The objective of this research is to propose a new drying technique for increasing drying rate of spinach blades by changes in physiological activity (particularly, avoid water deficits) with heat pretreatment. The physiological activities (cell membrane stability (CMS) as an index of the biological reactions of the cell membrane, and ratio of variable fluorescence to maximum fluorescence (Fv/Fm) an index of life activity) and the drying characteristics (moisture content and surface area) of the spinach were measured. The CMS of samples after pretreatment were evaluated by focused on the shift in the coordinates of the top of the circular arcs of Cole-Cole plots. The correlations between the Fv/Fm ratio and the surface area ratio of dried samples were significant (P < 0.01). We found that the decreased physiological activity of spinach with heat pretreatment is one of the factors that increase the hot air drying rate of spinach. (C) 2015 Elsevier Ltd. All rights reserved.