Influence of fat globule membrane composition on water holding capacity and water mobility in casein rennet gel: A nuclear magnetic resonance self-diffusion and relaxation study

The effects of the composition of the fat globule surface on water holding capacity and water diffusion were studied in different rennet-derived retentates. Water holding capacity was determined from nuclear magnetic resonance (NMR) relaxation measurements; the water diffusion coefficient was estimated using Pulse Field Gradient NMR. Reconstituted fatty retentates were prepared from fat-free retentate mixed with different fat-in-water emulsions stabilized with native phosphocaseinates (NPCs) or sodium caseinates. Coagulation of retentate reconstituted with native fat globules (fresh cream) and of industrial fatty retentate was also investigated. The study showed that the fat droplet/water interface influenced the water diffusion coefficient in the cream-reconstituted retentate gel only. No effect was observed in the NPC- and Na-caseinate-reconstituted retentate and in the fatty industrial retentate after coagulation. The results of the relaxation measurements in the gelled fatty reconstituted retentates showed that the nature and the composition of the fat interface influence the syneresis behaviour.