Study On Fermentation Characteristics And Gastrointestinal Digestion Characteristics And Prebiotic Activities Of Lycium Barbarum Linnaeusas And Lycium Ruthenicum Murray

Goji berry,is a kind of traditional medicine and food homologous ingredients,which has attracted broad attention at home and abroad.Natural goji berry plants grow under extreme conditions of drought and cold.The unique geographical conditions have shaped the excellent ecological characteristics what are cold resistance,salt and alkali resistance,drought resistance,etc.,and have given fruits high edible and medicinal value.The plant secondary metabolites such as polysaccharide,polyphenol and alkaloid that are not only inherent factors make goji resistance to harsh environments,but also have ideal pharmacological activities,including antioxidant,anti-tumor,and immune regulation,etc.Which are in line with consumer's concept of nutrition and the pursuit of health.However,the taste of goji berry directly is relatively simple.Fermentation is a safe food processing method.Moderate microbial degradation is conducive to the release of small molecule nutrients and aroma components in the food matrix.At present,there are few research reports on water extracts of goji at home and abroad,and it is still in the initial stage of exploration to improve the quality of goji by microorganism fermentation.Studies on the feasibility of medicinal and food ingredients have not been reported.In this paper,the Lycium barbarum Linnaeusas(LB)and Lycium ruthenicum Murray(LR)were respectively treated with water extraction and short-term fermentation,which were used to evaluate the feasibility of fermenting goji berry by lactic acid bacteria and the changes of flavor.During juice fermentation process,the regularity of bioactive ingredients was in-depth excavated through non-targeted metabolomics.With the help of static and dynamic bionic gastrointestinal digestion models and in vitro colonic fermentation to study the release of phenolic compounds and intestinal benefits in fermented goji berry juice.Comparative analysis of the different digestive behaviors of 4 juices and their potential impact on intestinal health.The research results are as follows:1.Study on fermentation characteristics of Lycium barbarum Linnaeusas and Lycium ruthenicum MurrayTaking LB and LR as research objects,total of 21 lactic acid bacteria obtained by screening were used for moderate microbial fermentation.Comparative analysis of fermentation characteristics in two kinds of goji berry juices under different lactic acid bacteria by observing some changes,which are concentration of plant chemical components(total phenol,total flavonoids,total anthocyanins),the ability of scavenge oxidative free radicals(ABTS,DPPH),color and phenolic fingerprints.The results showed that most strains can better adapt to the food matrix and use the carbohydrates in goji berry juice for life metabolic activities.After fermentation,the color of juice is more brighter,the concentration of phenolic compounds and antioxidant activity are generally improved.The 16 kinds of goji berry juices fermented by 13 lactobacillus strains(Lactobacillus pingfangensis 8,L.fermentum S-A,15,L.delbruckii subsp.bulgaricus GD-A1,L.pentosus L17,3,6,11,13,GD-A3,GD-3A,L.paraparai subsp.tolerans S-NA,S-NB),have excellent fermentation characteristics.Compared with LB juice,LR juice showed higher phenolic content and antioxidant levels before and after fermentation.2.Study on flavor characteristics of different types of goji berryBased on the previous research,16 kinds of goji berry juices with good fermentation characteristics were selected.The electronic nose and electronic tongue were further used to analyze the odor and taste.The results suggested that the flavor characteristics were significantly different before and after fermentation.Then the headspace-solid phase microextraction-gas/mass spectrometry(HS-SPME-GC/MS)technology was applied to identify aromatic components.The total of 71 and 46 volatile compounds were detected in the fermentated LB and LR respectively,and the characteristic aroma components of different fermentation samples were very different.Combined with electronic nose analysis suggested that the 5 kinds of goji berry juice fermented by 4 strians(L.fermentum S-A,L.pentosus L17,L.paracasei subsp.tolerans S-NA,and S-NB)had better flavor characteristics.Finally,based on the comprehensive evaluation of fuzzy mathematics,the fermented goji berry juice by L.fermentum S-A with higher sensory score and the most unique flavor was obtained.3.Non-targeted metabolomics of different types of goji berryTwo kinds of fermented goji berry juices by L.fermentum S-A with better quality were obtained through macro-evaluation of nutritional value and flavor characteristics.With the help of non-targeted metabolomics research methods,the bioactive ingredient metabolisms during the fermentation process were further explored,and the specific differences in micro-levels of goji berry before and after fermentation with lactic acid bacteria were compared and analyzed.The results showed that,compared with non-fermented juice,the type and abundance of metabolites were significantly charged after fermention,and the number of metabolites before and after fermentation of LR was higher than LB.Most metabolites are mainly involved in the PPAR signal transduction pathway as nutrients.The biosynthesis of flavonoids,linoleic acid,and phenylpropanoids what further enrich the secondary plant metabolites of goji berry.Compared to non-fermented samples,the bioactive compounds such as borneol A,vernomenin,montanin,apocynin,D-mannosyl-L-rhamnosyl-D-galactose-1-diphospholipidcantharidin,etc.,that may be potential biomarkers in fermented goji juices.4.Study on gastrointestinal digestive characteristics and prebiotic activity of different types of goji berryThe static and dynamic in vitro biomimetic gastrointestinal digestion model and in vitro simulated colonic fermentation were used to evaluate the fate and antioxidant activity of phytochemical components of LB and LR fruit before and after fermentation.The digestion results showed that no significant change in phenolic compound concentration over time,and the decease between concentration of phytochemical components and the ability to scavenge free radicals might due to the dilution of different pH simulation solutions.However,compared with non-fermented goji berry juices,the fermented still has considerable phenolic content and antioxidant levels,which can reach the colon site and be reused by the intestinal flora.LEfSe analysis was used to obtain 26 characteristic microorganisms with significant differences in the genus level.Among them,LR-S-A has the highest species richness compared with other digestive samples.Including 15 strains such as Barnesiella,Bifidobacterium,Ruminococcaceae_UCG₀13,Ruminococcus₂,etc.,have potential biological significance in maintaining intestinal homeostasis and promoting body health.