Physico-functional and structural characterization of ultrasonic-assisted chemically modified elephant foot yam starch.

Limited studies are present on dual modification of elephant foot yam (EFY) starch and no study investigated the combined effect of citric acid (CA) and ultra-sonication (US). In the present study, EFY starch was subjected to different concentrations of CA with and without US. Changes in different properties such as functional, morphology, thermo-pasting etc. were examined. Both treatments increased the water and oil absorption capacity of starch. Pasting properties significantly (p < 0.05) reduced with US modification, except pasting viscosity and pasting temperature. CA modification decremented the glass transition temperature which further reduced with US. Starch morphology revealed aggregation of individual granules upon CA modification whereas CA + US broke the aggregates and caused surface fissures and cracks. Overall crystallinity enhanced with an increase in the citric acid concentration. Changes in functional groups identified by FTIR analysis showed new peak formation (1710-1690 cm-1) associated with CA modification. The results showed that CA and CA + US changed the functionality, morphology and other structural characteristics of EFY starch which enable us to use the modified starch in the range of application i.e. bakery products, extruded products, thickening agent and other.