ENCAPSULATION OF ANTIOXIDANT PHENOLIC COMPOUNDS IN ZEIN ULTRA-THIN FIBERS VIA ELECTROSPINNING

Abstract

Phenolic compounds are of great interest for the food industry, in particular due to their antioxidant capacity. Nevertheless, their relevance as bioactive substances is often hindered by poor stability and solubility. Phenolic compounds can be encapsulated for that better maintaining their bioactivity. In this work, we explore an alternative for the encapsulation of phenolics using zein (Z), a food-grade biopolymer, as the carrier material. In particular, gallic acid (GA) and naringenin (NAR) were homogeneously incorporated in ultrathin zein fibers by means of a simple one-step electrospinning process. Morphology, cargo stability and cargo-carrier molecular interaction were studied. The phenolics release behavior was analyzed in aqueous media at different pH conditions. Pure Z fibers present a ribbon-like structure of variable dimensions, characteristically ranging between 230 – 396 nm in width up to 0.8 μm. Incorporation of the antioxidants did not visibly affect this morphology. Loading values were 4.93 ± 0.15% (GA) and 5.12 ± 0.60% (NAR). Phenolic loadings remained stable for the period observed (~3 months) at room storage conditions. Release studies revealed a burst release trend with a cumulative release threshold minimum for pH 2 and maximum for pH 7. Results show that this is a promising approach for phenolic compounds encapsulation.

Phenolic compounds are of great interest for the food industry, in particular due to their antioxidant capacity. Nevertheless, their relevance as bioactive substances is often hindered by poor stability and solubility. Phenolic compounds can be encapsulated for that better maintaining their bioactivity. In this work, we explore an alternative for the encapsulation of phenolics using zein (Z), a food-grade biopolymer, as the carrier material. In particular, gallic acid (GA) and naringenin (NAR) were homogeneously incorporated in ultrathin zein fibers by means of a simple one-step electrospinning process. Morphology, cargo stability and cargo-carrier molecular interaction were studied. The phenolics release behavior was analyzed in aqueous media at different pH conditions. Pure Z fibers present a ribbon-like structure of variable dimensions, characteristically ranging between 230 – 396 nm in width up to 0.8 μm. Incorporation of the antioxidants did not visibly affect this morphology. Loading values were 4.93 ± 0.15% (GA) and 5.12 ± 0.60% (NAR). Phenolic loadings remained stable for the period observed (~3 months) at room storage conditions. Release studies revealed a burst release trend with a cumulative release threshold minimum for pH 2 and maximum for pH 7. Results show that this is a promising approach for phenolic compounds encapsulation.