Passum was a sweet, slightly thick syrup made by the Romans from partially-dried grapes.
Partially-drying the grapes first made them sweeter.
Some sources say Passum could also be made from must, but that would make in effect make it defritum or sapa, or that it could be made from wine, but that would make it Caroenum.
Literature & Lore
"Mago advises that the best passum is made in the following way, and I myself have made it like this. Collect early grapes when they are fully ripened, discarding mouldy or damaged ones. Put stakes in the ground 4 feet apart and join them with poles. Place reeds on top, and spread your grapes out on them in the sun, covering them at night so that they don't get damp from the dew. When they are dried, pluck the stalks off them, and put them in a cask or large earthen-ware jar, cover them with the best must you have, so that they are completely submerged. When the dried grapes have taken in all the liquid that they will, [let sit] for 6 days then put them in a basket and with a wine press extact the passum. Afterwards stomp the leftover grape skins, adding must freshly made from other grapes dried in the sun for 3 days. Mix well (with the first passum extraction), then put this mixture through the wine press. Put the results of this second pressing in sealed vessels, so that it doesn't become bitter. After 20 days, when it stops fermenting, decant into other vessels, and immediately seal the openings with gypsum and skins."
Grape SyrupCaroenum; Defritum; Grape Syrup; Passum; Sapa; Wine Syrup
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