Composition of free amino acids in infant formulas

The relative percentage of the enantiomeric forms of free amino acids threonine, valine, isoleucine, leucine, methionine, phenylalanine, lysine, alanine, glycine, serine, proline, aspartic acid, glutamic acid, taurine and tyrosine in 9 infant formulas containing different whey protein/casein ratio was determined using a gas chromatographic method that allows the determination of the chiral composition Each formula showed different amino acids patterns. Glutamic acid was the major amino acid in most of the formulas; methionine and lysine were not detected in some samples and in others their percentage was very low. It was not possible to establish a relationship between the amino acid patterns and the whey protein/casein ratio. The used method allows a good resolution of the most enantiomeric forms of the analyzed amino acids and therefore, to evaluate their trend to racemization in the infant formulas investigated. D-enantiomeric form was only detected in alanine, the enantiomeric excess was among 48-96%.