Isolation,Identification Of Lactobacillus Plantarum W-4 And Its Application In Chopped Pepper

Chopped pepper is an important fermented vegetable in China,and its processing technology is mainly the traditional natural fermentation or salt embryo desalination fermentationin.Natural fermentation was fermented with the microorganisms that existing on the surface of pepper.Although the aroma of natural fermented pepper is more concentrated and pure taste,which has longer fermentation period and the fermentation conditions is difficult to control.Most of factories take salt embryo desalination fermentation to prolong the storage period of peppers.This process is simple and inexpensive,but the flavor,taste and nutrients are lost during longer shelf life and desalination process.Using starters for vegetable fermentation,which exhibited lots of advantages,such as shorter fermentation time,controllable processing conditions and stable product quality,which is the main way to carry out industrial upgrading.In this study,the lactic acid bacteria isolated from fermented vegetables were screened and identified to obtain good strains.In order to further understand the effect and mechanism of the isolated strain on the fermentation process of chopped pepper.Study on inoculation of the inoculated fermentation and natural fermentation,whose microflora,organic acids and volatile components,the results are as following:(1)Isolation,Screening and Identification of excellent Lactic Acid Bacteria in Fermented Vegetables.The lactic acid bacteria were isolated from fermented chopped pepper,and five strains belong to Lactobacillus sp.were isolated based on the acid-producing ability and nitrite depletion.After the biochemical identification and genetic analysis based on 16 SrDNA sequence,strain W-4,5,and 12 were identified as L.plantarum,and the other two strains 25 and 31 were identified as L.brevis.The stress response indicated that the L.plantarum had a better survival under acid and osmotic stress compared with L.brevis,and L.plantarum W-4 had the strongest tolerance ability.(2)Study on the application of fine strain inoculated fermented chopped pepper.In the process of chopped pepper fermentation,the chopped pepper of inoculation fermentation has higher lactic acid content and faster increasement in total acid,while the citric acid and malic acid contents are higher in natural fermentation.The colonies counts and the lactic acid bacteria counts in the process of fermentation showed the increase first and then decrease,afterwards to tending to stabilize.And there are more quantity counts in inoculated fermentation.The number of fungus increased first(0-6 d),and then tending to stabilize(8-10 d),afterwards to increase(>10 d).The enterobacteria only appeared at the beginning of fermentation and did not exist at the end of fermentation.Inoculation fermentation were significantly superior to the natural fermentation group in terms of taste and odor,and the color and brittleness are similar to natural fermentation.In the study of volatile flavor compounds,natural fermentati chopped pepper was isolated 61 volatile compounds,while inoculated fermentation chopped pepper has isolated 64 compounds by GC-MS.The main substances are hydrocarbons,esters and aldehydes,and other substances such as sulfur compounds are also detected.With the increase of fermentation time,the number of volatile substances in natural fermentation group was increased first and then decreased,while the inoculated fermentation group was decreased first and then increased.