Evolution of water proton nuclear magnetic relaxation during milk coagulation and syneresis: Structural implications

NMR transverse relaxation times of water were obtained in skim milk after renneting and during the syneresis of the curd. New data analysis using the maximum entropy method was applied to relaxation curves to investigate the distribution of water between the whey and the curd during the shrinkage of the milk colt. It is shown that the T2 relaxation behavior is best presented as a continuous spectrum of relaxation times. Quantitative estimation of the amount of water inside the curd and in the whey can then be obtained at any stage of syneresis in an undisturbed way. Furthermore, transverse relaxation data were interpreted in terms of the miscroscopic structure of the water compartment inside the curd., and information about the water pore geometry and size distribution is deduced by inversion of NMR transverse relaxation data. / Des mesures relaxométriques RMN sont réalisées sur des laits coagulés et pendant la synérèse. Une nouvelle méthode de traitement du signal RMN est appliquée (Méthode de maximisation de l'entropie) pour étudier la répartition de l'eau entre le sérum et le caillé. Des mesures quantitatives sont réalisées au cours de la synérèse de façon non destructrice. De plus, à partir des données RMN, il est possible de disposer d'information sur la structure microscopique du gel.