Study On The Mixed Fermentation Technology And Ultrasonic Aging Of Malusasiatica Vinegar

Malusasiatica,also known as flower red fruit,wenlin fruit,Lin ye,is widely planted and has high yield in China,and its picking period and storage period are very short,only about 40 days.At present,more than 85% of the Malusasiatica is eaten directly as fruit,thus the Malusasiatica resource has not been well utilized.At the same time,because of the richness of organic acids and tannins and other polyphenols,it has a sour and astringent taste,which means its best choice is not direct consumption,but as a good raw material for brewing fruit vinegar.The traditional fruit vinegar is brewed by liquid fermentation,but the liquid fermentation often leads to poor flavor and taste due to the single raw material and fermentation bacteria.Therefore,this study used Malusasiatica as the main raw material to develop a Malusasiatica vinegar by means of mixed fermentation and studied the influence of ultrasonic on its quality.The main research results are as follows:1.Study on the technology optimization and fermentation process of mixed fermentation Malusasiatica vinegar: Prepare Malusasiatica juice.The growth curve of fermentation strains was plotted.The optimal inoculation time of lactobacillus plantarum B7 and acetobacter pasteurensis CGMCC1.41 was determined to be 20 h and 16 h,respectively.Lactobacillus plantarum B7 was added in the alcoholic fermentation process to optimize the conditions of mixed fermentation and monitor the fermentation process.The results showed that the two strains could promote and symbiosis fermentation with each other under the conditions of 0.2% inoculation amount of yeast,4.0% inoculation amount of lactobacillus plantarum B7 and fermentation temperature of 30℃.By measuring the physical and chemical indexes of mixed fermentation Malusasiatica vinegar,it was found that the total acid in the vinegar could reach 6.16 ± 0.33 g/100 m L,and the total ester could reach 3.95 ± 0.28 g/L,which were increased by 30.51% and 22.67% respectively compared with the single-fermentation vinegar.2.Study on the effect of ultrasonic on the aging of mixed fermentation Malusasiatica vinegar: Ultrasonic was used to accelerate the aging process of mixed fermentation Malusasiatica vinegar.Through single factor test,we can determine the ultrasonic power was 300 W,ultrasonic time was 60 min,and the amount of ethanol added was 0.6%.At the same time,by studing the effect of ultrasonic treatment on the physical and chemical quality of Malusasiatica vinegar,it was found that compared with that of the new vinegar the total ester of Malusasiatica vinegar increased by 23.45% and the total acid decreased by 17.49%.The total amount of free amino acids increased by 15.17%,among glutamate which presented an umami taste,increased by 25.6%,while,valine which presented a astringent taste,decreased slightly after ultrasound.A total of 55 volatile substances were detected by HS-SPME-GC-MS in three kinds of Malusasiatica vinegar,including Alcohols(11 species),Acids(11 species),Sters(25 species)and Other species(8 species).The volatile components in the three kinds of fruit vinegar samples showed little difference,namely 42 kinds,42 kinds and 44 kinds.After ultrasonic treatment,the relative contents of Alcohols and Acids in Malusasiatica vinegar were decreased,while the relative contents of Esters,Phenols,Ketones,Ethers,Aldehydes and Furans were increased.This is generally consistent with the changes of various substances in the natural aging process,indicating that ultrasonic treatment can accelerate the aging process of Malusasiatica vinegar.On the basis of qualitative and quantitative analysis of various volatile components,a total of 22 components contributing to the aroma of Malusasiatica vinegar were identified by OVA method,including 5 Alcohols,6 Acids,9 Esters and 2 Other compounds.Combined with radar analysis of aroma components of sago vinegar,it was found that the contribution to the characteristic aroma of Malusasiatica vinegar was in the order of Esters >Alcohols > Others > Acids.After ultrasonic treatment,the overall aroma strength was enhanced,and there were only 14 aroma active substances in fresh fruit vinegar.Ultrasonic and aging increased to 18 and 19,respectively.It indicates that the aroma of ultrasonic and Malusasiatica vinegar is more layered and complex.3.Preliminary study on the mechanism of ultrasonic aging of Malusasiatica vinegar: By measuring the yield of ultrasonic cavitation,the release of hydroxyl radical and the degree of hydrogen bond association the mechanism of ultrasonic aging of Malusasiatica vinegar was studied.When the ultrasonic power is 300 W and the ultrasonic time is 60 min,the cavitation yield of ultrasound is the largest,and the hydroxyl radical generated by ultrasound is also the largest,which is corresponding to the conclusion obtained in chapter 3 by optimizing the technological conditions of ultrasonic aging of Malusasiatica vinegar.The effect of ultrasonic on the degree of hydrogen bond association in fruit vinegar was studied by Fourier transform spectroscopy.It was found that the absorption peak of the hydroxyl group in Malusasiatica vinegar moved to the low-frequency region and the peak width increased after ultrasound treatment.In other words,ultrasound could increase the number of molecules associated with hydrogen bond and association group Malusasiatica vinegar and reduce the number of free molecules with stimulating taste such as ethanol and acetic acid,so as to soften the taste of fruit vinegar.It is deduced that ultrasonic wave can produce a large number of hydroxyl radicals by producing a strong ultrasonic cavitation effect in Malusasiatica vinegar.Under the action of hydroxyl radicals,it can further accelerate the esterification reaction,oxidation reaction and other chemical processes in Malusasiatica vinegar system to achieve the purpose of accelerating aging.This study provided experimental basis for the application of mixed fermentation technology in fruit vinegar brewing and ultrasonic technology in fruit vinegar aging.It also provides the possibility for fruit vinegar processing enterprises to improve the taste of fruit vinegar and shorten the production time.