| Tea processing is an important link in the formation of tea quality,and it is also a process with relatively high energy consumption and relatively weak quality control accuracy and consistency.For many years,tea processing research has mainly focused on tea making theory,processing technology and new product development,while less research is involved in energy saving,environmental protection and controllable technology.Energy shortage is a prominent problem in the world today,how to reduce energy consumption in production is an important issue of concern and research for the whole society,and so is tea production.The study of energy saving and environmental protection technology in tea processing,reducing energy consumption and environmental pollution in tea production,is the guarantee of low carbon production of tea products;at the same time,based on the formation of tea quality,improving the control technology of key aspects in tea processing will undoubtedly have a positive effect on improving the efficiency of tea processing and stabilizing and improving the quality of tea.In view of this,this study applies the air source heat pump technology with the characteristics of "energy saving,environmental protection and control" to the tea processing process,and improves the existing equipment according to the needs,and develops new equipment suitable for tea processing.The differences in the intrinsic components,sensory quality,non-volatile metabolites and aroma compounds were analyzed and compared.This study and the main results are as follows:1.The results of comparing the processing efficiency and controllability are as follows: using air source heat pump technology to process white tea not only has high efficiency and strong controllability,but also meets the white tea standard and the quality is stable.Using air source heat pump technology to ferment black tea not only has high efficiency and strong controllability,but also the fermented black tea has uniform color,few flowers and stable fermentation quality.Using air source heat pump technology to dry unfermentation puer tea can save13.84% of energy consumption and 68% of drying time per ton.2.The content and sensory quality of white tea,fermented black tea and dried unfermentation puer tea processed by different methods were analyzed.The results showed that there was no significant difference in water extract,caffeine and amino acids among white tea processed by different methods,but there were significant differences in tea polyphenols,catechins and flavonoids.Tea polyphenols content was ACK 18.95%,A19.73%,and catechin content was ACK 6.56%,A 10.9%.The content of flavonoids is ACK 5.65mg/g,A 7.43mg/g.The white tea processed by air source heat pump technology has a light apricot yellow color,bright aroma,slightly flower and fruit aroma,sweet and fresh taste,and has a higher score in color,aroma and taste,with a comprehensive score of 86.2 and a traditional processing score of 82.65.The contents of tea polyphenols,caffeine and flavonoids in black tea fermented by different methods were not significantly different,but the contents of water extract,catechin and amino acid were significantly different.The content of water extract was BCK 41%,B 43%,the content of catechin was 18.29mg/g,the content of23.16mg/g was BCK,the content of amino acid was BCK 2.2%,B 2.1%.The ratio of BCK TR/TF was 13.29 and the ratio of B was 12.92.Black tea soup made by air source heat pump fermented black tea had bright orange color,rich aroma,long-lasting,sweet and mellow taste,and had higher scores in color,aroma and taste,with a comprehensive score of 89.2 and traditional black tea of 85.65.The results of sensory evaluation of different drying methods of unfermentation puer tea are as follows: there is no significant difference in water extract,caffeine,amino acid and tea polyphenols,but there is a significant difference in the content of flavonoids.The content of flavonoids is CCK 7.93mg/g,C 5.88mg/g.Air source heat pump dried unfermentation puer tea scored higher in soup color,aroma and taste,with a comprehensive score of 86.5,and traditional dried unfermentation puer tea scored 81.35.3.Non-volatile metabolites in white tea,fermented black tea and dried unfermentation puer tea were detected by gas chromatography-mass spectrometry(GC-MS).The results showed that a total of 721 differential metabolites were detected in white tea samples.compared with traditional white tea samples,402 substances were significantly up-regulated and 319 substances were significantly down-regulated.The relative content of most metabolites in white tea increased,indicating that air-source heat pump technology and equipment can promote the production and accumulation of most metabolites in white tea.A total of 1225 metabolites were detected in black tea with different fermentation methods,and the relative content of most metabolites in black tea fermented by equipment increased significantly,indicating that air source heat pump fermentation can promote the production and accumulation of most metabolites.A total of590 differential metabolites were detected in different drying methods of unfermentation puer tea,of which 414 differential metabolites were significantly up-regulated and 176 down-regulated.The drying temperature and time of air source heat pump drying unfermentation puer tea are more stable,so the formation and accumulation of metabolites are more regular in the drying process,which makes the content of metabolites more abundant.4.The volatile metabolites in white tea,fermented black tea and dried unfermentation puer tea were detected by gas chromatography-mass spectrometry(GC-MS).In the detection of volatile metabolites in white tea samples,there were 31 differential metabolites,of which 25 substances were significantly up-regulated and 6 substances were significantly down-regulated,including alcohols,aldehydes,acids,esters and other different categories.Alcohols,aldehydes,acids,esters and heterocyclic compounds are the main aroma components.A total of 146 different metabolites were detected in black tea fermented in different ways,of which 134 metabolites were significantly up-regulated and 13 metabolites were significantly down-regulated,including alcohols,aldehydes,ketones,terpenes and so on.Four kinds of differential metabolites were detected in different drying methods of unfermentation puer tea,including alcohols,aldehydes and esters.To sum up,the use of air-source heat pump technology to process white tea can effectively improve the quality and efficiency of tea,and the type and quantity of metabolites are obviously more.Compared with traditional fermentation,air source heat pump technology has the advantages of high efficiency,strong controllability and stable quality.Air source heat pump technology is conducive to the production and accumulation of non-volatile metabolites.At the same time,it also helps to improve the brightness and taste of black tea,and can improve the overall fermentation quality of black tea.Compared with traditional dry pressed tea,air source heat pump technology has better drying effect,better tea quality and lower energy consumption.Therefore,the application prospect of this technology is very broad,and it will help to improve the efficiency and sustainable development level of the tea industry. |
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