Bioavailability, rheology and sensory evaluation of fat-free yogurt enriched with VD3 encapsulated in re-assembled casein micelles

Abstract

Vitamin D₃ (VD₃) deficiency is a global problem. Better ways are needed to enrich foods with this important nutraceutical. VD₃ is fat-soluble, hence requiring a suitable vehicle for enriching nonfat foods. Our objectives were to assess the bioavailability of VD₃, from fat-free yogurt, in re-assembled casein micelles (rCMs) compared to that in polysorbate-80 (PS80/Tween-80) a commonly used synthetic emulsifier, and to assess and compare their rheology and palatability. We enriched fat-free yogurt with VD₃ loaded into either rCM (VD₃-rCMs) or PS80 (VD₃-PS80). In vivo VD₃ bioavailability was evaluated by a large randomized, double blind, placebo-controlled clinical trial, measuring serum 25(OH)D increase in subjects who consumed fat-free yogurt with 50 000 IU of either VD₃-rCM, VD₃-PS80, or VD₃-free placebo yogurt. Both VD₃-rCM and VD₃-PS80 increased the serum 25(OH)D levels by ∼8 ng ml⁻¹ and no significant differences in mean 25(OH)D levels were observed, evidencing the fact that VD₃ bioavailability in rCM was as high as that in the synthetic emulsifier. VD₃-rCM yogurt had a higher viscosity than VD₃-PS80 yogurt. In sensory evaluations, panelists were able to discern between VD₃-rCM and VD₃-PS80 yogurt, and showed a dislike for PS80 yogurt, compared to rCM or the unenriched control. These results complement our past results showing higher protection against thermal treatment, UV irradiation, and deterioration during shelf life, conferred to hydrophobic nutraceuticals by rCM compared to that by the synthetic surfactant or to the unprotected bioactive, in showing the advantageous use of rCM over the synthetic emulsifier as a delivery system for the enrichment of food with VD₃ and other hydrophobic nutraceuticals.