Optical screening for presence of banned Sudan III and Sudan IV dyes in edible palm oils

ABSTRACT

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.

Graphical abstract

KEYWORDS:

• Edible oil
• palm oil adulteration
• refractive index
• VIS/NIR spectrophotometry
• excess refractive index
• principal component analysis

Acknowledgments

The authors would like to thank Dr Marti Mäkinen and Dr Sari Suvanto for their assistance and support during measurements. The work is part of the Academy of Finland Flagship Programme, Photonics Research and Innovation (PREIN), decision 320166. Business Finland also supports this work through the ChemiReader project (2387/31/2017).

Declaration of interest statement

The authors declare no competing interests.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This work was orted by the Academy of Finland [320166]; Business Finland [2387/31/2017].