Study and preparation of polysaccharide nanoparticles to stabilize Pickering emulsions

Abstract

The main challenge in the production of food emulsions is their kinetic stabilization by using safe components for human health. Emulsions stabilized by solid particles, the "Pickering" emulsions, are an alternative to the classical emulsions stabilized by surfactants. These emulsions are characterized by high coalescence stability and decreased susceptibility to environmental changes, such as pH and ionic strength. The objective of this study is to produce nanoparticles from polysaccharides (chitin, chitosan and gellan) and from a residue of the food industry rich in fiber (coffee grounds) to act in the stabilization of "Pickering" emulsions. Two main strategies will be evaluated for production of nanoparticles from polysaccharides. Firstly the production of nanocrystals by acid hydrolysis of polysaccharides will be evaluated. The preparation of the crystals will be confirmed through X-ray diffraction and polarized light microscopy. In the second strategy nano/microparticles will be obtained by ionic gelation of chitosan and gellan and by polyelectrolyte complex formation between chitosan and gellan. The coffee grounds nanoparticles will be obtained by reducing the particle size through milling or high pressure homogenization. The particles obtained will be characterized according to their size distribution, zeta potential, morphology and contact angle at the oil/water interface. After that the oil/water emulsions will be prepared using soybean oil or hydrocarbon (n-hexadecane) as apolar phase and the polysaccharide particles will be used as the unique emulsifying component of the systems. Emulsions will be characterized for stability, shear and dilational rheology, morphology, droplet size distribution and zeta potential.