Spray-Dried PectiPhen Microparticles: A High-Value Antioxidant Excipient From Grape Processing Waste Via Electric Field-Assisted Maceration

In the current framework of sustainability, recycling and circular economy, this work pursued two main objectives: (i) to exploit green techniques assisting simple maceration to enhance polyphenols recovery from waste bentonite coming from organic white must filtration, and (ii) to develop a high value-added antioxidant excipient for pharmaceutical/cosmetic applications. The efficiency of polyphenol recovery was evaluated comparing simple maceration with ultrasound- or electric field-assisted maceration, using PEG 200 and/or propylene glycol as unconventional solvents. While the ultrasound-based approach did not yield remarkable results, careful selection of the process parameters for the electric field-assisted technique afforded a coloured extract with the highest polyphenols content (TPC) and antioxidant power (AP). Despite these promising results, the extract resulted unstable over time (≈15–20% reduction in TPC and AP after 9 months) likely due to its high water content. Consequently, it was further mixed with a citrus pectin dispersion, in the appropriate ratios and concentrations, to obtain a feed mixture suitable for spray drying. This process afforded PectiPhen microparticles in the form of a coloured powder characterised by high loading efficacy, poor flowability due to small particle size, negligible residual water content and hygroscopicity and, importantly, high storage stability (< 3% reduction in TPC and AP after 9 months). Based on these findings, the proposed PectiPhen microparticles could be considered a stable high value-added antioxidant solid hydrophilic excipient capable of preserving the activity of polyphenols.