Study On Quality And Flora Composition Of Softening And Color-changing Pickled Radish In A Factory Of Chongqing

Pickled radish is a traditional fermented food,with a special flavor.In the process of factory production,as it is not easy to control the factors because of the amount,the phenomena of softening and color change occurs from time to time,affecting the overall flavor of pickled radish.This paper chooses the softening,yellowing,red and black pickled radish of a factory in Chongqing as study object.The quality indexes of normal pickled radish and the abnormalities,the differences between the sensory and flavor substances were explored,and Study on microbial community structure by using high-throughput sequencing,find the bacteria may cause qualitative change.Research indicates:1.The pH value,acidity and salinity of radish with different softening degree were measured.The pH of the normal radish was 3.74±0.02,and the total acid and salinity were the lowest,which were(0.59±0.006)g/100 g and(5.96±0.03)respectively.Has a greater degree of lower pH value is,the more the total acid content.The salinity of the softened radish was higher than that of the normal radish.On the aspect of texture index,the texture index of the normal radish were better than that of the softened,each texture index was positively correlated with the degree of softening.To some extent,the texture index could reflect the softening degree of pickled radish.Color difference,the four samples were yellow-green color tone,and tissue softening did not cause color changes.Sensory evaluation,correlation analysis found that color,smell,taste,texture and other factors would not influence the sensory quality individually but decide comprehensively.Flavor,normal softening,moderate softening,severe softening pickled radish were detected 41,32,37 and 30 kinds of flavor components,the greater the degree of softening,the less flavor substances were detected.These 9 materials,Dimethyl trisulfide,eucalyptol,α-terpineol,terpineol,isoamyl alcohol,propionaldehyde diethyl acetal,myrcene,terpinene and limonene were not detected in normal pickled radish,but detected in three softened pickled radish.It can be used as the main material to distinguish normal and softened pickled radish.The volatile flavour component that detected in the normal,mild and moderate softened pickled radish are mainly esters and sulfur,but in the severe softening pickled radish,except esters and sulfur,aldehyde were detected,and the content of the aldehyde is higher than the first two compounds.)Principal component analysis,the original 67 kinds of flavor components are divided into three main components,the contribution rate of the first principal component 51.958%,the second main component contribution rate of 28.211%,the third main component contribution rate of 19.831%.According to the main ingredient factor scatter plot analysis,the impact of pickled radish aroma components of the flavor material,the 11 materials that impact the aroma components of the pickled radish are ethyl butyrate,isoamyl acetate,ethyl caproate,pHenylethyl acetate,ethyl 3-p Henylpropionate,dibutyl sulfate,Trans-2-hexenoate,linalool,isoamyl alcohol,(-)-limonene,and propanal diethyl acetal.According to the score of different softening degree of pickled radish after the standardization of the main ingredient,the ranking is the normal pickles> mild softening pickled radish> moderate softening pickled radish> serious softening pickled radish.This result has no difference with the sensory evaluation.2.Measuring the pH,the total acid and the salinity of the yellowing,red and black pickled radish.The pH and acidity of the red samples were close to those of the normal samples,which were(3.55±0.005)and(0.62±0.003)g/100 g respectively.The total acid of the yellowish and black samples significant increased,were(0.71±0.002)g/100 g and(0.73±0.001)g/100 g respectively.The salinity of the yellowing,redness and blackening samples was higher than that of the normal samples,which were(8.23±0.175)g/100 g,(10.52±0.006)g/100 g.The texture properties of the normal pickled radish sample is better than the yellow,then the red and the following is the black sample;discoloration will lead changes to the pickled radish,but the change is not obvious.Color difference,normal,yellowing,black pickled radish showing yellow and green tone,and red pickled radish showing red and yellow tone.Sensory evaluation,the comprehensive score of the normal radish is the highest,red samples as the second,yellowing samples followed and the worst is the black.Flavor composition,the numbers of volatile compounds that detected in the pickled radish of different colors is: yellow> black> normal> red,47 kinds of flavor ingredients detected in the yellow pickled radish in total,42 kinds in black,41 in the normal and 32 kinds in the red pickled radish.The common volatile components contained in the pickled radish of different colors are methyl thioacetate,ethyl butyrate,isoamyl acetate,ethyl n-hexanoate,pHenethyl acetate,dimethyl disulfide,linalool,decanal.Analysis the flavor components of the pickled radish,the contribution rate of the first principal component was 39.717%,the second was 36.734%,and the third was 23.549%.Analysis the scattergram of three principal component factors,linalool,dibutyl sulfate,ethyl oleate,2-decanone,1-methylnapHthalene,ethyl dicarboxylate,2-methylpropionic acid-3,7 Dimethyl-2,6-octanediol,1-acetylcyclohexene,4-methylnonane,pHenethyl acetate,n-octyl aldehyde,neryl acetate,ethyl salicylate,dimethyl Based disulfide and other 14 kinds compounds are the most important volatile ingredients that effect the flavor of the pickled radish.The comprehensive score of pickled radish samples of different colors is in order to black pickled radish> yellow pickled radish> normal pickled radish> red pickled radish.This result has a certain different with the sensory scoring.3.Measuring the total number of bacteria,yeast and lactic acid bacteria,severe softening sample(B1),moderate softening(B2)mild softening(B3)and normal samples(A1),the total number of bacteria and the number of yeast increased,and the number of lactic acid bacteria decreased.Black sample(C1),red(C2),yellowing(C3),the number of the bacteria increased,the number of yeast is close to the normal sample(A1),the number of lactic acid bacteria decreased significantly.(38.4%),Marinospirillum(5.4%)and Pediococcus(40.7%).The fermentation broth in Sichuan(2)was mainly composed of Pediococcus(9.0%),and the fermentation broth),Bacillus(55.3%)and Lactococcus(12.1%).The proportion of Marinospirillum,Halanaerobium,Marinobacter,Idiomarina,Suttonella and other bacteria in the fermentation broth of the radish fermentation broth increased,and the proliferation of these bacteria could lead to radish Of corruption.In the normal buds,Kazachstania is the most important bacterium,while the softened pickled radish has more than 60% of Pichia and has proliferated Wickerhamomyces,Debaryomyces,Millerozym and other yeast,indicating that Pichia is likely to cause texture and softening of the radish And so on.Blackish pickled radish mainly includes Debaryomyces(67.7%),Pichia(17.3%)and Kazachstania(12.3%),which may be due to a certain kind of bacteria in the Debaryomyces.Pichia in yellowish and red pickled radish accounted for more than 80%,but the texture of the pickled radish did not change obviously,indicating that the color change is likely lead by bacteria rather than fungus.Analysis the microbial flora on clustering tree in the fermentation of the pickled radish,the bacterial community structure and the fungal community structure of the normal pickled radish fermentation broth were different from those of the other samples.The bacterial community in the fermentation broth of black and red pickled radish showed similarity,indicating that there may be some common bacteria that leads the color change of the pickled radish.The bacterial community and the fungal community in the fermentation broth of the mildly softened and the yellowish pickled radish had a high similarity,indicating that certain microbes would not only cause the pickled radish to soften,but also lead the pickled radish turns yellow.