Caffeic Acid Encapsulated Centrifugally Spun Antioxidant Fibers: Characterization and Incorporation in Cakes

The primary aim of this study was to formulate a cake with high antioxidant activity through the incorporation of centrifugally spun gelatin-based fiber which was enriched with caffeic acid. Characterization analyses were conducted to evaluate fibers with different concentrations of caffeic acid (2% and 4%), while simultaneously the effects of thermal and citric acid crosslinking on the physical and functional properties of the encapsulated fibers were investigated. The study revealed varying encapsulation efficiencies of caffeic acid in gelatin fibers (56.34-94.55%), markedly affected by substantial reduction of thermal crosslinking, contrasting with citric acid's minimal impact. Additionally, citric acid increased total phenolic content (TPC), but thermal treatment notably decreased antioxidant activity (AOA) due to its impact on radical scavenging and phenolic group dissociation. The addition of citric acid significantly reduced water vapor permeability by 22% suggesting an induced crosslinking in both thermal-treated caffeic acid and citric acid samples. The study highlighted reduced AOA and phenolic content in thermally treated fibers (thermally treated gelatin with 2% caffeic acid vs thermally treated gelatin with 4% caffeic acid), suggesting lower water solubility and improved thermal stability with approximately 24% remaining weight after thermogravimetric analysis. Despite this, cakes with thermally treated fibers had higher AOA due to improved heat resistance of fibers. Generally, adding fibers to cakes decreased hardness and pH while increasing TPC, AOA, and volume index, showing a novel approach using centrifugally spun fibers to enrich foods with antioxidants.