Encapsulation of orange-derived hesperetin in zein/pectin nanoparticles: Fabrication, characterization, stability, and bioaccessibility

Orange pomace is a byproduct of the orange juicing industry that contains several polyphenols that can exert health benefits. However, incorporating orange pomace polyphenols into functional foods is challenging because of their poor water solubility and low bioaccessibility. This problem can be overcome by incorporating the polyphenols into protein nanoparticle-based delivery systems. The objective of this research was therefore to encapsulate hesperetin in core-shell biopolymer nanoparticles assembled from zein and high-methoxy pectin using an antisolvent precipitation/electrostatic deposition method. Hesperetin is a bioactive polyphenol derived from hesperidin, which can be isolated from orange pomace. Fluorescence spectroscopy indicated a strong interaction between hesperetin and zein. Fourier transform infrared spectroscopy suggested that this interaction was primarily due to hydrogen bonding and hydrophobic interactions, while the interaction between pectin and zein was mainly due to electrostatic attraction. Hesperetin-loaded zein nanoparticles had a mean diameter, zeta-potential, and encapsulation efficiency of 179 nm, 23.2 mV, and 93% before coating with pectin, and 357 nm, −22.6 mV, and 94% after coating with pectin, respectively. The pectin coating improved the stability of the nanoparticles to aggregation and sedimentation under different environmental conditions: pH 2.0–8.0; temperatures up to 90 °C; salt levels up to 50 mM NaCl; and storage for up to one month. The antioxidant activity and in vitro bioaccessibility of the encapsulated hesperetin were significantly higher than hesperetin dispersed in water. These results show that core-shell biopolymer nanoparticles may be a promising approach to incorporate hesperetin (and possibly other polyphenols) into foods and beverages.