The aim of this work was to determine if the molecular structure of starch from tomato ( Solanum lycopersicum L.) is influenced by fruit physiology and carbohydrate metabolism. The effect of fruit size, fruit ripening behavior, and assimilate availability on starch granule accumulation was examined in nine tomato samples. The percentage of (14)C-glucose partitioning to starch was similar among samples, but starch contents varied 10-fold, suggesting differences in metabolism. In contrast, granule size (10-20 microm), amylose content (19-23%), degree of crystallinity (26-31%), and enthalpy of gelatinization (14.8-17.2 degrees C) were similar. Some differences in structure were detected in starch from the largest and smallest fruit using more sensitive analyses such as thermal properties, chain length distribution of amylopectin, and susceptibility to in vitro alpha-amylase digestion. However, overall, our results suggest that granule characteristics are highly conserved in tomato fruit, and we conclude that this is likely due to inherent metabolic constraints.
Amylose Fruit