Abstract
Dietary diversification, from 4/6 months of age, is a key developmental period characterized by specific nutritional needs covered mainly by breast milk and/or Infant Follow-on Formulas (IFF), and the gradual introduction of complementary foods such as Infant Flour (IF). Lipids play a crucial role during this period, as the main energy supplier and carrier of essential fatty acids and their long-chain derivatives, which contribute to infant development. These fatty acids are particularly prone to oxidation due to their multiple double bonds, resulting in a loss of nutritional quality and the formation of potentially toxic compounds. Lipid oxidation is a complex, multifactorial mechanism that is difficult to predict in foods such as IFF and IF. The project aimed to identify key physico-chemical levers for optimizing the nutritional profile and oxidative stability of dispersed systems representative of IFF and IF enriched with polyunsaturated fatty acids (PUFA), while maintaining acceptable nutrients bioaccessibility. Storage tests ranging from 20 days to 9 months at 25 or 40°C were carried out on model systems representative of IFF and IF, and then declined in a panel of modalities according to formulation and structure parameters. Systems with the most improved stability properties were subjected to an in vitro digestion process to characterize nutrients bioaccessibility. The results showed that the composition of IFF was homogeneous and acceptable, whereas that of IF was variable, with overages in omega 6 and vitamins. Oxidation mechanisms are primarily characterized by losses of vitamins (A and E), while PUFA and their long-chain derivatives remain relatively stable. IF are characterized by slower oxidation propagation kinetics than IFF. While structural parameters (e.g. droplet or particle size, order of surfactant addition) have a limited effect, formulation parameters (e.g. raw material composition, nature of surfactants) have significant potential in controlling oxidative stability. The introduction of carotenoids in the presence of tocopherols leads to improved oxidative stability and vitamin A content. This synergistic effect is also observed in the presence of sphyngomyelin in IFF. The bioaccessibility of lipids and proteins is relatively acceptable and not matrix-dependent. These results pave the way for improved vectorization of long-chain PUFA and vitamins in infant foods.