By Harold McGee
Two ancient grape preparations make versatile ingredients in the kitchen. Fruits thinned six to eight weeks before the main harvest are crushed and filtered to produce verjus, a tart alternative to vinegar or lemon juice, slightly sweet, with a delicate green aroma. And ripe grapes are cooked down to a thick, sweet-tart, aromatic syrup (Roman sapa, Italian saba or mosto cotto, Turkish pekmez, Arab dibs). Like syrups from other fruit (pomegranates), grape syrup was an important sweetener in the times before cheap table sugar, but provides tartness and aroma as well as sweetness. It’s thought that balsamic vinegar may have evolved from grape syrup that was kept long enough to ferment.