Bioaccessibility of different types of phenolic compounds co-encapsulated in alginate/chitosan-coated zein nanoparticles

Simultaneous administration of different phenolic compounds might produce a synergistic effect offering a greater activity against chronic non-communicable diseases. This has prompted significant interest in developing nanodelivery systems that simultaneously encapsulate different bioactives and protect them from gastrointestinal digestion. This work aimed at evaluating the suitability of zein (ZN) and zein/polysaccharide-based nanoparticles to co-encapsulate different types of phenolic compounds and understand how increasing the complexity of the nanoparticulate systems affected the bioaccessibility of the polyphenols. Two phenolic acids, two glycosylated flavonoids, and three flavonoid aglycones were successfully co-encapsulated in the three nanoparticulate systems. The encapsulation efficiency of phenolic compounds loaded on ZN ranged between 95.3 and 98.5%. The incorporation of the coating-layers (alginate - algZN- and chitosan -alg/chiZN-) significantly increased the encapsulation efficiency of phenolic acids and glycosylated flavonoids. The bioaccessibility of phenolic compounds loaded on ZN increased by at least 50.2%. Enhanced bioaccessibility of phenolic acids and glycosylated flavonoids was observed upon coating with alginate, while the greatest polyphenol bioaccessibility was seen for the alg/chiZN (over 65.8%). The greatest bioaccessibility was observed for polar phenolic acids, followed by glycosylated flavonoids. Therefore, the developed systems could be potentially useful to co-encapsulate different types of phenolic compounds and to improve their bioaccessibility.