ß-lactoglobulin as a vector for ß-carotene food fortification.

Food fortification is a strategy to overcome vitamin A deficiency in developing countries. Our aim was to investigate the involvement of the bovine milk protein ß-lactoglobulin (ß-Lg), a potential retinoid carrier, in vitamin A absorption. In vivo experiments were conducted by force-feeding mice with retinol or ß-carotene associated with either ß-Lg or oil-in-water emulsion, with subsequent determination of both vitamin A intestinal mucosa and plasma contents. Caco-2 cells were then used to investigate the mechanisms of vitamin A uptake when delivered by either ß-Lg or mixed micelles. We showed that ß-Lg was as efficient as emulsion to promote ß-carotene, but not retinol, absorption in mice. Similar results were obtained in vitro. Interestingly, an inhibitor of the Scavenger Receptor Class B Type I significantly decreased the uptake of micellar ß-carotene but not that of ß-carotene bound to ß-Lg. Overall, we showed that ß-Lg would be a good vector for ß-carotene food fortification.

Interactions of ß-lactoglobulin variants A and B with Vitamin A. Competitive binding of retinoids and carotenoids.

ß-Lactoglobulin (ß-Lg) is the major whey protein of bovine milk present at a concentration of 2-3 g L(-1). Its biological role is still not well-known. However, many studies have suggested that ß-Lg may play either nutritional or specific transporter role. The high affinity of ß-Lg for retinol and other retinoids was reported. The results of interaction studies of ß-Lg with carotenoids, that is, ß-carotene, ß-cryptoxanthin, and α-carotene, which display similar structures are reported in this study. The affinities of ß-Lg for binding of retinoids and carotenoids were compared, providing more information about the binding site(s) of these molecules by ß-Lg. Interactions were followed by the measurements of quenching of ß-Lg tryptophan fluorescence and retinol fluorescence. The obtained results indicate that carotenoids are bound by ß-Lg with high affinity of the order of 10(-8) M. Measurement of retinol competition with carotenoids for binding by ß-Lg suggests that the binding of these two ligands occurs at two different sites of ß-Lg.

Interlocking of ß-carotene in beta-lactoglobulin aggregates produced under high pressure.

Vitamin A deficiency is one of the major causes of mortality and morbidity in the developing World. This deficiency can be prevented by alimentary or pharmaceutical supplementation. However, both vitamin A oxidation and isomerization should be prevented, as these phenomenons result in loss of nutritional efficacy. The aim of this study was to investigate the effect of a food protein matrix, ß-lactoglobulin (ß-Lg) aggregates produced by high pressure (HP), on the stabilization of ß-carotene during storage and gastro-duodenal digestion and therefore on its bioavailability. In vitro gastro-duodenal digestion of ß-Lg aggregates entrapping ß-carotene showed that up to 12% and 33% of total ß-carotene was released after peptic and pancreatic digestion, respectively. Overall, our study showed that ß-Lg aggregates are efficient for caging and stabilization of ß-carotene during storage and digestion. Hence, it may be an interesting approach for the protection and the delivery of vitamin A.