Ethylene-Induced Postharvest Changes in Five Chinese Bayberry Cultivars Affecting the Fruit Ripening and Shelf Life

Ethylene is an essential indicator of fruit ripening and climacteric or non-climacteric nature. This study investigated the postharvest behavior of five Chinese bayberry cultivars ‘Biqi’, ‘Dongkui’, ‘Fenhong’, ‘Xiazhihong’, and ‘Shuijing’. The fruits were harvested mature and stored at room temperature (25 °C) and under cold storage conditions (4 °C) to investigate the dynamics of ethylene production, firmness, anthocyanin content, and cell wall polysaccharide composition, as well as basic fruit physicochemical characteristics. The results show that Chinese bayberry is a climacteric fruit with ethylene production peaking shortly after harvest, especially at room temperature. Fruit color intensified over time due to anthocyanin accumulation, particularly in the flesh core. Darker cultivars produced more ethylene, which correlated with higher anthocyanin levels. At room temperature, ‘Biqi’ (black) had the highest ethylene production (4.03 µL·kg−1·h−1) and anthocyanin content (0.91 mg/g FW), while ‘Shuijing’, the white cultivar, had the lowest ethylene levels (1.9 µL·kg−1·h−1) and anthocyanin content (0.03 mg/g FW). Firmness significantly decreased at room temperature due to the degradation of hemicellulose and insoluble pectin, whereas cold storage mitigates this effect. After 3 days at room temperature, the average of firmness decreased by 23.7% in the five cultivars, compared to 12.7% under cold storage. Total soluble solids increase during storage, enhancing sweetness, especially at room temperature, with ‘Biqi’ increasing from 9.2 to 10.9% at 4 °C. Titratable acidity slightly decreased over time: the value for ‘Biqi’ decreased from 1.2% to 0.95% at room temperature and 1.1% at 4 °C. Citric, malic, and tartaric acid generally declined at room temperature but stabilized under cold storage. Sucrose, fructose, and glucose increased or remained stable, with significant varietal differences. Our results indicate that storing Chinese bayberry at 4 °C effectively preserves its quality and extends postharvest life. These findings underscore ethylene’s key role in regulating ripening, postharvest quality, and shelf life by influencing fruit color, firmness, and overall consumer appeal.