Effect of pressure treatment of recombined whole milk on fat globule membrane composition and acid gelation functionality

Recombined whole milk was prepared by pressure treating skim milk (200 to 600 MPa/30 min) then homoge-nizing with milkfat (HPHO) or by homogenizing milkfat with skim milk then pressure treating the recombined whole milk (HOHP). 13-Lactoglobulin denaturation increased at higher pressures. Low levels of a-lactalbumin were denatured at 600 MPa only. Denaturation was similar in the HPHO and HOHP milk. The HPHO milk had statistically similar levels of total protein, higher levels of whey protein and x-casein and lower levels of as-casein adsorbed to the fat globules compared with the HOHP milk. The HPHO milk had a higher proportion of 13-casein directly at the interface at all pressures and a higher proportion of x-casein and a lower proportion of denatured whey proteins at pressure up to 400 MPa than the HOHP milk. Acid gels prepared from the HOHP milk had higher final G ' and yield stresses than those from the HPHO milk. These differences are discussed in relation to the compositions of the proteins adsorbed to the fat globules and how these interact during acidification.