Study On The Variation Of The Microbial Community Diversity And The Flavor Quality During Strains Synergism Fermention Of Industrialized Pickled Radish With Different Salinity

Pickles industry as one of vegetable processing industry in China, most of pickles enterprises take high salt concentration pickled measurements to improve pickled vegetable storage period. With the rapid development of pickles industry, the problem of high salinity wasted water in pickles production cannot achieve demands by increasingly attached great importance to environment protection, in order to sustainable development and market requirement, low salinity artificial inoculated fermentation vegetable will be a growing trend gradually in most of pickles enterprises. By testing 7 eminent lactic acid bacteria production and inter strains antagonism assay in this paper, screened 4 excellent predominant strains and optimized combination matching ratio, then inoculated pickled radishes industrialized of different salinity concentration according to optimal matching ratio to proceed strains synergism fermentation, and natural fermentation as contrast to analyze the variation of the microbial community diversity and quality in fermentation process. The main research results were as follows:1. Test 7 lactic acid bacteria ability of salt tolerance, acid production and nitrite degradation, and evaluated productivity using weighted method, meanwhile took richness of addition strains into consideration. finally, ascertained lactobacillus planetarum N3 and 3m-1, Weissella cibaria SJ14, Leuconostoc mesenteroides 8m-9 as subsequent trial strains. The antagonism assay indicated 4 strains there were no antagonism between the two and could conduct strains synergism fermentation.2. Using white radishes as row materials and under 20℃ temperature controlled, mixed with N2,3m-l,SJ14,8m-9 by the way of single, two of the them, three of them, all of them and added 6 percent salinity pickled radishes respectively and put them into jar to imitate industrialized fermentation. Treated sensory evaluation and acid productivity situation as index, then gained combination 16th to be optimal strains combination, analyzed volatile flavor component of pickled radishes samples under natural fermentation, single strain fermentation and four strains fermentation, the results showed under four strains synergism fermentation, pickled radishes had rich volatile flavor component and homogeneous content, further verified 16th strains combination was the optimal matching combination.3. Adopted traditional cultivate counting method combined PCR-DGGE technique, took the industrialized pickled radishes of 12 percent salinity under natural fermentation as contrast, through analyzing the variation of the microbial community diversity of different salinity industrialized pickled radishes under strains synergism fermentation, the results showed that four ways of fermentation had strains quantity maintained at 105～108cfu/mL in the pickled water, and reflected the variation trend that increased in the beginning, then went down, slowly rose to plain at last. Lactic acid bacteria had more influence on salinity, the lactic acid bacteria count of high salinity pickled radishes were less than low salinity, and natural fermentation were less than strains synergism fermentation. Yeast had a high ability of salt tolerance, but had influence on temperature. By temperature increasing, yeast count increased continually, there was no significant difference on four ways of fermentation. Coli existed during early stage of fermentation, and disappeared after 58 days fermentation. In four modes, bacteria and fungi species of pickled radishes were similar, the main advantage strains included Weissella cibaria、Lactobacillus curvatus, Leuconostoc mesenteroides, Lactobacillus graminis. Lactobacillus alimentarius, Lactobacillus plantarum, Pediococcus ethanolidurans, Halomonas taeanensis etc, most of them were lactic acid bacteria, the advantage fungi included Kodamaea ohmeri, Debaryomyces sp., Candida sp., Kazachstania siamensis etc., yeast were the main microbial community. But it existed quantity differences on advantage strains in each period.Compared natural fermentation with strains synergism fermentation pickled radishes, both of them were no significant difference on advantage bacteria species and quantity under early fermentation stage and middle stage, after 88 days, though the bacteria species with natural fermentation were slightly higher than strains synergism fermentation. Leuconostoc mesenteroides under natural fermentation couldn’t be detected or fewer existed. Contrast to each pickled radish of different salinity strains synergism fermentation, the increase of salinity obviously restrained part of bacterial growing. Natural fermentation and strains synergism fermentation had no obvious different about fungal species, but the former fungal count was more during the whole fermentation. There was no obvious different among pickled radish of strains synergism fermentation with different salinity during early stage fermentation, however, fungal species and count made a different because of different salinity after 28 days fermentation, the increase of salinity inhibited some yeast growth.4. Compared with natural fermentation, pickled radish of strains synergism fermentation shortened the fermentation period which had faster speed for lactic acid accumulation and reducing sugar consumption through analysis of sensory and physicochemical index for pickled radish during fermentation period (188 days), and it had an apparent advantage in taste, smell, color. Among pickled radish of strains synergism fermentation with different salinity, pickled radish with higher salinity had lower speed in acid production. In whole fermentation period, salt slowly transfer into radish and reach an equilibrium finally, nitrite concentration always remained a lower level and its maximum value was 2.2mg/kg. Compared with natural fermentation, pickled radish of strains synergism fermentation had higher concentration of tartaric acid and lactic acid, and it had more abundant volatile flavor compounds species and higher free amino acid concentration in 88days of fermentation through analysis of flavor compounds for pickled radish during fermentation period. Pickled radish with 10% salinity had richer organic acid, volatile flavor compounds species, free amino acid species and concentration among pickled radish of strains synergism fermentation with different salinity, and keep good flavor in 188 days of fermentation.This research conducted systematic study about strains synergism fermentation of industrialized pickled radish, it provided the data reference for creating a relationship between flavor quality variation and microbial community variation. Salinity reduction alleviated problems of product quality and security and water pollution caused by high salinity.