Abstract
This brief overview covers some important aspects of microchannel (MC) emulsification, especially for food-grade applications. We introduce typical MC emulsification systems; fundamental characteristics of their droplet generation; and preparation of food-grade monodisperse emulsions, microparticles, and microcapsules. Major advantages of grooved MC emulsification plates include detailed direct observation of droplet generation from parallel MCs and a wide droplet size range. Straight-through MC emulsification plates are advantageous for higher productivity of monodisperse emulsion droplets. The uniquely mild droplet generation for MC emulsification exploits interfacial tension dominant at the micron level, suppressing degradation and denaturation of heat- and shear-sensitive emulsion components. Information on devices and operating parameters affecting the resultant droplet size is summarized, and effects of properties of MC array surfaces and emulsion components on droplet generation behavior are discussed. Layer-by-layer (LBL) deposition improves the stability of monodisperse oil-in-water (O/W) emulsion droplets prepared by MC emulsification. Coating with a maximum of seven layers of surface active components with alternating positive or negative charges changed the ζ-potential of the oil droplets, depending on the electrostatic properties of the outer layer. Several combinations of differently charged surface-active components have already been successfully applied for LBL deposition.
