Methods for the preparation of a free-flowing, storage-stable fatty acid metal salt product by forming a reactive admixture of (a) an unsaturated fatty acid glyceride feedstock; and (b) from about 1 mol to about 3 mol of at least one monovalent metal hydroxide or at least one divalent metal hydroxide; and heating the admixture to a temperature at which said fatty acid glycerides saponify to form fatty acid metals salts; wherein said monovalent metal is potassium; and wherein said divalent metal is selected from the group consisting of calcium, copper, magnesium and zinc. The fatty acid glycerides are saponified in an atmosphere in which the partial pressure of oxygen has been reduced by an amount effective to provide an improvement in storage stability until a free-flowing, storage-stage product is obtained. Storage stable metal salts of unsaturated fatty acids prepared by the inventive methods are also disclosed.