The Effect Of Fu Brick Tea Addition On Fermentation Characteristics And Functional Activities Of Fermented Glutinous Rice

Fermented glutinous rice products are consumed all over the world with a long history,which are based on glutinous rice and fermented by microbes in special environments.The studies and development of traditional fermented foods have been carried out world widely for many years,including the research on the exploration and improvement of fermentation strains,the reports on improving the nutritional and functional activities of fermented foods,a new functional food with more healthy benefits.Fu brick tea is a kind of dark teas fermented by a complex microflora,bacteria,fungi and saccharomycete,which contains a large number of polyphenols,flavonoids,anthocyanins and other compounds that have cholesterol-lowering activity,anti-obesity and anti-metabolic activity.As Fu brick tea has a natural probiotic flora,which have a good ability to secrete extracellular amylase,cellulase and protease,thus,the natural micro-flora and enzymes of Fu brick tea has a good potential for the fermention of glutinous rice.In this study,the natural microflora of Fu brick tea was used as a "Qu" in China,and the glutinous rice was fermented together with the traditional starter Koji to produce a new functional food.The study investigated the effects of the Fu brick tea addition on the physicochemical properties and flavor quality of glutinous rice fermentation process,and compared the fermentation characteristics and functional properties of mixed fermented glutinous rice(MF-GR)and Koji fermented glutinous rice(KF-GR).The protective effects of oxidative damage on PC 12 cells and their mechanisms were studied.The main results were as follows:1.Effects of Fu brick tea addition on the physicochemical properties and main enzyme activities of fermented glutinous riceThree cultivate filamentous fungi has been extracted and identified from Fu brick tea extract through morphological observation and molecular biology techonologies as coronoid process powder capsule bacteria Eurotium cristatum("golden flower"),Rhizopus oryzae and Aspergillus oryzae.L*,a*and b*,fermentation time,juice extraction rate and sensory evaluation indicators were used to determine the amount of brick tea addition.The optimal effect was adding 2%Fu brick tea and 0.3%wine to ferment glutinous rice.In 0 to 48 hours in the fermentation process,the effects of the addition of brick and tea on the main enzyme activities during the fermentation of glutinous rice,including amylase,?-glucosidase,protease and lipase,were analyzed.It was found that with the prolongation of fermentation time,the main enzyme activity increased first and then increased.The activity of amylase of MF-GR reached the maximum at 33 h after fermentation,which was significantly higher than that of KF-GR.The protease activity of MF-GR reached the maximum at the 24 h of fermentation,and was significantly greater than that of KF-GR during the first 27 h.The lipase activity of MF-GR changed little with time,and the difference from KF-GR was insignificant;The change of ?-glucosidase activity was detected in MF-GR during fermentation,and reached the maximum when fermented for 33 hours,but no activity of ?-glucosidase was detected in the liqueur.In the range of 15 to 48 hours,the effects of Fu brick tea addition on the main physical and chemical indicators during the fermentation of glutinous rice,including pH,total acidity,reducing sugar content,soluble solid content and alcohol content,were analyzed.The utilization efficiency of the biomass is significantly higher than that of KF-GR,and the effective utilization and biotransformation of the biomass can be achieved earlier.Therefore,the fermentation time was determined to be 30 hours by comprehensive judgment.The study also investigated the effect of the addition of sorghum brick on the biomass of yeast during the fermentation of glutinous rice.It was found that with the prolongation of fermentation time,the yeast entered the logarithmic growth phase after about 18 h of fermentation;the yeast was fermented for 42 h at MF-GR.The biomass of the bacteria reached the maximum of 7.1 ×106 CFU/g,and the KF-GR reached the maximum at the same time,which was 6.7 × 106 CFU/g.At 30 h of the fermentation end point,the biomass of the yeast in the MF-GR was 4.8 × 106 CFU/g;The biomass of yeast in KF-GR is 3.9 × 106 CFU/g.2.Effects of Fu brick tea addition on organic acids,short-chain fatty acids and flavor compounds in fermented glutinous riceThe types and contents of organic acids and short-chain fatty acids in MF-GR and KF-GR were determined by high performance liquid chromatography.The organic acid content of MF-GR is significantly higher than that of KF-GR,while the short-chain fatty acid content of MF-GR is significantly smaller than that of KF-GR.Among them,the content of tartaric acid,lactic acid and propionic acid in MF-GR was significantly higher than that of KF-GR,while the content of acetic acid was significantly lower than that of KF-GR,and malic acid and pyruvic acid not found in KF-GR were detected in MF-GR.In addition,there was insignificant difference in the contents of formic acid,succinic acid,oxalic acid and citric acid.The salty,astringent,sour and umami intensity of MF-GR was significantly lower than that of KF-GR by electronic tongue technology.The overall flavor of MF-GR was softer than KF-GR,but the bitterness and bitterness of MF-GR.The aftertaste and aftertaste are significantly higher than KF-GR,which is due to the unique taste of the brick tea.In addition,there is no significant difference in the fresh aftertaste.The concentration of aromatic compounds of aromatics and alkanes in MF-GR was higher than that of KF-GR by electronic nose technology.In addition,the aromas contributed by amines,organic sulfides and olefins had an impact on the difference in flavor between MF-GR.The composition and relative content of volatile flavor compounds in MF-GR and KF-GR were determined by HS-SPME-GC-MS.A total of 94 volatile flavor compounds(16 alcohols,11 acids,32 esters)were identified,including 11 aldehydes,3 ketones,2 ethers,3 furans,2 terpenes,4 hydrocarbons,6 phenolic compounds,3 aromatic hydrocarbons and 1 nitrogenous compound,of which 35 compounds were unique aroma compounds in MF-GR.Also,the fuzzy mathematics were applied for sensory evaluation analysis,MF-GR is significantly higher than KF-GR in terms of color,smell,taste,texture and comprehensive score.3.Effect of fermented glutinous rice with addition of Fu brick tea on the antioxidant and protective activity of DNA oxidative damageThe addition of Fu brick tea significantly improved the antioxidant capacity of KF-GR.Based on the evaluation indexes of six antioxidant activities,such as ABTS ability,DPPH ability,iron ion reducing ability,reducing potential,metal chelation ability and hydroxyl radical scavenging activity,the antioxidant activity of the MF-GR and MF-GR were analyzed and compared.The in vitro antioxidant capacity of KF-GR was also investigated,and the protective effects of both on DNA oxidative damage were investigated.The two extraction reagents(deionized water and 80%ethanol)were used to extract the functional active compounds in MF-GR and KF-GR.The results showed that 80%ethanol solvent can extract more phenolic compounds than deionized water.And MF-GR's 80%ethanol extract has strong ability to scavenge ABTS free radicals and DPPH free radicals,as well as better iron ion reducing ability and reducing potential,EC50 values are 10.75±0.24 ?g/mL,15.97±0.21 ?g/mL,13.23±1.87 ?g/mL and 126.42±3.83 ?g/mL,respectively,indicating its anti-oxidation ability and positive photographic imitation.Microbial fermentation has a significant effect on the utilization of Fu brick tea and glutinous rice substrate and the release and conversion of phenolic compounds.MF-GR has the highest total phenol content after fermentation(alcohol extract contains 1.362 ± 0.010 mg GAE/g extract;water extract contains 0.821 ± 0.009 mg GAE/g extract),the total antioxidant capacity is the highest(alcohol extract 1.051 ±0.014 mg GAE/g extract;water extract 0.628± 0.012 mg GAE/g extract),the strongest antioxidant capacity,DNA protection.The degree of oxidative damage is greatest.In addition,the types and contents of phenolic compounds such as catechins in MF-GR and KF-GR were analyzed by high performance liquid chromatography.The results showed that MF-GR contained a variety of phenolic compounds,which was significantly higher than KF-GR.According to the Pearson correlation analysis,the type and content of phenolic compounds in the samples were closely related to the antioxidant activity exhibited by the sample.4.Protective effects of MF-GR and KF-GR on H2O2-induced oxidative damage of PC12 cellsThe protective effect of MF-GR and KF-GR on oxidative stress of PC 12 in neurons was investigated by establishing H2O2-induced oxidative damage model of PC 12 neuron cells.The extracts of MF-GR and KF-GR were compared at the concentrations of 100-500?g/mL.The effect of the concentration range on the survival rate of oxidative damaged cells was observed under the protective effect of different concentrations of samples,and the difference in cell morphology was observed by inverted phase contrast microscope and fluorescence microscope.Under the protection of MF-GR extract,the survival rate of oxidative damaged PC 12 cells was 75.0%,which was significantly higher than 68.3%of KF-GR extract and 46.3%of H2O2 injury group.Biochemical analysis showed that MF-GR and KF-GR extracts can significantly inhibit the occurrence of intracellular lipid peroxidation,protect cell membranes from oxidative damage,maintain their integrity,and effectively alleviate intracellular lactate dehydrogenase.Overflow;MF-GR and KF-GR extracts can significantly reduce the level of intracellular reactive oxygen species in oxidative damaged cells,ensure smooth mitosis,reduce the enzyme activity of the apoptotic enzyme Caspase-3,and thus reduce the damage caused by oxidative stress.MF-GR and KF-GR extracts can significantly enhance the cell's own antioxidant system,including increasing the activity of antioxidant enzymes and increasing the content of antioxidant peptides.The results showed that the protective ability of MF-GR extract on oxidative damage of PC 12 was significantly higher than that of KF-GR extract,and showed a dose-dependent mode.