Effects of different harvesting seasons on the physical, chemical, and aromatic properties of tea leaves

This study evaluated the influence of seasonal harvesting on the physical, chemical, and bioactive characteristics of tea leaves. Moisture content declined from 75.3% in May to 70.5% in September, indicating reduced freshness and altered storage stability. pH values (5.1-5.6) and total ash content reflected seasonal differences in mineral absorption. Color parameters showed a notable decrease in L*, consistent with chlorophyll degradation over time. Mineral composition varied significantly, with potassium decreasing and calcium increasing toward the end of the season, while microelements such as manganese and iron were more abundant in early harvests. FTIR analyses revealed shifts in functional groups associated with polyphenols and other biochemical components. Aroma profiling showed that total volatile compounds peaked in July, whereas benzyl alcohol and benzaldehyde increased in later harvests. Antioxidant activity declined from 49.83 to 27.74 μmol TE/g, confirming that earlier harvests contain higher phenolic content and stronger antioxidant potential.