Microwave vacuum combined drying of Macrobrachium rosenbergii meat: Effects of moisture transition points on drying kinetics, microstructure, quality, and flavor characteristics

During microwave vacuum drying (MVD) of Macrobrachium rosenbergii meat, quality degradation and flavor loss becomes more pronounced in the later stage of drying, highlighting the necessity of developing MVD-based combination technique. Herein, a combined drying strategy was employed with MVD as the first-stage of drying, followed by hot air drying (HAD), heat pump drying (HPD), and vacuum freeze drying (VFD), respectively. Effects of moisture transition point (50%, 40%, and 30%, wet basis) on the drying kinetics, physicochemical properties, microstructure, and volatile flavor compounds were systematically analyzed, and overall quality was evaluated using comprehensive scoring and hierarchical cluster analysis. The results indicated that the MVD-VFD combination at a 30% moisture transition point (30-VFD) achieved the best overall performance, characterized by minimal lipid oxidation (0.41 mg MDA·kg−1), moderate hardness (186.28 N), the highest porosity (9.63%), and superior water-holding capacity. Scanning electron microscopy revealed a uniform porous structure, while flavor analysis demonstrated a well-balanced aroma profile, resulting in the highest comprehensive quality score. In contrast, MVD-HAD led to darker color, higher hardness, greater energy consumption, and increased protein oxidation, whereas MVD-HPD required longer drying times and produced denser structures with limited rehydration capacity. Overall, the MVD-VFD strategy, particularly at a 30% moisture transition point, provides an effective approach for producing high-quality dried M. rosenbergii meat with improved energy efficiency, highlighting its strong potential for industrial application in aquatic product drying.