From waste to value: Upcycling white grape pomace through a multiproduct biorefinery approach

Abstract

The wine industry generates significant amounts of white grape pomace (WGP), a lignocellulosic byproduct with untapped potential for valorisation. This study presents an integrated biorefinery approach to maximize the utilization of WGP through a combination of hydrothermal and organosolv treatments, followed by solid state fermentation (SSF). Hydrothermal pretreatment was optimized to maximize sugar extraction, achieving up to 80.94 g L-1 of reducing sugars, which can serve as a substrate for microalgae cultivation. Organosolv treatment enabled the selective recovery of polyphenols and lignin, with the highest polyphenol yield (2.27 g kg-1 DW) obtained at 150 degrees C and a lignin yield of 34.72 \% at 200 degrees C. The remaining solid fractions were subjected to SSF using Aspergillus oryzae, Neurospora intermedia, and Rhizopus oryzae, leading to a significant increase in protein content, with A. oryzae achieving a protein content of 17.6 \% on dry weight basis. This multi-step integrated approach demonstrates a scalable and sustainable strategy for converting WGP into multiple high-value bioproducts, promoting circular economy principles in the food sector.