International audienceThe association of $\beta$-lactoglobulin ($\beta$-Lg) and $\alpha$-lactalbumin ($\alpha$-La) with milk fat globule membrane (MFGM), when whole milk was heated in the temperature range 60-95 °C, was investigated using one- and two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) under reducing and non-reducing conditions. In SDS-PAGE under reducing conditions, $\beta$-Lg was observed in MFGM material isolated from milk heated at $\geq$60 °C for 10 min; small amounts of $\alpha$-La and $\kappa$-casein were also observed in the MFGM material of milk heated at $\geq$65 °C for 10 min and $\geq$75 °C for 10 min, respectively. However, these proteins were not observed in SDS-PAGE under non-reducing conditions. Two-dimensional SDS-PAGE of MFGM material isolated from heated milk showed that the protein complexes that remained at the top of the non-reducing gel (first dimension) were resolved into $\beta$-Lg, $\alpha$-La and the major original MFGM proteins in the reducing gel (second dimension). These results indicate that $\beta$-Lg and $\alpha$-La associated with MFGM proteins via disulfide bonds during the heat treatment of whole milk. The amounts of $\beta$-Lg and $\alpha$-La that associated increased with an increase in the temperature up to 80 °C, and then remained almost constant. These maximum values for $\beta$-Lg and $\alpha$-La were ~1.0 mg*g-1 fat and ~0.2 mg*g-1 fat, respectively. Of the major original MFGM proteins, xanthine oxidase and butyrophilin were not affected by the heat treatment of whole milk, whereas PAS 7 was heat labile and PAS 6 decreased to some extent during heating.Interactions des protéines sériques avec les protéines de la membrane des globules gras induites par le traitement thermique du lait entier. Les interactions de la $\beta$-lactoglobuline ($\beta$-Lg) et de l'$\alpha$-lactalbumine ($\alpha$-La) avec les composants de la membrane des globules gras (MFGM), contenues dans le lait entier, chauffé entre 60 et 95 °C, ont été étudiées par électrophorèse mono ou bi-dimensionnelle, en gel de polyacrylamide et dodécyl sulfate de sodium (SDS-PAGE) en conditions réductrices ou non. En conditions réductrices, les gels de SDS-PAGE indiquaient la présence de $\beta$-Lg dans les MFGM isolés du lait chauffé dans des conditions $\geq$ à 60 °C - 10 min ; de faibles quantités d'$\alpha$-La étaient également détectées dans les MFGM pour ce même traitement thermique. Un traitement thermique plus intense ($\geq$ à 75 °C - 10 min) montrait la fixation de caséine $\kappa$. Aucune de ces interactions n'était observée en conditions SDS-PAGE non réductrices. La caractérisation en SDS-PAGE bi-dimensionnelle des MFGM isolés du lait chauffé montrait que les complexes protéiques qui restaient au sommet des gels non réducteurs (1e dimension) étaient résolus en $\beta$-Lg, $\alpha$-La et composants protéiques majeurs des MFGM en conditions réductrices (2e dimension). Ces résultats confirment l'association de la $\beta$-Lg et de l'$\alpha$-La avec les protéines d...
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