Filippo Evangelisti

Sterol oxidation in infant milk formulas and milk cereals.

7-Ketocholesterol and 7-ketositosterol were chosen as reliable markers of the oxidation of cholesterol and phytosterols in infant milk formulas and infant milk cereals. A reversed-phase HPLC method was developed to measure them simultaneously in infant formulas. This method was then tested on a wide range of infant milk formulas and milk cereals on sale in Italy whose lipid composition is representative of the most common commercial formulas. The analytical results revealed no significant differences in the extent of oxidation of cholesterol and sitosterol. As the level of 7-ketocholesterol often followed the cholesterol level, a cholesterol content similar to that of human milk produced amounts of cholesterol oxides with possible negative effects on infant health. In contrast, the low cholesterol content of milk cereals never produced amounts of cholesterol oxides high enough to cause concern. The contents of phytosterols and hence their oxides were always low.

Determination of free amino acids in infant formulas

Abstract A fast and reliable method for the determination of free amino acids in infant formulas was developed. The method emphasizes the determination of taurine, methionine, arginine and tyrosine, as they are often added to these formulas in order to adapt them to the nutritional requirements of infants. The method involves the precipitation of the protein fraction, its separation by centrifugation, and the HPLC analysis of the o -phthaldialdehyde (OPA) derivatives of the free amino acids. The method was applied to several commercial formulas, as their actual content of free amino acids may be reduced by the development of Maillard reaction during processing and storage. The detected amounts of free taurine and methionine were often lower than those listed by the manufacturers. In some samples significant amounts of free arginine, tyrosine and methionine were detected, although they had not been listed among the added ingredients.