政和白茶品质特征及挥发性成分研究

Quality Characteristics and Volatile Components of Zhenghe White Tea

摘要:

【目的】探究政和白茶的主要品质特征及挥发性成分。【方法】以3个白牡丹样品和2个寿眉样品为研究对象，采用感官审评、理化分析、微生物测定、气相色谱-质谱联用（GC-MS）等方法对其进行检测分析。【结果】白牡丹样品香气具有毫香，滋味醇爽，叶底芽头较肥嫩或肥壮；寿眉样品香气清纯，滋味浓郁。所有样品的水分和水浸出物质量分数均符合GB/T 22291—2017《白茶》和GB/T 22109—2008《地理标志产品 政和白茶》的要求。偏最小二乘判别分析（PLS-DA）结果表明，游离氨基酸、茶多酚、水浸出物和咖啡碱是区分白牡丹和寿眉的主要理化成分。所有样品中均未检出致病菌，但不同样品间的菌落总数和霉菌数存在差异，其中寿眉饼茶（BC）的菌落总数和霉菌数较低，白牡丹3号（BMD3）的菌落总数和霉菌数较高。挥发性成分结果表明，白牡丹以醇类和酮类为主，具有甜香、花香、毫香的特点，其中香叶醇、芳樟醇和氧化芳樟醇Ⅱ的相对含量较高；寿眉以醇类、酮类和酯类为主，香气带有花香、药香和木质香特征，其中水杨酸甲酯、二氢猕猴桃内酯和β-紫罗酮的相对含量较高。主成分分析（PCA）和聚类分析（HCA）结果显示，白牡丹与寿眉的挥发性成分存在显著差异，白牡丹香气浓郁清纯，而寿眉香气较淡且带有闷味。【结论】研究结果可为政和白茶风味品质特征评价和安全性评估提供参考。

Abstract:

[Objective] This study aims to explore the major quality characteristics and volatile components of Zhenghe white tea. [Method] Three representative samples of Baimudan tea and two samples of Shoumei tea were chosen and studied by sensory evaluation, physicochemical analysis, microbial determination, and gas chromatography-mass spectrometry (GC-MS). [Result] Baimudan tea samples showed a tip aroma and a fresh and mellow taste, and the leaf residue bud was tender or stout. Shoumei tea samples exhibited a pure aroma and a rich taste. The mass fractions of water and water extracts of all the samples met the requirements of the national standards White Tea (GB/T 22291—2017) and Quality Requirements for Product of Geographical Indication—Zhenghe White Tea (GB/T 22109—2008). The results of partial least squares-discriminant analysis (PLS-DA) showed that free amino acids, tea polyphenols, water extract, and caffeine were the main physicochemical components to distinguish between Baimudan tea and Shoumei tea. Pathogens were detected in none of the samples, while there were differences in the total plate count and mold count, which were lower in Shoumei cake tea and higher in Baimudan 3 (BMD3). The analysis of volatile components showed that the volatile components of Baimudan tea were mainly composed of alcohols and ketones, conferring Baimudan tea with a sweet, floral, and tip aroma. In addition, geraniol, linalool, and linalool oxide II had higher relative content in Baimudan tea. The volatile components of Shoumei tea were mainly composed of alcohols, ketones, and esters, which endowed Shoumei tea with a floral, medicinal, and woody aroma. Additionally, Shoumei tea had higher relative content of methyl salicylate, dihydroactinidiolide, and β-lonone. The results of principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed that the volatile components were significantly different between Baimudan tea and Shoumei tea. Specifically, Baimudan tea had a strong and pure aroma, while Shoumei tea had a light aroma and a dull taste. [Conclusion] This study can provide references for the flavor characteristic and safety evaluation of Zhenghe white tea.