A comparative study on dual modification of banana (Musa paradisiaca) starch by microwave irradiation and cross-linking

Effect of dual modification by cross-linking with POCl3 (0.05 and 0.1%) and microwave irradiation (90 and 180 s) on the properties of banana starch was investigated. The degree of cross-linking was increased with an increased concentration of phosphorous oxychloride and higher period of microwave irradiation. Dual modification had decreased the solubility, swelling index and water absorption capacity of the banana starch. With a higher degree of cross-linking the retrogradation properties and freeze-thaw stability found to be minimized in the modified starches. SEM micrographs displayed minor surface damages in the modified starches. FT-IR spectroscopy results indicate that the cross-linking reaction merely added some new groups to the starch chain and did not damage its underlying chemical structure. A type diffraction pattern was noticed in all starch samples and crystallinity of modified starches was reduced at higher microwave irradiation.