Effects Of Spreading Process With Heated Air Conditions On Quality Of High Quality Flat Green Tea

To improve quality and raise rate, many corporations have begun to adopt heated air spreading in west of Sichuan regions. Heated air spreading replaced old common temperature spreading. However, holding the conditions of green tea technics is resorted by manipulators'experiences. Only relying on the accumulate of experience is difficult to gain right and effective the processing parameters. It is empty of material theoretic gist. Therefore, improving on,optimizing technology and optimal matching for quality tea production are imperative.Normal spreading temperature does not only take time, but also the rate is low. At present, some manufacturers depend on experience to confirm the exact air temperature when they adopt hot air in the spreading processing. It is devoid of veracity. According to the tea industrial requirement and the research actuality, this paper study the variation of major chemical composition in the spreading, as well as the impact on the quality of tea with different tedding air temperature. At the same time, it posts the improvement and optimization of technical parameters of green tea. The results were as follows:1. There were obvious effects of hot air on weight loss rate of fresh tea leaves during spreading. If the tea fresh leaves were treated with different air temperature during spreading, when the weight loss rate reached the same, the spreading time used was observably discrepancy. When the weight loss rate of tedding leaves arrived at about 20 percents, the spreading time needs six hours with common air temperature.20℃air treated with a half and an hour,25℃air treated with needs only one hour and 30℃needs shortest time. The temperature is higher, weight loss rate is faster. And the rate is observably higher than common air temperature spreading.2. There was remarkably different variance of main chemic components in fresh tea leaves with different air temperature during spreading. (1) Contents of polyphenols took on diverse course during different air temperature spreading. Content of polyphenols reduced at first, then increased during spreading with common air temperature. However, content of polyphenols gradually reduced under 20℃,25℃and 30℃spreading. (2) Content of amino acid increased under common air temperature spreading. Content of amino acid increased at first, then reduced with 20℃and 25℃spreading. But content of amino acid decreased in the first instance, and then increased. (3) Content of caffeine gradually increased under normal temperature and 20℃spreading. Content of caffeine showed a state of flux and reflux. Common air temperature spreading was better for holding contents of caffeine than heated air spreading. (4) Content of water extract gradually increased under common air temperature spreading. Content of water extract increased in the beginning, then decreased under 20℃and 25℃spreading. Nevertheless, content of water extract reduced under 30℃spreading. (5) Content of total soluble sugar increased a bit besides under 20℃spreading. (6) Content of total Esters-catechins reduced,but content of simple catechins increased under common air temperature, 20℃,25℃, and 30℃spreading. Spreading with different conditions, physical and chemical changes of tea fresh leaves in the rate of change is not equal. The conditions of different spreading changed the main ingredients ratio in tea, which as to improve the quality of tea provides the material base.3. This experiment was compare test on some factors as the spreading air temperature, spreading time, spreading thickness. The product was manufactured by the process of flat famous green tea. The data, which were the best combination of spreading process with heated air parameters of different tenderness tea, were verified through tea organileptic evaluation and the analysis on the chemical components of made tea. (1)The quality of the tea at 20 percent weight loss rate treated with heated air under spreading was higher than that under normal temperature by organileptic evaluation. (2) The contents of amino acid and total chlorophyl treated with heated air under spreading were more than that under normal temperature spreading. But the content of polyphenol under normal temperature spreading were more than that treated with heated air under spreading. Heated air temperature spreading process was better for the simple catechins reservation in tea than normal temperature spreading. Hot air treatment spreading is also beneficial to the reservation of glutamic acid, aspartic acid and other components of free amino acids in tea. (3) Effects of spreading air temperature, time, and thickness on the quality level were significant. The best combination of hot air Spreading process was 25℃of spreading air temperature, one hour of spreading time,6cm of spreading thickness. And the weight loss rate of spreading fresh leaves was about 20%, which is best.