Abstract:
Sauvignon blanc grape marc is an underutilised and problematic by-product in the wine
industry. However, this material is known to be rich in valuable phenolic compounds that
possess desirable antioxidant and antimicrobial properties.
This thesis describes the optimisation of a solid-liquid extraction protocol to target the
extraction of individual phenolic compounds from Sauvignon blanc grape marc. It also reports
for the first time that the important aroma precursor compounds cysetine 3-sulfanylhexan-1-ol
and glutathione 3-sulfanylhexan-1-ol can be extracted from grape marc. The aroma precursoroptimised
grape marc extract was subsequently added pre-fermentation to synthetic grape
medium and yielded wines with increased 3SH concentrations. The extract was found to
accelerate fermentation rate rather than cause any inhibition or toxicity and thus could become
a valuable tool to winemakers for modulating wine aroma.
Grape marc extracts were also investigated as a base for the formation of new polyester
materials, with the aim of creating novel polymers that retain the desirable properties of the
phenolic compounds. The phenolic-rich extract was reacted with a range of commercially
available and synthesised diacyl chlorides. Quercetin and synthesised selectively protected
quercetin species were also polymerised with these diacyl chlorides. The resulting materials
were characterised using FT-IR and in some case, solid-state NMR. A selection of these novel
polyesters were subjected to electrospinning and dropcasting to form films, and the formation
of fibres through use of the former technique was confirmed using SEM. Preliminary
antimicrobial studies showed that a selection of these materials were active against
Staphylococcus aureus, providing a sound platform for further exploration.
