Preparation of Protein‐Stabilized β‐Carotene Nanodispersions by Emulsification–Evaporation Method

Abstract

This work was initiated to prepare proteinstabilized b-carotene nanodispersions using emulsificationevaporation. A pre-mix of the aqueous phase composed of a protein and hexane containing b-carotene was subjected to high-pressure homogenization using a microfluidizer. Hexane in the resulting emulsion was evaporated under reduced pressures, causing crystallization and precipitation of b-carotene inside the droplets and formation of b-carotene nanoparticles. Sodium caseinate (SC) was the most effective emulsifier among selected proteins in preparing the nanodispersion, with a monomodal b-carotene particlesize distribution and a 17-nm mean particle size. The results were confirmed by transmission-electron microscopy analysis. SC-stabilized nanodispersion also had considerably high f-potential (-27 mV at pH 7), suggesting that the nanodispersion was stable against particle aggregation. Increasing the SC concentration decreased the mean particle size and improved the polydispersity of the nanodispersions. Nanodispersions prepared with higher b-carotene concentrations and higher organic-phase ratios resulted in larger b-carotene particles. Although increased microfluidization pressure did not decrease particle size, it did improve the polydispersity of the nanodispersions. Repeating the microfluidization process at 140 MPa caused the nanodispersions to become polydisperse, indicating the loss of emulsifying capacity of SC due to protein denaturation.

Optimized conditions to produce water-in-oil-in-water nanoemulsion and spray-dried nanocapsule of red ginseng extract

“…This method involves the homogenization of an organic phase containing lipid and an organic solvent with an aqueous phase containing water and an emulsifier, which followed by the evaporation of the organic solvent from the lipid droplets which occurs the droplets to shrink in size (Lee & McClements, 2010). The solvent evaporation technique has already been successfully conducted to manufacture ß-carotene nanoemulsions as food grade ingredients (Tan & Nakajima, 2005;Chu et al, 2007). Ethyl acetate is usually used as a solvent for the solvent evaporation method, and Food and Drug Administration of USA declares ethyl acetate as being generally recognized as safe (GRAS) for application in foods and beverages 59 (Lee & McClements, 2010).…”

Recent Development on Synthesizing and Characterizing Food-Grade Microemulsions

“…The whole process from sample negative staining to obtaining results takes only ten minutes [11] . Chu B-S et al [12] measured particle size distribution and microstructure of microemulsion using Transmission electron microscope. The Transmission electron microscope results confirmed the results from Dynamic light scattering, showing that β-carotene particles were spherical, with an average diameter of 20nm.…”

Nanoparticles and Nanoemulsions

“…Some of the emulsifiers used to produce nanoemulsions, in particular the small molecule surfactants, are more effective to form smaller droplets than protein or polysaccharide-based emulsifiers (Yin et al, 2009;Qian and McClements, 2011). However, proteins and polysaccharides are able to impart better emulsion stability by electrostatic or steric repulsive forces (Chu et al, 2007a;McClements and Rao, 2011).…”

“…This explains why caseins possess excellent emulsifying properties. During emulsification, caseins readily adsorb at the surface of oil droplets in aqueous solution, decrease the interfacial tension at the droplet interface and stabilize the emulsion by electrostatic and steric repulsive forces (Chu et al, 2007a). Caseins are available as sodium caseinate commercially.…”

“…Both sodium caseinate and whey proteins were used to prepare ␤-carotene nanodispersions using emulsification and/or a solvent displacement method (Chu et al, 2007a(Chu et al, , 2007b. It was shown that sodium caseinate produced nanodispersions with smaller particle size and had better stability than those prepared with whey proteins due to the caseins' molecular structure and chemical properties.…”