Quality, bioactivity and cytotoxicity of thymol nanofiber-fortified bread: Insight into molecular interaction mechanism

Thymol, a bioactive compound, offers significant potential in functional foods but its application is limited by poor stability, solubility and bioavailability. This study aimed to enhance thymol's stability and bioactivity by encapsulating it in pullulan-whey protein isolate-based electrospun nanofibers and evaluating its effects in bread fortification. The impact of encapsulation on thymol's recovery, functional properties, bioavailability and cytotoxicity was assessed. The results showed that bread fortified with thymol encapsulated pullulan-whey protein isolates-based nanofiber (THY-PW-NF) significantly improved flour pasting properties and bread texture, while also enhancing thymol's recovery (78.07 %) during bread preparation compared to using free thymol. THY-PW-NF in bread preserved its bioactivity after gastrointestinal digestion. It increased its inhibitory effects on alpha-amylase, alpha-glucosidase and pancreatic lipase as revealed by molecular docking and molecular dynamic simulations. Cytotoxicity assays on Caco-2 cells confirmed that exposure to free thymol, thymol extracted from nanofibers and THY-PW-NF derived from fortified bread within a concentration range of 0-20 μg/mL did not significantly impact cell viability compared to control cells over 24 h. These findings suggest that encapsulation effectively incorporates thymol into functional foods, maintaining its health benefits without compromising safety.