Study On The Mixed Fermentation Technology Of The Liquid Tea Beverage

As we all know,China is a big country of tea production.But,the utilization rate of low-grade tea is fairly low.So,the development of tea comprehensive processing technology and the exploitation of tea functional components should be an important way to improve the utilization rate of low-grade tea.This thesis aims to develop a new type of tea beverage to improve the utilization of low-grade tea,and provide a reference for the study of the phenomenon of low-grade tea to ease unmarketable.The author took the low-grade green tea as raw material and combined with the theoretical knowledge of Microbiology for developing a new type of tea beverage made several studies:1.The isolation and identification of the dominant bacteria from Fu Brick Tea.Take Anhua dark tea as raw material to get 2 strains of Anhua dark tea fermentation strains by dilution plate method and streaking method.Then take the measured strains of18 S rDNA sequence with the known sequences in the GenBank database for homology analysis by using Blast tool.Conclusion: the 2 strains of bacteria from Fu Brick Tea were Eurotium Cristum and Aspergillus niger.2.Study on the effects of Monoxenie Fermentation and Mixed Fermentation on the quality of tea beverage.Green Tea was inoculated with the 2 strains of the dominant bacteria from Fu Brick Tea to make Monoxenie Fermentation and Mixed Fermentation respectively.Results:(1)The sensory quality scores of the Green Tea that without microbial fermentation only71.80 points.Greenish yellow liquor color,suspension,aroma harsh and stale,ripe taste and astringency;(2)The sensory quality scores of the Eurotium Cristum tea fermentation liquid is 80.90 points.Orange yellow liquor color,unique and heavy arohid flavour,with a sense of cool,mellow taste,slightly sour,slightly sweet aftertaste;(3)The sensory quality scores of the Aspergillus niger tea fermentation liquid is 79.25 points.reddish auburn liquor color,aroma pure and sweet,heavy and thick,bitter,sweet after taste;(4)The sensory quality scores of the Mixed Fermentation liquid is 89.60 points.Reddish auburn liquor color,deep,but lighter than the Aspergillus niger tea fermentation liquid,both arohid flavour and sweet aroma,but do not conflict with tea aroma.Taste mellow and thick,Cool sweet mouth thick,long aftertaste,with tea flavor.Conclusion: The microbial fermentation technology can significantly improve the sensory quality of green tea,especially Mixed Fermentation.The Mixed Fermentation is higher than the Monoxenie Fermentation in the sensory evaluation of the liquor color,aroma and taste.3.Optimization of the Mixed Fermentation conditions.Select the inoculum concentration,fermentation time,shaking speed and the ratio of tea to water as factors of influencing the Mixed Fermentation liquor quality to design single factor test.The optimum levels of these four factors were: inoculum concentration4 %,fermentation time 12 days,shaking speed 150 r/min,and the ratio of tea to water 1:30.Based on that,L9(34)orthogonal experiment schemes was designed to optimize the Mixed Fermentation conditions.Then,the results of orthogonal test were analyzed by variance analysis.The results showed that the effect of fermentation time and the ratio of tea to water on the sensory quality of mixed bacteria tea fermentation liquor were extremely significant;the effect of inoculum concentration and shaking speed on the sensory quality of mixed bacteria tea fermentation liquor were not significant.Therefore,we can select the combination that is the most economic benefit according to the actual situation.The optimal combination of this study was: inoculum concentration 4 %,fermentation time 10 days,shaking speed 150 r/min and the ratio of tea to water 1 : 40.At this time,the fermentation broth overall darker,reddish brown,clear and bright,both arohid flavour and sweet aroma,no smell,strong coordination,Taste mellow and thick,Cool sweet mouth thick,long aftertaste,with tea flavor.4.Preliminary amplification of Mixed Fermentation conditionsAccording to the ratio of tea to water 1: 40 to prepare tea culture,has access Eurotium Cristum and Aspergillus niger,time intervals for 3 d,inoculation ratio is 1: 1,inoculum concentration is 4 %,the laboratory experiment in 3 L fermenter,the temperature is 28 ?,the stirring speed of 120 r/min,the fermentation time for 6 days,after the end of the fermentation of sensory evaluation.The sensory quality scores of the Mixed Fermentation liquid is 86.90 points.Reddish auburn liquor color,deep,both arohid flavour and sweet aroma,slightly thicker,no smell,Taste mellow and thick,Cool sweet mouth thick,long aftertaste,with tea flavor,cotton slip sense.But it can't get the same quality products with the shaking table test.Conclusion: the preliminary amplification of Mixed Fermentation conditions still need to be confirmed by a large number of experiments,which needs further study.