This study presents an exploratory analysis of the kinetics and mechanisms involved in the cooking process of 27 béchamel sauces. The evolving béchamel sauces during their elaboration were investigated using a hand-held near infrared spectroscopy (NIRS) sensor in combination with multivariate curve resolution-alternating least-squares (MCR-ALS) approach. MCR-ALS under hybrid hard-and soft-constraints as well as other active constraints within the ALS optimization phase was applied to elucidate the mechanism of the cooking process of evolving béchamel sauces aiming to resolve kinetic profiles and pure spectral signatures of the monitored products, being the rate constants outputted as additional information. The evolving béchamel sauces could be described with a kinetic model based on a first-order reaction (A k → B). These two species (A and B) involved on the process were related to changes in the scattering and in the nature and state of the water. Differences in the kinetic constants between béchamel sauces were found, which were associated with differences in the initial temperature of the cooking process. The obtained results were coherent with the images observed using a scanning electron microscopy (SEM). The methodology presented in this work offers a new strategy to study the elaboration of béchamel sauces in a nondestructive way, with the aim to give industrial producers a better understanding of their manufacturing process in a rapid and real time manner.