降解亚硝酸盐乳酸菌的筛选及其在菜用枸杞浆水发酵中的应用

该研究从甘肃天水、定西等地农家自制浆水中分离乳酸菌，通过形态观察、生理生化实验及分子生物学技术进行菌种鉴定后，应用盐酸萘乙二铵法测定菌株体外亚硝酸盐降解能力，筛选能高效降解亚硝酸盐的菌株，并将其应用于菜用枸杞浆水的发酵，通过感官指标、总酸、pH、有效成分和亚硝酸盐含量等指标综合评价菜用枸杞浆水的品质。结果表明，分离得到35株乳酸菌，经鉴定，29株为植物乳杆菌（Lactobacillus plantarum），3株为副干酪乳杆菌（Lactobacillus paracasei），3株为发酵乳杆菌（Lactobacillus fermentum）。通过复筛获得亚硝酸盐降解率＞90%的5株乳酸菌进行菜用枸杞浆水发酵，菌株天水A14发酵的菜用枸杞浆水感官评分最高，为91.67分，亚硝酸盐含量为1.74 mg/kg，总酸含量为0.28%，pH值为3.69，菜用枸杞浆水中多糖和总黄酮含量分别较鲜样增加1.2 mg/g、0.13 mg/g，说明菌株天水A14既能高效降解亚硝酸盐又适用菜用枸杞浆水发酵，可作为生产低亚硝酸盐浆水的候选菌株。

Screening of high nitrite-degrading lactic acid bacteria strains and their application in Jiangshui with Lycium barbarum fermentation

The lactic acid bacteria were isolated and purified from the homemade Jiangshui (a traditional Chinese fermented vegetable food) of Tianshui, Dingxi and other areas in Gansu. The strains were identified through morphological observation, physiological and biochemical tests and molecular biology techniques, and the nitrite degradation ability in vitro were determined by N-N-naphthylethylenediamine dihydrochloride. The strains that could efficiently degrade nitrite strains were screened, which was applied in Lycium barbarum fermentation, and the L. barbarum Jiangshui quality was comprehensively assessed by sensory evaluation, total acid, pH, effective composition and nitrite content indexes. The results showed that a total of 35 strains of lactic acid bacteria were isolated and identified, including 29 strains of Lactobacillus plantarum, 3 strains of Lactobacillus paracasei, and 3 strains of Lactobacillus fermentum. After re-screening, the 5 strains with degradation rate＞90% were used in L. barbarum Jiangshui fermentation, strain "Tianshui A14" had the highest sensory evaluation score of 91.76, the nitrite content was 1.74 mg/kg, the total acid was 0.28%, and the pH was 3.69. Compared with the unfermented sample, the polysaccharide and total flavone contents of L. barbarum Jiangshui increased by 1.2 mg/kg and 0.13 mg/kg, respectively, which indicated strain "Tianshui A14" was efficient in degrading nitrite and suitable for the L. barbarum Jiangshui fermentation, and could be a candidate strain for low-nitrite Jiangshui production.