in the antique Rome's very popular, viscous grape syrup made by boiling down fermented grape was made on a small fire. For this purpose, vessels were also made out lead used, which gave the drink a sweet taste and juicy texture and also contributed to the preservation, but of course was very detrimental to health. According to reports by some authors like Pliny the Elder (23-79) the grape must was cut in half after Varro (116-27 BC) and Columella (1st century AD) even thickened to a third of its original volume (there were probably different uses). This thickened must was also fermented, which resulted in heavy and sweet wines.
Defrutum was also used to improve the taste of thin wines. Similar products were Caroenum with a little less volume reduction and sapa. According to the ancient models, the popular one developed into the 18th century Firewine, Traditionally, even today in Italy Vino cotto designated wines produced for private consumption. See also under must such as concentrated grape must,