Characterisation of aged infant formula powder based on ingredients produced by membrane filtration

International audience

إنجليزي. The global infant formula (IF) market is expanding rapidly, driven by the increasing working women population, which limits breastfeeding opportunities. Spray-dried powdered IFs are widely used for their enhanced stability and reduced storage and transport. However, physicochemical changes such as the Maillard reaction, lactose crystallization, and fat oxidation during storage can compromise IF quality. Understanding these changes is essential for optimizing production and storage conditions, especially for minimally processed IFs designed to preserve nutritional integrity, for which the literature is scarce. Hence, we aimed at evaluating the physicochemical stability of IFs during storage. Three IF powders were produced at the semi-industrial scale: T-, without heat treatment; T+, with pasteurization of the concentrate alone (75°C, 2 min); T+++, combining milk pasteurization (72°C, 30 s) and heat treatment of the concentrate (85°C, 2 min) before spray-drying. They were then packaged in sealed metal cans under modified atmosphere and stored at room temperature and in a heat chamber at 40°C for periods of up to 11 and 6 months, respectively. Physicochemical properties, including moisture content, water activity, total fat and free fat content, whey protein denaturation were monitored. Maillard reaction was specifically assessed by monitoring lactosylation of whey proteins, and furosine and Nε-carboxymethyl-lysine content and color.All IF powders demonstrated satisfactory microbiological stability after 8 months at room temperature. No significant changes in moisture content or color were observed after 10 months at room temperature. Some variations were observed at room temperature for water activity, but it remained below 0.3. Protein denaturation was negligible, even after 6 months at 40°C. However, higher levels of lactosylation were detected across all IF powders, indicating the early stage of Maillard reaction took place despite low water activity. Thus, minimally processed IFs could achieve stability comparable to classically heat-treated ones, with lactosylation remaining as a challenge.