Comparative evaluation of the effects of drying methods on quality attributes of Zanthoxylum bungeanum Maxim.

Abstract

Zanthoxylum bungeanum Maxim. is a popular condiment and medicinal resource that requires effective drying processes to preserve its quality and functional efficacy. This study comprehensively evaluated the impact of hot air drying (HAD: 60 °C, 12.21 hours), vacuum freeze drying (VFD: cold trap temperature −45 °C, vacuum pressure 35 Pa, shelf temperature 35 °C, 22.07 hours), and microwave-assisted vacuum freeze drying (MVFD: cold trap temperature −45 °C, vacuum pressure 35 Pa, shelf temperature 35 °C, microwave treatment 1000 W, 7.42 hours) on the process-related parameters, bioactive components, flavor-active components, and antioxidant capacity (DPPH˙, ABTS˙, FRAP, and superoxide anion (˙O₂⁻) scavenging) of Z. bungeanum Maxim. The results revealed that MVFD-processed samples exhibited the lowest moisture content (10.44 ± 0.27%), highest drying rate (90.13 ± 4.95 g (h kg)⁻¹), minimum specific energy consumption (15.19 ± 0.97 kWh kg⁻¹), and superior retention of bioactive components, including total anthocyanins (820.66 ± 25.16 nmol g⁻¹, d.w.b.), total alkaloids (1.23 ± 0.04 mg g⁻¹, d.w.b.), total phenols (31.78 ± 0.19 mg g⁻¹, d.w.b.), and total flavonoids (57.33 ± 0.22 mg g⁻¹, d.w.b.). MVFD also outperformed HAD and VFD in preserving flavor-active components, yielding higher free amino acids (4599.95 ± 5.94 µg g⁻¹, d.w.b.), pungent agents (45.72 ± 1.05 mg g⁻¹, d.w.b.), and volatile diversity (40 identified constituents). Antioxidant assessment consistently demonstrated the following ranking: MVFD > VFD > HAD, aligning with phytochemical retention trends. These findings underscored MVFD as an advanced industrial processing method for Z. bungeanum Maxim., effectively maintaining its bioactive components, flavor properties, and functional performance while providing technical references for the manufacturing of high-quality Z. bungeanum Maxim. products.