关键词: 茶叶；杏仁香；香气成分；苯甲醛；适制性

Abstract: To evaluate the tea processing suitability of the leaves of ‘Guixing’ tea, a wild tea plant germplasm resource in Guangxi, the water extract content, polyphenolic composition, sensory properties and volatile aroma composition of the tea leaves as well as green, oolong, white and black tea processed from the tea leaves were measured and compared with each other. The results showed that ‘Guixing’ tea was a unique tea germplasm resource with low caffeine content and a ratio of phenol to ammonia of 11.8, which was more suitable for black tea production. After processing into white and black tea, the epigallocatechin content in the leaves decreased to 0, and the catechin content of green tea decreased significantly compared with that of the leaves. The results of sensory evaluation showed that white and black tea had a rich almond-like aroma, while the other kinds of tea did not. A total of 53 aroma components were detected, which could be divided into two types. Each type had same aroma components. The first type included tea leaves, green tea and oolong tea, without almond-like aroma, and had 40 aroma components, the major ones being β-linalool and limonene. The second type included white tea and black tea, with strong almond-like aroma, and contained 42 aroma components, the main one being benzaldehyde. A total of 28 aroma components were found to be common to these tea samples, all of which contained benzaldehyde. The decreasing order of the relative contents of benzaldehyde in them was black tea (61.97%) > white tea (31.73%) > oolong tea (14.65%) > leaves (4.24%) > green tea (2.88%). Benzaldehyde was mainly produced during withering, rolling and fermentation. With extended withering time, the content of benzaldehyde increased. The higher the content of benzaldehyde, the stronger the almond-like aroma of tea. Therefore, benzaldehyde is key for almond-like aroma formation.

Key words: tea; almond-like aroma; aroma components; benzaldehyde; processing suitability