Determination of Sulfites by UV-Vis Spectrophotometry in Red Wine and White Wine

Abstract

Sulphites are natural or synthetic additives widely used by the food industries. They are used to improve and preserve the stability and quality of the organoleptic characteristics of food. Due to potential serious cases of hypersensitivity beyond a threshold, the presence and content of sulphites must be monitored in food, and more particularly in wine, in order to thus preserve the health of consumers. To do this, it is essential to develop reliable methods for the quantification of sulphites in wine and this is the subject of this study. UV-Visible spectrophotometry programmed at 565nm was used to determine the sulfite concentrations (µg/mL) in a sample of commercially purchased white and red wine. The results showed that the method used was linear (range of linearity ranging from 0.05 µg/mL to 5 µg/mL with a coefficient of determination of R2 = 0.9969), accurate (CV ranging from 0.823% to 1.976% for intra-day precision and 1.229 to 1.487 for inter-day precision), accurate (average recovery rate of 98.59%) and stable (added reagents promote sulfite stability) in accordance with Agency guidelines French Standardization. The application of this method for the determination of sulphites revealed respective levels of 57.271 mg/L and 136.063 mg/L for red wine and white wine, levels in accordance with European regulations which set the maximum limit at 150 mg /L for red wine and 200 mg/L for white wine. This method could therefore make it possible to determine the quality of wines on the market and prevent the harmful effects of sulphites on the health of consumers.