Effects of Plasma Treatment on Chemical and Physical Properties of Pigmented Rice Flour

Abstract

Abstract The objective of this research was to study the effects of plasma treatment at different power levels (100, 120, and 140 W) and exposure times (5, 10, and 15 min) on the physical and chemical properties of pigmented rice flours from Kum Doi Saket cultivar. An increase in plasma power and exposure time resulted in decreases of moisture contents, solubility, and swelling power of the rice flour, while the resistant starch content was increased. The amylose content tended to decrease when plasma power and exposure time was increased. In this study, plasma treatment at 140 W for 10 min maintained the highest anthocyanin content in Kum Doi Saket rice flour (68.35 – 98.63 mg/100 g). Pasting property analysis by RVA revealed decreases in peak viscosity, breakdown and setback viscosities. The pasting temperature of Kum Doi Saket rice flour was significantly decreased (P ≤0.05) after plasma treatment. Plasma treatment did not affect the onset temperature (To) and ΔH of starch gelatinization as analyzed by a DSC, while peak temperature (Tp) and end set temperature (Te) of flour sample were increased (P ≤0.05). Plasma effects on size, shape and surface roughness of flours were observed by SEM. Higher plasma power and treatment time caused more micro-pores on the surface of flour particles, especially after being treated at 140 W for 15 min. Keywords: Pigmented rice flour, Cold plasma technology, Flour properties, Cross-linking