Triple-Wavelength Spectrophotometric Determination Activity of Alliinase in Onion

The activity of alliinase in onion was determined by triple-wavelength spectrophotometry. Not only the interference due to background and asymmetry of absorption peak, but also baseline sloping due to linear absorption of interfering components were eliminated by the proposed method. The absorbance ΔA was calculated by the formula ΔA= A2-［(λ2-λ3)A1+(λ1-λ2)A3］/(λ1-λ3), where values of absorbances, A1, A2 and A3 were measured at the wavelengths of 426 nm (λ1)、 446 nm (λ2)、 506 nm (λ3). Linear relationship between values of ΔA and mass concentration of sodium acetylformate acid was found in the range of 8.8-44.0 mg·L-1. Values of average recovery and RSD (n=5) found were 99.8% and 0.13% respectively.