Effect Of Malic Acid-lactic Acid Fermentation On The Quality Of Sea Buckthorn Puree And The Development Of Sea Buckthorn Fermented Beverage

Sea buckthorn fruit（hippophae rhamnoides linn.）is rich in flavonoids,phenolic compounds,vitamins and fatty acids and other active substances,and its nutritional value is extremely high.Sea buckthorn puree has a high content of organic acids,especially malic acid,which affects the taste of drinking due to its too sourness.This article studied the anti-inflammatory and antioxidant activities of sea buckthorn extract flavonoids;using sea buckthorn puree as raw material,using Lactobacillus plantarum and Oenococcus otococcus for malolactic fermentation（MLF）,Measure the changes of metabolites,antioxidant capacity and volatile components during the fermentation process,and developed a sea buckthorn fermented beverage.The results are as follows:（1）Griess and enzyme-linked immunosorbent assay were used to study the anti-inflammatory and antioxidant capacity of sea buckthorn flavonoids.Sea buckthorn flavonoids at 50～250μg/m L can significantly increase the phagocytic ability of cells and significantly inhibit the intracellular nitric oxide（NO）,interleukin-6（IL-6）,tumor necrosis factor-α（TNF-α）and cyclooxygenase-2（COX-2）in mouse peritoneal macrophages（Raw264.7 cells）is produced with a dose-dependent effect;the ability of sea buckthorn flavonoids to scavenge DPPH free radicals and ABTS free radicals is equivalent to ascorbic acid（Vc）（IC50 values are 9.014μg/m L,136.86μg/m L,respectively）.The hydroxyl radical scavenging ability and total antioxidant（FRAP）of sea buckthorn flavone at a concentration of 80μg/m L were 59.35%and 2.36mmo LFe SO₄/L,respectively.（2）To study the changes of physical and chemical indexes,functional components and biological activities during the fermentation of Oenococcus oeni CICC6066 sea buckthorn puree.Fermentation of Oenococcus oeni significantly increased the p H value of sea buckthorn puree,the content of malic acid was reduced by 86.01%,and the content of lactic acid was increased by 378.64%;the sugar acid of sea buckthorn puree was increased by 4.80 than 2.40;total flavonols and total phenolic acids increased by49.35%and 29.63%,respectively Among them,quercetin,kaempferol,isorhamnetin,gallic acid,p-hydroxybenzoic acid and catechins have the most significant increase;SOD enzyme activity is 8.06 times that before fermentation;antioxidant capacity(hydroxyl radicals,DPPH The scavenging capacity of free radicals,ABTS free radicals and superoxide free radicals and total antioxidant capacity were increased by 18.22%,9.92%,40.23%,5.90%and 16.41%,respectively.A total of 79 volatile substances were analyzed and identified during the fermentation.The newly added flavor substances after fermentation were mainly esters and alcohols.The content of hydrocarbons and aldehydes decreased significantly,and the total amount of aromatic substances increased.（3）To analyze the changes of metabolites and volatile components during the fermentation of sea buckthorn puree by Lactobacillus plantarum ATCC 14917.After fermentation by Lactobacillus plantarum,the p H value of sea buckthorn increased significantly,and the total acid decreased.The malic acid content decreased 82.55%,and the lactic acid increased;the total sugar decreased slightly,of which glucose and fructose decreased by 9.82%and 10.09%respectively;Flavonols and total phenolic acids increased by 11.98%and 18.42%,respectively,of which quercetin,isorhamnetin,gallic acid,p-hydroxybenzoic acid,catechin,caffeic acid,epicatechin,ferulic acid and coumarin,etc.Significant increase;SOD enzyme activity,hydroxyl free radicals,DPPH free radicals,ABTS free radicals and superoxide free radicals scavenging capacity and total antioxidant capacity increased by 242.01%,28.81%,5.26%,23.05%,9.39%and 13.93%,respectively;A total of 73 volatile compounds were identified by GC-MS analysis,the content of alcohols and esters increased significantly,after fermentation,the total amount of aromatic substances increased,and the content of hydrocarbons,acids and aldehydes decreased significantly.（4）Optimize the fermentation process of sea buckthorn puree and the formula of fermented beverage,and analyze the quality of sea buckthorn fermented beverage.The best fermentation process of sea buckthorn puree is:inoculation amount 5.0%,fermentation temperature 28℃,fermentation time 6 days,initial p H 3.5,under these conditions,the degradation rate of malic acid reaches 87.411%;the optimal formula of sea buckthorn fermented functional beverage is:fermentation The amount of sea buckthorn juice added is 25%,honey 2%,and sugar 7%.Under these conditions,the sensory score of the product is 89 points;the total phenols and total flavonoids in the sea buckthorn fermented beverage are 0.34 mg/m L and 56.33 mg/L,respectively;Good antioxidant capacity;SOD enzyme activity is 935.48 U/m L,which is significantly higher than unfermented sea buckthorn puree;the flavor and taste analysis of electronic nose and electronic tongue shows that the beverage has a unique flavor and a soft taste.Tests show that both Oenococcus oeni CICC 6066 and Lactobacillus plantarum ATCC 14917 can perform MLF in sea buckthorn puree,which can effectively reduce the acidity of sea buckthorn puree,increase the antioxidant activity of sea buckthorn puree,and increase the content and types of aromatic volatile components after fermentation.The addition of Oenococcus oeni CICC 6066 fermented sea buckthorn puree is more effective in reducing acidity than Lactobacillus plantarum ATCC14917fermentation.Therefore,the use of Oenococcus oeni CICC 6066 fermented sea buckthorn puree is finally used to develop functional beverages.This study provides reference data for the biological acid reduction of seabuckthorn puree and the development of functional beverages.