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The effects of ratio of the amount of fish to that of wash water, kinetic energy of impinging water, method of water application and concentration of available chlorine in the wash water on the washing of eviscerated fresh cod of various caught-ages were studied. The studies were designed to provide information of practical value to engineers interested in designing machines to wash slime and bacteria from fish received at filleting plants. A quantitative relation between kinetic energy of impinging wash water and fish to water ratio was established for one practical type of spray washing equipment. Effective spraying was found to be more efficient than fluming or dipping. However, fish dipped several times in water deposited less bacterial load on a clean surface than fish washed effectively on the skin side only by a jet of water. Thus, washing out the body cavity was found to be important. Caught-age was found to influence the results only for washing methods of relatively low effectiveness, namely in fluming and in washing inefficiently with a jet or spray of water. Ineffective spray washing was shown to be associated with waste of equipment and high costs while serving no useful production purpose. Highly effective methods of spray washing fish of all caught-ages were shown to be suitable for efficient application in fish filleting and skinning lines. Free chlorine concentrations as high as 100 ppm in the wash water did not increase washing effectiveness as measured by a bacteriological method.

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