Curcumin nanoemulsions stabilized with natural plant-based emulsifiers

Abstract

The effect of natural plant-based emulsifiers, citrus peel pectin, and gum Arabic, on the stability of oil-in-water (O/W) nanoemulsions encapsulating curcumin using a microfluidizer were studied. Pectin was more efficient than gum Arabic for nanoemulsions formation, with lower amounts of emulsifier (2% w/w) needed for the generation of smaller droplets (d3,2–220 nm). The stability of prepared nanoemulsions was measured using the LUMiSizer® analytical centrifugation test. The results showed that pectin gave better protection against droplet coalescence with temperature (40–60 °C). However, gum Arabic provided more protection of oil droplets from coalescence against a series of environmental treatments, including a range of pH variations (3–9) and NaCl additions (100–500 mM). Both emulsifiers showed adequate protection against freeze-thawing treatment. Furthermore, droplet size aggregation was more critical in pectin-stabilized emulsions during 7 days of storage at 4 °C. These results were explained by the formation of bridging flocculation within the pectin biopolymers. However, gum Arabic gave greater curcumin retention (85%) and stability against degradation compared to pectin (70%) after 7 days of storage. This was attributed to the thick and high-density layers formed by gum Arabic, which could provide better physical and chemical barriers against environmental stresses. The results from this study offer important information in developing “label friendly” products for encapsulating labile lipophilic bioactive compounds for use in the food and beverage industries.