A unit dose fabric treatment system comprises a water soluble container in which a liquid fabric treatment composition is disposed, the composition comprising one or more fatty acid esters wherein, in at least one of the fatty acid esters, the average proportion of C18 chains is less than 60%, preferably less than 50%, more preferably less than 40%, e.g. less than 30% by weight of the total weight of fatty acid chains in the fatty acid ester.