Study On The Starter Of China Northeast Sauerkraut

Chinese sauerkraut is a traditional fermented food,which is popular in China due to its characteristic of rich flavor,unique taste and high nutritional value.The traditional way of fermentating sauerkraut is using vegetables and the microorganisms carried in the environment to ferment in a low-salt environment.The fermentation process is not easy to control,and it is prone to unstable quality and excessive nitrite content.In this study,we intended to screen and identify the lactobacilli strain with excellent fermentation performance in natural sauerkraut,and applied it to quality control in the sauerkraut fermentetation.At the same time,the biological characteristics of the strain were studied to explore the optimum growth environment for the strain.The strain with excellent fermentability was used in the sauerkraut fermentation.Using natural and continuous fermentation of sauerkraut as a control to evaluate the quality of inoculated sauerkraut.Lactobacilli strains were screened in different Chinese sauerkraut samples using a modified MRS screening medium(with 6.0% NaCl,pH 4.5).Secondly,15 lactobacilli strains were screened by catalase test,Gram stain test,cell morphology observation and lactic acid production test.Lactobacillus sp.LS-5,a strain with high acid production,good nitrite degradation,and good bacteriostatic effect was obtained.Combined with morphological identification,physiological and biochemical identification and 16 S rRNA gene sequencing,it was identified and named Lactobacillus paraplantarum LS-5.By analyzing the biological characteristics of L.paraplantarum LS-5,the optimum growth temperature of this strain is 37?,the optimum initial pH of the culture medium is 6.0,and it can tolerate 6.0% NaCl.L.paraplantarum LS-5 have good inhibitory effects on Escherichia coli,Listeria monocytogenes,Staphylococcus aureus,Salmonella.The optimization of the technological conditions for the inoculation of fermented sauerkraut with L.paraplantarum LS-5 was carried out with pH,total acid content and nitrite content of pickled cabbage.The best fermentation sauerkraut conditions were fermentation temperature of 35°C,salt content of 3.0% and inoculation amount of 4.0%.Compared with natural and continuous fermented sauerkraut,L.paraplantarum LS-5 fermented sauerkraut products were tested using optimal fermentation conditions.The results showed that the total acid content of L.paraplantarum LS-5 fermented sauerkraut was up to 0.47% and the nitrite content was 0.31 mg/kg.The acidity was in accordance with provisions of DBS 22/0.25 “Local Standard Sauerkraut” and the nitrite content was in accordance with GB.2714 "Pickles".