AbstractThe effectiveness of different sulfite‐based treatments to prevent melanosis in fresh deepwater pink shrimp (Parapenaeus longirostris) was evaluated. Increasing the concentration of sulfites, different methods of application (immersion and dust) and synergy with other compounds, such as citric acid and chelants, were investigated. The level of SO2 residues in the muscle was determined in a selection of the most effective treatments. One‐hour dip treatment with 50 g kg−1 sulfite, together with citric acid and chelants, was effective for melanosis prevention for at least one week. With this treatment, the statutory limit of 0.3 g kg−1 SO2 in edible part was not exceeded by the majority of samples analysed. Copyright © 2005 Society of Chemical Industry