中国农业科学 ›› 2021, Vol. 54 ›› Issue (18): 3984-3997.doi: 10.3864/j.issn.0578-1752.2021.18.016

• 食品科学与工程 • 上一篇    下一篇

外源茉莉酸甲酯诱导茶树鲜叶及其采后乌龙茶加工关键工序中七种脂溶性色素变化

施江1(),王佳童1,2,彭群华1,吕海鹏1,BALDERMANN Susanne3(),林智1()   

  1. 1中国农业科学院茶叶研究所/农业部茶树生物学与资源利用重点实验室,中国杭州 310008
    2中国农业科学院研究生院,中国北京 100081
    3德国莱布尼茨蔬菜与园艺作物研究所,德国柏林 14979
  • 收稿日期:2020-10-26 接受日期:2020-12-29 出版日期:2021-09-16 发布日期:2021-09-26
  • 联系方式: 施江,E-mail: shijiang@caas.cn。
  • 基金资助:
    国家现代农业产业技术体系建设专项资金(CARS-23);国家自然科学基金面上项目(NSFC31270734);中国农业科学院创新工程(CAAS-ASTIP-2014-TRICAAS)

Changes in Lipid-Soluble Pigments in Fresh Tea Leaves Treated by Methyl Jasmonate and During Postharvest Oolong Tea Manufacturing

SHI Jiang1(),WANG JiaTong1,2,PENG QunHua1,LÜ Haipeng1,BALDERMANN Susanne3(),LIN Zhi1()   

  1. 1Tea Research Institute, Chinese Academy of Agricultural Sciences/Key Laboratory of Tea Biology and Resource Utilization of Ministry of Agriculture, Hangzhou 310008, China
    2Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
    3Leibniz Institute of Vegetable and Ornamental Crops, Theodor-Echtermeyer-Weg 1, 14979 Großbeeren, Germany
  • Received:2020-10-26 Accepted:2020-12-29 Published:2021-09-16 Online:2021-09-26

摘要:

【目的】系统开展外源茉莉酸甲酯诱导以及“做青”阶段机械损伤双重胁迫下茶叶中脂溶性色素的动态变化研究,阐明外源茉莉酸甲酯诱导后茶树鲜叶制得乌龙茶中类胡萝卜素含量提高的机理,为合理利用外源诱导提升鲜叶品质和加工制得的乌龙茶品质提供科学依据。【方法】0.25%外源茉莉酸甲酯喷施3—4年生盆栽‘金萱’茶树叶面,至均匀挂滴,对不同诱导时间(0、12、24、48和168 h)的鲜叶及利用该鲜叶制作得到的乌龙茶样品进行基于UPLC-QToFMS的靶标代谢组学分析,解析叶黄素、β-胡萝卜素、新叶黄素、玉米黄质、α-胡萝卜素和叶绿素a/b的含量变化;同时对乌龙茶制作的关键工序“做青”以及杀青后揉捻阶段样品中这些脂溶性色素的动态变化进行监测分析。同时,开展不同诱导时间采摘的鲜叶加工得到成品乌龙茶的香气感官评价。【结果】靶标代谢组学分析结果表明,叶黄素是‘金萱’鲜叶中含量最高的类胡萝卜素,其含量达到(405.06±17.71)µg·g-1,在成品乌龙茶中含量显著下降,仅为(277.36±32.72)µg·g-1。外源茉莉酸甲酯诱导后,脂溶性色素含量变化显著,诱导48 h内,茶树鲜叶中叶绿素a含量较对照鲜叶中(0 h)增加,随后显著下降;叶绿素b在诱导后的鲜叶中始终处于减少的趋势。叶黄素在12 h样品中含量显著下降,在24 h的样品中其含量均较对照升高;β-胡萝卜素在诱导后的鲜叶中含量始终低于对照,其中12 h的样品中含量仅为116.36 µg·g-1,减少34.55%。利用茉莉酸甲酯诱导后的鲜叶(12、24和48 h)制作得到的成品茶样品中叶绿素a含量较对照均显著下降;叶黄素含量显著升高,其中48 h的样品中含量最高,达到377.82 µg·g -1。“做青”过程中(W1—W3),对7种脂溶性色素含量变化进行相应的热图分析,与对照相比,叶绿素a含量均显著下降,而叶绿素b含量则在12 h样品中显著升高。5种类胡萝卜素的含量动态变化则更加复杂,含量最高的叶黄素在12 h样品中含量显著下降,随后在24和48 h的样品中含量略有升高;β-胡萝卜素的含量始终低于对照。此外,玉米黄质和α-胡萝卜素在诱导12 h以后的样品中始终维持非常高的含量。揉捻阶段的样品,7种脂溶性色素也呈现出显著变化,除了β-胡萝卜素含量较对照样品减少,叶黄素、新叶黄素、玉米黄质以及α-胡萝卜素的含量在诱导12 h后的样品中均比对照高。茉莉酸甲酯诱导的样品中,叶绿素a的含量降低,叶绿素b的含量在诱导12 h后增加。此外,茶叶感官审评结果表明,外源茉莉酸甲酯诱导后茶树鲜叶加工得到的乌龙茶香气品质显著提升,具有持久浓郁的花香,然而其叶底明亮度和柔软性较未处理的对照样品有所下降。【结论】外源茉莉酸甲酯诱导茶树鲜叶,24 h内可以显著提高鲜叶及成品茶中的类胡萝卜素含量,诱导12 h后鲜叶加工得到的成品茶香气品质显著提高,具有浓郁的花香。外源诱导与“做青”机械损伤双重胁迫激发茶鲜叶中脂溶性色素的差异积累。

关键词: 茉莉酸甲酯, 做青, 脂溶性色素, 类胡萝卜素, 乌龙茶

Abstract:

【Objective】The dynamic changes of lipid-soluble pigments in tea under the dual stress of exogenous methyl jasmonate induction and mechanical damage trigged during "making green" stage were systematically studied. It could greatly clarify the mechanism of improvement in the content of carotenoids in making oolong teas prepared from the leaves treated by methyl jasmonate. This will offer the scientific guidance applying of exogenous elicitors improving fresh tea leaves quality and the made tea quality.【Method】The 3-4-years ‘Jinxuan’ tea cultivars in greenhouse were used as plant materials, which were applied 0.25% (v/v) methyl jasmonate solution by spraying on tea leaves homogenously until it was evenly dripped. Fresh leaves under different treated time duration (0, 24, 48, and 168 h) and the responding made oolong teas were prepared using the fresh leaves. In this study, the targeted metabolomics analysis was carried out utilizing UPLC-QToFMS aiming at analysis of changes in content of lutein, β-carotene, neoxanthin, zeaxanthin, α-carotene and chlorophyll a/b. At the same time, the dynamic changes of the lipid-soluble pigments during crucial procedure “making-green” and rolling stage were monitored. Furthermore, the sensory evaluation of made oolong teas focusing on the aroma quality was investigated.【Result】The quantitative results showed that the content of lutein reached (405.06±17.71) µg·g -1 in fresh leaves which was the highest of all other carotenoids, however, it decreased dramatically in made oolong teas (277.36±32.72) µg·g-1. Lipid-soluble pigments changed significantly in methyl jasmonate treated tea samples. In the first 48 h after methyl jasmonate inducement, chlorophyll a behaved significantly increased in content compared with control (0 h) in fresh leaves, successively decreased in 168 h samples. Chlorophyll b decreased in all methyl jasmonate induced samples. Lutein exhibited an apparently decreasing in 12 h samples, thus achieved improvement in content in 24 h samples. The content of β-Carotene was lower in methyl jasmonate induced samples than that in controls, especially in 12H samples, its content was 116.36 µg·g -1, decreased by 34.55%. In made oolong teas prepared from methyl jasmonate-induced tea leaves (12, 24 and 48 h), the content of chlorophyll a behaved significantly decrease compared with 0 h, whilst lutein prompted quite absolutely, especially in 48 h, whose content reached 377.82 µg·g -1. Aiming at a clear glance, the heatmaps of the content changes of the lipid-soluble pigments were prepared, and the results showed that the content of chlorophyll a decreased in all treated samples during “making-green” stage (W1-W3) comparing with the control samples. Meanwhile, chlorophyll b apparently increased after 12h duration of methyl jasmonate inducement. Besides, the changes of the carotenoids behaved more complicated. Lutein behaved a decreasing tendency in 12 h samples, however increased in 24 and 48 h samples. β-Carotene exhibited a lower content in all treated samples, thus, zeaxanthin and α-carotene maintained a higher content compared with the control samples. In the rolling stage, the above-mentioned lipid-soluble pigments changed significantly in content. With exception of β-carotene which decreased in all treated samples, lutein, neoxanthin, zeaxanthin, and α-carotene achieved a higher content in 12, 24 and 48 h samples. It was clear that chlorophyll a decreased in methyl jasmonate treated samples in rolling stage, whilst chlorophyll b increased after 12 h. Moreover, the sensory assessment confirmed the results of aroma quality promotion in made oolong teas prepared from methyl jasmonate treated fresh leaves, however with a loss of brightness and softness in the foliage fundus.【Conclusion】In conclusion, the content of carotenoids in fresh tea leaves and the made oolong tea were absolutely improved within 24 h time duration after methyl jasmonate treatment. It was confirmed that the aroma quality was improved in made oolong tea prepared from MeJA-treated fresh leaves after 12 h which was in rich of fragrancy flavor. Differential accumulation of lipid-soluble pigments was primed under the dual stress of exogenous methyl jasmonate induction and mechanical damage trigged during “making-green” stage.

Key words: Methyl jasmonate, making-green, lipid-soluble pigments, carotenoids, Oolong tea