Oechslegrad is the basis for calculating the sugar content in wines, which provides information about the later alcohol content of the wine. The evaluation system is based on the research of the pharmacist Christian Ferdinant Oechsle (1774 - 1852), who, with the Oechsle scale, was the first to produce an instrument with which the sugar content of grapes and thus their level of ripeness could be read.
Oechsle's invention is based on the physical principle that sugar is heavier than water. Thus, the difference between the weight of the liquid contained in the grapes and the weight of water in the same amount provides information about the sugar content of the wine, which is later fermented into alcohol. Today, the alcohol content is determined using a modern refractometer, which records the sugar content based on light refraction.
A table can be used to convert the determined value of the grape in degrees Oechsle into the expected late alcohol content. If a bunch of grapes reaches 70 degrees Oechsle, an alcohol content of 9.1% vol. can later be expected in the wine. 80 degrees Oechsle, on the other hand, corresponds to an alcohol content of 10.6% vol. As a rule of thumb, the Oechsle degree is more important in northern regions than in southern countries, since the grapes ripen well under good growing conditions.
This test does not require any aids. Based on the organoleptic test, the quality of a wine is evaluated - for example by a taster - exclusively on the basis of the natural senses.