Application of vibrational spectroscopy tandem with chemometrics in the assessment of authenticity and adulteration of sport whey protein supplements

Nowadays, one of the major concerns among athletes is finding authentic sports supplements following some illegal adulteration and contamination scandals. Whey protein powder is one of the most used supplements among athletes to build a muscular body which makes this supplement attractive for fraudsters. It could be adulterated by some cheaper materials such as milk powder. Hence, the determination of the authenticity of sports supplements has become a worldwide concern. This work aimed to propose near-infrared spectroscopy (NIR) as a fast and non-destructive testing tool for the detection of adulteration of whey protein supplements. After some investigations; we found out, whey protein powder could be adulterated with milk powder, maltodextrin, and milk whey powder in our country. These adulterants are used as bulking agents because of their lower price. Therefore, we made our adulterated samples in a range of 2% WW-1 to 100% WW-1 by each of these adulterants. NIR spectra were collected from samples in a range of 10000 cm-1 to 4000 cm-1 three times and the average of them was used for multivariate analysis. A variety of data pretreatments including first derivative, standard normal variate (SNV), multiplicative scatter correction (MSC) and combination of SNV-detrend, MSC-detrend, first derivative-SNV-detrend, and first derivative-MSC-detrend were examined after applying mean center. The best preprocessing method was selected according to the pattern of discrimination analysis which was principal component analysis (PCA) in this study. One hundred and ten sport whey protein supplements were purchased from the market and all these steps were repeated for them as a test set. The PCA results revealed a good pattern of classification after first derivative preprocessing. Thus, it seems NIR could be implemented as a rapid screening method for the detection of milk powder, maltodextrin, and milk whey powder in sport whey protein supplements.