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Whey protein microparticles are of great potential in diverse applications such as fat replacement, emulsification, cargo delivery and formulation of high-protein beverages. We developed a method by which the major whey protein, β-lactoglobulin, (β-lg) is at first encapsulated through a facile procedure within CaCO3 micro-templates, followed by enzymatic crosslinking of the protein and succeeding removal of the template to form protein microparticles. Protein encapsulation increased the colloidal stability and influenced the micro-morphology of CaCO3 microparticles. Dynamic light scattering and ζ-potential measurements, supported by gel electrophoresis indicated that β-lg was entrapped in monomeric form. Heating of the protein-loaded CaCO3 microparticles to gel protein as an alternative to enzymatic crosslinking, was not feasible because pH reduction to 7.0 before heating caused considerable agglomeration and deformation of the carbonate particles. In subsequent to enzymatic crosslinking and template dissolution, confocal laser scanning microscopy illustrated that the resulting protein particles were spherical, micron sized (≈3μ) and structurally homogenous. It was found based on Fourier transform infra-red spectroscopy that enzymatic crosslinking twisted the β-sheet structures of β-lg. Gel electrophoresis and intrinsic fluorescence measurement showed that in addition to the enzymatic polymerization, thiol-disulfide exchange reactions contributed in protein particles formation. It was also concluded based on intrinsic fluorescence measurement that tryptophan microenvironment was not influenced by the enzymatic crosslinking. The fabricated β-lg particles did not undergo significant denaturation by subsequent heating. This may open a route to deliver near-native whey protein microparticles to final consumers.

Improving the nutritional and health properties of food products, e.g. infant milk formula, by the addition of functional ingredients is of primary importance. This study focused on bioactive milk polar lipids (PLs) recovered from dietary sources that are of increasing interest. The chemical compositions of buttermilks and butter serums were determined and the modulation of the fatty acid composition of milk PLs was investigated. Butter serums contain a higher amount of milk PLs than buttermilks (88 vs. 13-18g/kg dry matter), with a higher proportion of sphingomyelin (34 vs. 19% of PLs, respectively) interestingly close to human milk PL profile. Butter serums are also interesting sources of choline, an important nutrient for infant brain development. We demonstrated that the unsaturated fatty acid content of milk PLs recovered in the buttermilks and the butter serums, mainly the amount of C18:3n-3 and C22:6n-3 (DHA) that are of nutritional interest, can be increased by dietary strategies. This work opens perspectives for a better valorization of milk PLs in human nutrition (both infants and adults) to benefit their functional, nutritional and health properties.

The process of manufacturing infant milk formulas (IMFs) involves heat treatments that can lead to whey protein denaturation. The objective of the study was to determine how protein composition affects the denaturation kinetics of the whey proteins within IMFs. Three model IMFs (1.3% of cow’s milk protein) were produced with a caseins: whey proteins ratio of 40:60, differing only by the whey protein composition. The kinetics of heat-induced denaturation of α-lactalbumin, β-lactoglobulin and lactoferrin were investigated between 67.5 °C and 80 °C by chromatographic quantification of the residual native proteins. Results showed that the heat-denaturation of α-lactalbumin was reduced when β-lactoglobulin was absent. The heat-denaturation of lactoferrin was not affected by the composition of the IMFs but its presence enhanced the heat-denaturation of β-lactoglobulin. This study revealed that, for higher heat treatments (90 °C/15 s, 75 °C/15 min), IMF containing α-lactalbumin and lactoferrin preserved a higher proportion of native whey proteins than IMFs containing β-lactoglobulin.