Construction Of Pickles' Quality Control Model And Its Regulation Of Intestinal Flora

As a traditional fermented food,pickle not only retains a variety of nutrients,but also has a variety of health functions.The traditional natural fermentation is dominated by high salt with long fermentation time,so the nitrite content is high and the product quality is unstable.However,the volatile components of the inoculated pickle are less than pickle with natural fermentation.In order to reduce the content of nitrite to ensure its safety,and also maintain the flavor value of traditional salting,this experiment used available mustard as raw material,then combined traditional salting and artificial inoculation to optimize key process parameters.After fermentation,the experiment used cluster analysis and principal component analysis to screen out the core quality indicators.Based on this,the model was established by analytic hierarchy process to obtain the best process of pickle processing,and the function of pickle's insoluble dietary fiber was determined.And structural indicators provide theoretical data support for the development and application of pickle.The research results are as follows:(1)The optimal process conditions for salting by single factor experiment are: salting concentration was 25%,salting temperature was30 °C and salting for 6 days.During the post-fermentation process,p H value generally decreased first and then remained stable,the trend of total acid content was basically opposite to the change of p H and the nitrite content increased gradually,then decreased after reaching the peak value,finally became stable.Compared with the natural fermentation,the volatile components of the pickle fermented by the above composite process were found to improve the volatile components of pickle.The volatile components of the pickle of composite process were mainly aldehydes,alcohols and alkanes,while the pickle of natural fermentation mainly contain alcohols,acids and aldehydes.(2)Using the method of principal component analysis and cluster analysis,five core indicators were selected from 11 quality evaluation indicators: free amino acid,a value,b value,fracturability,lactic acid bacteria number.By using analytic hierarchy process,the mathematical model for obtaining the quality evaluation of pickle was established:Y=0.1632×free amino acid+0.03967×lactic acid bacteria number+0.3700×a value+0.3541×b value+0.07293×fracturability,and the comprehensive score of pickle under each process was calculated and sorted.The comprehensive quality of process 9 with 0.96 is the best,followed by process 10 with 0.81.On this basis,the hydration properties,choline adsorption capacity and structural characteristics of the insoluble dietary fiber of pickle by optimal composite process and natural fermentation were determined.The results showed that the order of water holding capacity,swelling capacity and choline adsorption capacity was: Process 9 >Process10>Natural fermentation;IDF of pickle with natural fermentation exhibits a strip-like structure with a compact and flat surface,while the modified IDF of pickle with composite process was mainly supported by cellulose,showing an obvious spiral shape.The porous structure indicatied that the composite process fermentation can change the structure of IDF in pickle,which is beneficial to improve the functional and chemical properties of pickle.(3)Using Illumina high-throughput sequencing technology,the changes of intestinal microflora in mice with low,medium and high dietary fiber and high fat diet were studied.During the experiment,the average food intake of each group gradually increased with time,then reduced;all groups of mice had increased body weight,and high-fat diet would lead to weight gain in mice with a trend of obesity,but with the extension of intervention time,IDF had a tendency to slow weight growth;blood biochemical indicators in mice showed that IDF had no significant difference in regulating blood lipids and blood glucose in mice;IDF could inhibit the increase of ALP level caused by high-fat diet,prevent liver function damage caused by high-fat diet to a certain extent,and play a role in protecting the liver;IDF could increase the abundance of intestinal flora in mice;medium and high dietary fiber intervention could improve the intestinal diversity of mice,suggesting that IDF could protect the intestinal diversity of mice;high-dose dietary fiber could alleviate the intestinal flora imbalance caused by high-fat diet,and had certain corrective effect.The proportion of intestinal flora of high-dose dietary fiber group was similar to that of normal diet group.