Tomato fruit, pectin function

Tomato fruit appeared to represent a unique system for investigating possible variability in the functions of pectins in texture modifications. Firstly, the tomato fruit is composed of distinct tissue types, including locular gel and pericarp which exhibit markedly different patterns of tissue autolysis. Locular gel develops prior to ripening of pericarp and eventually, toward the terminal stage of ripening, exhibits an almost liquid nature. This developmental scenario is in some respects similar to the ethylene-induced maceration of watermelon fruit (27), a process involving greatly increased levels of EDG and extensive solubilization and depolymerization of pectins (23). In contrast, tomato locular gel has been reported to contain little ( ) or no EDG activity (28). The objective of this study was to examine some of the structural features of pectins from tomato pericarp and gel, and to relate this information to the textural characteristics of these tissues. 

These studies demonstrate the diverse nature of the role of pectins in the texture changes of ripening tomato fruit. The inverse relationship between EDG activity and the extent of softening in gel and pericarp emphasize that EDG does not play a major role in the early, dramatic period of gel formation. The marked losses in pectin neutral sugars, including xylose, occurred simultaneously with initial gel formation although the mechanism and function of these losses in this tissue remain unknown. 

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