Encapsulation of Grape (Vitis vinifera L.) Pomace Polyphenols in Soybean Extract-Based Hydrogel Beads as Carriers of Polyphenols and pH-Monitoring Devices

In this work, novel bio-based hydrogel beads were fabricated by using soybean extract asraw waste material loaded with Lambrusco extract, an Italian grape cultivar. The phenolic profile andthe total amount of anthocyanins from the Lambrusco extract were evaluated before encapsulatingit in soybean extract-based hydrogels produced through an ionotropic gelation technique. Thephysical properties of the produced hydrogel beads were then studied in terms of their morphologicaland spectroscopic properties. Swelling degree was evaluated in media with different pH levels.The release kinetics of Lambrusco extract were then studied over time as a function of pH of therelease medium, corroborating that the acidity/basicity could affect the release rate of encapsulatedmolecules, as well as their counter-diffusion. The pH-sensitive properties of wine extract werestudied through UV-Vis spectroscopy while the colorimetric responses of loaded hydrogel beadswere investigated in acidic and basic solutions. Finally, in the framework of circular economy andsustainability, the obtained data open routes to the design and fabrication of active materials aspH-indicator devices from food industry by-products.