Impact of storage temperature on green tea quality: an assessment based on compositional changes

Green tea contains a variety of beneficial ingredients. However, the loss of its active ingredients under improper storage conditions will reduce the overall value. In this study, H-GT (Huangshan Maofeng tea) and L-GT (Lu'an Guapian tea) were stored at 25, 8, 4, 0 and -20 °C for 300 days. The impact of different storage temperatures on green tea quality was evaluated by analyzing changes in physicochemical properties, taste-related constituents and antioxidant capacity.

During storage, the intrinsic components and antioxidant activity of both green teas changed markedly. The total catechin content decreased continuously, while theanine content initially increased before declining. In terms of antioxidant activity, both ABTS radical scavenging rate and FRAP reducing power initially rose and then fell, whereas DPPH radical scavenging rate steadily decreased. Furthermore, antioxidant capacity showed significant positive correlations (R² > 0.65) with specific compounds: EGCG, CAF and GC in H-GT, and EGCG, ECG, EGC, CAF, Asp and Phe in L-GT. Based on kinetic modeling of these key components, it was found that the storage stability of both teas was optimal under dry-zone (4 °C) and frozen-zone (-20 °C) conditions, which most effectively preserved their quality and bioactivity.

After 300 days of storage, the dry storage zone (4 °C) not only showed excellent preservation performance but also offered lower storage costs, making it the optimal condition for the long-term storage of green tea. This study contributes to establishing a comprehensive database for dry-stored green tea under refrigeration and provides a scientific basis for low-temperature, dry-zone storage strategies. © 2025 Society of Chemical Industry.