Enhancement of Saltiness Perception in Microwave-Heated Pork Patties Induced by Sodium Inhomogeneous Distribution and Matrix Microstructural Changes

The mechanism of microwave heating in saltiness perception enhancement and inhomogeneous sodium distribution was explored in this study. The sensory analysis result showed that the pork patty treated by microwave heating with the power of 6 W/g could achieve 20% salt reduction while maintaining a higher saltiness perception compared to steam heating. The saltiness perception enhancement was directly related to the higher sodium retention of whole pork patty treated by microwave heating about 1.1–1.3 times that of steam heating. In addition, the stronger saltiness perception and higher sodium content of the outer layer compared to the inner layer in the pork patty treated by microwave heating (P < 0.05) demonstrated the formation of inhomogeneous sodium distribution, which was also related to the increased perception of saltiness. Meanwhile, the formation of inhomogeneous sodium distribution was also associated with the changes in water distribution and the formation of a porous and compact microstructure favorable for water migration carrying sodium, originating from the ordered structure of the protein in the outer layer. These findings suggested that microwave heating could be a valuable technique for developing sodium-reduced meat products.