Must weigher
A must scale or Oechsle scale is a device for determining the must weight , i.e. the density of grape must. The must scale is also used in the production of juice and fruit wine from other fruits. Basically, it is a drop or spindle scale ( hydrometer ) with adapted scale graduation.
Drop scales for determining the quality of must have been used for over 300 years, but it was not until the 1820s that the Pforzheim mechanic Ferdinand Oechsle provided them with a practical scale, the Oechsle scale named after him . This is mainly used in Germany , Switzerland and Luxembourg .
Oechle's invention is based on the knowledge that sugar is heavier than water. So he proceeded with the graduation of his scales from the specific weight of the water: Does the must have the spec. Weight 1.075, the Oechsle scale shows 75 degrees Oechsle. The Oechsle balance uses the density of water at +20 ° C (rounded to 1 g · cm −3 ) as the zero point . If the must temperature deviates from the reference temperature of +20 ° C, the displayed value must be corrected. In the case of must scales with an integrated thermometer, the value to be added or subtracted is displayed directly. Otherwise the following approximation can be used in the case of small temperature deviations:
- At temperatures above +20 ° C, 1 ° Oe is added for every 3.5 ° C
- At temperatures below +20 ° C, 3.5 ° C is subtracted per 1 ° Oe
Since the Oechsle scale uses the density of water as the zero point, it not only shows the content of sugar, but also the content of all dissolved substances, the so-called total extract, in the must. In order to be able to determine the sugar content in the must, the content of sugar-free extract in the must must be known. Since the determination of the sugar-free extract is only possible with laboratory equipment, there are table values for many types of fruit in practice, and when they are used, year-related fluctuations must be taken into account. Since alcohol has a lower density than water under the same ambient conditions, the Oechsle scales can display negative values in dry wines and fruit wines depending on the alcohol content and the sugar-free extract content. In liquids containing carbon dioxide, such as fermenting wines, the Oechsle scale does not show any meaningful values. The carbon dioxide must be shaken out before the measurement.
In Austria, the Klosterneuburger Mostwaage (KMW) is used for measurements, whereby 1 ° KMW (Klosterneuburger sugar degrees) corresponds to 4.86 ° Oe. In contrast to the Oechsle balance, the presumed sugar-free extract content of the grape must is deducted from the start, which is why the Klosterneuburg must balance has a different zero point than the Oechsle balance.
literature
- Paul Arauner: homemade wines and juices, liqueurs and schnapps. Falken-Verlag, Niedernhausen 1985, ISBN 3-8068-0702-7 .