Study On Processing Techology And Property Of Aronia Melanocarpa Juice Fermrnted By Latic Acid Bacteria

Aronia.melanocarpa is a native wild berry in the Europe.The fruit is rich in anthocyanins.It was introduced to China in recent years and mainly planted in northestward.However,the development and utilization of A.melanocarpa is not well developed and new products are required to be explored.Lactic acid bacteria fermentation is an effective measure to improve original nutrition and extend shelf life.It can not only improve the utilization rate of resources but also enrich product varieties to develop new lactic acid bacteria fermentation drinks of A.melanocarpa.In this study,processing technic of fermented juice using A.melanocarpa as raw material was optimiezed.Furthermore,the nutrient component,antioxidant capacity and flavor profile change of the juice during fermentation were tested.The main research results and conclusions are listed as follows:The single factor experiment was used to determine the fermentation conditions based on soluble solids,pH value and the number of the bacterium.The fermentation conditions were determined as follows:0.5%fermentation strain TUST-392 was inoculated into 30%A.melanocarpa juice,the fermentation was performed at 37℃ for 96 hours,while 5%glucose was added as carbon source.Based lactic acid content,the orthogonal test was used to determine the best fermentation technic.The best fermentation conditions were determined as follows:the inoculum amount of bacterium was 0.5%,fermentation temperature was 37℃ and the carbon source content was 5%.After fermentation,the values of a*,B*,L*of the juice increased,which indicating that the product changed to red,yellow,bright after fermentation.The contents of oxalic acid,citric acid,succinic acid,fumaric acid and lactic acid increased.However,the malic acid decreased significantly after fermented.One of short chain fatty acids,acetic acid,increased significantly.The content of glucose and fructose decreased significantly.The antioxidant activity of the fermented liquid was improved gradually during the process of fermentation,including the total antioxidant capacity and the scavenging capacity of DPPH and ABTS free radicals.In addition,the content of total phenol was unchanged and the content of total flavonoids decreased significantly.Anthocyanins in the fermentation juice were identified by liquid chromatography-mass spectrometry(LC-MS)including cyanidin-3-galactoside,cy ani din-3-glucoside,cyanidin-3-arabinoside and cyanidin-3-xylanoside.The changes of these four anthocyanins in the fermentation process were determined by liquid phase spectrometry(LC)analysis.The results showed that the content of these four anthocyanins decreased rapidly at beginning and decreased slowly during subsequent fermentation.Finally,the cotent of the four anthocyanins became stable.Gas chromatography-mass spectrometry(GC-MS)was used to determine the volatile components in the fermentation process.The results showed that aldehydes and ketones are important flavor substance before and after fermentation.The kinds of flavor substance increased from 24 to 37 after fermentation including the alcohols and esters.The changes of volatile aroma compositions were significant after fermentation.