Initial studies into the characterisation of ripening stages of Emmental cheeses by mid-infrared spectroscopy

Abstract

Experimental Emmental cheeses were analysed to evaluate the potential of mid-infrared spectroscopy to follow the ripening process. Cheeses were sampled at seven different ripening stages and were analysed. The infrared spectra were obtained by placing the cheese slices directly over the attenuated total reflectance crystal. Analysis of variance showed significant (P ≤ 0.05) absorbance changes between spectral sets in the regions assigned to vibrations of alcohol, amide and hydrocarbon chains. Principal component analysis (PCA) made it possible to describe four groups including samples ripened during 21, 27 and 34 days (G1), 51 and 58 days (G2), 65 days (G3) and the samples at the end of the ripening (mould opening, about 85 days) (G4). Using general discriminant analysis of spectral data, it is not possible to correctly distinguish samples according to seven dates of sampling, but samples belonging to the four groups identified by PCA are predicted well by the regression model.