The plural form of the German word Milch

Did you know that there was a plural form of the German word ‘Milch’? The standard work for German spelling, the Duden, states the following: Milch, die; Plur. (fachspr.*) –en… In other words, in the milk industry, they talk about ‘die Milchen’ (in English, milks; in Dutch ‘de melken’).
Substances such as blood or concrete and foodstuffs such as barley and milk can come in various qualities and sorts. So, instead of saying, in German, ‘Blutsorten’ (blood types), ‘Betonqualitäten’ (qualities of concrete), or ‘Gerstenarten’ (varieties of barley), the specialists in these fields simply refer to them as ‘Blute’, ‘Betone’ or ‘Betons’, ‘Gersten’ and ‘Milchen’.

* fachsprache: specialised communication