ABSTRACT Melanosis in seafood is a natural post-mortem enzymatic process that results from the action of polyphenol oxidase from the animal’s own tissues. It reduces the organoleptic quality of the shrimp and their commercial value. This work concerns prevention of melanosis in pink shrimp (Parapenaeus longirostris) using the latest technology of enzymatic biosensor for sulphite detection. Three application methods (dipping, dusting, and spraying) with four commercial products were tested. Sulphite concentrations (1–3%) were applied for 1–10 min. Parameters measured included residual SO2 levels, pH, melanosis, and odour. Findings showed that the dusting method gave the best sensory scores, but had harmful residual SO2 values. The dipping method provided safe SO₂ levels below normative limits, when using products with 240 g Kg−1 SO₂ content applied at 1.25% bisulphite/seawater for 1 minute. Regarding the spraying method, the results remain promising. Nevertheless, further studies are necessary to understand its potential and limitations fully.