1 FYT er den mængde enzym, der frigiver 1 μmol uorganisk fosfat pr. minut fra fytat ved reaktionsbetingelser med en fytatkoncentration på 5,0 mM ved pH 5,5 og en temperatur på 37 °C under 30 minutters inkubation.
One FYT is the amount of enzyme that releases 1 μmol of inorganic phosphate from phytase per minute under reaction conditions with a phytate concentration of 5,0 mM at pH 5,5 and a temperature of 37 °C during 30 minutes of incubation.