Blanching‐Assisted Freeze–Thaw Pretreatment Improves Drying Efficiency and Preserves Anthocyanin and Aroma Quality in Black Carrot

Black carrot is an anthocyanin‐rich vegetable with potential as a natural colorant and functional ingredient. Hot‐air drying is widely used to extend its shelf life but often leads to quality deterioration. Pretreatments such as freeze–thaw (FT) and blanching can modify drying behavior and quality; however, their combined effects on black carrot remain unclear. One FT cycle shortened the drying time by approximately 27%, while additional cycles provided only limited further improvement. Blanching also promoted drying and, when combined with FT, further improved drying efficiency. However, FT alone caused pronounced quality deterioration. After one FT cycle, DPPH scavenging activity decreased to approximately one‐third of the FT‐0 level, and anthocyanin content decreased by approximately 65%. Anthocyanin profiling revealed acylated cyanidin derivatives as the dominant pigments, which were extensively degraded after FT treatment. In contrast, blanching before FT retained more than 95% of anthocyanins. Volatile analysis showed that FT increased aldehydes associated with off‐flavor, whereas blanching mitigated these changes and maintained a terpene‐dominated aroma profile. FT improves drying efficiency but compromises quality, whereas blanching prior to FT effectively balances drying performance and quality retention. Blanching followed by one FT cycle provided the best balance between drying acceleration and the retention of anthocyanin, antioxidant, and aroma quality.