Emulsifying properties of biopolymer extracts from Opuntia ficus indica cladodes

Abstract

The use of natural extracts in the field of cosmetics and pharmaceuticals is increasing due to the growing demand for sustainable and safe products, together with their potential therapeutic benefits. Bioextracts from the parenchyma of Opuntia ficus indica cladodes were characterized and evaluated as emulsifying agents. They contain pectin together with variable amounts of arabinogalactan-protein complex (AGP), as in many polysaccharides of natural origin. Their protein content varies according to the purification steps: 11.4 wt% for the raw mucilage (Mofi), 4.7 wt% for the pectin fraction (Pofi) and less than 0.5 wt% for the filtrated pectin fraction (FPofi). Part of the AGP contained in the Mofi and Pofi extracts precipitates as particles with a ∼5 µm diameter. Mofi at 1.5 wt% concentration is an efficient emulsifier of oil-in-water emulsions of medium-chain triglycerides or sunflower oil with stability against coalescence for more than three months. Pofi is less efficient and FPofi does not allow the stabilization of emulsions. The performance of emulsifiers is directly related to the protein content of the extracts and the role of the insoluble particles is essential. The insoluble particles of AGP are responsible for the stabilization through a Pickering effect. The emulsions have the characteristic properties of Pickering emulsions.