The present invention relates to an enhanced starch resin composition, methods of making the enhanced starch resin composition using environmentally benign, water-based processes, and products produced using the enhanced starch resin composition. The enhanced starch resin composition comprises a native starch and/or a waxy starch crosslinked with a multi-functional polycarboxylic acid. The starch resin composition is formed by a water-based reaction comprising using a non-toxic, water-soluble catalyst to catalyze esterification of the native starch and/or the waxy starch with the multi-functional polycarboxylic acid, thereby yielding a crosslinked starch resin composition having at least one enhanced mechanical property and/or reduced moisture absorption as compared to the native starch and/or the waxy starch.