Consumption Trials and Edible Fractions of Various Commercially Important Species of Fish and Shellfish

Abstract

A consumption trial determines the proportion of edible material in a whole fish, and this proportion is used to interpret the consumption survey data employed in the assessment of maximum permissible discharge rates for aqueous radioactive effluent from nuclear installations in the United Kingdom.

Consumption survey data are usually in the form of average and maximum numbers or weight offish consumed. These figures can be converted into edible material by data from the consumption trials. In the trials determinations were made of: 1. the weight of a raw whole ungutted fish, 2. the weight of a raw whole gutted fish, 3. the weight of a whole cooked fish, 4. the weight of the inedible material. Two methods of cooking are employed, frying and boiling.

Species investigated were: cod (Gadus morhua), sole (Solea vulgaris), plaice (Pleuronectesplatessa), whiting (Gadus merlangus), herring (Clupea harengus), sprat (Clupea sprattus), brown trout (Salmo trutta), crab (Cancer pagurus), lobster (Homarus vulgaris), shrimp (Crangon vulgaris), scampi (Nephrops norvegicus), dab (Pleuronectes limanda), skate-thornback ray (Raja clavata).

The results, expressed as the percentage of (i) cooked edible material to raw whole ungutted fish, and (ii) raw edible material to raw whole ungutted fish, show that the highest fractions of edible material are associated with the herring and sprat (approximately 60%) and the lowest fraction with skate (20%). The distribution of edible fractions for a particular species is Gaussian and the standard deviation of the mean can reach 25% of the meanvalue, reflecting wide variability in eating habits.