红树莓叶茶的制备及与红树莓叶片、绿茶品质的比较

本实验以‘秋福’红树莓叶片为原料，以红树莓叶茶的可溶性糖、总酚和游离氨基酸含量为指标，确定红树莓叶茶的最佳制作工艺；并对红树莓叶片、叶茶和市售绿茶3 种实验原料的活性物质含量、抗氧化活性和抑菌活性进行比较；最后采用气相色谱-质谱联用法比较3 种实验原料香气物质的区别。结果表明：摊晒时间1 h、蒸汽杀青（杀青时间45 min、杀青温度100 ℃、摊放密度5 g/dm2）、揉捻时间25 min、热风干燥（温度50 ℃、时间12 h、摊放密度5 g/dm2）为红树莓叶茶最佳制作工艺。红树莓叶片、叶茶及市售绿茶均含有一定量的多酚、黄酮和原花青素类活性物质，并表现出不同的抗氧化能力，其中市售绿茶的铁离子还原能力最强，且3 种实验原料对3 种细菌（大肠杆菌、枯草芽孢杆菌、金黄色葡萄球菌）均有较好的抑菌能力；通过气相色谱-质谱联用分别从红树莓叶片、叶茶和市售绿茶中鉴定出8、14、18 种香气物质，红树莓叶片和叶茶除2-庚醇外无相同香气物质，前者以2-庚醇和桃金娘烯醛为主要香气物质，后者以己醛、2-正戊基呋喃为主要香气物质，且含有丁醛、2-乙基呋喃等独特的香气物质，市售绿茶香气物质种类较多，主要以醇类、酯类为主。本研究可为进一步开发和利用树莓叶资源提供理论参考，也能为红树莓叶茶进入市场提供理论支撑。

Preparation of Red Raspberry Leaf Tea and Comparison of Its Quality with Red Raspberry Leaves and Commercial Green Tea

The production process of red raspberry leaf tea from the ‘Autumn Bless’ cultivar was optimized based on the contents of soluble sugar, total phenol, and free amino acids. The bioactive substances, antioxidant activity and bacteriostatic activity of red raspberry leaves, red raspberry leaf tea and commercial green tea were compared, and gas chromatography-mass spectrometry (GC-MS) was used to compare the differences in their aroma profiles. The results showed that the optimum preparation conditions were as follows: spread-drying time 1 h, steam fixation for 45 min at 100 ℃ with spreading density of 5 g/dm2, rolling time 25 min, and hot air drying for 12 h at 50 ℃ with spreading density of 5 g/dm2. All three materials contained polyphenols, flavonoids and proanthocyanidins, and showed different antioxidant capacities. Among them, commercial green tea exhibited the strongest ferric reducing antioxidant power (FRAP). Besides, all of them showed good antibacterial activity against Escherichia coli, Bacillus subtilis and Staphylococcus aureus. Totally 8, 14 and 18 aroma substances were identified from red raspberry leaf, red raspberry leaf tea and commercial green tea by GC-MS, respectively. Only 2-heptanol was shared by red raspberry leaves and red raspberry leaf tea; in the former, 2-heptanol and myrylene aldehyde were the major aroma substances, while the latter contained hexaldehyde and 2-n-pentylfuran as the major aroma substances as well as some unique aroma components such as butyraldehyde and 2-ethylfuran. Commercial green tea contained more aroma substances, mainly alcohols and esters. These results provide not only theoretical references for further development and utilization of raspberry leaf resources, but also theoretical support for the entry of red raspberry leaf tea into the market.