Changes in physical properties and cell wall polysaccharides of tomato (Lycoperskon esculentum) pericarp tissues

Abstract

Green and red tomato pericarp tissues were subjected to stress‐relaxation analyses to evaluate their physical properties. Significant decreases in the initial stress, minimum stress‐relaxation and maximum stress‐relaxation times in the red tissues predict the losses of both viscosity and elasticity in the tissue. Cell walls of red fruit yielded more water‐soluble polysaccharides and less pectin, hemicelluloses and cellulose. Average molecular mass of pectin determined by gel filtration chromatography was similar in the green and red, but molecular mass of hemicellulose of red fruit walls was reduced to 50% of that of the green fruit. The decreases in the amount of hemicellulose B and in the average molecular mass were associated primarily with the degradation of xylo‐glucans. These data demonstrate that pectin solubilization, depolymerization of xyloglucans and over‐all changes in the quantity of cell wall polysaccharide fractions contribute to tomato fruit softening.