Effects of microwave-discharged cold plasma on synthesis and characteristics of citrate derivatives of corn starch granules.

The objectives of this study were to identify the potential function of microwave-discharged cold plasma (MCP) treatment in preparing starch citrate (SC) non-thermally and to investigate the physicochemical properties of MCP-induced starch citrates. SCs were prepared by either dry heating in a convection oven (as a reaction control; COV) or MCP treatment using N2 (N2-MCP) and N2-O2 (N2/O2-MCP). Fourier transform-infrared spectra of the MCP-induced SCs revealed new peaks indicating ester bonds. The molar degree of substation was 0.013-0.015 depending on the reaction conditions. The plasma-formed dents were observed more on the surfaces of granular starch citrates (GSCs) treated with N2/O2-MCP than N2-MCP. Relative to COV, MCP-induced GSCs possessed lower resistant starch content, solubility, and gelatinization temperatures and higher swelling power. The pasting viscosities were higher with N2-MCP GSCs and lower with N2/O2-MCP GSCs. The results suggest that MCP can be used as a novel catalyst for non-thermal starch citration.