STUDY OF THE PROPERTIES AND COLLOIDAL STABILITY FOR THE TECHNOLOGICAL APPLICATION OF ZEIN-BASED NANOSPHERES

Nanospheres of alpha-zein fabricated by antisolvent precipitation are promising carriers for hydrophobic bioactives in foods. The objective of this research was to study the changes in the properties of zein nanoparticles (size, zeta-potential, PDI, loading efficiency and pH colloidal stability) by using different copolymer coatings (sodium caseinate and pectin), ethanol concentrations (75 to 95% v/v) and solvent/antisolven or zein/krill oil ratios. Smallest particles (< 200 nm) can be obtained with the use of sodium caseinate as coating. This is the first time that zein nanospheres are used as encapsulating agents for a krill oil extract. These nanoparticles with a zeta-potential value around -25 mV are stable at neutral to basic pH values based on their zeta-potential and visual analysis. The use of pectin as coating produced the largest particles (< 400 nm) indicating that an increase in hydrophobic interactions allows the formation of bigger assemblies. Pectin-coated nanoparticles increased the LE of krill oil in about 9% compared with non-coated particles. Moreover, the hill oil/zein ratio was found to be a suitable way to increase the LE of the nanoparticles. The encapsulation of krill oil within the zein nanoparicles improved the antioxidant activity of the particles (non coated and casein-coated particles). All types of nanoparticles were capable to nano-entrap appreciable amounts of a hydrophobic krill oil extract.