Batch and Flow Ultrasound-Assisted Extraction of Grape Stalks: Process Intensification Design up to a Multi-Kilo Scale

Abstract

Nowadays, approximately 1 billion kg/y of grape stalks, with a remarkable polyphenols content, are produced worldwide. In this paper, the extraction process intensification of polyphenols in water was achieved under ultrasound-assisted recovery, focusing on kinetics and scaling-up factors. Immersion and cup-horn systems were exploited as acoustic cavitation sources, and the total phenolic content (TPC) was chosen to assess the process efficiency. The kinetics were evaluated by Peleg’s hyperbolic model, and the effect of both the initial feedstock granulometry and ultrasound size-reduction were determined. The results were compared with conventional extraction methods (data analysis by ANOVA). The best polyphenols yield was obtained after 45 min of sonication, giving between 29.71 and 31.89 mg/g (gallic acid equivalents over the dry matter). The extracts were characterized using HPLC-DAD, UPLC-ESI-MS/MS, DPPH• assay (2,2-diphenyl-1-picrylhydrazyl), TEAC assay (Trolox equivalent antioxidant capacity), and proanthocyanidin content determination. The flow-mode extraction procedure of grape stalks (2 kg) was carried out in a 15 L reactor. A semi-industrial decanter unit and a bag-filter were the keys units of the downstream operations. The resulting particle-free solution underwent nanofiltration on a membrane pilot skid, providing a final polyphenols-enriched stream concentrated up to 355.91%, as shown by the antioxidant activity and TPC.

Ultrasound extraction optimization for bioactive molecules from Eucalyptus globulus leaves through antioxidant activity

“…Few of them have showed the relative importance of all the variables (individually or in combination) involved in the extraction process and their influence on the antioxidant capacity of the extracted components. Major technological efforts for their large-scale industrial application are being successfully pursued [28] .…”

Cellulose Recovery from Agri-Food Residues by Effective Cavitational Treatments

“…According to their features, US have been largely applied on biomasses for a large number of purposes. The application of acoustic cavitation for the recovery of secondary metabolites from vegetal matrixes is well known in the literature [37,38]. Furthermore, the acknowledgment of US as a green technique for biomass exploitation has been established by more than 5000 recent papers produced only in the last five years, concerning US-assisted extraction (UAE) [39].…”

From Seaweeds to Cosmeceutics: A Multidisciplinar Approach

“…TPC was determined according to the Folin-Ciocalteu method, as previously described [28]. Briefly, polyphenols quantification was performed by applying a calibration curve of gallic acid as reference compound (dilutions between 5 and 250 µg/mL) in aqueous solutions.…”