Optimal Silver Nitrate Concentration to Inhibit α‐Amylase Activity During Pasting of Rice Flour

Abstract Endogenous α‐amylase interferes with accurate determination of the pasting properties of cereal flour. Silver nitrate (AgNO 3 ) solutions at seven different concentrations (0.001‐0.1 m ) plus a deionized water (dH 2 O) control are compared for their ability to inhibit α‐amylase activity during gelatinization of rice flour with medium to high amylose content (AC). Pasting properties are assessed using a Rapid Visco Analyzer (RVA). The optimal concentration of AgNO 3 to inhibit α‐amylase in the flour of rice cultivar Doongara during gelatinization is 1% (w/v) (≈0.06 m ). This concentration is tested further in three other types of rice for confirmation of the effects on RVA pasting properties. Peak viscosity is significantly higher using 1% AgNO 3 than in the dH 2 O control, while breakdown and pasting temperature are significantly lower. In conclusion, the incorporation of 1% (w/v) AgNO 3 into samples for RVA inhibits the α‐amylase activity in rice flour with medium to high AC, allowing pasting properties to be accurately measured using an RVA.