Studies On The Mechanism Of Stale Process And The Technique For Improving The Quality Of Puer Tea

Puer tea is a major product of Chinese theditional brick tea. With the unique charactersand outstanding health-callng functions, Puer tea has comrnanded the good reputation inworidwide. ln our investigation vtriance in the contents of main chemical comPonents of YurmanPuer tea were studied at different storage condition. At the same time, the influence of radiationon the quality of Puer tea was investigated.The results of the studies indicated that with the time of storage and the rising in temPeratupe,all of the contents of watersoluble sugar, amino acid, and tea polyPhenols were decreased. Theinitial water content co--worked with temPerafore posed a great imPact on transformation of themduring storage. The increasing in initial water content could cause the increasing degradation inamino acid and tea polrphenols, but the course of degradation in sugar contellt was oppositelyslowed. To the end of treamient, under the room tCmPehalre, the maximal decrement of sugar,amino acid and tea polyPhenols were 37.15%, 50.09%, 23.2l%, respectively. Catechins,especially, comPound catechins, inclined to decreasing in the whole period of storage. Stored atroom tCmPerature for 225d comPound catechins were reduced by 85.40. On the other hand, gallicacid contefit was increased with time eXtsion, except for treated under 55 C.TIansformation rate of caffeine during storage was relatively slow, though, the trCnd ondecline of caffeine content still could be observed. At room temPerature, the correlationcoefficient betWeen caffeine and stOrage time was -0.7646**(P<0.0l), but no significantcorrelation existed between caffeine and initial water content. TemPerature had an active role onaccelerating the rising of caffeine content, with a significant correlation coefficient0-8524**(P<0.0l). Stored at 55 oC, post 45d, content of caffeine could be incredsed by 6.45%.The oxidation products of tea polyPhenols -- theaflavins (TF), thearubigins (TR), andtheabrownin (TB) were increasing with time during storage. The increment of TB, under the 55 C,was lower comPared to other managed temPeratUr. At 55 oC, even could leading to decreasing onTB, to the end of treatment TB content fell by 2.31%.The high significant difference was observed in watersolub1e matter when treated withvarious temPeTature and storage time extension. The correlation coefficient betWeen water-solublematter and temPerature was -0.5657**O<0.0l), but no significant correlation betweenwatersoluble matter and storage time. Treated with 12%-55C, led to the uPmost decline ofl2.l3%. OPPositely, under the treatments of 9%--room temPeratllre, 9%--27 eC, 7%--roomtemPehalre, the water--soluble matter was raised.Thrugh organoleptic tasting fOund that it was the interaction of transfOrmation on somecomPonents in Puer tea that caused the changes on itS quality. Based on studies results, wesuggested thatt stored at room temPeratUre, half year was aPpropriate storage time extension;under 37C, l35d was right; but if tfeated with 55t, 45d was advised. Furthermore, within theappropriated storage time extension, under different storing temPerature could cause differentaroma styles f under room temPetalre, it was stale; under 37oC, it was musty, but with time thearoma becam camerised, tmder 55oC, jujube-like aroma was smelled, if storage overtimed itwould deteriotale to sour.Analyzed all the data and formulated several mathematical models on which could be basedto predicted the transformation of the main components contents under the different storagecondition.The effect of radiation on the quality of Puer tea during storage was discussed. Settingseveral trCatmellts of various dosages of radiation and with differeflt initial water contents in Puertea, it found that contents of amino acid, tea polrphenols and the oxidation products ofpolrphenols were kind of increasing; oppositely, caffeine and catechins, particularly, comPoundcatechins were decreasing. Conthested...