Evaluating sensory impacts of SO₂ alternatives in Chardonnay using the difference from control (DFC) test

Abstract

Lees ageing is a common practice in Chardonnay winemaking, contributing to complex flavours and textures through yeast autolysis. To preserve wine during this process, sulfur dioxide (SO₂) is widely used for its antioxidant and antimicrobial properties. However, concerns over potential allergenic effects have prompted the exploration of SO₂ alternatives. This study investigates the sensory effects of adding SO₂ alternatives during lees ageing in Chardonnay using the Difference from Control (DFC) test for sensory analysis. Wine added with 60ppm of SO₂ before lees ageing was used as a control, and treatments included the addition of chitosan (500ppm, CH) and glutathione-enriched inactivated dry yeast (400 ppm, GR) with either no SO₂ or half the control SO₂ dosage (CHS30, GRS30). Sensory analysis compared each treatment to the control using pre-selected sensory attributes with an intensity scale ranging from much stronger (+3) to much weaker (-3). Wine professionals were used without further training. A blind control was included to check the internal validity of the assessors and statistical analysis was conducted using Dunnett’s test. Significant differences were found in the attributes related to malolactic fermentation and yeast autolysis. CH showed lower butter/cream/cheese intensity, while GRS30 resulted in lower bread/toast/nut intensity, highlighting the sensory impact of these SO2 alternatives. These findings provide valuable insights for winemakers seeking to use SO2 alternatives to make suitable wine styles with desirable characteristics.