Controlled Co-Precipitation of Biocompatible Colorant-Loaded Nanoparticles by Microfluidics for Natural Color Drinks
Natural colorants, which impart a vivid color to food and add additional health benefits, are favored over synthetic colorants; however, their applications are limited by their low solubility in water and low stability. Here, we develop a versatile microfluidic strategy to encapsulate natural colorants in shellac nanoparticles with controlled physicochemical properties. The rapid mixing in microfluidic channels ensures the mixing time is shorter than the aggregation time, thus providing control over the co-precipitation of colorant and polymer. By introducing molecular interactions, colorant nanoaggregates are efficiently embedded in the shellac polymer matrix, forming hierarchical colorant-loaded nanoparticles. The colorant-loaded nanoparticles dispersed in water are transparent and stable over a wide pH range and their polymer matrix also provides a favorable microenvironment that greatly improves the shelf life of colorants. The improved solubility, stability and bioavailability of natural colorants suggest that shellac nanoparticles are ideal carriers and dispersions of the biocompatible colorant-loaded nanoparticles in water constitute a new type of stable, transparent, natural color drinks.