another Linear B tablet from Knossos illustrating the syllabogram JU, KN 21 J i 14:

barley

Knossos Linear B tablet 21 J i 14

This tablet from Knossos deals with barley stalks in conjunction with the syllabogram JU, which clearly is also a crop, but which kind we do not know. Wine is also mentioned on this tablet. So we may very well be dealing with barley wine, which of course is what the Mycenaeans and ancient Greeks called beer. So now we have a hint as to what JU might mean, i.e. hops or a draught, but my bet is on the former.