Analysis Of Quality Of Needle-shaped Famous Green Tea And Processing Of Shaping Pattern

The needle-shaped famous green tea brands on the market are complex and have different qualities.In order to understand the current development status of needle-shaped famous green tea,we collected representative brands from different regions for centralized evaluation.Aiming at the quality problems that are likely to occur in the needle-shaped famous green tea,the shaping process is optimized and the quality changes during the processing are studied.1.Analysis on the quality status of needle-shaped famous green teaSensory evaluation and Chemical analysis were conducted on 29 representative needle-shaped famous green teas from all over the country.The results show:The sensory evaluation scores of all tea samples ranged from 83.8 to 89.7.Among them,8 samples scored 88.0 and above,which basically met the requirements of needle-shaped famous green tea.The sensory evaluation showed that the appearance is tight and even,the color is green,the soup color is bright yellow and green,the chestnut fragrance is long,the taste is fresh and mellow,the leaf bottom is uniform,tender yellow and green.The samples scored 88.0 points and below 21,all showing certain quality problems.Dry tea has poor uniformity,broken tea leaves,unclear soup color,staleness of ripeness,grassy odor and even slight smoke,slightly astringent taste,and slightly mixed leaves at the bottom of the leaves.There is little difference between L* value and b* value range of dry tea.The a*value of dry tea and the b*/a* value of dry tea are quite different.The b*/a* value ranges from-70.18 to-4.79,the average value is-14.49,and there are 20 tea samples higher than the average value.This indicates that most tea samples have a higher ratio of yellow to green.The tea soup a* has a large difference and a high average value(6.29),indicating that the greenness of the tea soup is generally low.The content of water extract is between 64.89% and 52.36%,with an average content of 57.31%,which is quite abundant.The content of tea polyphenols ranges from23.59% to 30.23%,which is at a relatively high level.The free amino acid content rangedfrom 2.19% to 4.60%,with an average content of 3.17%.The difference between the tested tea samples was large.The soluble sugar content ranges from 1.55% to 4.55%,with an average content of 3.22%,and the content varies greatly.2.Research on the shaping and polishing process of needle bud type famous green teaOn the basis of the single-factor test in the early stage,the polishing process is set up with three-level orthogonal test of water content,temperature and time.The results show that the water content of the tea body,the shaping and polishing temperature and the time mainly affect the sensory quality of the needle bud-shaped tea,especially the compactness,greenness,smoothness and taste quality of the tea.The primary and secondary factors are in order.The water content,time and temperature of the green tea.The analysis results of the contained components show that,except for the influence of water content on soluble sugars,temperature on amino acids and soluble sugars,and time on tea polyphenols,the three factors have little influence on other contained components.According to the actual production,the shape and polishing process of needle bud-shaped green tea should control the water content of the tea body 15%?22%,room temperature,and time 5?7 h.It is appropriate to control the water content of 15%—variable temperature—7 h,and the water content of 22%—room temperature— The combination of 7 h,15% water content—room temperature—5 h has the best overall performance.3.Analysis of quality changes during processing of needle bud type famous green teaIn this experiment,the five key processes of the processing of Hubei needle bud type famous green tea,namely,finalizing,first trimming,second trimming,polishing,and drying,were studied.The water content,soluble sugar,amino acids,and tea in each sample were studied.Seven indicators of polyphenols,catechin components,chlorophyll components,and aroma components were analyzed.The results show:The water content of tea dropped from 72.92% of fresh leaves to 7.60%,and the water loss rate of each process of finishing,stripping and drying was between 17.27% and 21.71%,and the waterloss was even.The content of soluble sugars,tea polyphenols and phenol-ammonia ratio decreased,and each component of catechins decreased to varying degrees;the overall amino acid content showed an upward trend and decreased during the drying stage;the total chlorophyll decreased,except for pheophytin a Except for the increase in b content,the other components all decrease;the total amount of aroma substances is significantly reduced during the processing process,from fresh leaves to dry tea are mainly alcohols,hydrocarbons,alcohols,acids and esters,aldehydes The content decreases,and the content of ketones and nitrogen oxides increases.The similarity of fresh leaves and dry leaves was 0.76,and the scent type changed.