A method for the in situ production of an emulsifier in a foodstuff, wherein a lipid acyltransferase is added to the foodstuff. Preferably the emulsifier is produced without an increase or without a substantial increase in the free fatty acid content of the foodstuff. Preferably, the lipid acyltransferase is one which is capable of transferring an acyl group from a lipid to one or more of the following acyl acceptors: a sterol, a stanol, a carbohydrate, a protein or a sub-unit thereof, glycerol. Preferably, in addition to an emulsifier one or more of a stanol ester or a stanol ester or a protein ester or a carbohydrate ester or a diglyceride or a monoglyceride may be produced. One or more of these may function as an addition emulsifier.