Study On Column-type Dynamic Extraction Characteristics Of Baked Green Tea

Tea extraction technology is one of the key of the tea deep processing,it also has an important impact on product quality and yield of tea beverage,instant tea powder and tea function extractives.At present,the tea beverage extraction is mainly used in the tank-basket extraction or trough groove countercurrent extraction,and these methods are easy to operate and the product yield is high,but there also has some problem,like that the concentration of leaching solution is low and the quality of the extract is not easy to control,and not conducive to the application of instant tea or tea concentrate.In this paper,we study on the leaching characteristics of green tea is based on the column-type extraction by comparing with the traditional tank extraction.The leaching rule of green tea under different conditions was proved,directional extraction technology of tea infusion and its application are put forward.The main results are as follows:1.The results showed that traditional extraction of compositions in the pre-leaching stage(0 ~ 5 min)rapid leaching,column-type compositions have been growing.We also found the leaching rules of traditional and column-type extraction are in accordance with the quasi-second order kinetics equation,and traditional leaching of the material leaching rate is faster,while the column leaching can significantly improve the leaching yield,and has a better flavour than the traditional leaching in the early time of extraction,but the flavor quality was significantly lower with a higher bitter and astringent taste than traditional extraction in the later.2.The results showed that it can increase of amino acids content and reduce the content of polyphenols and caffeine in tea infusion in the first stage of extraction under the condition of lower velocity(10.5 mL/min)or larger granularity(10 mesh)or larger quality(180 g).Through clustering analysis showed that the characteristics of tea infusion were similar in the first 10 min under different velocity,and increase the flow rate enlarged the tea infusion taste in the later stage of the extraction process and lead to the turning point of tea taste appear earlier;The characteristics of tea infusion were similar between 0 ~ 10 and 10 ~ 20 and 20 ~ 40 minutes under different granularity.The characteristics of tea infusion with 180 g in the range of 0 to 10 minutes were significantly different from 120,150 g,and tea taste quality change inflection point sooner with less amount of tea.By comprehensive considering the influence of each factor,it is shown that the effect of temperature on the solids content is greater than than that of the other three in the first 10 minutes.while the effect of grain size is the second largest influencing factor in the time from 15 to 25 minutes,in the end,the granularity became the dominant factor.When it comes to overall flavour,temperature and velocity hold the dominant position in the first 10 min,during the period of 15 ~ 20 minutes,the influence of velocity and quality increased gradually and became the dominant factor,the overall flavour was mainly affected by velocity and quality in the time of 30 to 40 minutes.3.Based on the analysis of leaching of green tea quality components of column-type extraction under different conditions,and study on the effects of different combinations of temperature extraction on the leaching characteristics of green tea.The results showed that the extraction temperature of 50 ?in the first 15 min and adopted 90 in the later 25 minutes,which could effectively improve the flavor ?of later tea infusion which extraction by 90 ?,and make up the low yield of 50 defects;? The first 15 minutes with 19.5 mL/min,and adopted 10.5 mL/min in the later 25 minutes,which can effectively make up the low concentration of tea infusion in the later 19.5 mL/min,but also to some extent followed the high umami characteristics of tea infusionby 10.5 mL/min.It can obtian high umami green tea infusion in the first stage of column-type extraction under the condition of larger granularity and higher quality with the low temperature of 50 ? and a flow rate of 10.5 mL/min.In addition,we can get high yield mid-quality tea infusion under the 21.5rpm flow rate at 90 ? in the early stage,and then using the 10.5 mL/min flow rate with 70 at 10 ~ 25 min;Finally 10.5 mL/min flow rate with 50 ? ? were used in 25 ~ 40 min.