Effect of relative humidity on shrinkage and color changes in dehydrated strawberry

Abstract

Dehydrated fruits are prone to discoloration during storage. Many natural pigments are unstable in dried fruits, and brown pigments can be formed. The rate of physical and chemical changes in dried vegetables and food models is slow in the glassy state. At temperatures above the glass transition, in addition to decreasing viscosity and increasing rate, other changes such as crystallization and structural collapse affect the rate of discoloration (Karmas et al. 1992). Diffusion-controlled chemical reactions are particularly dependent on translational diffusivity of the reactants (or on the viscosity of the matrix material) and are thus susceptible to the physical state of the system (Slade et al. 1995). It has been shown that matrix collapse caused by storage above the glass transition temperature (Tg) or by mechanical compression and porosity (Burin et al. 2004; White and Bell 1999) affected browning rates, indicating that besides water content, system structure plays a relevant role.