Background

Functional food ingredients can improve human health. However, the bioavailability of many functional food ingredients after oral administration is low because of their instability in the human gastrointestinal tract and low solubility in water. Food-grade pH-sensitive nanoparticles can efficiently deliver functional food ingredients into the human intestine, improve their solubility, and enhance absorption through enteric epithelial cells. In addition, these nanoparticles are biocompatible and non-toxic. Thus, food-grade pH-sensitive nanoparticles are promising carriers for delivering functional food ingredients.

Scope and approach

This review first introduces a few important functional food ingredients, their benefits for human health, and challenges regarding human intake. Then the existing food-grade pH-sensitive nanoparticles from the literature are categorized into three groups for review: polysaccharide-based, protein-based and lipid-based pH-sensitive nanoparticles. Examples are provided to illustrate the preparation methods and working principles of food-grade pH-sensitive nanoparticles.

Key findings and conclusions

Food-grade pH-sensitive nanoparticles can increase the bioavailability of functional food ingredients by improving their stability in the human stomach and by controlling their release into the intestine. Further investigations are needed to examine the effects of other factors in the human gastrointestinal tract (e.g. ions and digestive enzymes) on the stability of food-grade pH-sensitive nanoparticles. The non-toxicity of food-grade pH-sensitive nanoparticles needs to be confirmed. Combinations of in vivo and in vitro experiments could provide helpful information that would accelerate the commercialization of food-grade pH-sensitive nanoparticles.