The pH value of the aqueous liquors derived from fish muscle tissue is connected through statistical relations with the buffer action of the liquor, the log bacterial count of the sample, and with a subjective estimate of freshness determined on the basis of odour. In the case of pH and odour rating the relation is not a correlation but, instead, a linear relation between the means of a series of populations. By means of the latter it is possible from observations of the pH of the aqueous liquor in the sample to determine objectively the freshness of a parcel of canned chum salmon to any desired degree of accuracy by increasing the size, n, of the sample taken for examination.