A team of researchers at the University of Bologna has developed a system to harness the chemicals in grape waste from the winemaking process, according to a paper published in the Royal Society of Chemistry’s Green Chemistry journal.
The paper suggests that a multi-purpose biorefinery could be developed to turn the millions of tonnes of grape residue created every year into products for use in the cosmetic and preservatives industries, as well as biogas.
According to the International Organisation of Vine and Wine, 27 billion litres of wine were produced globally in 2014, 44 per cent of which was in Italy. To produce this much wine, however, around five million tonnes of grape seeds and skin are left as waste of the winemaking process.
Referred to as ‘pomace’, this waste was traditionally used to create spirits like grappa, but amendments to EU legislation in 2008 reduced subsidies to distillers in an attempt to encourage more productive use for the waste.
Polyphenols – natural antioxidants used in cosmetics and preservatives – and biomethane had previously been extracted from red grape pomace, but no system that would be considered economically feasible has yet been put into practice on an industrial scale.
The team at the University of Bologna, however, led by Lorenzo Bertin, has developed a system that would use grape waste to produce polyphenols, fatty acids, biopolymers and biomethane.
The system exposes the pomace from red grapes to ‘supercritical carbon dioxide’ to extract polyphenols and sugars, before using anaerobic digestion to produce other useful compounds such as fatty acids.
Leftover solid waste then undergoes microbial treatment to produce methane, with liquid waste fermented to produce polymeric materials that are said to be environmentally friendly.
According to the researchers, the range of products created from a single source by the process would make it much more industrially viable.
Process ‘minimises lifecycle impacts of waste streams’
Evan Beach, a biorefinery specialist at Yale University, told the Royal Society of Chemistry: “This is an excellent example of life-cycle thinking applied to green technology. It’s been a major challenge to go beyond isolating a single product of interest. Bertin’s team have designed a process that yields a range of valuable products, which helps improve the process economics while minimising the lifecycle impacts of waste streams.”
Gonzalo Martinez, who worked on the project, added: “We’ve only shown one strategy for this biorefinery. If we change the order of steps, we will obtain different materials – for instance if we anaerobically digest the pomace before extracting the polyphenols, we’ll obtain other fatty acids, which will be even more interesting.”
Read the full paper on the University of Bologna’s study into a grape waste biorefinery system.
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