Sulfur dioxide (SO₂) replacement by p-coumaric acid: a green alternative in wine industry.

Introduction: Sulfur dioxide has been traditionally used in winemaking as an effective preservative even though it often has negative taste and health-related effects on consumers, particularly when used in excess. Furthermore, it can induce both the SO₂-related resistance and the SO₂-related viable but not culturable (VBNC) state of different wine yeast and bacteria species. Currently, sulfur dioxide replacement by plant-derived compounds, used as food bio-preservatives, has been proposed in winemaking, at laboratory scale, as a green and healthier alternative.

Purpose: To replace sulfur dioxide with p-coumaric acid, a plant-derived phenolic compound, in winemaking on an industrial scale in order to produce a safe, natural wine that is more sustainable, genuine and healthier.

Methods: Winemaking of both sulfur dioxide- and p-coumaric acid-treated wine was conducted in parallel at a winery on an industrial scale (into two 10,000 L stainless steel tanks) using the same quantity of the same grape variety (10,000 kg of Lemnos Island organic white wine grapes, Muscat of Alexandria) during the harvest of 2019 and following the same oenological procedures. The influence of p-coumaric acid on wine properties and quality has been compared with that of sulfur dioxide under the same conditions, after 3 months of storage in a bottle. To this end, several analytical parameters of wine related to oenological, microbiological, antioxidant, sensory and safety properties were determined according to the International Standards Organization (ISO) and International Organization of Vine and Wine (OIV) official analytical methods for both wine samples.

Results: In general, there were no significant differences observed in stability, microbiological, antioxidant and oenological profiles due to sulfur dioxide replacement by p-coumaric acid, while the sensory profile was slightly ameliorated.

Significance: This replacement technology resulted in a suitable green alternative to sulfur dioxide and could be easily applied by the wine industry in order to guarantee high quality green products.