🍷 Fructose

Fructose is the second main sugar of grapes after glucose. It is sweeter than glucose, so it affects the sense of sweetness in taste. In a ripe berry there are roughly equal amounts of fructose and glucose.

During fermentation yeast turns sugar into alcohol, but not evenly. It ferments glucose faster, and fructose is left toward the end. So if fermentation stops early, it is often fructose that stays in the wine. This is the residual sugar in sweet wines.

Fructose dissolves well and strengthens a sweet taste. Because of this even a small amount of residual sugar is perceived as noticeable sweetness. Dry wines have almost no sugar left.

This is useful to know not only for wine lovers. Fructose is found in fruit, honey and many juices, and grape juice is one of the richest in it. Its sweetness and fresh acidity are the basis of wine balance.