Impact of power density on the drying kinetics, quality profiles, and microstructure of pork chip snacks dried by microwave vacuum drying

This study aimed to investigate how microwave vacuum drying (MVD) affects the drying kinetics, quality profiles, and microstructure of pork chip snacks (PCS). Fresh pork longissimus lumborum was sliced and dried under different power densities (4, 6, and 8 W/g) in a microwave vacuum oven. Five classical thin-layer drying models were used to evaluate the nonlinear fitting of the experimental data. The results indicated that the Midilli et al. model was the optimal model for describing the drying kinetics of PCS. Moreover, as the temperature increased during MVD, the surface of PCS gradually browned. Meanwhile, temperatures of 130.2 °C and 139.9 °C were critical for preventing severe browning and scorching of PCS. Furthermore, power densities induced accelerated drying of PCS, which led to microstructural damage and the formation of a porous structure. However, higher power density led to more pronounced drying non-uniformity of PCS, as well as severe lipid oxidation (P < 0.05), which notably altered the flavor of PCS. In summary, employing 4 W/g for 22 min in MVD emerged as the optimal parameter for PCS preparation. This study provides a novel strategy for the application of MVD in the processing of meat snacks.