Impact of atmospheric pressure pin-to-plate cold plasma on the functionality of arrowroot starch

Abstract

The present study focused to modify the functionality of arrowroot starch (ARS) by a novel atmospheric pressure pin-to-plate cold plasma. The top electrode consists of multiple pins arranged in such a way to shower corona discharge of electrons to provide effective modification. Arrowroot starch (10 g) was exposed to the cold plasma processed at three input voltages (190, 210, 230 V) for 5–15 min and studied for the changes in intrinsic viscosity average molecular weight (MWv), powder flow properties (bulk and tapped density, Hausner's ratio, Carr's index), functional (water and oil binding capacity, pH, gel hydration, turbidity), rheological (pasting and steady shear flow), thermal (DSC) and structural (FTIR, XRD, SEM) properties. With cold plasma treatment, MWv of the ARS was increased evincing the cross-linking phenomenon which has also shown in increase in peak viscosity of the starch pastes (4.33%–11.98%). The steady shear viscosity at 50 s−1 of the plasma-treated starch also increased remarkably (15.44%–223.83%) than the untreated. Inclusion of acidic and hydrophilic functionalities along with surface etching of starch observed under SEM have resulted in the pH reduction (from 5.41 ± 0.03 to 4.01 ± 0.01), Increase in water (22.5% rise in 230–15) and oil binding (8.46% in 230–15), swelling volume (50% increase) and solubility index (240% increase), reduction in paste turbidity. The increase in % of crystallinity in the plasma-treated arrowroot starch was associated with the increase in gelatinization enthalpy showing the thermal stability of plasma-indued crosslinking of arrowroot starch. This proves that cold plasma can be a potential green modification technology to produce clear, highly viscous, more hydrating, shear, and thermally stable starches.