Abstract: Disclosed is a method for determining the degree of freshness of such raw, frozen and processed perishable foodstuffs as meat, poultry and fish and an instrument therefor. The degree of freshness can be easily determined by the method of the present invention in shorter periods of time than by the conventional methods.The method of this invention comprises determining the amount of certain decomposition products of adenosine triphosphate such as hypoxanthine, inosine and inosinic acid by measuring the consumption of dissolved oxygen while each compound is subjected to action by certain enzymes, i.e., hypoxanthine by xanthine oxidase, inosine by nucleoside phosphorylase and inosinic acid by alkaline phosphatase, nucleoside phosphorylase and xanthine oxidase.