Study And Product Development Of Summer Tea Fermented By Lactic Acid Bacteria To Cure Alcohol And Protect Liver Function

Alcoholic liver disease refers to liver damage caused by one or long term excessive alcohol consumption.Currently,although the drugs used to treat alcoholic liver disease can alleviate alcoholic liver injury to a certain extent,improper use or excessive use can increase the burden on the liver.Now,natural plant-based ingredients are becoming a new trend in liver care products.Summer tea contains a large amount of polyphenols,such as catechins and anthocyanins.Studies have shown that tea polyphenols can activate the antioxidant system in the body and protect cells from free radical damage,so as to protect the liver.However,due to the bitter taste of summer tea,the utilization of summer tea resources is limited.Lactic acid bacteria are important microorganisms in fermented tea drinks.In the process of tea fermentation,lactic acid bacteria can reduce the astringency of summer tea,and complement with tea polyphenols,making fermented tea products with unique flavor.Therefore,in this study,Lactobacillus plantarum NCU201.1,a strain of Lactobacillus plantarum with good antioxidant properties,was used to ferment summer tea to reduce its bitter astringency and improve its active components.Meanwhile,an acute liver injury model was established to investigate the protective effects of summer tea and fermented summer tea on mice with acute liver injury and the possible mechanism of action.Orthogonal experiment was designed to obtain the optimal addition amount of tea water ratio,sucrose and citric acid.On this basis,the effects of different contents of iso Vc sodium on the basic physical and chemical indexes and active components of fermented tea beverage during storage were explored.The main research results and conclusions are as follows:(1)By comparing the physicochemical indexes and active ingredients of summer tea before and after fermentation,it was found that the acidity increased from the initial0.31 g/kg to 0.41 g/kg,which was the result of lactic acid production by lactic acid bacteria during the fermentation process.The water extract content of summer tea increased from 36.21% in the original tea to 37.93% in the final tea,and the water extract content was the highest at 36 h of fermentation.The content of free amino acids in tea decreased from 5.48% to 5.10%,which may be due to the hydrolysis,decarboxylation and condensation of amino acids,which formed the aroma of tea and were consumed and utilized by growing microorganisms.The content of polyphenols in tea decreased slightly from 15.03% to 13.27%.In addition,epigallocatechin gallate(EGCG)increased from 267.56 μg/g to 303.61 μg/g in the original tea.Epicatechin gallate(ECG)increased from 65.93 μg/g in the original tea to 72.28 μg/g at the end of fermentation,possibly because the acidic conditions produced by lactic acid bacteria were conducive to the esterification of non-ester catechin,resulting in the increase of ester catechin and the decrease of non-ester catechin in fermentation solution.Epigallocatechin(EC)and epigallocatechin(EGC)increased first and then decreased,but their contents were always higher than those in the unfermented group,and there was a significant difference before and after fermentation(P<0.05).By measuring the DPPH free radical scavenging rate,superoxide anion free radical scavenging rate and hydroxyl free radical scavenging rate,it was found that fermentation could improve the antioxidant activity of summer tea,possibly because fermentation increased the content of antioxidant substances such as EGCG in summer tea.(2)Acute alcoholic liver injury mouse model was established by 56° liquor.The activities of aspartate aminotransferase(AST)and alanine aminotransferase(ALT)in serum of summer tea tea decoction group and fermented summer tea tea decoction group could be reduced to different degrees.Improve the activity of ethanol dehydrogenase(ADH)and acetaldehyde dehydrogenase(ALDH).In addition,the activity of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px),catalase(CAT)and glutathione(GSH)content in liver tissue can be decreased by increasing the activity of Xiacha tea decoction group and fermented Xiacha tea decoction group.Increase triglyceride(TG)level in serum and liver and total cholesterol(TC)content in serum to enhance the antioxidant capacity of the body and reduce lipid peroxidation.By observing the pathological changes of the liver tissue of mice,it was found that the liver injury of mice in the model group was obvious.The summer tea tea soup group and fermented summer tea tea soup group could improve the histopathological changes of the liver of mice with acute liver injury,inhibit cell apoptosis and necrosis,promote the repair and regeneration of liver cells,reduce the degree of liver injury,and have a certain protective effect on the liver.In addition,the fermented Xiacha tea decoction group was superior to Xiacha tea decoction group in enhancing ALDH activity,CAT activity,GSH-Px activity and reducing AST activity.(3)After the optimization of the formula,the optimal formula of tea beverage is the ratio of tea to water 1:40,the amount of sugar added is 8%,the amount of citric acid added is 0.01%.The p H value of control group,0.01% isovc sodium treatment group,0.02% isovc sodium treatment group and 0.03% iso Vc sodium treatment group changed little during storage.The contents of tea polyphenols and free amino acids showed a decreasing trend.The contents of tea polyphenols and free amino acids in the0.03% iso Vc sodium treatment group had little overall change,which decreased by9.22% and 13.88%,respectively.The reduction range of tea polyphenols was much lower than that in the other three treatment groups,indicating that iso Vc sodium had a certain protective effect on the active ingredients in tea drinks.By measuring the color difference,it was found that the 0.01% iso Vc sodium treatment group showed a good effect in protecting the a* and b* values.During tea beverage storage,the centrifugal precipitation rates of the four treatment groups were controlled within a reasonable range,all lower than 0.4%.In addition,through the analysis of the change trend of six catechin monomers in different treatment groups,it was found that sodium iso Vc had a certain protective effect on the reduction of catechin content during storage,and the protective effect on EGCG and ECG was more significant.