Study On Degradation And Control Of Nitrite In Fermented Vegetables

Pickles are a traditional fermented vegetable products,not only unique flavor,but also has good nutritional value and health care function,and has become one of the essential for the vast number of consumers daily food,has a good market prospect.However,the fermentation vegetables are mainly traditional fermentation methods,microbial flora is complex and changeable,the fermentation period is long,the content of nitrite is high,and the safety of product is poor.Therefore,this paper starts from the kinds of organic acid in pickles and and its degradation mechanism on nitrite,to solve the problem of high nitrite content and slow degradation in the process of fermentation of pickles,it provides an effective way for degrading and controlling nitrite.The main research contents and results are as follows:1.The types of organic acid produced of pickle in natural fermentation process were analyzed by HPLC,the results showed that: the pickles contains oxalic acid,tartaric acid,lactic acid,acetic acid,succinic acid and other organic acids.By researching different kinds of organic acid degrading nitrite in vitro.The results showed that oxalic acid,lactic acid,acetic acid,tartaric acid,malic acid,citric acid,succinic acid can degrade nitrite,increasing the concentration of organic acids,improving the temperature can accelerate the nitrite degradation,the order of ability of nitrite degradation was: oxalic acid > tartaric acid > citric acid > malic acid > lactic acid > succinic acid > acetic acid,and nitrite degradation rate also increases with the increase of the initial concentration of nitrite.2.Based on the mechanism of nitrite degradation,inoculating lactic acid bacteria strains,strengthening lactic acid fermentation,to degrade and control nitrite,By carrying out the single strain and mixed strains fermentation of lactic acid bacteria(Lab).In the end,selected the ratio of composite agent of Lactobacillus(LP):Leuconostoc(LM)=1:2 as compound fermentation bacterium agent,and thecompound fermentation bacterium agent was used for the research of process of nitrite degradation of fermentation radish,by means of single factor and orthogonal experiment on the amount of sucrose added,the amount of salt added,the inoculation amount,fermentation time and fermentation temperature,obtained the optimal fermentation process of nitrite degradation: The amount of sucrose was 0.5%,the amount of salt was 4%,the inoculation amount was 4%,the fermentation time was72 h,the fermentation temperature was 28 ?.Under the condition of nitrite degradation process,the content of total acid in fermented radish was 0.72g/100 g,and the nitrite content was 0.255mg/kg.3.On the basis of nitrite degradation process,The experiment was conducted with the addition of calcium chloride,calcium lactate and calcium propionate as the experimental factors,and the single factor and orthogonal test were conducted with the crispness and sensory score as the indexes,It was concluded that the best ratio of compound brittle agent was calcium chloride: calcium lactate: calcium propionate=1:0.5:1.5,and compound brittle agent was made with the calcium chloride,calcium lactate,calcium propionate,because of the synergistic effect of each component,the effects of the crispness and the sensory evaluation of the fermented radish are superior to single crispness agent,and the total adding amount of composite crispness agent was 0.1%(which calcium chloride: lactic acid calcium: calcium propionate =1:0.5:1.5)can significantly improve the textural properties of fermentation radish and obtain the best sensory quality.4.On the basis of the crispness process,sensory evaluation was the evaluated index of the test,The single factor experiment and response surface optimization experiment were conducted with the addition amount of anise,garlic,ginger and pepper as the experimental factors,to determine the addition level of the four factors,Finally,the best technological formula of fermented products was: the addition of the anise was 0.30%,the amount of garlic was 0.90%,the amount of ginger was 0.80%,and the amount of pepper was 0.90%.Under this fermentation process,the sensory evaluation score of product was 92.3 points,and the product had normal color,tender crispness,suitable taste with sour and spicy and outstanding aroma.