Study On Extraction,Antioxidant And Antibacterial Activity Of Proanthocyanidins From Sorbus Melanocarpa

The fruit of Sorbus melanocarpa is a new small berry,which contains a lot of polyphenols and is a natural functional food raw material.However,the fresh fruit of Sorbus melanocarpa has short storage time,poor transportation performance,and astringent taste,so that it is rarely used.Therefore,in order to expand the application range of Sorbus melanocarpa,the research on its specific components has changed.It is especially important.It is known that the content of proanthocyanidins in Sorbus melanocarpa is the most among all fruits and vegetables,and proanthocyanidins themselves have a variety of pharmacological activities,such as anti-cancer,antibacterial,and cardiovascular reduction.Therefore,this thesis uses ultrasound-assisted eutectic solvent to extract proanthocyanidins from Sorbus melanocarpa,and study its antioxidant and antibacterial activities.The specific research content is as follows:1.Extraction of Proanthocyanidins from Sorbus melanocarpa by eutectic solventPrepare eutectic solvents with different ratios of choline chloride and malonic acid,and use them to optimize the process of extracting proanthocyanidins from S.melanocarpa.The best process is:the solvent ratio is choline chloride:C Diacid=1:1.2,the water content of the solvent is 10%,the material-to-liquid ratio is 1:15 g/m L,the extraction time is 40 min,the extraction temperature is 50℃,the ultrasonic power is200 w,and the highest content of extracted proanthocyanidins is 63 mg/g.The results of the orthogonal experiment showed that the optimal extraction process was basically the same as the single factor experiment.Using 70%acidic ethanol solution for comparative verification,the extraction content is 23 mg/g,which is 1/2 of the extraction content of the eutectic solvent,indicating that the eutectic solvent is a good extraction solvent.Finally,DM130 macroporous resin was used to purify the crude extract,and the content of proanthocyanidin in the purified product was 82.4%.2.Antioxidant activity of Proanthocyanidins from Sorbus melanocarpaThe experiment investigated the scavenging ability of proanthocyanidins on DPPH,OH^-,O^2-,ABTS these four kinds of free radicals and the total gas reduction ability,and vitamin C was used as a control experiment.The results show that the scavenging ability of proanthocyanidins on DPPH free radicals is greater than that of V_C in the concentration range of 0.1～4 mg/m L,the scavenging ability of OH^-and ABTS free radicals is basically the same as that of V_C,and the scavenging ability of O^2-free radicals is less.V_C,its total reduction ability is greater than V_C.3.Antibacterial activity of Proanthocyanidins from Sorbus melanocarpaThe bacteriostatic properties of proanthocyanidins were determined qualitatively and quantitatively by the Oxford cup method and the micro broth dilution method,and the growth inhibition curve of 30%ethanol and proanthocyanidins on the tested strains within 72 h was drawn.The results showed that the inhibitory effect of proanthocyanidins on S.aureus was stronger than that of E.coli,but had no inhibitory effect on Penicillium and A.niger.The MIC of S.aureus is smaller than that of E.coli.The growth curve indicated that proanthocyanidins almost completely inhibited the growth of S.aureus and E.coli at the MIC concentration.4.Application of extract of Sorbus melanocarpa in the preservation of fresh-cut fruitsThe purified proanthocyanidins were applied in fresh-cut apple preservation experiments.The results showed that the weight loss rate of fresh-cut apples in the proanthocyanidin group was stronger than that of the 30%ethanol treatment group and the blank group.The hardness and sugar content of the proanthocyanidin group were basically the same as those of the other two groups.From the color difference value,it can be seen that the L*value of the proanthocyanidin group is lower than the other two groups,while the C*value is higher than the other two groups.The MDA content of the procyanidin group was significantly lower than the other two groups.The total number of bacteria contained in the MIC procyanidin group was much smaller than the other two groups.This thesis uses a eutectic solvent to extract proanthocyanidins from Sorbus melanocarpa by ultrasonic assisted extraction.Compared with ethanol,the extracted content is doubled.The crude product is purified by DM130 macroporous resin;then the purified product is subjected to antioxidant and the study of antibacterial activity shows that it has strong anti-oxidation and antibacterial ability;finally,its application in the preservation of fresh-cut apples shows that it has a certain preservation effect.