采用九龙袍品种颗粒型乌龙茶的毛茶样为材料,在120℃(高火)、100℃(中火)和80℃(低火)3个温度下分别烘焙2βh,分析比较了不同烘焙温度对颗粒型乌龙茶感官品质、主要理化成分及挥发性成分的影响。感官审评结果表明,低温烘焙(80℃)茶样的感官审评得分最高,且香气和滋味最好;化学成分分析表明,水浸出物和氨基酸总量随着烘焙温度的升高呈现明显的降低趋势,而儿茶素总量、咖啡碱、黄酮化合物等随着温度的升高变化不显著;此外,茶氨酸、天冬氨酸、丝氨酸、谷氨酸等氨基酸成分随着烘焙温度的升高而降低,而EGC、C等儿茶素成分含量随着烘焙温度的升高而升高;挥发性成分分析表明,随着烘焙温度的升高,醇类、酮类、酯类物质以及含氮化合物的相对含量均呈现降低趋势,碳氢化合物含量呈现上升的趋势;具有清新花香的挥发性成分(如β-芳樟醇及其氧化物、橙花叔醇、己酸叶醇酯、异戊酸己酯、β-丁酸苯乙酯、苯甲酸己酯、茉莉酸甲酯、己酸己酯、α-紫罗酮、香叶基丙酮、顺-茉莉酮、吲哚等)的相对含量随烘焙温度的升高而降低,而碳氢化合物成分(如β-月桂烯、柠檬烯、5-甲基-辛-1,3-二烯、2,4,6-三甲基-1,3,6-庚三烯、β-倍半水芹烯、十二烷等)以及含氮化合物(如苯乙腈等)相对含量随着烘焙温度的升高呈现大量增加的趋势。
In order to investigate the optimum baking temperature for granular shaped oolong tea processing, final firing tea was used to bake at 120℃, 100℃and 80℃, respectively. By sensory evaluation, we found that the score of Jiulongpao Oolong teas with 80℃baking temperatures were higer than other Jiulongpao oolong teas. The quality of Jiulongpao Oolong tea baked with 80℃ temperature was the best. Chemical analysis indicated that the contents of the major biochemical components of oolong tea, such as tea polyphenols, the water extract and the amino acid decreased with the increase of baking temperature, but the contents of caffeine, the total catechins and the flavonoid constituents revealed no significant differences. The contents of L-Theanine, Aspartic aicd, Serine, Glutamic acid were decreased while the content of EGC and C were increased with the raise of baking temperature. The aroma constituents of Jiulongpao Oolong tea with different baking temperature treatment were determined by HS-SPME/GC-MS.The content of alcohols, esters, ketones and nitrogenous compounds were decreased but the alkane and the vinyl compounds were increased. Concentration of aromatic constituents with aroma of flowers such as linalool, linalool oxides, nerolidol, hexanoic acid, 3-hexenyl ester, (Z)-butanoic acid, 2-methyl-, hexyl ester, β-phenylethyl butyrate, benzoic acid, hexyl ester, methyl jasmonate, hexanoic acid, hexyl ester, α-Jonone, 5,9-Undecadien-2-one,6,10-dimethyl-, cis-Jasmone, indole decreased. The Hydrocarbon compounds such as β-Myrcene, Limonene, 5-Methylenecycloocta- 1,3-diene, β-sesquiphellandrene, 2,4,6-Trimethyl-1,3,6-heptatriene, dodecane and the nitrogenous compounds such as benzyl nitrile increased distinctively.
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