Understanding the atmospheric cold plasma-induced modification of finger millet (Eleusine coracana) starch and its related mechanisms

Abstract

This research was conducted to evaluate the effects of cold plasma (CP) on finger millet starch (FMS). FMS was exposed to partially ionized gas at varying voltages (170, 200, and 230 Volt) for varied time (10, 20, and 30 mins). The impact of treatment was studied using physico-chemical, and functional properties, and the mechanisms of starch modification occurring were stated. A significant reduction in the degree of polymerization was noticed based on parameters like reducing sugar, amylose content, solubility, and molecular weight. However, in certain voltage and time combinations, crosslinking was also confirmed by analysis such as XRD, FTIR, DSC, etc. The properties of starch were altered such as remarkable increase in water solubility by 6.7 times for highest voltage and longest time (230 V/30 min) was registered. NMR data suggested valuable findings- oxidation of OH group at C6 position of starch led to formation of carbonyl group followed by carboxyl group. NMR also showed a decrease in OH protons confirming crosslinking and hence all these analyses helped to conclude findings about the quality changes using CP. It was observed that the highest voltage and considerably longer exposure time of 20 and 30 min induced significant changes in the FMS.