Elucidating the underlying mechanisms of quality and anthocyanin alterations during the plum drying process using metabolomics

Anthocyanins are key nutrients in plums. However, their short shelf life makes drying essential for preservation, and the influence of different varieties on the specific components of plums is unclear. This study employed hot air-drying technology at 65-85°C to examine the effect of drying temperature on the drying characteristics, anthocyanin content, and antioxidant capacity and other quality aspects in Falanxi and Nvshen plums from the Xinjiang Uygur Autonomous Region, China. Results showed that drying increased total flavonoid and phenolic content (e.g., 5.89 mg RE/g flavonoids in Falanxi at 75°C) but significantly reduced ascorbic acid (e.g., after drying at 65, 70, or 75°C, the samples demonstrated a 20-fold decrease in Falanxi and Nvshen), leading to lower antioxidant activity. Expression profiles of 27 anthocyanins differed between varieties, with 11 up-regulated and 16 down-regulated. The optimal drying temperature was 75°C, with Falanxi plums retaining better quality. Additionally, anthocyanin degradation appeared to be linked to antioxidant effects in plum drying. These findings provide insights into anthocyanin metabolism and antioxidant regulation under drying stress, providing valuable information for improving plum nutritional quality in food processing. • Dried plum antioxidant decline linked to anthocyanin degradation. • 27 anthocyanins show differential expression in Falanxi vs Nvshen plums. • 75°C hot-air drying enhances plum flavonoid and phenolic content.