Due to the proven carcinogenicity of Sudan III and IV dyes, they are considered global public health issues. They are banned in all forms as food colourants. We propose the monitoring of simple and easy-to-measure optical properties of palm oils, such as the refractive indices and spectrophotometric properties, as efficient indicators to detect adulteration. Coupling these results with principal component analysis, excess refractive index, and integration of transmittance introduces a novel detection tool for the authentication of edible palm oil. This opens a new opportunity for accurate handheld devices to detect adulteration and provide control in the field. This work assessed in total of 49 samples, some collected from different parts of Ghana and others, in-house adulterated samples. The Ghana Food and Drugs Authority, who performed a complex and expensive chemical analysis of the samples, confirmed our results with good agreement.

Background: Palm oil is one of the most useful vegetable available. Sudan IV dye is used as hue enhancer in palm oil despite the ban as food colorant due to its carcinogenicity and mutagenicity by the International Agency for Research on Cancer (IARC). Methods: Surface enhanced Raman spectroscopy (SERS) coupled with chemometric methods was applied to detect the presence of Sudan IV in some edible palm oil samples. Results: We studied the samples within the 1200–1800 cm^− 1 Raman frequency range. In predicting adulteration, we used 1388 cm^− 1 Raman peak that is associated with Sudan IV as our marker. We were able to confirm adulteration in four of the five palm oil samples provided by the Food and Drug Authority of Ghana. Conclusions: With these methods, we confirmed the results from Food and Drug Authorities of Ghana by proving that there were indeed Sudan IV adulteration in some palm oil samples.