Structural characteristics and texture during the microwave freeze drying process of Chinese yam chips

Fresh Chinese yam is difficult to store and easily deteriorates during storage, and dehydrated yam chips processed by different methods are widely consumed as a kind of snack food. Freeze drying (FD) is often used to produce high-quality yam chips, but the extralong drying time limits its industrial application. Microwave freeze drying (MFD) has the potential to replace the conventional FD method. Therefore, this research used MFD to dry Chinese yam chips. In this study, the brittleness and hardness of Chinese yam chips during the MFD process were investigated. It was found that the brittleness of Chinese yam chips had a close relationship with the moisture content. The hardness of Chinese yam chips mainly depended on the porosity and moisture content. Moreover, the DoseResp model of the brittleness could effectively predict the brittleness change during the MFD process. The regression equation based on the porosity and moisture content could accurately describe the hardness of the Chinese yam chips during the MFD process.