Formation of dimethyl sulphide from S‐methylmethionine in onion seedlings (Allium cepa)

Homogenates of onion seedlings catalyse the decomposition of S ‐methyl‐methionine into dimethyl sulphide and homoserine. The reaction is rather slow and seems not to be of primary importance in onion flavour formation or S ‐methylmethionine metabolism. Extracts of scarlet runner bean seedlings are also active, whereas dormant onion bulb and other seedlings tested showed no or very low activity.