Abstract: 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.

Key words: red raspberry; red raspberry leaf tea; bioactive substances; aroma components; gas chromatography-mass spectrometry