Harmonizing expression of measurement results in wine analysis: Best practices when testing and reporting sugar in wine

Abstract

This technical brief addresses using appropriate methodology and uniform terminology to ensure consistency in measurement and interpretation of wine components described as sugars, when required in wine trade. Different analytical approaches when testing for sugar in wine, variation in reporting units, and non-uniform interpretation of sugar terminology are known to create unnecessary barriers in wine trade. This brief proposes a unified system of reporting sugar in wine that is grounded in scientific and practical knowledge to reduce potential trade barriers. The following are suggested best practices when testing and reporting sugar in wine: clarify the meaning of the abbreviation “RS” when used, since it could stand for residual sugars, reducing sugars, or reducing substances, which have different meanings (1), define residual sugar as the sum of glucose, fructose and sucrose expressed as g/L of wine (2), use methods that are specific for wine sugars, rather than non-specific methods that test for reducing substances, to avoid erroneously high results (3), avoid reporting sugar alcohols, such as glycerol, as a sugar (4), avoid testing for sugars not expected in wine, such as maltose and lactose (5).