Dual modification of banana starch: Partial characterization

Banana starch was double modified by cross-linking and substitution, using two different cross-linking agents, i.e. phosphorus oxychloride (POCl ₃) and a mixture of sodium trimetaphosphate/sodium tripolyphosphate. The morphological and physico- chemical properties and the absorption capacity for heavy metals of the modified starches were assessed. Double modified starch granules (cross-linked carboxy-methyl starches CCSA and CCSB) presented changes in the surfaces. These starches had a bigger average particle size than unmodified starch due to the swelling of the granules during the chemical modification, also aggregates were formed. The double modified banana starches presented an A-type X-ray diffraction pattern with slightly decreased crystallinity compared with the unmodified counterparts. The double modification of banana starch decreases the temperature and enthalpy of gelatinization and the decomposition temperature. These results are related to partial disorganization during the chemical treatment. The double modified banana starch possess sorption capacity for heavy metal ions in the order Cd²¹ > Pb²¹>Cu²¹>Hg²¹. Due to their physicochemical characteristics and absorption capacity, the double modified banana starches can be used in diverse applications.