Increasing Value of Winery Residues through Integrated Biorefinery Processes: A Review

Abstract

The wine industry is one of the most relevant socio-economic activities in Europe. However, this industry represents a growing problem with negative effects on the environment since it produces large quantities of residues that need appropriate valorization or management. From the perspective of biorefinery and circular economy, the winery residues show high potential to be used for the formulation of new products. Due to the substantial quantities of phenolic compounds, flavonoids, and anthocyanins with high antioxidant potential in their matrix, these residues can be exploited by extracting bioactive compounds before using the remaining biomass for energy purposes or for producing fertilizers. Currently, there is an emphasis on the use of new and greener technologies in order to recover bioactive molecules from solid and liquid winery residues. Once the bio compounds are recovered, the remaining residues can be used for the production of energy through bioprocesses (biogas, bioethanol, bio-oil), thermal processes (pyrolysis, gasification combustion), or biofertilizers (compost), according to the biorefinery concept. This review mainly focuses on the discussion of the feasibility of the application of the biorefinery concept for winery residues. The transition from the lab-scale to the industrial-scale of the different technologies is still lacking and urgent in this sector.

Grape Pomace as a Natural Source of Phenolic Compounds: Solvent Screening and Extraction Optimization

“…Wine is an alcoholic beverage produced from a sequence of processes applied to grapes, including stalk removal, crushing, fermentation, and pressing [ 4 , 5 ]. Among the solid waste produced, grape pomace (GP), which is constituted by stalks, skins, and seeds, is one of the most relevant winery residues [ 2 , 4 , 5 , 6 ].…”

“…Wine is an alcoholic beverage produced from a sequence of processes applied to grapes, including stalk removal, crushing, fermentation, and pressing [ 4 , 5 ]. Among the solid waste produced, grape pomace (GP), which is constituted by stalks, skins, and seeds, is one of the most relevant winery residues [ 2 , 4 , 5 , 6 ]. Indeed, GP has become an attractive natural source of phenolic compounds, which are well known for their high antioxidant activity and nutraceutical benefits [ 6 , 7 ].…”

“…Bioactive compounds, such as phenolic molecules, can be recovered from a solid matrix through extraction processes assisted by solvents, microwaves, ultrasounds, etc. One of the most common and traditional extraction techniques for the recovery of phenolic compounds is solid−liquid extractions (SLE) [ 5 , 6 , 11 ]. SLE is based on mass transport phenomena that are affected mainly by the extraction solvent type, temperature, and extraction time [ 12 , 13 ].…”

“…SLE is based on mass transport phenomena that are affected mainly by the extraction solvent type, temperature, and extraction time [ 12 , 13 ]. The extraction time and temperature are among the most important parameters to be optimized to achieve high recoveries of compounds [ 5 , 6 ]. According to the published results, an increase in the operation time may enhance the extraction efficiency, since the release of phenolic compounds from the matrix occurs gradually [ 14 , 15 ].…”

“…Grape pomace has become an attractive natural source of phenolic compounds through solvent extraction processes [ 5 , 24 , 25 ]. However, there is a lack of explorative and systematic approaches to selecting the best conditions for the extraction of these compounds.…”