No abstract

Hydrophilic tannic acid and hydrophobic resveratrol were successfully co-encapsulated in zein nanoparticles prepared using antisolvent precipitation and then coated with pectin by electrostatic deposition. The encapsulation efficiencies of the tannic acid and resveratrol were 51.5 ± 1.9% and 77.2 ± 3.2%, respectively. The co-encapsulated nanoparticles were stable against aggregation at the investigated pH range of 2.0 to 8.0 when heated at 80 °C for 2 h and when the NaCl concentration was below 50 mM. The co-encapsulated tannic acid and resveratrol exhibited stronger in vitro antioxidant activity than ascorbic acid, as determined by 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH·) and 2,2′-azinobis (3-ethylberizothiazoline-6-sulfonic acid) radical cation (ABTS+·) scavenging assays. The polyphenols-loaded nanoparticles significantly decreased the malondialdehyde (MDA) concentration and increased the superoxide dismutase (SOD) and catalase (CAT) activities in peroxide-treated human hepatoma cells (HepG2). An in vitro digestion model was used to study the gastrointestinal fate of the nanoparticles. In the stomach, encapsulation inhibited tannic acid release, but promoted resveratrol release. However, in the small intestine, it led to a relatively high bioaccessibility of 76% and 100% for resveratrol and tannic acid, respectively. These results suggest that pectin-coated zein nanoparticles have the potential for the co-encapsulation of both polar and nonpolar nutraceuticals or drugs.

Ionic liquids (ILs) have arisen as alternatives to organic solvents and been used in natural pigment extraction in recent decades. However, the solubility and stability of carotenoids in phosphonium- and ammonium-based ILs are insufficiently explored. In this work, the physicochemical properties of the ILs, and the dissolution behavior and storage stability of three carotenoids (astaxanthin, β-carotene, and lutein) in the IL aqueous solution were investigated. The results showed that the solubility of the carotenoids in the acidic IL solution is higher than that in the alkaline IL solution, and the optimal pH is about 6. The solubility of astaxanthin (40 mg/100 g), β-carotene (105 mg/100 g), and lutein (5250 mg/100 g) was the highest in tributyloctylphosphonium chloride ([P4448]Cl) due to the van der Waals forces with [P4448]+ and hydrogen bonding with Cl−. A high temperature was beneficial to improve the solubility, but it can reduce the storage stability. Water has no significant effect on the carotenoid stability, but a high water content decreases the carotenoid solubility. A IL water content of 10–20%, an extraction temperature of 338.15 K, and a storage temperature of less than 298.15 K are beneficial for reducing the IL viscosity, improving carotenoid solubility, and maintaining good stability. Moreover, a linear correlation was found between the color parameters and carotenoid contents. This study provides some guidance for screening suitable solvents for carotenoid extraction and storage.