Evolution of available lysine and furosine contents in milk-based infant formulas throughout the shelf-life storage period

The evolution of the Maillard reaction (MR) by measuring the available lysine and furosine (FUR) contents in adapted and follow-up powdered milk-based infant formulas over the shelf-life storage period, at 20 and 37 °C, was studied. Available lysine and FUR contents were determined by fluorimetry and high-performance liquid chromatography respectively. Statistically significant differences were found between adapted and follow-up infant formulas with respect to the available lysine and FUR contents. Available lysine contents decreased significantly throughout the storage time, and the contents at 37 °C were lower than at 20 °C. A statistically significant increase in FUR contents was observed during the storage period, with the contents being high at 37 °C than at 20 °C. A simple regression analysis between the available lysine and FUR contents during (a) the first year (b) the second year and (c) the two storage years was applied. The best correlations were obtained during the first year of storage. The results obtained show a clear MR evolution during the storage of infant formulas.