Detection and quantification using ATR-FTIR spectroscopy of whey protein concentrate adulteration with wheat flour

Expensive and time-consuming methods are currently used to identify manipulated whey protein concentrate (WPC). We tested the application of attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy to detect and quantify adulteration of WPC with wheat flour (WF). ATR-FTIR is based on the interaction between IR radiation and the molecular bonds in the samples, allowing the capture of its vibration energy and the acquisition of spectra with information that can be used to identify and quantify functional groups. WPC Samples were adulterated with different percentages of WF and spectra were collected. Amide I and II bands exhibit a decreasing protein content when more WF is added. Conversely, at the carbohydrate characteristic band (1080 cm−1), there is an increasing intensity as more WF is added. Partial least squares (PLS) regression models presented low prediction errors and high coefficients of determination. Furthermore, one of the models was chosen for a blind prediction test of 10 samples adulterated with random amounts of WF, and it could make reasonable predictions of the actual levels of adulteration. Therefore, ATR-FTIR spectroscopy coupled with multivariate analysis shows strong potential to detect adulteration in WPC with WF and the capability to quantify the added mass content.