Recent progress in hydrogel delivery systems for improving nutraceutical bioavailability

Nutraceuticals are bioactive molecules found in foods that may improve human performance, wellbeing, or health. The potential health benefits of many nutraceuticals are not fully realized because they are chemically degraded during storage or within the gastrointestinal tract. Consequently, there is a need to develop food-grade delivery systems to encapsulate and protect nutraceuticals until they reach an appropriate location within the human body, e.g., mouth, stomach, small intestine, or colon. Hydrogel beads (microgels) assembled from proteins and/or polysaccharides can improve nutraceutical performance by protecting them from chemical degradation. These beads can be fabricated using simple and inexpensive processing operations that typically involve two steps: (i) formation of biopolymer-enriched particles; (ii) cross-linking of the biopolymers. Hydrophilic nutraceuticals are usually mixed directly with the biopolymer solution prior to formation of the hydrogel beads, whereas hydrophobic nutraceuticals are typically incorporated into lipid droplets (emulsions or nanoemulsions) prior to mixing with the biopolymer solution. Common particle-formation methods include injection, shearing, templating, and phase separation, whereas common cross-linking methods include changes in solvent quality, counter ion addition, enzyme addition, heating, and cooling. This article provides an overview of recent progress in the design and fabrication of food-grade hydrogel beads to encapsulate and protect nutraceuticals, including some examples of their potential applications. (C) 2016 Elsevier Ltd. All rights reserved.