Study of NaCl and KCl effects on molecular structure of cheese by Mid-infrared spectroscopy

In this study, five Cantal-type cheeses with different salts (NaCl and KCl) and two ripening times (5 and 15 days) were analyzed for their physicochemical characteristics, their structure at a molecular level and their rheological properties during heating (20 to 60 °C). The analysis of the molecular structure of cheeses was investigated by MIR spectroscopy coupled with ICA (Independent Components Analysis) and rheological properties by small-amplitude oscillatory rheology. ICA on physicochemical characteristics showed a good discrimination of the cheeses as a function of their chemical characteristics and ripening time. ICA applied to MIR spectra gave Independent Components (ICs) that were attributed to the molecular characteristics of protein, water and fat. Signal proportions of each IC depicted information regarding changes in those ICs with salts, heating and ripening. In addition, similar fat melting temperatures were obtained, regardless the technique used (oscillatory rheology and MIR) for all cheeses. This study demonstrated that MIR spectroscopy coupled with ICA is a promising tool to monitor and characterize modification of cheeses at a molecular level depending on temperature, salt content, and ripening time