Effects of thermal processing and pH on the physicochemical properties, stability, and structure of taxifolin-loaded nanostructured lipid carriers

Abstract

In the present study the potential of nanolipid carriers (transfersomes) for improving the oral delivery of taxifolin, a poorly water-soluble bioactive compound with high antioxidant and anti-inflammatory activity was evaluated. Two transfersome formulations were prepared using lecithin, Span®60, and Tween®80, with cholesterol as a stabilizer (FA) and without cholesterol (FB), by the Ethanol Injection Method (EIM). The influences of thermal treatment (60-90°C) and pH (2, 4, 6, and 8) on physical stability, structure, and taxifolin degradation were evaluated. The transfersomes were physically and chemically stable during heating at lower temperatures (≤70°C), while thermal treatment at 80–90°C led to an increase in particle size (an increase of around 200 nm) and a decrease in taxifolin encapsulation. Moreover, there was no significant difference in particle size or polydispersity index (PDI) at high temperatures. The particle sizes of transfersomes FA and FB increased from 128 and 182 nm at pH 7 to 224 and 331 nm at pH 2, respectively. Both transfersome preparations remained relatively stable, with consistent antioxidant activity (IC50 = 0.64 mg/ml) over four weeks of storage at different temperatures (4, 25, and 40°C), showing higher stability at lower temperatures. The in vitro digestion experiment indicated physical stability after exposure to the simulated stomach stage. However, the reduction in the nanovesicles' surface charge after incubation with gastric juice, increased particle size. Based on these results, taxifolin-loaded transfersomes can be pasteurized at low temperatures, for incorporation into enriched food and beverage products.