Effects of Vacuum Freeze-Drying and Spray-Drying Coupled with Maltodextrin and β-Cyclodextrin on Cactus (Opuntia ficus-indica) Postbiotic Powders

Fruit- and vegetable-derived postbiotic powders represent promising functional ingredients; however, systematic evaluations of different drying technologies and drying aids for these products remain limited. In this study, Opuntia ficus-indica fruit juice was fermented using Lacticaseibacillus paracasei HNU502 and subsequently inactivated to prepare postbiotic broth, which was further processed into powder by vacuum freeze-drying and spray-drying with maltodextrin and β-cyclodextrin as drying aids. Results showed that the drying process and carrier formulation jointly influenced the structural, sensory, and antioxidant characteristics of cactus postbiotic powders. Vacuum freeze-drying combined with β-cyclodextrin exhibited favorable structural and sensory properties under the tested conditions, whereas spray-drying combined with β-cyclodextrin showed favorable antioxidant performance. Additionally, β-cyclodextrin-containing formulations showed favorable powder characteristics and functional properties under the tested conditions, although the effects were influenced by both carrier formulation and drying process. Among the tested formulations, vacuum freeze-drying combined with β-cyclodextrin exhibited the highest crystallinity (77.4%) and distinct structural features, as characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR) analyses. The spray-dried β-cyclodextrin formulation achieved the highest sensory score (74.75), while exhibiting high radical scavenging activity. DSC analysis indicated that all formulations maintained thermal stability, with no exothermic degradation observed below 180 °C. These findings suggest that β-cyclodextrin-assisted drying strategies can influence the structural and functional characteristics of cactus postbiotic powders and that drying strategy selection should consider specific product quality requirements and processing feasibility.