Discrimination of Cheddar and Kefalotyri Cheese Samples: Analysis by Chemometrics of Proton-NMR and FTIR Spectra

Abstract

Cheddar and Kefalotyri cheese belong to the category of hard cheeses. Cheddar has an English origin, while Kefalotyri is a traditional cheese in Greece and a well-consumed dairy product in Cyprus. Discrimination of dairy products can be determined through several chemical methods. The aim of this study was to discriminate the samples of Cheddar and Kefalotyri cheese by analyzing various samples, from different brands. Two spectroscopic techniques namely proton nuclear magnetic resonance (1H-NMR) and Fourier-transformed infrared (FTIR) spectroscopy were chosen in order to chemically characterise the samples. The first step of the methodology was the freeze-drying process for lyophilisation of the samples. The number of samples reached 28, including 14 Cheddar samples and 14 samples of Kefalotyri cheese. After that, measurements for each sample have been obtained by FTIR (% transmittance-wavenumber in cm-1) and 1H-NMR (signal intensity-chemical shift in ppm) techniques. The data were analysed using SIMCA software. The proposed techniques along with chemometrics allow the discrimination of those two types of cheese. Both techniques employed are of significant importance, since they provide information about good classification of the samples when they are combined together. Interpretation of results and classification by using chemometric methods confirmed the different recipe of the two types of cheese. This study is the initial step of the future work. Future research will focus on discrimination based on the species’ origin of milk of these and other cheese samples.