Emulsifying Properties of Coffee ( Coffea arabica L.) Pulp Pectic Polysaccharides

Abstract

Coffee pulp is a major residue of coffee processing and represents an environmental concern due to its large volume and inadequate disposal. In this study, three coffee pulp pectic fractions, acid-extracted pectin (CAP), hot water-soluble pectic fraction (HWSP), and chelating agent-soluble pectic fraction (CSP), were evaluated as stabilizers of oil-in-water emulsions containing medium-chain triglycerides (MCTs) or long-chain triglycerides (LCTs). Emulsions were prepared by high-shear homogenization followed by microfluidization, and pH 3.5 was selected after preliminary tests. Rheology, droplet size distribution, interfacial tension, microscopy, fluorescence, and Turbiscan analysis were used to assess emulsion formation and stability over 21 days. HWSP produced the most stable emulsions, especially with MCT, which is probably associated with its higher protein content, degree of acetylation, and arabinogalactan-protein content, favoring interfacial adsorption and reducing interfacial tension. These findings contribute to a better understanding of the potential of coffee pulp pectic fractions as emulsion stabilizers.