Comparative Microencapsulation of Six Vegetable Oils in Gum Arabic Freeze-Dried Systems: Surfactant Effects on Encapsulation Efficiency and Stability

Gum arabic (GA) is a promising polymer for oil microencapsulation due to its emulsifying and film-forming properties and regulatory acceptance. Here we introduce a fully natural, low-energy emulsion–freeze-drying route and a head-to-head screening framework that compares surfactant chemistry and oil identity under identical processing conditions. Rice oil was used as a model to evaluate two oil: GA ratios (1:3 and 1:0.3, solid basis) and three surfactants (Tween 80, sodium cocoyl glutamate (SCG), and lecithin) at 0.1–1%. Emulsions were characterized by Dynamic Light Scattering (DLS) (z-average, PDI), emulsification index, and viscosity, then freeze-dried and evaluated for encapsulation efficiency (EE). High oil load (1:0.3) gave EE = 0% for all conditions, whereas GA-rich emulsions (1:3) enabled encapsulation, with 0.1% surfactant selected as optimal. Using this formulation window, six oils (rice, jojoba, aloe vera, sweet almond, safflower, sesame) were screened, yielding EE values from 0 to 95%. Safflower and sesame showed high EE without surfactant, while rice, sweet almond, aloe vera, and jojoba benefited mainly from SCG or lecithin. Despite producing smaller droplets, Tween 80 generated polydisperse, low-stability emulsions and did not improve EE. Overall, EE is governed by GA–surfactant interfacial cohesion and oil chemistry rather than droplet size alone.

Link to the full article: https://www.mdpi.com/2504-5377/10/1/22