Rectified Grape Must

or RGM

Appears in

Oxford Companion to Wine

Oxford Companion to Wine

By Jancis Robinson

Published 2006

  • About

rectified grape must or RGM is preserved grape juice that has been rectified, processed to reduce the concentration of solids other than sugars. It is generally further treated by removing water to yield rectified concentrated grape must, or RCGM, which is a common commodity used principally in Europe for enrichment. The eu authorities were at one time keen to promote its use in place of sugar as a way of helping reduce the European wine lake. Many winemakers who need to use it in northern Europe have a natural antipathy to introducing a product made from what they view as inferior grapes. There are several major producers of RGM in Europe who absorb surplus grape production from areas such as the languedoc, La mancha, sicily, and puglia. They submit it to such modern technological processes as ion exchange and reverse osmosis together with super-efficient filtration and evaporators to produce what is in effect a concentrated invert sugar (glucose and fructose) solution from grape juice. See also concentration.