Abstract: The aim of this study was to identify and analyze the difference in aroma components and contents of freeze-dried and hot-air-dried Guire2 black tea, and explore the influence of key processing parameters of freeze-dried black tea on quality. The aroma components extracted with solid phase microextraction (SPME) were identified by gas chromatography-mass spectrometry (GC-MS). And odor activity value (OAV) was used to evaluate the contribution of aroma components and determine the key flavor components. Combined with sensory evaluation, aroma evaluation and inclusion difference analysis, Guire2 black tea was evaluated comprehensively. A total of 37 aroma components were identified, which including a relatively high content of caffeine, linalool, methyl salicylate, phenyl ethanol and benzyl alcohol. Linalool was the key flavor component (OAV>1), and 2-methyl-butaldehyde, iso-butaldehyde, geraniol, phenylacetaldehyde, dimethyl sulfide, and methyl salicylate were the modified flavor components (0.1<OAV<1). Moreover, the freezing-drying treatment could retain the water extract, tea polyphenols, catechin and other contents of black tea to a large extent, and was superior to the hot-air drying treatment in appearance, liquor color and brewing simplicity, but slightly inferior in aroma evaluation and cost-saving. GC-MS combined with OAV could realize the identification and evaluation of black tea aroma. The comprehensive evaluation of hot-air-drying plus aroma-improving black tea (HD2) was the best. In this study, a freeze-drying plus aroma-improving process (FD4) solved the problem of the heavy grass flavor of the freeze-dried black tea and had advantages in appearance, brewing simplicity and retention of the contained nutrients, which can be used in the processing of characteristic black tea.
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