A recent publication (here – open access) describes the development and validation of a smartphone reader to combat the previously reported fraud of adding red dye to cheaper species of tuna and passing them off as Thunnus thynnus (red tuna). The red colour is associated with freshness in the minds of consumers. The authors built a reference database of colourimetric readings (as CE XYZ data) using a spectroradiometer. This classified tuna by species and/or by adulteration with beetroot extract. They then used the pro camera on a commercial smartphone (Galaxy 7) to read test samples. Reading with the smartphone required a dark room. They used statistical functions to convert the camera’s RGB reading to CEXYZ and an achromatic reference sample to convert to CIELAB colour space to then match samples against the classification model. They reported good matching, with a 0.6% false negative rate and 10% false positive rate for validation samples classified as adulterated or mis-labelled.
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