Morphological molecular and physicochemical characterization of oxidized and lintnerized banana starch

A morphological, molecular and physicochemical characterization was made of the starch extracted from the banana (Musa paradisiaca L.), chemically modified by oxidation and by lintnerization. Native banana starch was used as reference. The modification level was evaluated through polarized light microscopy, X-ray diffraction, infrared spectroscopy and the viscoamylographic profile. The oxidized starch presented a substitution degree of 0.13 and 0.03% of carbonyl and carboxyl groups. The native and modified starches presented the Maltese cross (birefringence) indicating a crystalline organization. The three starches presented diffraction pattern between A- and B-types. Infrared spectroscopy revealed the presence of a high level of organization within the granules: 1.678, 1.689 and 1.883 for the native, oxidized and lintnerized starches. There were no differences (p > 0.05) in the viscosity profile of the native and oxidized starches, whereas the lintnerized starch presented lower values due to a probable hydrolysis provoked during the modification. The lintnerized starch also presented the least changes in its enthalpies (AH) of gelatinization and retrogradation, suggesting the formation of smaller and more imperfect crystals. The characterization made on the modified banana starches could suggest their possible industrial applications.