For a standard infant formula milk powder, browning reactions were shown to become limiting for shelflife for storage at higher temperature rather than lipid oxidation. Advanced glycation end (AGE) products were found in the temperature range 65e115 C to have an energy of activation for their formation of 28 kJ mol1 following crystallisation of the powder using an indirect ELISA method for determination of AGE. This energy of activation was larger than the energies of activation of 6.5 and 5.7 kJ mol1, as found for formation of the Strecker aldehydes 2- and 3-methyl butanal, respectively. Formation of AGE occurred in the browning reaction sequence later than Strecker degradation. At 25 C less than 0.1 ng mg1 AGE was formed in storage for 2 months. Toxicity could only be detected for storage for longer than 1 month at 65 C, where AGE formation is approximately 2 ng mg1.