat salted chilli samples, combined with gas chromatography-mass spectrometry detector (GC-MS),then analyzed volatile substances of the uninoculated and inoculated salted chilli, the volatile aroma substances in salted chilli mainly include alcohols, acids, esters, aldehydes, ketones,alkane and many other complex aroma components, the largest amount of volatile substances is esters. The kinds of alcohols, acids, esters from volatile substances are significantly increased in inoculated salted chillis than uninoculated ones, so inoculation will help accelerating the formation of flavor substances. |
PDF Full Text Request