Physical and Chemical Property Changes, Cooked-Off Flavor Formation, and Its Alleviation During Storage of Green Tea Beverages

Quality deterioration, characterized by browning and cooked-off flavor (COF) development, often occurs in green tea beverages (GTBs) during shelf life. Changes in sensory quality and physical and chemical properties, as well as COF formation and its alleviation under different storage conditions, were comprehensively investigated in beverages prepared from five green teas and one jasmine-scented green tea. As the storage temperature increased and the storage duration extended, all GTBs exhibited a noticeable decrease in total sensory score (TSS), along with remarkable increases in total color difference (ΔE) and COF. Contents of total polyphenols declined markedly during storage of GTBs, while levels of caffeine and free amino acids changed insignificantly. Among the nine volatiles negatively correlated with TSS and positively correlated with COF, linalool, geraniol, 1-octanol, and 3-methylbutanal were identified as key COF contributors due to their high relative odor activity values. These results indicate that quality deterioration of GTBs during storage is closely associated with polyphenol loss, accumulation of COF-related components, and shifts in volatile composition and ratios. Notably, beverages prepared from jasmine-scented tea exhibited higher sensory scores and slower quality deterioration during storage than those prepared from unscented tea. This study identifies the key volatile contributors to COF and demonstrates that jasmine scenting effectively mitigates quality deterioration, offering a practical strategy for extending the shelf life of GTBs.