Development of a Lipid Particle for β-Carotene Encapsulation Using a Blend of Tristearin and Sunflower Oil: Choice of Lipid Matrix and Evaluation of Shelf Life of Dispersions

Abstract

Solid lipid particles are colloidal carriers that have been studied for almost 20 years in the pharmaceutical field and recently have been investigated by food researchers due to their capacity to enhance the incorporation of lipophilic bioactives and their bioavailability in aqueous formulations. The aims of this study are to choose a suitable lipid matrix to produce solid lipid particles, which would be used to encapsulate β-carotene, and to evaluate the capacity of dispersions to protect the incorporated carotenoid. Bulk lipid mixtures of tristearin and sunflower oil were analysed by differential scanning calorimetry and wide angle X-ray diffraction, and the mixture with the highest degree of structural disorganisation was chosen. β-Carotene was then encapsulated in solid lipid particles produced with this mixture, composed of 70 % tristearin and 30 % sunflower oil (6 % total lipid) and stabilised with hydrogenated soy lecithin and Tween 80 (3 % total surfactant) by hot pressure homogenisation. Two types of particles were produced, using one or two passages in the homogenisation step. Average particle size, zeta potential, thermal behaviour, crystallinity and β-carotene concentration were monitored over 4 months of storage (under refrigerated conditions). The results showed minor differences between the systems in terms of size distribution, although the particles produced with one passage through the homogeniser were slightly more efficient at protecting the β-carotene from degradation and also suffered few microstructural alterations after 4 months.

Keywords

• solid lipid particles
• β-carotene
• encapsulation