Breeding Of Nitrite-Degenerating Bacteria In Tianjin Dongcai And Its Application

It is a difficult problem to decrease the amount of nitrite in a normal limit of vegetables pickling. The intake of excessive nitrite is poisoned to human through turning the hemoglobin to the metahemoglobin in the blood. More seriously, the nitrite is one of the precursor of strong carcinogen - nitrosamine. Variation law of nitrite content has been focused during pickling of last few years. Relatively, there were fewer researches on beneficial microorganisms which had the degeneration ability to nitrite in pickled vegetables. The article studied the lactic acid bacteria isolated from the Tianjin Dongcai with the degeneration ability to nitrite, and carried on the preliminary appraisal and optimizing of the degeneration influence factor. It is of great significance to the process of vegetables pickling.It improved the extraction of nitrite in vegetable used in Griess. It was found that there is a better effect with the buffer pH above 7. The experiments were obtained as the optimum condition for extraction for 70℃, and 10 min respectively.There are 3 lactic acid bacteria isolated from the Tianjin Dongcai which has the degeneration ability to nitrite. Through the physiology and biochemistry experiment, LAB-ME-0603 and LAB-ME-0609 were Leuoconostoc mesenteroieds, LAB-0615 was Lactobacillus plantarum. they all have the degeneration ability to nitrite, the amount of degeneration to nitrite surpass 95%, It proved that enzyme is the primary factor with its nitrite degeneration as LAB-ME-0603 and the effect factors of the nitrite-degenerating were studied. The conclusions as follows: the most suitable pH and temperature for enzymosis were 5.5 and 30℃respectively; If other factors were not changed, the amount of degeneration to nitrite in early fermentation period varied directly with the inoculation amount. The effect of temperature, pH on the amount of degeneration to nitrite by enzyme of lactic acid bacteria were directly concerned with affecting nitrite reductase of lactic acid bacteria and not very concerned with the bacteria density. The most optimum substrate concentration was 200mg/L; the most optimum inducement period was that the bacteria was cultured for 18 hours; the most optimum inducement time was 12-18 hours after the substrate was put into the media for 18 hours.Two of the LAB strains, namely, LAB-ME-0603 (Leuconostoc mesenteroides) and LAB-0615 (Lactobacillus plantarum) were used as starter cultures for cabbage fermentation, the spontaneous fermented cabbage took the comparison, the variation of nitrite content was determinated in fermented cabbage. The result indicated that, the nitrite content in the inoculated fermentation cabbages was lower than the spontaneous one during the fermentation, and it had not formed "the nitrite peak", the content of lactic acid was higher than the spontaneous one. The forming of "the nitrite peak" can be suppressed by the method of inoculated fermentation...