Chemometric Tools and Ftir-Atr Spectroscopy Applied in Milk Adulterated With Cheese Whey

Abstract

Brazilian law forbids the addition of cheese whey in milk. However, adulteration with cheese whey is one of the most applied fraud due to its low cost. The detection of this fraud is the quantification of Caseinomacropeptide (CMP). The CMP is a constituent of the whey that can be used as adulteration marker. Thus, an analytical method capable of identifying CMP by Fourier Transform Infrared Spectra (FTIR) was developed using chemometrics methods. Firstly, we attempted to develop an exploratory analysis model by Hierarchical Grouping Analysis (HCA) and Principal Component Analysis (PCA) that indicated similarity between samples of raw milk and semi-skimmed milk. Moreover, in the PCA scores, it was possible to observe a tendency of separation between samples with different concentrations of CMP. Afterwards, multivariate regression models were used for Partial Least Squares (PLS), Partial Least Square with Interval Synergism (siPLS) and Supporting Machines with Least Squares (LS-SVM) to quantify the adulteration in different types of milk by Cheese serum through the CMP. All the models were then compared to each other and the results of the official method with Liquid Chromatography Tandem mass spectrometry (LCMS/MS) analysis used by the Ministry of Livestock and Supply (MAPA). The model LS-SVM, employing the full spectrum, obtained the best result compared to the other models (PLS and siPLS) to quantify the CMP in the milk samples.

How Chemometrics Can Fight Milk Adulteration

“…HCA helped them to find the more appropriate number of clusters which was used later in the classification of the samples. Vinciguerra et al [38] used HCA as an exploratory treatment on the pre-processed measurements obtained by FTIR-ATR. By using both the Euclidean distance and Ward's method, a dendrogram was generated, however no pattern related to the caseinomacropeptide concentration was observed in the dendrogram, and multivariate regression was followed.…”

“…It was used by Delatour et al [99] on data collected from eight different NIR and MIR miniature sensors to measure the amount of semicarbazide hydrochloride, ammonium sulfate, and cornstarch in skimmed milk powder [96]. Another different use of PLS regression, synergy interval PLS (siPLS) [100], has been used by Vinciguerra et al to quantify cheese whey in cow's milk samples through MIR spectroscopy [38]. In this method, the MIR spectra were divided into different intervals (8, 16, 32, 64, and 128) with the same number of variables, applying a PLS on each interval.…”

“…Artificial neural network (ANN) regression methods, namely generalized regression-NN [106] and back propagation-ANN [107], were used to assess the amount of melamine, wheat flour, and corn flour in milk powder samples [108] and acidity in cow's milk samples [109], respectively, both through Raman spectroscopy. Least squares support vector machine (LS-SVM) [110] was applied on both NIR and dielectric spectroscopic data to quantify mature bovine milk in colostrum samples [111] and on MIR data to assess cheese whey in bovine milk [38], providing better results than PLS. A generalized linear model with lasso regularization (GLM-Lasso) [112] coupled with MALDI-TOF mass spectroscopy provides better results than PLS too, in this case, to detect bovine milk in caprine and ovine milk [113].…”

Artificial neural networks in the prediction of fraud in integral milk powder by adding whey powder

“…While the fraud executed in powdered milk raises the manufacturer's profitability, it lowers the nutritional value of the food. This occurs due to the reduced protein and fat levels, apart from inducing changes in the product in terms of the technological properties (VINCIGUERRA et al, 2019).…”

Mid-Infrared Spectroscopy as a Valuable Tool to Tackle Food Analysis: A Literature Review on Coffee, Dairies, Honey, Olive Oil and Wine

“…However, other adulterants are harmful because they cause serious adverse health effects such as the addition of urea, formaldehyde, detergents, ammonium sulfate, boric acid, benzoic acid, salicylic acid, hydrogen peroxide, sugars and melamine [ 68 , 70 ]. A recent study [ 71 ] suggested the use of FTIR associated with chemometrics to quantify the cheese whey added in milk, which can be used as a marker of adulteration. Although the use of cheese whey in some products is allowed, particularly in Brazil, it is often used as adulterant for pasteurized, Ultra High-Temperature Pasteurized and dry milk.…”