GRANULOMETRY OF FATTY GLOBULES OF HUMAN MILK

Despite its importance regarding fat digestion in the infant, data available regarding the size of human milk fat globules in the 2 first days postpartum (p. p.) was scarce. Therefore, we measured the fat globule size distribution and its typical size parameters in colostrum and transitional milk from 17 mothers during 4 days p. p. The results were compared with mature milk from other mothers and infant formulas. The change in size after freezing and the electrokinetic potential (zeta) of mature milk fat globules was also measured for one mother. Before 12 h p. p., the mode diameter was 8.9 +/- 1.0 mu m vs 2.8 +/- 0.3 mu m at 96 h p. p. (P < 0.02). The specific surface area thus increased from 1.1 +/- 0.3 to 5.4 +/- 0.7 m(2)/g between colostrum and transitional milk (P < 0.02). In mature milk, the average modal diameter was 4 mu m and increased throughout lactation. Freezing increased the diameter by 10%. Lipid droplets in infant formulas were much smaller, namely sizing 0.4 mu m-potential of the mature human fat globules studied was -7.8 +/- 0.1 mV, which is a lower charge than for bovine milk fat globules. These structural differences could be of nutritional significance for infants and toddlers.