1 BGU er den mængde enzym, der frigiver 1 μmol reducerende sukker (cellobioseækvivalenter) fra byg-ß-glucan pr. minut ved pH 4,8 og 50 °C.
1 BGU is the amount of enzyme which releases 1 μmol of reducing sugar (cellobiose equivalent) per minute from ß-glucan of barley at pH 4,8 and 50 °C.