a method for obtaining 2 - hydroxy - 4 - methylthiobutyric acid in primarily free form which is stable in storage by distilling a product solution containing mha and by producing mha product mixtures with improved storage stability from such a distillate . the distillate can be produced directly starting from mha raw products from any mha production process , which can optionally also contain solvent or water . the starting material may also be a commercial mha product .