Effects of various culinary treatments on the amino acid content of green beans

The effects of four culinary treatments (steaming and boiling in a covered pot, a pressure cooker or a microwave oven) on amino acid content in green beans (Phaseolus vulgaris) were studied. Proteins were hydrolyzated with hy drochloric acid and amino acids were derivatized with Phenyl isothiocyanate , separated on a C-18 column by HPLC and detected by ultra-violet detector. Steamed-and microwave cooked green beans did not show changes on the amino acid contents, whereas cooking of green beans in a covered pot or pressure cooker caused important losses of amino acids with regard to the raw sampl e.