Community Research and Development Information Service - CORDIS

Selection of quality criteria to evaluate the general quality of farmed fish

The results obtained within the project show that the quality criteria usually applied to wild fish is adequate to farmed fish. Therefore the following criteria should be applied:
Freshness criteria
-Sensory evaluation of raw fish using the Quality Index Method (QIM). This scheme is based mainly on skin appearance (brightness), abdomen colour, shape/colour of eyes and colour/odour of gills. A maximum of 3 demerit points (d.p.) score each parameter: 0 represents high freshness and higher score indicated low fish quality. The scores of all characteristics are summed to give an overall score. Lower total d.p. corresponding to a higher freshness/quality of fish. In the case of sea bream the QIM scheme has a total of 20 d.p. and the following scale could be used to assess its freshness/quality:
0 - 6 d.p. : very fresh fish
7 – 12 d.p. : fish with good quality
12 – 16 d.p. : fish with acceptable quality
Above 17 d.p. : fish in the borderline of acceptability

-K1 value (based on the ATP products degradation) as chemical indicator. Values below 10% indicate high freshness

Nutritional criteria Mainly based on the fatty acids composition of fish flesh:
-High w3/w6 ratio
-Good levels of EPA+DHA (minimum of 1g/100g muscle)

The applicability of sensory evaluation
Sensory evaluation of food is always affected by high variability since it consists in the subjective evaluation of the appearance and/or organoleptic properties of food. This aspect is very important in the case of acceptance/preference tests in which untrained people are used and the feeling of each person is important for the final result. Therefore, a high number of people should be used in this kind of tests. Contrary, when a trained panel is consulting low number of panellists could be used. In both cases sensory tests are a useful and important tool to determine the affective status of a food product and for quality changes evaluation.
A small trained panel (three to 5 people) is generally used to assess the quality/freshness of fish and this kind of sensory test could be widely applicable in a fish farm since few farm workers could be trained in the sensory attributes, in particular the ones related with the appearance (form and colour of eyes, skin pigmentation, among others), which reflects well the freshness and quality of fish.

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