Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt FTIR-ATR spectroscopy as a tool for the rapid detection of adulterations in butter cheeses Antonio Iranaldo Nunes Leite a,b , Cristina Guimarães Pereira a , Jonathan Andrade a , Nívea Maria Vicentini c , Maria José Valenzuela Bell a , Virgílio Anjos a,* a Grupo de Engenharia e Espectroscopia de Materiais, Departamento de Física, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, s/n - São Pedro, 36036- 900, Juiz de Fora, Minas Gerais, Brazil b Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte, 59380-000, Currais Novos, Rio Grande do Norte, Brazil c Embrapa Gado de Leite, Rua Eugênio do Nascimento, 610, Bairro Dom Bosco, 36038-330, Juiz de Fora, Minas Gerais, Brazil ARTICLE INFO Keywords: Butter cheese Vegetable oil Adulteration Authentication Chemometrics ABSTRACT This study assessed the potential application of Fourier-Transformed Infrared spectroscopy using Attenuated Total Reflectance (FTIR-ATR) coupled with multivariate approaches to characterize and detect adulterations in butter cheeses (BC) with soybean oil (SO). In general, as the adulterations were performed, there is a decrease in band intensities related to proteins, while for most bands related to lipid, the substitution of butter oil (BO) by SO led to increases in their intensities up to 70% of fraud. The band near 3007 cm -1 was evinced only in adulterated cheeses. Principal component analysis differentiated the samples validating the spectral observa- tions. A partial least squares model allowed the prediction of the percentage of SO added into the samples with low residuals. FTIR-ATR spectroscopy associated with chemometrics showed good performance in the detection of butter cheeses’ adulterations. 1. Introduction Cheeses are consumed worldwide and have a great commercial importance within the food industry (Dankowska, Małecka, & Kowalewski, 2015). In the Northeast region of Brazil, the type of cheese named “butter cheese” (BC) has a prominent position among dairy products because of its historic and cultural roots. Its processing con- sists of the coagulation of whole or skim milk, desorption of the curd obtained by acidification, washing of the mass with water and/or milk, salting, melting of the mass with butter oil (BO) and molding the cheese (Nassu, Lima, & Andrade, 2009). Milk is the only source of the fat content in BC and the addition of different fats is considered fraud. Among several possibilities of adul- terations, vegetable oil such as soybean oil (SO) is a very common one. In reality, it became a real issue for the dairy industry in Brazil (Dankowska et al., 2015). The adulteration generates an un- characterized product with problems regarding food quality and safety (Danezis, Tsagkaris, Camin, Brusic, & Georgiou, 2016). Analytical methods for lipid detection include the determination of physicochemical properties (i.e. melting point), water-soluble and -in- soluble volatile fatty acid profiles, or triacylglycerol composition (Koca, Kocaoglu-Vurma, Harper, & Rodriguez-Saona, 2010). However, most of them are based on wet-chemical analysis requiring hazardous chemicals as well as skilled and experienced staff. Also, they are time-consuming techniques with requirements of extensive sample preparation. Attempts using spectroscopic methodologies to investigate authen- ticity issues have been done using mainly the UV–Visible, FT-NIR, FT- MIR and Raman spectroscopies (Brandao, dos Anjos, & Bell, 2017; Brandao, Gouvea Neto, dos Anjos, & Bell, 2017; Mishra et al., 2016). Advances in MIR spectroscopy instrumentation and analysis allowed the extraction of information related to the composition of food com- ponents from complex spectra (Koca et al., 2010) and allowed the de- tection of adulteration in different foods (Jawaid, Talpur, Sherazi, Nizamani, & Khaskheli, 2013; Rohman, Sismindari, Erwanto, & Che Man, 2011). A wide variety of food has been subjected to adulteration including dairy products and others (Danezis et al., 2016; Pereira et al., 2018). However, so far, little information is available on the literature attesting the authenticity of BC using MIR spectroscopy. Considering the importance of monitoring adulterations of genuine cheeses, this study assessed the potential application of the FTIR-ATR spectroscopy, coupled with multivariate approaches (Principal Component Analysis (PCA) and Partial Least Squares (PLS) regression for characterization and quantification of BCs adulterated by SO, re- spectively. Besides physical-chemical parameters (protein, moisture, fat https://doi.org/10.1016/j.lwt.2019.04.017 Received 24 August 2018; Received in revised form 4 March 2019; Accepted 6 April 2019 * Corresponding author. E-mail address: virgilio.anjos@ufjf.edu.br (V. Anjos). LWT - Food Science and Technology 109 (2019) 63–69 Available online 08 April 2019 0023-6438/ © 2019 Published by Elsevier Ltd. T