Influence of acetylation on physicochemical and morphological characteristics of pigeon pea starch

Abstract Native starches exhibit some technological drawbacks in industrial food applications associated with poor physico-chemical properties; however, modification of starch can remedy the lack of functionality. Starch was extracted from pigeon pea seeds, modified by esterification with acetic anhydride to obtain 0.05, 0.09 and 0.14 degree of substitution (DS). Acetylation decreased the heat transition temperatures and enthalpy of gelatinization. DS (0.05) starch showed the least retrogradation tendency (30.54%). FTIR spectra showed characteristic absorption peaks at 1245, 1370 and 1732 cm−1 (C–C, C–O and C =O stretch vibrations, respectively). Integrated band intensities of all three characteristic FTIR peaks increased linearly with increasing DS. SEM imaging showed that acetylation did not lead to any observable change in starch granule shape and size; however, there was a significant rupture of starch granules at 0.14 DS. The physicochemical properties of the acetylated starches were significantly improved, demonstrating its potential usefulness as food additive.