or a long time, it was thought that lachrymatory factor was produced by alliinase, a critical enzyme in a pathway of onion flavor synthesis. (An enzyme is a protein that helps speed up a reaction, in this case a conversion of one compound into another.) However, in 2002, a previously unknown enzyme – not alliinase – was shown to be responsible for synthesizing lachrymatory factor. This new enzyme was termed lachrymatory-factor synthase, a very straightforward name. The discovery was significant because inhibiting alliinase would lead to reduction of both lachrymatory factor and other flavor compounds, whereas inhibition of lachrymatory-factor synthase would only prevent the synthesis of lachrymatory factor, thus making you no longer tearful, while keeping the flavor intact.