Effect of microwave vacuum drying time on the quality profiles, microstructures and in vitro digestibility of pork chip snacks

Abstract

In present study, the quality profiles, microstructures and in vitro digestibility of pork chip snacks (PCS) prepared by microwave vacuum drying (MVD) under different drying times (20, 21, 22, 23, and 24 min) were investigated. The results revealed significant decreases in the moisture content and L*-value of PCS, while the protein/ash contents, a*-value, and b*-value of PCS markedly increased with prolonged MVD time (P < 0.05). Additionally, as MVD time extended from 20 to 24 min, the textural characteristics of PCS, particularly brittleness and crunchiness, initially increased and then gradually decreased (P < 0.05). Scanning electron microscopy (SEM) images showed that a moderate MVD time (22 min) resulted in the formation of larger pores in PCS, enhancing brittleness and crunchiness. However, excessive MVD time (24 min) led to the melting of these pores, subsequently reducing the brittleness and crunchiness of PCS. Furthermore, in vitro protein digestibility of PCS gradually decreased with increasing MVD time, primarily attributed to increased protein aggregation, as indicated by changes in sulfhydryl contents. In summary, our findings highlight that PCS subjected to 22 min of MVD exhibited the highest overall acceptability. This study provides a novel strategy for the application of MVD in the processing of meat snacks.