Exploring the biological properties and bioaccessibility of orange peel extracts using deep eutectic systems

The ability to recover bio-compounds from by-products offers a significant chance for their use as bio-additives in the food industry. Carotenoids are known for their properties as antioxidants, antimicrobials, and food colorants. In the present study, the potential of hydrophobic natural deep eutectic systems (HDES) for the revalorization of orange peels was explored. Extracts were obtained, and their biological properties were evaluated in vitro, such as cytotoxicity, antiproliferative capacity, antioxidant capacity, and antimicrobial potential against Staphylococcus aureus and Escherichia coli. To support the potential application of orange peel – HDES extract as a functional ingredient or food additive, INFOGEST in vitro static digestion was performed. The results showed that Octanoic acid: Proline (C8:Pro) extract and Menthol: Eucalypthol (Me:Eu) had higher selective index meaning that these HDES have a higher selectivity towards human colorectal adenocarcinoma cell lines. Also, C8:Pro showed a higher carotenoid extraction yield extracting 168 μg/100 g of lutein with ORAC value of 34.8 mM TE. In general, just C8:Pro extract showed inhibition against both bacteria. Bioaccessibility of β-cryptoxanthin was enhanced in C8:Pro extract in 10.1%, indicating high stability during gastrointestinal digestion. These results reveal that orange peel – HDES are promising to be of use in industrial food applications.