The Sea Fish Industry Authority (Seafish) has published the results of trials conducted to find alternatives to sodium metabisulphite.

Sodium metabisulphite has been used by the UK fishing industry for many years to control the effects of melanotic blackening in Nephrops.

Seafish has conducted trials to identify alternative treatments for maintaining shelf life in prawns. The various treatments used are outlined in the attached table and were applied at sea using standard dipping procedures before being stored on ice. Samples were assessed ashore by processors who undertook standard checks for appearance, odour, texture and taste over a full shelf life. Further samples were sent to a laboratory for microbial and sulphite residue analysis, and information was collected on treatment cost and supplier.

Trials have also identified non sulphite based treatments which yield similar shelf life benefits to metabisulphite but, significantly, are excluded from allergen labelling. These treatments will be of particular interest for suppliers marketing prawns free from all additive labelling. The downside to these alternative treatments is that they are generally more expensive than sodium metabisulphite.

No treatment will prevent melanotic blackening in prawns. This is an inevitable part of the spoiling process although good handling practice and strict temperature control are undoubtedly the first steps to maintaining a quality product. The result of these trials has shown that alternative treatments are effective for shelf life extension and are less hazardous to use than sodium metabisulphite. Further information containing trial results will be available as a Seafish key features document in due course.