Innovative far-infrared radiation assisted pulsed vacuum freeze-drying of banana slices: Drying behaviors, physicochemical properties and microstructural evolution

Abstract

High operational cost and excessive energy consumption remain the global challenges in the application of vacuum freeze-drying (VFD) technology. Accordingly, a novel far-infrared radiation assisted pulsed vacuum freeze-drying (FIR-PVFD) technology was developed. This study systematically evaluated the effects of vacuum pressure duration (5 and 15 min) and dehydration temperature (40, 50, and 60 °C) on drying behaviors, physical properties (color, texture, rehydration), bioactive compounds, and the potential relationship between quality and microstructural changes in banana slices. Results showed that the FIR-PVFD process significantly reduced the drying time by 33.33 %–40 % compared to VFD, due to the synergistic effect of the emitted FIR energy and sustained disruption of the boundary layer. Shorter drying times were achieved at higher temperatures and shorter vacuum durations. Moreover, the FIR-PVFD treated samples exhibited improved appearance, texture, and rehydration performance, coupled with higher retention of sugars, starch, flavonoids, and antioxidant capacity. Microstructural analysis demonstrated that they had the more uniform and regular porous structure. In particular, the retention of phenolics and ascorbic acid were particularly sensitive to the balance between drying temperature and vacuum pressure duration.

Industrial relevance

FIR-PVFD presents a promising alternative to conventional VFD, offering enhanced drying efficiency while producing high-quality dried products. This technology has the promising potential for supporting energy-efficient production in the food industry and expanding the application of freeze-drying techniques.