Mid Infrared Spectroscopy and Multivariate Analysis Evaluation of Adulteration in Whey Protein Powder

Abstract

Mid infrared (MIR) spectroscopy was combined with multivariate approaches Principal Component Analysis (PCA) and Partial Least Squares (PLS) regression to assess modifications in spectral profile of whey protein concentrate (WPC) powder due to changes in formulation level using caffeine, creatine and lactose, simulating fraud. Adulterations were made by replacing WPC in different levels from 5 to 50% (w/w - 5% steps) with three adulterants in separate. The spectra comparison of the samples allowed the identification of peaks associated to characteristic chemical bonds of each adulterant. PCA was carried out and 89% of the total variability of the spectral data was explained by three principal components, which allowed the confirmation of variables influencing each sample mixture and validating the spectral observations. Above 20% decrease in WPC content (20% adulteration), it was possible to differentiate all the three substances used. Predictions of percentage of WPC substitution were made through PLS regressions. The best prediction models were: lactose > creatine > caffeine. However, predictions resulted in overall good accuracy, low relative errors and coefficients of determination of fitting of calibration and validation curves above 0.97 in all cases. Therefore, techniques employed here aid the quality assessment of food products as alternative analytical tools.

Use of mid infrared spectroscopy to analyze the ripening of Brazilian bananas

“…We claim that this negative absorption is due to the emission of some gas in the banana ripening process. The assignments regarding the observed bands are as follow: symmetrical ester C-O-P stretch (1025 cm −1 ), phospholipids (1020 cm −1 to 1282 cm −1 ), asymmetrical C-O stretch of C=O-O-C (1170 cm −1 ), asymmetrical phosphate diester PO2 (1245 cm −1 ), lipids C-H stretch (1400 cm −1 to 1477 cm −1 ), amide I (1650 cm −1 ), amide II (1540 cm −1 ), H-OH stretching (1650 cm −1 ), lipids C=O (1750 cm −1 ), CH3, CH2 stretch (2900 cm −1 ), OH bend (2900 cm −1 ) (Andrade et al, 2020;Pereira et al, 2020;Meng et al, 2014). Some factors may contribute to a negative absorbance spectrum, such as: inadequate cleaning of the ATR crystal, Christiansen effect, high humidity, among others.…”