Whey proteins modify the phase transition of milk fat globule phospholipids

The phospholipids extracted from milk fat globule membranes were composed o f three major classes, phosphatidylethanolamines (37.2 %), phosphatidylchol ines (30.0 %), sphingomyelin (28.2 %), and two minor classes, phosphatidyli nositols (2.0 %) and phosphatidylserines (2.6 %). The thermogram showed tha t the extracted phospholipids presented a single wide-phase transition cent ered at 18.3 degrees C. The effects of temperature on the phase behaviour o f milk phospholipids in the presence of beta-lactoglobulin and alpha-lactal bumin have been studied at pH 4.0 and 7.0 (with or without calcium) using F ourier transform infrared spectroscopy. Principal component analysis carrie d out on the spectra in the 3 000-2 800 cm(-1) region showed that the bindi ng of the whey proteins to the phospholipids modified the lipid phase trans ition in different ways, depending on the in-solution protein. (C) Inra/Els evier, Paris.