X-ray diffractometry and differential scanning calorimetry were employed to study the gelatinization behaviors of the native and retrograded starches. The native crystal polymorph of banana starch was found to be a B-type in this study. Retrogradation resulted in formation of crystalline regions in cooked starch pastes. Degree of crystallinity, after cooling the cooked pastes to room temperature along with the retrogradation storage and freezedry was calculated in Table 4. A high rate of retrogradation of cooked banana starch was found through X-ray diffraction analysis (Fig. 4). DSC results showed potato starch had the lowest onset and gelatinization temperatures, while banana starch had the highest values (Table 5A). Moreover, banana starch exhibited the highest enthalpy values (17.5 J/g), which agreed with the results of Espinosa-Solisa, Jane, and Bello-Pereza (2009). DSC thermal data confirmed that the crystals formed during storage of gelatinized
banana starch had the largest thermal stability because they dissociated at higher temperature accompanied by a larger
enthalpy change (Table 5B). Retrogradation properties suggested the greater retrogradation (reassociation) on cooling after cooking that makes these complexes in banana starch and banana starch-containing foods less susceptible to enzymic degradation.
Bello-Perez, Ottenhof, Agama-Acevedo, and Farhat (2005) studied
the retrogradation phenomenon of banana starch extrudates and
found that banana starch retrogradation reached a maximum value
at approximately 11 h of storage. Banana starch showed a fast retrogradation
kinetic that could be related to the amylopectin chain
length.