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In this study, three organic acids (citric, lactic, and acetic acid) were pretreated separately on P. rotundifolius starch, and their effects on the structural, functional, and rheological properties of cold water soluble (CWS) starches were investigated. In comparison to native starch, all the modified samples showed granular swelling, and acid pretreatment led to degradation and leaching of the granules. In FT-IR spectra, a peak at 1724 cm−1 confirmed the esterification of organic acids. All the modified starches lost their A-type diffraction pattern and showed a significant (p ≤ 0.05) decrease in the relative crystallinity. HPG showed a significantly higher cold water swelling power than native (2.13 g/g) starch, and lactic acid pretreatment enhanced the cold water swelling power to 9.91 g/g. Citric acid esterified CWS showed a significant increase in cold water solubility (63.1%) and freeze-thaw stability. Thus, this study found that each organic acid treatment affected CWS P. rotundifolius starch differently and has potential application in a refrigerated, instant, or frozen food products.

In the present study, non-conventional talipot starch was subjected to single and dual modifications using two non-thermal techniques; ultrasonication and γ-irradiation (1 kGy and 10 kGy). Free radical-mediated low dose γ-irradiation made remarkable changes in the morphological, physicochemical, and functional properties of ultrasonicated talipot starches compared to single modifications. Dual (ultrasonication+γ-irradiation) modification created deep grooves, reduced relative crystallinity and peak intensity of OH and CH2 groups by cavitation and radiolysis. Compared to ultrasonicated and γ-irradiated starches, dual-modified starches showed significantly reduced (p ≤ 0.05) pH, amylose content, and swelling power, and improved storage stability by lowering the retrogradation tendency. The in vitro digestibility of dual-modified talipot starches was increased by the enhanced action of digestive enzymes with starch. The gelatinization, pasting, and rheological properties significantly decreased (p ≤ 0.05) with the increasing dose of γ-irradiation in dual-modified talipot starches and represented soft gel possessing shear-thinning stability.