CONICET | Buscador de Institutos y Recursos Humanos

Plant by-products is a source of bioactive compounds, and their use and exploitation are key in the reduction and reuse of food waste. Encapsulation of bioactive compounds in biopolymer matrices represents a great possibility in the development of functional foods. Ca(II)-alginate hydrogels show isotropic dispersion and are modeled as a mass fractal system by SAXS analysis which allows to evaluate the network that is agglomerated by structures defined as rods generated by multimers which are aggregates of dimers formed by two antiparallel polyguluronate chains (egg-box structure).Ca(II)-alginate beads were prepared by the dropping method, using sodium alginate 1.5%, containing the extracts of by-products (beetroot and cowpea) then characterized by total phenolic compounds and antioxidant capacity. The microstructural characterization was performed at the LNLS SAXS2 beamline in Campinas, Brazil at λ = 0.1488 nm. The wave vector (q) range was selected in the range 0.096 nm−1 < q < 2.856 nm−1.Stems and leaves of beet and cowpea pods showed significant content of bioactive compounds, obtaining a phenolic content and an antioxidant activity (based on the loading efficiency) between 27 and 43 %. To analyze the microstructure, SAXS data should be treated as follows: 1. display as a function of the wave vector (q) and intensity (I), plotting on a log-log scale to obtain 1, 2 and 3. 2. R1 and R2 radius, are calculated by Kratky plots consisting of the scattering intensity multiplied by the square modulus of the scattering vector, I(q)∙q2.It has been demonstrated that SAXS provides valuable information about the microstructure of Ca(II)-alginate beads. The presence of natural extracts drives important structural changes in the network, that are follow from the molecular (arrangement of alginate polymer dimers) to the supramolecular (interconnection of the rods that built up the microstructure of the hydrogel) by SAXS.