Investigating the ability of mid-infrared spectroscopy to analyse dietary supplements (from type to digestion): a preliminary study on sulforaphane supplements

Abstract Dietary supplements are popular but poorly regulated, leading to concerns about their quality and accuracy of labelling. Developing fast, simple, and sustainable methods to analyse these supplements could help protect consumers by improving quality control and regulation. This study aimed to differentiate protein-based sulforaphane supplements of similar composition using mid-infrared (MIR) spectroscopy, investigate the impact of production age on spectral profiles, and assess the ability of MIR spectroscopy to monitor in vitro digestion of these supplements. Supplements were stored for 12 weeks and analysed using an attenuated total reflectance module attached to a MIR instrument every 2 weeks. In addition, INFOGEST static in vitro digestion was performed, and MIR measurements were taken before, during, and after each phase. It was observed that the principal component analysis (PCA) score plots and loadings were different between the type of protein used to prepare the supplement. The PCA analysis of the stored samples showed a similar trend between the samples. The partial least squares regression models were able to predict the type of samples and days of storage, however, with differences. Overall, MIR spectroscopy could be considered a potential tool to be further investigated for quick and qualitative analysis of dietary supplements.