Study On The Fermentation Of Dandelion Jiangshui By Lactic Acid Bacteria And Its Characteristics

Jiangshui is a kind of drink with unique sour taste and fragrance,which was fermented by a variety of microorganisms,vegetables and noodle soup in a natural state.In the fermentation process,the rich nutrients in vegetables and noodle soup were utilized by a variety of microorganisms,so that the finished jiangshui was riched in beneficial microorganisms,organic acids and volatile flavor substances that made jiangshui not only has good taste,but also good at health.Dandelion is a kind of excellent medicine and food plants.It was not only an important traditional Chinese medicine,but also an edible wild vegetables for a long time.Using dandelion as raw material to make jiangshui can improve the function and enrich the variety of jiangshui products.In this experiment,three samples jiangshui were collected from Pingliang,Dingxi and Tianshui.A total of 8 strains with good performance were isolated from 3samples as fermentation bacteria.The effects of the types of substrate noodle soup,the types of carbon source and amount added on the total acid and flavonoids retention were investigated.The process parameters was determined of inoculated fermentation dandelion jiangshui.Fermentation rates,volatile matter and antioxidant ability between the inoculated and natural fermentation dandelion jianshui was compared.The research results were as follows:1.A total of ten representative LAB strains with differences in morphology and characteristics was identified by 16 SrDNA,based on the determination of low pH resistance,bile salt tolerance and growth performance of the isolated LAB strains,PL2,PL3,PL4,DX1,DX4,TS1,TS3 and TS4 were selected as mixed LAB strains.2.The effects of pea noodle soup,wheat noodle soup and corn noodle soup on the fermentation rates,volatile matter of dandelion jiangshui were compared.Selected total acid and flavonoids as indicators determined that adding 0.3% sucrose was beneficial to the fermentation of jiangshui.3.With total acid content(mg/mL)as an index,the effects of inoculum size,initial pH and temperature to total acid were explored based on single experiment and response surface method.The results indicated that the optimal technology was 6.5%inoculum size,temperature 33 ? and initial pH 6.3.4.The optimal technological conditions were adopted.Compared to natural fermentation dandelion jiangshui(NFDJ)and inoculated fermentation dandelion jiangshui(IFDJ)fermentation rates and volatile substances in the whole fermentation,the results show that the changes of basic physical and chemical indicators in inoculated fermentation and natural fermentation was similar.A total of 17 amino acids were detected in dandelion jiangshui.At the end of fermentation,the total amino acid contents of IFDJ and NFDJ were 19.22 mg/100 mL and 8.58 mg/100 mL.The results showed that IFDJ total amino acids was higher than NFDJ(P<0.05).a total of 39 and 30 volatile aroma compounds were identified in NFDJ and IFDJ respectively.These compounds belong to alcohols,aldehydes,acids,ketones,esters,hydrocarbons,and other compounds.A total of 10 alcohols,6 aldehydes,5 ketones,4esters,3 hydrocarbons,and 2 other compounds were identified in IFDJ,13 alcohols,4aldehydes,5 esters,3 ketones,13 hydrocarbons and 1 other compounds were identified in NFDJ.(-)-4-Terpineol,alpha-terpineol,limonen were the main volatile aroma components,which played an important role in the taste of IFDJ and NFDJ.5.DPPH radical scavenging rate,hydroxyl radical scavenging rate and superoxide anion radical scavenging rate were determined to determine their antioxidant capacity in vitro.The result shows that all three kinds of jiangshui had significant difference scavenging capacity for all three kinds of free radicals.The scavenging effect of free radicals was IFDJ > NFDJ > IFCJ.