Determination of Glycerol in beer

Glycerol is a natural by-product of alcoholic fermentation. Its production increases under yeast stress conditions (high wort osmolarity, nutrient deficiency, ethanol stress). Variations in glycerol concentration contribute to the mouthfeel and the perception of “smoothness” in beer. At low glycerol concentrations (1–2 g/L), the sensory contribution is minimal and almost imperceptible. The beer may appear “drier” or lighter. At medium to high concentrations (3–10 g/L), glycerol begins to have a noticeable effect, imparting a rounder, fuller, and more velvety sensation on the palate. At excessive glycerol concentrations, above 10 g/L—uncommon in traditional beer but possible under stressed fermentations or in the presence of contaminations (e.g., wild yeasts or lactic acid bacteria)—the result may be unbalanced or give a “sticky” mouthfeel.