Vacuum freeze drying combined with catalyzed infrared drying of chive: Effects on flavor and quality characterization

Vacuum freeze drying (VFD) combined with thermal drying can solve the defects of vacuum freeze-dried chives, such as faint flavor, unpleasant color, and taste. However, the mechanisms for enhancing flavor, reducing lightness, and improving taste through combined drying remain to be explored. In this study, the effects of vacuum freeze drying combined with hot air drying, vacuum freeze drying combined with infrared hot air drying, and vacuum freeze drying combined with catalytic infrared drying (VFD-CIRD) on the flavor and quality characteristics of chive leaves and stems were investigated. The results demonstrated that VFD-CIRD had the richest flavor, attributed to the key aromas hydroxyacetone and 2-ethyl-6-methylpyrazine. Combined drying eliminated the wax layer on the surface of chive leaves, which reduced lightness. Furthermore, VFD-CIRD could degrade phenolic compounds in chives, thereby reducing the bitterness. VFD-CIRD has the potential to become the basis for the industrial production of high-quality dried chives.