086: Physicochemical Properties and Bioaccessibility of Vitamin D3 Olive Oil Emulsions Stabilized With Pea Protein-Alginate Conjugates and Lecithin

Introduction

Recent advancements in nutraceutical delivery systems prioritize natural emulsifiers for sustainable, plant-based products. While plant proteins are emulsifiers, their emulsifying capacity and emulsion stability at acidic pH are to be improved. Glycating plant proteins with a polysaccharide and incorporating a small molecular surfactant like lecithin can enhance emulsion stability at various environmental stresses and encapsulation of bioactive compounds, improving quality and health benefits of products like salad dressings.

Methods

Pea protein isolate (PPI) was glycated with propylene glycol alginate at mass ratios of 2:1, 1:1, and 1:2 in an ultrasonic bath at pH 11.0 and 40°C for 45 min, followed by neutralization of pH and freeze-drying. Emulsions were prepared with 50.0% v/v olive oil containing 0.02% w/v VD3 and the pH 7.0 aqueous phase with 2.0% w/v freeze-dried conjugates and 1.0% w/v lecithin, by homogenization at 20,000 rpm for 5 min and sonication at 60% amplitude for 2 min. The prepared emulsions were also adjusted to pH 3.5. Control emulsions were prepared with comparable amounts of PPI and lecithin. Emulsions were characterized for visual appearance, structures, 30-day refrigerated storage stability, stability after heating (90°C, 25 min) and at 0-500 mM NaCl, lipid oxidation, VD3 retention after 30-day refrigerated storage and heating, and bioaccessibility of VD3 following simulated gastrointestinal digestion.

Results

The control emulsions exhibited creaming within a few days, while those prepared with 1:1 and 1:2 conjugates at pH 7.0 and 3.5 did not show creaming and significant increases in droplet diameter (10.29-19.69 mm) after 30-day refrigerated storage. These conjugates emulsion showed the improved physical stability in NaCl solutions and after heating, and oxidative stability during storage at 50°C. These emulsions retained 71-81% VD3 following refrigerated storage and 59-72% after heating followed by refrigerated storage. The bioaccessibility of VD3 in these emulsions was 62-66%. In comparison, VD3 directly dissolved in olive oil had retention of only 12-36% and bioaccessibility of 20%.

Significance

The emulsions in this study show great potential for manufacturing food products such as salad dressings as well as delivering VD3.

Authors: Surangna Jain, Qixin Zhong