Investigating the impact of cracking and size on quality changes in jujube during on-tree drying

Large fruit size variation and high cracking rates constrain the development of China's jujube industry. To investigate the impact of fruit size and cracking on quality, four types of jujubes were examined: large uncracked (DW), small uncracked (XW), large cracked (DL), and small cracked (XL). Using pre-marking and equal-time sampling, we monitored changes in cracking and quality indicators during on-tree drying. Results indicated no significant increase in cracking rate (P > 0.05), but initial moisture content differed significantly among the four types (P < 0.05). The drying process exhibited a decelerating trend, with hardness initially decreasing and then increasing due to moisture changes. Soluble solids, titratable acid, ascorbic acid, total flavonoids, and total phenolic content all decreased during air-drying. However, reducing sugar content increased significantly in uncracked jujubes (P < 0.05), suggesting that both cracking and fruit size influence quality changes. Comprehensive evaluation revealed that uncracked jujubes scored higher in later stages of on-tree drying, while cracked jujubes had the lowest scores. These findings indicate that tree-based air-drying enhances jujube quality, but cracked jujubes are more suitable for early harvesting and processing.