Relationship Between Blocked Lysine and Carbohydrate Composition of Infant Formulas

The quantity of blocked lysine in spray-dried infant formulas in Italy was calculated by the furosine method. This quantity was then correlated with the composition of the carbohydrate fraction. In formulas containing only lactose as carbohydrate its presence in large quantities (6.7–7.5 g/100 mL of formula as fed), with a lysine-rich protein fraction, may lead to amino acid blocking of >20%. In formulas in which lactose was substituted with low-DE maltodextrin a reduction of lysine blocking was possible. Addition of glucose may result in high levels of blocked lysine.