Behavior of vitamin E acetate delivery systems under simulated gastrointestinal conditions: lipid digestion and bioaccessibility of low-energy nanoemulsions.

Colloidal delivery systems are needed to incorporate oil-soluble vitamins into aqueous-based foods and beverage products. In this study, we encapsulated vitamin E acetate into oil-in-water nanoemulsions produced using either a low-energy method (Emulsion Phase Inversion, EPI) or a high energy method (microfluidization). Oil-in-water nanoemulsions (d<200 nm) could be produced using both low- and high-energy methods from a non-ionic surfactant (Tween 80) and medium chain triglycerides (MCTs). The influence of surfactant-to-oil ratio (SOR) on lipid digestion and vitamin bioaccessibility of EPI nanoemulsions was determined using a gastrointestinal tract (GIT) model that simulated the mouth, stomach, and small intestine. There were increases in the size and negative charge of the oil droplets after passage through the GIT, which was attributed to droplet coalescence and changes in interfacial composition. The rate and extent of lipid digestion decreased with increasing surfactant concentration, but the bioaccessibility of vitamin E acetate was high in all of the samples (>95%). No appreciable influence of the preparation method (low-energy versus high-energy) on lipid digestion and vitamin bioaccessibility was observed. The major advantage of the EPI method for forming nanoemulsions is that no expensive equipment is required, but relatively high surfactant concentrations are needed compared to microfluidization.