Scaling-Up Microchannel Emulsification Foreseeing Novel Bioactives Delivery Systems

Abstract

In the recent years, emulsification technologies that generate droplets individually have attracted a great deal attention in various fields, e.g., for chemicals, cosmetics, foods, and pharmaceuticals. Such drop-by-drop emulsification technologies include membrane emulsification using microporous membranes and microchannel (MC) emulsification, among others. The authors developed MC emulsification chips, consisting of parallel microgrooves or compactly arranged straight through-holes. Using this MC emulsification technique, the authors have evaluated the formulation a two-phase system consisting of size-controlled O/W emulsions loaded with bioactive molecules, such as β-carotene or γ-oryzanol, PUFAs or polyphenols. The MC emulsification process enabled the production of β-carotene-loaded O/W emulsions with average droplet size (dav) of 27.6 μm and coefficient of variation (CV) of 2.3% and γ-oryzanol-loaded droplets with dav of 28.8 μm and CV of 3.8%. The highly monodisperse O/W emulsions were physically stable during up 4 months storage in darkness at 5 °C. In addition, we investigated the formation characteristics of O/W emulsion droplets in the presence of electrolyte by MC emulsification using differently charged surfactants. Droplet formation was conducted by pressurizing a dispersed phase (refined soybean oil) through the MC silicon chip into a continuous phase containing 1.0 wt% of sodium dodecyl sulfate (SDS) or polyoxyethylene (20) sorbitan monolaurate (Tween 20), and an electrolyte (NaCl) (0–1.0 mol/L). Monodisperse O/W emulsions with an dav of 26 μm and a CV below 5% were produced when the NaCl concentration was lower than a threshold level that is 0.3 mol/L for SDS and 0.5 mol/L for Tween 20. The authors also developed a large MC emulsification device including a newly designed asymmetric MC array chip to realize the mass production of uniformly sized droplets on a liter per hour scale, so that satisfying the minimum droplet productivity needed for industrial-scale production. The large MC emulsification device has a potential droplet productivity exceeding several tons per year, which could satisfy a minimum industrial-scale production of monodisperse microdispersions containing emulsion droplets, microparticles, and microcapsules loaded with bioactive compounds. Such systems have as continuously increasing potential application in the formulation of functional foods, providing a good opportunity to improve the solubility of bioactive compounds, so that increasing their bioavailability.