Analysis of the sulphite content in shrimps and prawns

Food additives are redefined in European legislation (EC Regulation No. 1333/2008). Sulphur dioxide (E220) and sulphite (E221- E228) are widely used in food processing as preservatives because they slow down bacterial growth on foods and prevent oxidation or browning developing on shrimp and lobster. Shellfish processors, farmers and fishermen have long used sulfiting agents in a variety of species of warm and coldwater crustaceans as a treatment to prevent prawns and shrimps melanosis (blackspot), which is a natural process that makes the shell black after harvesting caused by Polyphenoloxidase enzyme systems which remain active during refrigeration or ice storage. Sulfite-induced hypersensitivity is the most well-established adverse response in humans to this food additive. In the present study the presence of sulfites in different frozen and thawed shrimp and prawn species belonging to Penaeoidea superfamily has been evaluated by the Monier-Williams procedure, in order to carry out a risk assessment and evaluate the levels of consumer exposure to this class of additives from these fish products. In addition to assessing and monitoring the correct use of the additive, according to the limits imposed by the European regulations, the correct consumer information on labels was also evaluated. Analysis were performed on both whole shrimp (shell on) and inedible parts (head and peeled shell). Sulphites concentration in frozen samples (expressed as SO2 mg/kg mean value±S.D.) was 214±17.43 for head on shell on shrimps; 170.73±14.99 for shell on headless shrimps; 112.90±27.55 for peeled and deveined shrimps. Thawed shrimps were purchased at mass retailers channel and local fish markets and local seafood retailers and purveyors: for these samples, all head on shell on, the sulphites concentration (expressed as SO2 mg/kg mean value±S.D.) was 160.05±26.15 and 292.54±146.04, respectively. Non-edible parts showed, in all samples, much higher concentrations.