Role of genetic and environmental factors in determining the chemical attributes of processed tomato juice

The plant cell wall is a major determinant of texture of fruits and vegetables, and changes in the matrix pectins and other non-cellulosic polysaccharide structure and architecture are implicated in softening that occurs during ripening. Changes in tomato pericarp cell wall composition and architecture impact many desired quality traits in tomato products that, consequently, determine both the quality and factory yield of the processed products. I have analyzed the composition and linkage structure of the cell walls of several tomato fruit cultivars from Grass Green through Red Ripe stages of development, and subsequently in Red Ripe fruits stored post-harvest for 4, 8 and 13 days. The cultivars varied in the ripening behavior during the time course, but in all cultivars except one, processed tomato fruit juice samples showed a marked loss of galactose followed by loss of arabinose during the ripening. Linkage analyses showed that the loss of arabinose and galactose is due to the depolymerization of (1→5)-α-L-arabinan and (1→4)-β-D-galactan side-chains of RG I, with a subsequent decrease in the degree of branching of the RG I backbone. FTIR spectroscopy confirmed that the changes in wall composition are consistent with changes in arabinan and galactan content. I hypothesize that RG I and its subtending neutral side-chains function as an architectural scaffold whose modifications are responsible for changes in ripening texture