Fat-Related surface tension and wetting properties of milk
Résumé
The surface tension of milk was found to decrease logarithmically with time, regardless of fat content. Moreover, the surface tension decreased with fat content up to about 35 g.kg-1. Above 10 MPa, homogenization resulted in increased surface tension, probably due to the lower creaming and lack of caseins in the continuous phase. The initial contact angle of homogenized milk on glass was similar to that of skim milk, probably due to the presence of casein micelles on the globule surface. After the first immersion, skim milk wetted glass surfaces completely. Conversely, the contact angle of whome milk increased with time, suggesting the formation of a hydrophobic adborption layer on glass. The composition and conformation of this layer can affect fouling and cleaning in technological dairy processes involving fat globules.