Analysis Of Microbial Diversity And Identification Of Dominant Flora In Rose Jam

Rose jam is a traditional fermented food in China,which is rich in nutrients.It is generally processed in an open environment,without any heating or sterilization treatment,and often contains rich microorganisms.There are many rose jam producing areas in China,but there is no unified production standard.it is difficult to maintain a stable and consistent quality and flavor of spontaneously fermented rose jam products from different batches and different origins.Microorganisms have a crucial impact on the physical and chemical properties and flavor of fermented food.In order to further understand the microbial diversity,dominant flora and potential probiotics in rose jam,in this paper,the microbial diversity and flora structure in rose jam were determined by high-throughput sequencing technology,and the dominant microorganisms and potential probiotics in rose jam were screened and identified combined with traditional methods.Probiotic was used for fermentation of rose jam,and the physicochemical indexes and flavor substances of rose jam were analyzed to evaluate the fermentation performance of the strain,try to promote the standardization of rose jam production strains,and to lay the foundation for the standardized production of rose jam.The main conclusions are as follows:1.The microbial diversity of nine rose sauces in China was analyzed by highthroughput sequencing.The results showed that at the genus level,the dominant bacteria were Pseudomonas,Rosenbergiella,Pantoea,Burkholderia and Ralstonia,and the dominant fungal genera were Zygosaccharomyces,unclassified,Botrytis,Diaporthe and Thermomyces.The abundance distribution of fungi in rose jam is more uniform and diverse than that of bacteria.Compared with other fermented foods,the microorganism in rose jam has no obvious difference at the phylum level,but has great difference at the genus level.2.This study uses PICRUSt to predict the functional genes of the bacterial community of fermenting rose jam based on high throughput sequencing and 16 S r RNA gene sequence of the microbial genome.It was found that many functional genes of bacteria in rose jam were related to amino acid metabolism,membrane transport,energy metabolisms,cellular processes and signaling,and carbohydrate metabolisms.3.In the present study,61 strains of lactic acid bacteria and 16 strains of yeast were isolated from 9 spontaneously fermented rose jams.After the experiments of p H,bile salt,simulated artificial gastric fluid and antibiotic resistance of lactic acid bacteria,an excellent potential probiotic strain MP13 was screened.The optimum growth temperature of the strain was 37 ?,and the strain had good tolerance to high sugar osmotic pressure.4.Using the P.pentosaceus MP13 strain as a starter to ferment the rose jam and comparing it with the naturally fermented rose jam.The results showed that the contents of anthocyanins,total flavonoids,total phenols and antioxidant properties of DPPH in rose jam were increased,and the flavor and quality of rose jam were improved.5.The flavor of the two rose sauce jams with P.pentosaceus MP13 strain added and naturally fermented was compared by GC-IMS technology.In this study,a total of50 VOCs were detected,including 13 alcohols,nine ketones,17 aldehydes,three esters,two ethers,one pyrazine,and six other compounds.Compared with natural fermentation rose jam,added MP13 strains as starter cultures in rose jam some alcohol((E)-2-hexene,pentane,terpine,and 2-methylbutane)and aldehyde(benzene acetaldehyde,benzaldehyde,3-methylbutanal,2-methylbutanal,pentanal,hexanal,heptanal,and octanal)contents decreased,whereas some ketone(3-hydroxybutan-2-butanone,2,3-butanedione,2-butanone and 2-pentanone),alcohol(3-methylbutane,2-phenylethanol and n-hexanone),and ester(ethyl acetate and ethyl hexanoate)contents increased,,which enriched the flavor of rose jam.