The Surface Concept in Measurement of Fish Spoilage

Abstract

The contact plate method as used for cod muscle has revealed that the major changes rendering fish unfit for human consumption can be attributed almost entirely to surface pollution of the fish with spoilage bacteria. This is confirmed by three chemical tests, trimethylamine, tyrosine, and surface pH. The relative rates of increase in all three are much greater at the surface than in the interior of cod and haddock fillets. The more rapid surface changes are taken as evidence that tests for spoilage in fish products should be based on samples from the surface of the products and not from composite samples.

Application of chemical methods for the assessment of beef quality. II. Methods related to protein breakdown

“…The procedure was essentially that described by Wood, Sigurdsson and Dyer: 17 Two grams of prepared minced sample were weighed out into the 100 ml vortex beaker of an MSE Homogeniser and 40 ml of 5 % trichloracetic acid solution were added. After homogenisation for 2 min the macerated mixture was filtered.…”

Assessment of meat freshness in quality control employing chemical techniques: A review

“…3~ Although the method cannot be considered to be specific for proteolysis, the tyrosine value has been regarded by Canadian workers, in particular, as affording a good general index of protein breakdown in fish, including herrings.33 Therefore the technique could prove useful for the assessment of spoilage in meat, particularly if a more rapid modification is employed. 34 The amount of bufferextractable nitrogen decreases during frozen storage, whereas the products of proteolysis increase, Above freezing, however, whilst protein breakdown is considerable, the changes in extractability of the nitrogen fraction or in the available -SH groups are negligible. Khan35 therefore proposed, for assessing deterioration in poultry, the use of the 'quality index', which represents the ratio of the SH groups to the products of protein breakdown (tyrosine value).…”

Effect of potassium sorbate and gamma irradiation on the shelf-life of Hilsa shad, Tenualosa ilisha (Hamilton, 1822) at low temperature

“…Tyrosine value was determined by following the method as described by Wood et al (1942). To determine the pH of fish about 5gm macerated fish sample was taken in a homogenizer and 25 ml of water was added in the homogenized sample.…”