Determination of peroxide value in edible oils based on Digital Image Colorimetry

Abstract

Edible oils are naturally oxidized under heat or light, generating compounds responsible for undesirable flavors and tastes, which lead to the depreciation of products that contain them. The first compounds formed in oil oxidation are hydroperoxides, which can be estimated by determining the peroxide value (PV, meq O2/Kg) based on iodometric titration, requiring large amount of hazardous reagents and presenting difficulties detecting the endpoint. Thus, this work aimed to develop an economical and non-subjective method to predict the PV in edible oils based on Digital Image Colorimetry. First, six standards were prepared with hydrogen peroxide solutions. After reaction with potassium iodide, the mixtures were imaged using a smartphone camera. The color parameters from the RGB, HSV, CMYK, L*a*b*, or XYZ systems were calibrated against the meq O2 of standards. A test set of 50 edible oil samples was used for validation based on the standard method. RMSE and R2 values of 3.21 meq O2/kg and 0.97 were obtained using M from CMYK color system as analytical signal. The amount of reagents consumed in the proposed method was 98.7% reduced compared to that of the standard method.