Investigation at the molecular level of soft cheese quality and ripening by infrared and fluorescence spectroscopies and chemometrics-relationships with rheology properties

Twelve traditional and 12 stabilised experimental soft cheeses were made according to a factorial design to two levels of dry matter (44% and 48%) and two fat on dry matter ratios (51% and 55%). Cheese samples were analysed using various methods to give physico-chemical data, uniaxial compression test data, emission spectra of tryptophan residues, excitation spectra of vitamin A, and the 900-1500, 2800-3000 and 1500-1700 cm−1 infrared regions. Common components and specific weights analysis showed that the common component 1 discriminating young and ripened cheeses explained 95%, 92%, 73% of the inertia of the 900-1500, 2800-3000 and 1500-1700 cm−1 infrared regions, respectively, and 51% of the rheology data. Common component 2 discriminating cheeses as a function of the technology explained 88%, 23% and 11% of the inertia of vitamin A spectra, chemical data and rheology data, respectively. The spectral patterns allowed molecular interpretations of the discrimination.