Yeso

In Spain, this powder which is rich in gypsum is used for the settling of certain wines
Found on http://www.hintsandthings.co.uk/livingroom/glossaryRSTUVWXYZ.htm

Yeso

This pure calcium sulphate comes in natural form in the typical chalk soil albariza in the Spanish DO area Jerez before and later also industrially manufactured. In the traditional and applied in ancient times process is used in the production of sherry Add the grapes before pressing Yeso (about 1 kg to 700 kg of grapes). This strengthens the acid ...
Found on https://glossary.wein-plus.eu/yeso
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