Size Distribution of Fat Globules in Goat Milk

Abstract

Milk from French-Alpine goats and Holstein cows was obtained from a bulk tank immediately prior to analyses. Fat globule size was determined by laser particle size analysis. Individual globules of fat in goat milk ranged from 0.73 to 8.58 m in diameter. The average diameter of particles based on volume to surface area ratio (d vs ) was 2.76 m and was less than the mean (d vs ) of 3.51 m for bovine milk, in which fat globules ranged from 0.92 to 15.75 m in diameter. The specific surface area of particles in caprine milk was 21,778 cm 2 /ml, whereas the specific surface area of particles in bovine milk was 17,117 cm 2 /ml. Ninety percent of the total particles found in goat milk were less than 5.21 m in diameter, whereas 90% of the total particles in bovine milk were less than 6.42 m based on the volume frequency distribution. Dissociation of casein micelles by urea in goat whole and skim milk caused larger d vs values due to the effect of fat particles and reduced the specific surface area in both milks because the total number of detectable particles in both whole and skim milk was reduced. (