烘焙程度对绿茶香气品质的影响

Effect of Different Roast Degree on Aroma Quality of Green Tea

利用顶空固相微萃取与气相色谱质谱联用(HS-SPME-GC-MS)并结合相关性分析研究了烘焙程度对绿茶挥发性风味成分品质的影响。结果表明:随着烘焙程度加深,绿茶的清香逐渐减弱,花香、果香及甜香以中度烘焙茶叶中最为丰富,深度烘焙的茶叶以烘焙香为主;不同烘焙程度绿茶香气主要区别在于吡嗪、吡咯类组分的生成与增加,醛类、醇类和酮类组分的减少或消失;并研究提出可把吡嗪、吡咯及呋喃类组分占香气总量的比例作为判断绿茶烘焙程度的重要参考指标,轻度烘焙中比例低于15%,中度烘焙的比例介于15%和30%间,当高于30%时为深度烘焙;进一步研究发现有28个香气组分与香气评分相关性较高,10个吡嗪类组分,8个吡咯、吡啶、呋喃等含氮化合物,3个醇类组分,4个醛类组分,还有二甲硫、己酸-顺3-己烯酯和β-紫罗酮,它们在不同烘焙程度绿茶中相关性显著且对绿茶的香气属性贡献较大。

Gas chromatography-mass spectrometry（GC-MS）and headspace solid phase microextraction（HS-SPME） combined with correlation analysis have been successfully applied to analyze the effect of different roast degree on aroma quality of green tea. The results showed that faint scent of green tea become weaker with the deepening of roast Floral, fruity and sweet flavor were very strong in medium roast,while heavily roasted green tea had the highest baking flavor;the major difference of green tea aroma in different roast degree was that pyrazine,pyrrole components increased while aldehydes,alcohols and ketones components decreased;the proportion of pyrazine,pyrrole and furan in total aroma was proposed as an evaluation criterion to judge roast degree of green tea;the proportion of light roast was less than 15%, medium roast between 15% and 30% and heavy roast up over 30%. Twenty-eight volatile compounds had high correlation with aroma attributes,such as ten pyrazine components,pyrrole,pyridine,furan and other nitrogen compounds,three alcohol components,four aldehyde components,dimethyl sulfide,cis-3-Hexenyl hexanoate andβ-ionone. They were significantly correlated with green tea aroma in different roast degree and had a bigger contribution to each aroma attributes.