Alginate particles for encapsulation of phenolic extract from Spirulina sp. LEB-18: physicochemical characterization and assessment of in vitro gastrointestinal behavior

Encapsulation can be used as a strategy to protect and control the release of bioactive extracts. In this work, an extract from Spirulina sp. LEB-18, rich in phenolic compounds, was encapsulated in biopolymeric particles (i.e., composed of alginate) and characterized concerning their thermal behavior using differential scanning calorimetry (DSC), size, morphology, swelling index (S), and encapsulation efficiency (EE%); the release profile of the phenolic compounds at different pHs and the particle behavior under in vitro gastrointestinal digestion were also evaluated. It was shown that it is possible to encapsulate the phenolic extract from Spirulina sp. LEB-18 in alginate particles with high encapsulation efficiency (88.97%). It was also observed that the particles are amorphous and that the encapsulated phenolic compounds were released at a pH 7.2 but not at pH 1.5, which means that the alginate particles are able to protect the phenolic compounds from the harsh stomach conditions but lose their integrity under intestinal pH conditions. Regarding bioaccessibility, it was observed that the encapsulated phenolic compounds showed higher bioaccessibility compared to phenolic compounds in free form. This work increases the knowledge about the behavior of alginate particles encapsulating phenolic compounds during in vitro gastrointestinal digestion. It also provides essential information for designing biopolymeric particle formulations encapsulating phenolic compounds for application in pharmaceutical and food products. The study was financially supported by the following programs and institutions: Science Without Borders—CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), CSF (Ciência sem fronteiras), CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior), Brazil, the University of Minho, Braga, Portugal, and Foundation for Science and Technology (FCT, POPH-QREN and FSE Portugal). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit, and by LABBELS–Associate Laboratory in Biotechnology, Bioengineering and Microelectromechanical Systems, LA/P/0029/2020.