The miscibility of milk sphingomyelin and cholesterol is affected by temperature and surface pressure in mixed Langmuir monolayers.
The miscibility of milk sphingomyelin (milk-SM) and cholesterol was investigated in this study. The effect of different physical states of milk-SM on its interactions with cholesterol was determined by the recording of isotherms of compression of Langmuir films for temperatures above and below the gel to Lα phase transition of milk-SM (Tm∼34°C). For T=15°C<Tm, the liquid expanded (LE) to liquid condensed (LC) phase transition of milk-SM monolayers was observed at surface pressures of 10-15mN/m. For T=43°C>Tm, the milk-SM molecules were in a LE phase regardless of the surface pressure applied. A phase diagram pressure - milk-SM/cholesterol composition was established. This study demonstrated that both temperature and surface pressure affected the miscibility between the milk-SM and cholesterol. The strongest attractive forces (i.e. condensing effect) were identified for 30mol% cholesterol when the milk-SM was in the LE phase state.
STLO, UMR1253, INRA, Agrocampus Ouest, 35000 Rennes, France.
Ken
K
Cheng
INRA, UR1268 Biopolymères Interactions Assemblages, 44316 Nantes, France.
Marie-Hélène
MH
Ropers
STLO, UMR1253, INRA, Agrocampus Ouest, 35000 Rennes, France. Electronic address: Christelle.Lopez@inra.fr.
Christelle
C
Lopez
D000818:Animals; D002417:Cattle; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism; D008892:Milk / Q000737:chemistry* / Q000378:metabolism; D044367:Phase Transition; D011312:Pressure; D013109:Sphingomyelins / Q000737:chemistry* / Q000378:metabolism; D013499:Surface Properties; D013696:Temperature
D013109:Sphingomyelins; D002784:Cholesterol
Langmuir film; Lipid domain; Melting temperature; Milk fat globule membrane