Iron fortification of foods is challenging due to iron’s chemical reactivity, limited bioavailability, and undesirable interactions with food matrices that can compromise product quality. Electrospinning offers a versatile approach to physically isolate micronutrients within polymeric carriers, potentially improving stability and digestive release. This study investigates the encapsulation of iron in electrospun pullulan fibres to control iron release during simulated gastrointestinal digestion.
Ferrous sulphate (FeSO4) and sodium iron ethylenediaminetetraacetic acid (NaFeEDTA) were encapsulated within electrospun pullulan fibres to achieve physical separation of iron from matrix interferences. Fibre morphology and structural characteristics were examined using electron microscopy, while Fourier transform infrared spectroscopy was used to confirm functional groups and successful iron incorporation. Iron release behaviour and bioaccessibility were evaluated using an in vitro gastrointestinal digestion model under simulated oral, gastric and intestinal conditions.
Uniform electrospun fibres were successfully fabricated across a range of pullulan concentrations. Microscopic analysis confirmed continuous fibrous structures, and spectroscopic analysis verified successful iron encapsulation within the pullulan matrix. During in-vitro digestion, source-dependent release behaviour was observed: FeSO₄ exhibited rapid gastric-phase release due to its high solubility under acidic conditions, whereas NaFeEDTA demonstrated slower release extending into the intestinal phase, likely due to the chelated complex requiring gradual dissociation before iron liberation. This delayed release favours iron delivery to the intestinal environment, the primary site of absorption, potentially improving bioaccessibility while minimising premature interactions in the gastric phase.
These findings demonstrate that electrospinning enables effective iron encapsulation and tunable digestive release profiles, offering a promising strategy to improve iron stability, targeted intestinal availability, and functional performance in fortified food systems.