Research of Maillard reaction and stability of liquid infant formulas during storage

Summary This study investigated the Maillard reaction (MR) and the stability of liquid infant formulas (LIFs) stored at 5 °C, 25 °C and 40 °C for 6 months. With the increase in storage temperature, the concentrations of 2‐furoylmethyl‐ε‐lysine (furosine) increased from 60.72 to 109.60 mg/100 g protein and Nɛ‐ Carboxy methyl lysine (CML) increased 106.82 to 197.04 mg/100 g protein. Colour became darker, yellower and redder, and pH values decreased. Negative charges increased during the first 3 months and decreased during the last 3 months. Fat globule sizes increased and particle size distribution (PSD) regressed, and the accumulation of fat was clearly observed by confocal laser scanning microscopy (CLSM). Shear thickened with the increase in shear rate, and the turbiscan stability index (TSI) values increased. In summary, these results indicated that lower storage temperature (5 °C) inhibits the MR and reduces unstable changes of LIF during storage period; thus, the nutritional value of LIF can be largely preserved. The early and late products of Maillard reaction, the observation of microstructure and the determination of multiple stability indexes of liquid infant formula were carried out at different storage temperatures after sterilization during a 6‐month observation period.