Development and Validation of an Optoelectronic Method for the Assessment of Frying Colours of French Fries Based on RGB Colour Values

High frying quality in terms of frying colour is an important trait for potatoes meant for French fry production. Determination of frying colour is often performed visually, which might be affected by biases and is therefore less suitable for research. Available laboratory methods also lack the capability to cover the whole sample and distinguish between tuber parts. Additionally, sample destruction is often required for colour analysis. Therefore, a new approach using RGB colour values and the subsequent R/G ratio of French fries to assess frying colour was tested in this research. Over the course of 3 years, 673 samples of the cultivar Innovator were assessed and compared to visual scoring, and some samples were also assessed for glucose content. A high correlation of R² = 0.8346 between the visual scoring and the optoelectronic assessment was found for 633 samples. The validation data set of 40 samples reached a correlation of R² = 0.7850 with the implemented model. These results show that French fry frying colour can be described using the R/G ratio. This promising approach is suitable for other researchers as well as industry professionals with further research.