Defrutum was a syrup made from grape must; it is not the same as the grape-juice syrup we buy today, although it makes an adequate substitute. Neither was it the full-bodied, savoury residue from reduced wine, as used in the kitchens of modern French restaurants. It was obtained by slowly reducing a quantity of must until it had the thick viscosity of treacle, which is how it is described by Palladius. Other authors suggest that it was thinner. According to Varro and Columella the must had to be boiled down to a third of its original quantity, but Pliny stipulated half.
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