Screening Of Degradation Nitrite Lactic Acid Bacteria And Its Applied Research In The Pickled Mustard Fermentation

In view of the problems of high nitrite content and vulnerability to contamination by bacteria in mustard products,this experiment aims to screen a high-quality lactic acid bacteria for pickled mustard.Firstly,the lactic acid bacteria capable of degrading nitrite were selected from the strains preserved in the laboratory.In order to investigate the properties of the strains of lactic acid bacteria,the characteristics of LAB under the fermentation environment of the mustard are studied.And then through vacuum freeze-dried to obtain the direct-injection starter with a high number of viable bacteria.The direct-injection starter is applied to the pickled mustard.The pre-industrial application is of great practical significance to enhance the quality stability of pickled mustard and the level of industrial development.The specific research results are summarized as follows:1.Screening of degradation nitrite lactic acid bacteria and evaluation of pickled mustard fermentation performance.A large number of lactic acid bacteria strains are screened,of which Lactobacillus plantarum LZ227,ZFM228 and ZJ316 have the highest nitrite de1 gradation ability,and the degradation rate is higher than 93%.They show strong acid production ability in the pickle juice culture medium containing 4%NaCl.Among them,L.plantarum ZJ316 produces the fastest,the pH of fermentation broth decrease to 4.10,and the titratable acidity reach 0.143%.Through GC-MS analysis,L.plantarum ZJ316 produces a large number of alcohol compounds and acid compounds in the fermentation process,which can give excellent mustard fermented flavor.In the mustard juice culture medium,the degradation rate of nitrite(125?g/mL)of L.plantarum ZJ316 is 95.23%,and the tolerance to nitrite concentration range is 0 to 3.2 mg/mL.2.Antibacterial effect of lactic acid bacteria L.plantarum ZJ316.The fermentation supernatant of L.plantarum ZJ316 was selected as the research object.It was able to effectively inhibit Staphylococcus aureus ATCC 25923?Listeria monocytogenes LM1 and Vibrio parahaemolyticus SCF16.3.Preparation of high-survival-rate powder of L.plantarum ZJ316 by Iypphilization.We using single factor and orthogonal test to optimize ratio of four protections(trehalose,skim milk powder,D-sorbitol and glycerol).The survival rate of L.plantarum ZJ316 was 90.25%and the viable count was 1.5×1012CFU/g,which showed that skim milk 10%,trehalose 1.5%,glycerol 1%,D-sorbitol 3.5%increased the survival rate of bacterial powder significantly.And the results of acute toxicity test showed that L.plantarum ZJ316 was safe.Thus,L.plantarum ZJ316 could be a potential candidate in food industry.4.Using L.plantarum ZJ316 starter to ferment pickled mustard.L.plantarum ZJ316 starter and commercial starter was inoculated in the pickled mustard.The number of LAB,The pH value,and the nitrite content in the pickle progress,as well as the amino nitrogen mustard content and the flavor components of the final were determined separately.The result showed that:For pickled mustard inoculated by L.plantarum ZJ316 starter,the number of lactic acid bacteria could reach 108CFU/mL,the pH value quickly reduced to 4 or less,the nitrite peak value appeared 4-7 days earlier than the control,which was lower than 3.66 mg/kg,and the amount of amino nitrogen could reach 2.17 g/L.What's more,through GC-MS analysis,L.plantarum ZJ316 produces a large number of alcohol compounds and acid compounds in the fermentation process,which can give excellent mustard fermented flavor.5.L.plantarum ZJ316 starter beneficial effect on pickled mustard.Harmful microorganisms are produced in the naturally fermented mustard,harmful microorganisms are also present in the fermented mustard inoculated by the commercial starter.It showed that L.plantarum ZJ316 made difference that a group of bacteria belonging to the was the main significant difference,the beneficial microorganisms are increased,and the harmful microorganisms are reduced.