Tainting

An alteration of the taste and smell of seafood is one of the phenomena which can often be observed after an oil spill. Simple contact of hydrocarbons present in the water with the skin or gills can give marine animals a taste and smell considered unacceptable by consumers. Such a taste, sometimes clearly perceived as an “oil-like” taste, sometimes simply recognised as different from the usual taste, is known as tainting.

This particular effect is a serious issue in the management of the consequences of an oil spill. Molluscs, such as oysters and mussels, can absorb, through filtering, considerable quantities of hydrocarbons present in water. For example, a 20 gramme oyster filters some 48 litres of seawater per day. It can multiply the concentration of a pollutant in its tissues by 70,000 in relation to the surrounding environment.

Sea bass in an experimentation tank

Tainting can occur very quickly. It only takes a few hours to a few days of contact for the taste and smell to alter. Tainting can be tested through olfactory or organoleptic tests and can be quantified by analyses of the total hydrocarbon content in the organism’s tissues. When transferred into hydrocarbon-free water, or when the pollution has ceased, the animals naturally purge themselves of the pollutant in a few weeks to a few months.

The tainting of crustaceans, fish and shellfish is common during an oil spill. The immediate response from authorities is to temporarily ban their collection or sale. It must then be determined whether the contaminated animals can be put on the market after decontamination or if they should be destroyed as a precaution. This question is an important issue in terms of the protection of consumers and the local economy, as well as the market reputation of the local seafood industry.

Organoleptic test on sea bass