soluble solids, also called total soluble solids (TSS) and total dissolved solids (TDS), refers to the collective concentration in unfermented grape juice of all solutes (dissolved molecules and ions). The predominant solutes, accounting for about 90% of the total, in the juice of ripe grapes are the reducing sugars glucose and fructose; others are acids (malic and tartaric), ions (organic and inorganic), and literally hundreds of inorganic and organic molecules that together contribute to the characteristics that make grapes such an adaptable and useful product. Collective concentrations of TSS range from 5 to over 25% and may be expressed in many ways, most usually either as degrees brix, baumé, or oechsle. See also must weight.
