Cold plasma induced morphological, structural, powder flow and rheological properties of Kodo millet starch

Abstract

In this study, Kodo millet starch (KMS) was treated using a multipin atmospheric cold plasma system at different voltage (10, 20, and 30 kV) and treatment durations (5 and 10 min). Native and modified KMS were characterized based on morphological, structural, powder flow, rheological and functional properties to assess the effect of voltage and time. Results indicate that amylose content decreased with the increasing of voltage and time due to depolymerization, with a maximum reduction to 26.33 % at 30 kV for 10 min. SEM analysis revealed that granule shape was retained but surface roughness increased. XRD and FTIR analyses showed minimal changes in crystalline structure and functional groups, respectively. However, the percentage crystallinity reduced from 29.74 % to 25.38 %. However, pasting properties demonstrated increased peak viscosity and reduced pasting temperature, indicative of enhanced starch-water interaction. Rheological assessment revealed shear-thinning behavior, with higher storage and loss moduli for plasma-treated starches, indicating stronger gel formation. Thermal analysis showed a slight increase in gelatinization temperatures, correlating with partial structural modifications. Syneresis tests indicated increased water expulsion, suggesting enhanced retrogradation. Overall, cold plasma treatment effectively modified KMS properties, presenting potential for tailored starch applications in the food industry.