Title : Natural bioactive delivery systems for functional bread: Microencapsulated essential oils and acorn flour
Abstract:
The increasing demand for functional foods has stimulated the incorporation of natural bioactive ingredients into everyday basics such as bread. Although essential oils (EOs) are recognised for many important bioactivities, including antioxidant properties, their volatility and susceptibility to degradation limit their direct application in food systems. Therefore, microencapsulation has been used as an effective strategy to improve their stability, enhancing their potential as nutraceutical ingredients. This work aimed to develop a functional bread using the under valorized natural resource acorn flour and enriched with encapsulated EOs from Portuguese medicinal plants, with different encapsulation matrices being explored regarding the stability and performance of the bioactive compounds.
EOs were chemically characterised by gas chromatography-mass spectrometry (GC-MS), and their antioxidant activity determined using standard spectrophotometric methods. Essential oils were microencapsulated using bacterial cellulose (BC), obtained as a by-product of vinegar production, and methylcellulose (MC). The stability of the encapsulated systems was evaluated visually and through diffusion-wave spectroscopy. Bread formulations were prepared to compare wheat bread containing encapsulated EOs with formulations in which part of the wheat flour was replaced by acorn flour, evaluating the compatibility of the encapsulated systems with different flour matrices. Acorn flour demonstrated strong potential as a functional ingredient confirming its suitability for the development of innovative gluten-free formulations. Among the EOs evaluated, two exhibited high antioxidant activity, highlighting their potential as natural bioactive ingredients for functional food applications. Importantly, the bread prepared retained considerable antioxidant capacity after baking, indicating that the encapsulation strategy successfully protected the EOs against thermal degradation. Overall, these findings demonstrate a promising approach to develop a functional bread with enhanced antioxidant properties and potential nutraceutical value using national natural resources.
Acknowledgments: Authors would like to thank Fundação la Caixa and FCT through the project “Plantas aromáticas do Alentejo, probióticos e farinha de bolota no desenvolvimento de pão funcional” (PD23-0025). Authors would like also to thank the CERES - Chemical Engineering and Renewable Resources for Sustainability Research Center, funded by Fundação para a Ciência e a Tecnologia (FCT) (https://doi.org/10.54499/UID/00102/2025), Plano de Recuperação e Resiliência (PRR) (https://doi.org/10.54499/UID/PRR/00102/2025) and EQUIPAR+2 (https://doi.org/10.54499/UID/PRR2/00102/2025) budgets."
