Enhanced stability of emulsions treated by Ultra-High Pressure Homogenization for delivering conjugated linoleic acid in Caco-2 cells

Abstract

Using novel technologies which offer higher protection and release of bioactive compounds is a current challenge in the food industry. Ultra-High-Pressure Homogenization (UHPH) is an emerging technology that produces physico-chemical and microbiological stable emulsions. The ability of oil-in-water emulsions stabilized by soy protein isolates (4%) to deliver conjugated linoleic acid (CLA, 6%), was studied. Emulsions were produced by UHPH at 200 MPa and by conventional homogenization (CH) at 15 MPa. For another batch of CH emulsions, a heat treatment was also conducted applying high-temperature-short-time conditions (72 °C for 20 s; CH-HTST). The physico-chemical properties of the emulsions were determined, as well as microbial, physical, and oxidative stability. The emulsions were subjected to in vitro digestion, and tested on absorptive Caco-2 cells. The presence of CLA isomers was followed throughout the process. When comparing similar formulations, UHPH emulsions showed smaller particle size and a homogeneous microstructure than emulsions prepared by CH or CH-HTST. Moreover, UHPH produced a sterile emulsion and showed better physical stability during storage compared to other treatments, maintaining an optimal oxidative stability until 3 months. After in vitro digestion and delivery in Caco-2 cells, similar percentages of bioavailability of CLA were found for all the emulsion treatments. The study has gone towards enhancing oil-in-water emulsions by using UHPH technology for delivering conjugated linoleic acid in functional foods.