What is "defrutum"

Defrutum, carenum, and sapa were reductions of must used in Ancient Roman cuisine. In Ancient Greek cuisine, they were referred to as both siraion (Greek: σίραιον ) and epsima (Greek: έψημα). They were made by boiling down grape juice or must (freshly squeezed grapes) in large kettles until it had been reduced to two-thirds the original volume, carenum; half the original volume, defrutum; and one-third, sapa. The main culinary use of defrutum was to help preserve and sweeten wine, but it was also added to fruit and meat dishes as a sweetening and souring agent and even given to food animals such as suckling pig and duck to improve the taste of their flesh. Defrutum was mixed with garum to make the popular condiment oenogarum and as such was one of Rome's most popular condiments. Quince and melon were preserved in defrutum and honey through the winter, and some Roman women used defrutum or sapa as a cosmetic. Defrutum was often used as a food preservative in provisions for Roman troops.