LED光照萎凋对贡眉白茶香气品质的影响

Effects of different LED lights during withering process on the aroma quality of Gongmei white tea

  • 摘要: 【目的】明确不同LED光照萎凋对贡眉白茶香气成分的影响,为白茶加工全天候和标准化光照萎凋生产提供理论支撑。【方法】以无光萎凋作对照,采用感官审评法,顶空固相微萃取法结合气相色谱—质谱联用技术(HSSPME-GC-MS),同时采用气味活度值(OAV),系统研究LED红光(630 nm)、黄光(570 nm)、蓝光(430 nm)和日光萎凋对贡眉白茶香气成分的影响。【结果】4种光照萎凋的贡眉白茶感官审评中香气得分均高于无光萎凋,其中黄光组的香气得分(89.1分)最高,呈现花香,其他3种光质以清香为主。所测样品中共检测出16种醛类、17种醇类、10种酯类、11种酮类、10种碳氢化合物及其他香气成分等共计68种,其中各处理共有成分58种。4种光质均可提高贡眉白茶样品的香气成分总量,其中黄光萎凋下贡眉白茶的香气成分总量(279.736 μg/L)最高,且醛类(46.787 μg/L)、醇类(173.163 μg/L)、酮类(16.889 μg/L)、杂氧化合物(6.823 μg/L)、碳氢化合物类(12.574 μg/L)、醚类(0.388 μg/L)及含硫化合物(3.608 μg/L)的成分含量均高于其他光质和无光处理。顺-氧化芳樟醇、反-氧化芳樟醇、顺-芳樟醇氧化物(呋喃型)、反-芳樟醇氧化物(吡喃型)、苯甲醛、苯乙醛、癸醛、β-环柠檬醛、顺-柠檬醛、丁醚和二甲硫等有益白茶香气品质形成的香气成分均为黄光组的含量最高。共得到5个OAV相对较高的香气成分,依次为β-紫罗酮、芳樟醇、壬醛、二甲硫和反-2-癸烯醛,对所测样品的香气形成贡献较大。【结论】LED黄光萎凋最有益于提高贡眉白茶的香气因子得分,可增加香气成分总含量,形成良好的香气品质特征,可优先考虑作为白茶全天候加工制作的补偿光源。

     

    Abstract: 【Objective】 The study aimed to clarify the effects of different LED lights withering on the aroma components of Gongmei white tea, which could provide reference for all-weather and standardized light withering production of white tea.【Method】 With no light withering as a control, effects of withering of red light (630 nm), yellow light (570 nm), blue light(430 nm) and sunligh on Gongmei white tea aroma compounds were analyzed by sensory evaluation and headspace solid phase micro-extraction combined with gas chromato graphy-mass spectrometry(HS-SPME-GC-MS) and odor activity value(OAV) in this study.【Result】 The aroma scores of Gongmei white tea in the four kinds of lights withering were all higher than those without light withered. Among them, the yellow light treatment had the highest aroma score (89.1), showing floral fragrance, and the other three light treatments were mainly clear fragrance. A total of 68 aroma components were detected in the tested samples including 16 aldehydes, 17 alcohols, 10 esters, 11 ketones, 10 hydrocarbon and others, of which 58 components were in each treatment. The four light qualities could increase the total aroma contents of Gongmei white tea samples. Among them, Gongmei white tea had the highest total aroma components(279.736 μg/L) under yellow light withering, and aldehydes (46.787 μg/L), alcohols (173.163 μg/L), ketones (16.889 μg/L), heterooxy-gen compounds(6.823 μg/L), ethers(12.574 μg/L), sulfur(0.388 μg/L) and sulphocompound(3.608 μg/L) contents were all higher than other lights and control. Cis-linalool oxide, trans-linalool oxide, cis-linalool oxide(furan type), trans-linalool oxide(pyran type), benzaldehyde, phenylacetaldehyde, decanal, β-cyclocitral, cis-citral, butyl ether, dimethyl sulfide that were beneficial to the aroma quality of white tea, all had the highest contents in the yellow light group. A total of five aroma components with relatively high OAV were obtained, followed by β-ionone, linalool, nonanal, dimethyl sulfide, and dimethyl sulfide, which made a greater contribution to the aroma formation of the tested samples.【Conclusion】 Yellow LED light withering is the most beneficial for improving aroma factor, increasing total content of aroma components and forming good aroma quality characteristics of Gongmei white tea, and can be prioritized as a compensation light source for all-weather processing of white tea.

     

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