Mass Transfer during Vacuum Frying of Shiitake Mushroom Chips

The mass transfer phenomenon in vacuum frying is very important for the quality and safety control of fruit and vegetable chips. The objective of this research was to determine the kinetics of water loss and oil uptake during frying of pre-treated shiitake slices(blanching,blanching+osmosing+coating)under temperature(80,90,100 ℃)and vacuum(0.075,0.085,0.095 MPa). The results showed that the moisture content of chips was gradually decreased with the increasing of frying time,the Pabis model for the study of the kinetics of water loss fitted the experimental data properly. According to Fick’s law,the effective diffusion coefficient of water in vacuum frying of Lentinus edodes was 3.00×10^-9~7.70×10^-9m²/s,which increased with the increasing of frying temperature and vacuum degree. Osmosing and coating treatment reduced the effective diffusion coefficient of water loss. The oil contents of products increased until reached a stable value with the increasing of frying time,and the oil content was reduced by osmosing and coating. The proposed model of the kinetics of oil uptake fitted the experimental data properly,the frying temperature and vacuum degree had little effect on the equilibrium oil content(Y_max)of various processed samples,and the oil absorption coefficient(K_Y)increased with the increasing of frying temperature and vacuum degree.