Study On Development Of Goji Berry Beverage Fermented By Probiotics And Its Alleviation Effect On Colitis In Mice

Ningxia goji berry(Lycium barbarum L.)is a characteristic plant resource in Ningxia,which is a kind of agricultural product with dual functions of medicine and food.It is rich in carotenoids,polysaccharides,amino acids and other active ingredients,has functions of anti-oxidation,lowering blood sugar,nourishing the liver,improving eyesight,and enhancing immunity,etc.It is mainly dried goji berry in market due to the poor storage resistance of fresh fruit.However,a large number of small or inferior fruits with poor sensory quality have been unsalable in the market,and the product conversion rate is low.In order to enhance the application rate and sensory quality of goji berry,and further explore the efficacy of fermented goji berry juice,in this study,Ningxia goji berry as the research object,analyzed the effects of the quality of goji berry juices fermented by six probiotics.On this basis,the dominant strains were selected for compound fermentation on goji juice,and the fermented conditions were studied.In addition,the effects of key processing units in the production of fermented goji juice on the active ingredients and volatile components of goji juices were investigated.And studied the alleviation effect of compound probiotics fermented goji juice on ulcerative colitis in mice used by animal model.The main research contents and conclusions are as follows:1.The difference in quality characteristics of goji juices fermented by different probiotics:(1)the contents of positively affecting aroma substances were higher in goji juices fermented by Lactobacillus bulgaricus or Streptococcus thermophilus,and sensory qualities were better.(2)The content of polysaccharides in goji juice fermented by Lactobacillus plantarum was highest.(3)The content of polysaccharides in goji juice fermented with Leuconostoc mesenteroides was higher,but the sensory quality score was lowest.(4)The contents of polysaccharides and amino acid in goji juice fermented by Lactobacillus reuter were higher,but more volatile aldehydes were lost.(5)There are no significant advantages in quality indexes of goji juice fermented by Lactobacillus rhamnosus compared with other strains.In summary,there were different advantages and disadvantages in goji juices fermented by different probiotics.Based on the different characteristics and sensory quality of different strains,L.plantarum,L.reuteri and S.thermophilus were selected as the subsequent fermentation strains for goji juice.2.Study on fermentation conditions of goji juice fermented by compound probiotics:the effects of different factors,including sugar content,inoculation content,proportion of compound strains,fermentation method and time,on the quality of goji juices fermented by L.plantarum,L.reuteri and S.thermophilus were evaluated by polysaccharide content,amino acid content,live bacteria count and sensory quality.The finally parameters of goji juice fermented by compound probiotics were determined as follows:2%sugar and 0.1%compound strains were added.The compounding ratio of L.plantarum,L reuteri and S.thermophilus was 1:3:5.After the fermentation of L.plantarum in goji juice for 6 h,added L.reuteri and S.thermophilus for secondary fermentation,the total fermentation time was 16 h.The quality of the goji juice fermented with these conditions complied with national standards and had edible safety.3.Effects of different processing units(beating,enzyme treatment,sterilization,primary fermentation and secondary fermentation)on the active ingredients and characteristic aroma of fermented goji juice:(1)The proportion of each monosaccharide of polysaccharides in each processing units of goji juices were changed significantly.Arabinose,galactose and galacturonic acid had always been the main monosaccharide in polysaccharides of goji juices.(2)The contents of free amino acids were affected by the processing,overall showed decline-rise-decline trend.(3)The content of phenolics were changed significantly during each processing stage.After enzymolysis,the total content of free phenols in goji juice was increased significantly,and its content was decreased significantly after sterilization.Fermentation promoted the total content of free phenols to increased continuously.The phenolic overall showed rise-decline-continue rise trend.(4)Aldehydes,ketones and alcohols were the mainly volatile components in goji juice,which had floral,fruity and oily oders.Enzyme treatment and secondary fermentation were the main changing stages of aroma.4.The alleviation effect of compound probiotics fermented goji juice on ulcerative colitis in mice:the raw goji juice and probiotics fermented goji juice were reduced the severity of apparent symptoms of dextran sodium sulfate(DSS)-induced ulcerative colitis in mice,including body weight loss,bloody diarrhea,colon tissue damage,splenomegaly and thymus atrophy.They also regulated the activities of T-SOD,GSH and MPO,decreased the secretion of inflammatory factors,including IL-1β,IFN-γ,IL-6,TNF-α and NO,in serum and colon in mice,increased the levels of IL-4 and IL-10 and the expression of intestinal epithelial tight junction proteins(ZO-1,claudin-1 and occludin).As well as increased the relative abundance of Bacteroidetes at the phylum level,decreased Proteobacteria and Verrucomicrobia.And increased the relative abundance of Helicobacter at the genus level.Both unfermented and fermented goji juices had shown potential to improve ulcerative colitis,and the compound probiotics fermented goji juice had a more significant alleviation effect.