Mulberry Tea Process Research And Its Quality Analysis

Mulberry is a dual-purpose scarce resource with drug and food. Domestic and foreign scientific research confirms the nutritional contents, pharmacologically active ingredient and its mechanism of mulberry resources.Mulberry leaves contain Flavonoids,Amino acids,Alkaloids,Volatile oil,Steroidal ingredients.These chemical constituents have pharmacological or clinical efficacy with lower blood pressure,lower blood fat,anti-inflammatory,anti-virus,anti-aging,weight loss.The existing processing technology for mulberry tea is green tea processing technology-based. Mulberry black tea is made and introduced exogenous bacterial suspension to the fermentation process of the Mulberry black tea production(Aspergillus nigerAS3.469).Tea sensory evaluation method and taste quality of the chemical identification method were used to assess its quality.Optimize the parameters of its fermentation conditions.Identify and analyze the change of containing components contents during fermentation process.Determinating and analyze its antioxidant capacity.Test results are as follows:1.Mulberry black tea was produced with ordinary black tea processing methods,after withering, rolled,fermented,dryed.Exploring the impact of mulberry black tea fermentation conditions factors to determine the optimization interval based on the single-factor test,and then obtain the best fermentation conditions parameters through three factors and three levels orthogonal optimization.The results showed that:Order of factors affecting mulberry black tea's fermentation is fermentation temperature,fermentation time,and relative humidity.The optimum process conditions were fermentation temperature of 20℃fermentation time of 3 h, and relative humidity of 90%.Under this optimum conditions,The sensory evaluation score of mulberry black tea is 70 points.Comprehensive quality of appearance, liquor color and taste were the best.The kinetics analysis of active ingredient in the fermentation process showed that:Contents of Free amino acids and 1-DNJ, chemical taste score increased by fermentation time during 5 hours in fermentation process, contents of Polyphenol and Flavonoids decreased.After fermentation,contents of Free amino acids and 1-deoxynojirimycin (DNJ) increased about 28%.2. New mulberry black tea was produced with black tea processing methods which add a certain amount of bacterial suspension in fermentation process.Exploring the impact of new mulberry black tea fermentation conditions factors to determine the optimization interval based on the single-factor test, and then obtain the best fermentation conditions parameters through Box-Behnken method. The results showed that:Order of factors affecting new mulberry black tea's fermentation is fermentation temperature,fermentation time,and amount of bacterial suspension.. The optimized model as follows:Y=5.08-2.70375X32.The optimum process conditions were fermentation temperature of 30℃,fermentation time of 5 h, and amount of bacterial suspension of 0.16%.Under this optimum conditions, the sensory evaluation score of new mulberry black tea is 68 points.Comprehensive quality of appearance, liquor color and taste were the best.The kinetics analysis of active ingredient in the fermentation process showed that:Contents of Free amino acids,Rutin, Quercetin,and score increased by fermentation time during 5 hours in the fermentation process, contents of Polyphenol and Flavonoids decreased. Content of 1-DNJ increased by fermentation time and gradually reduced after the highest.After fermentation,contents of Free amino acids,Rutin and Quercetin increased more than 30%.3.Sensory quality evaluation results show that:Both mulberry black tea and new mulberry black tea's comprehensive quality of appearance, liquor color and taste were good. It is feasible to produce mulberry black tea with black tea processing methods.Score of mulberry black tea is slightly higher than new mulberry black tea,and the liquor color is relatively brighter. Analyze from the containing components contents,contents of Total polysaccharides,Free amino acids, Quercetin,1-DNJ of both mulberry black tea and new mulberry black tea increased relative to mulberry leaves.Compared to mulberry black tea,most of the ingredients of new mulberry black tea were higher, while the 1-DNJ was relatively less.Contents of Total flavonoids, Total polysaccharides, Polyphenols, Free amino acids, Rutin, Qquercetin increased by 14.2972%,11.4584%,2.6712%, 3.6192%,92.5287%,29.4118%,1-DNJ reduced the 16.535%.4. Antioxidant capacity determination of mulberry leaves, mulberry black tea and new mulberry black tea showed:Clearance rate get lower along with the reduction of vitamin C and mulberry black tea concentration. CRSR of mulberry black tea and new mulberry black tea is 0.67 times to that of vitamin C, and CRSR of mulberry leaves is 0.45 times to that of vitamin C.With the concentration decreasing,DPPH scavenging ability of mulberry black tea reduced. While vitamin C on the DPPH scavenging ability don't obviously changed, which are maintained above 90%.Hydroxyl radical scavenging of vitamin C and mulberry black tea decreased along with the concentration declining. The scavenging rate of mulberry is about 0.65 times to that of vitamin C.The activity of new mulberry black tea is about 0.6 times to that of vitamin C. While the activity of mulberry black tea is approximately 0.55 times to that of vitamin C.Both the Fe2+ chelating ability of mulberry tea and mulberry leaves are lower than that of EDTA, the chelating rate of EDTA was up to 90%. Reducing ability of mulberry leaves is equal with that of vitamin C,and that of new mulberry black tea is 0.8 times to that of vitamin C. Moreover, reducing ability of mulberry black tea is about 0.6 times to that of vitamin C.