Development, physical stability and bioaccessibility of β-carotene-enriched tertiary emulsions

The aim of this study was to develop a beta-carotene-enriched tertiary emulsion (lactoferrin/alginate/epsilon-poly-L-lysine). Then, its physical stability as well as beta-carotene content under external stresses (temperature, pH and ionic strength changes) was evaluated. Furthermore, lipid digestibility and beta-carotene bioaccessibility of primary, secondary and tertiary emulsions were determined. Tertiary emulsion underwent a substantial particle size increase up to 13 mu m after extreme temperatures, acidic conditions and with salt addition. However, small particle size (0.41 mu m) and negative zeta-potential (-43.4 mV) was observed at basic pH. In addition, beta-carotene content in tertiary emulsions decreased only 40% when emulsions were subjected at temperatures <= 70 degrees C, in acidic conditions and below 0.3 M NaCl. After in vitro digestion, tertiary emulsion presented higher lipid digestibility (83.59 +/- 11.81%) and beta-carotene bioaccessibility (70.10 +/- 5.26%) compared with primary and secondary emulsions. This study provides knowledge to understand the behaviour of beta-carotene-loaded tertiary emulsions under different conditions, valuable for further application in foodstuffs.