The Study On The Fermentative Capacity Of Non-saccharomyces Yeast In Apple Juice

In the past, non- Saccharomyces cerevisiae yeast is considered as wine spoilage yeasts. In recent years, many studies have indicated that they can produce high amounts of ethyl acetate. But their use in the juice for fermentation indeed rarely reported. This study aims to develop a new low-alcohol fermented apple juice by non-Saccharomyces yeast screened from naturally fermented fruits and vegetables juice. Firstly yeasts were screened from the naturally fermented fruits and vegetables juice. Secondly, the screened yeasts were inoculated into apple juice and sensory evaluation of the fermented apple juice were done, by which the strain was selected because its highest score in sensory evaluation. According to the sequence of 26 S rDNA D1/D2, the strain was identified and phylogenetic tree was established. Thereafter, physicochemical characteristics and aroma components of fermented apple juice were analyzed. The results are as follows:(1) 411 yeasts was isolated from the naturally fermented apple and vegetable juice(apples, pears, kiwi, etc.). Firstly, we screened 110 strains by studying their gas production capacity, aroma production capacity and ethanol capacity. Then the 110 strains was inoculated into apple juice. We used sensory evaluation method rescreened and selected the highest score strain T2 as the optimal strain. Then we evaluated the morphological and molecular identification of T2 yeast. The results showed that: strain T2 is Candida inconspicua.(2) The selected strain T2 was inoculated to 15 °Brix apple juice, after fermented we analyzed its physical and chemical indicators. The Sterilized 15 °Brix apple juice as control. The results showed that: After fermentation the pH changed a little compared with the control group, the difference was not significant. The ethanol content increased, and the alcoholic fermentation was only a small part, which meet the characteristics of low-alcohol beverage. The reducing sugar and total sugar content had declined, while the total acid content increased, which indicated that T2 can use the carbohydrate metabolism to produce acidic substances. The content change in sugar affected the juice of sour and leaded to the change in taste.Then we studied the sensory evaluation of T2 fermented juice and the control samples. The results showed that: compared with the apple juice, T2 has greatly improved the taste and aroma.finally,weusedgc-msanalyzethearomacomponentsoft2 fermentedjuiceandsterilizedjuice,theresultsshowedthat:t2fermentationhad12speciesofesters,accountingfor46.13%ofallseparatecomponents,withtherelativecontentofethylacetate(9.31%),phenylethylacetate(30.05%)tothehighest.ethylesterhasafruityandfloweryflavour,phenylethylacetatehasasweethoneyflavor,andthehexylacetate,ethylbutyrate,propionateandothershavefruityandfloralaromacharacteristics.theapplejuicewasonlydetectedthreekindsofesters,whichcanbedeterminedthatt2 producedesters,improvedthearomaticcontour.fromt2 fermentedapplejuiceweisolatedsixkindsofalcohols.t2fermentedapplejuicehassixkindsofaldehydesandketones,andnineinapplejuices.theybothhavehexanal,therelativecontentis0.06%,0.28%,thiscompoundhastheappleflavor.byfermenting,thearomacomponentswasincreasedandthesensoryqualityhadgreatlyimproved,t2issuitablefortheproductionoflow-alcoholfermentedapplejuice..(3)thisresearchusedthedpphassayandabtsassaytocomparetheantioxidantactivityoft2fermentedapplejuiceandthesterileapplejuice.theresultsshowedthat:thedpphradicalandabtsradicalscavengingabilitywasincreasedafterfermentationoft2.