Amino acids

Amino acids are compounds that contain an amino group (–NH2) and a carboxyl group (–COOH), and they are one of the main building blocks of proteins. In sake, amino acids are an important element of taste, contributing in particular to sweetness, umami, acidity, and bitterness. Seishu (refined sake) contains about 19 types of amino acids, and their quantity greatly influences the flavor and body of the sake. Specifically, a sake with a high amino acid level has a rich, full-bodied taste, but an excess of amino acids can also introduce off-flavors. A sake with a low amino acid level, on the other hand, is characterized by a clean, light (tanrei) taste. Amino acids also tend to affect aging: the more amino acids a sake contains, the more readily it tends to mature. The amino acid level is an indicator of the richness and complexity of a sake's flavor, and it is generally around 1.3 to 1.7. The figure is measured by taking 10 ml of sake and using the formol titration method. Because amino acids form the basis of sake's umami, the general understanding is that a high amino acid level produces a rich sake with plenty of umami, while a low level produces a light sake with a clean taste.