The effect of different melanosis-inhibiting blends on the quality of frozen deep-water rose shrimp (Parapenaeus longirostris)

The influence of different melanosis-inhibiting formulations on sensory parameters, texture, water holding capacity and microbiological properties of frozen deep-water rose shrimp (Parapenaeus longirostris) was evaluated throughout 6 months of storage at -18 degrees C. Eight formulations were tested: three of them containing 4-hexylresorcinol (4-HR, 0.05, 0.1 and 0.25%, w/v) in combination with organic acids (citric, ascorbic and acetic) and chelating agents (ethylenediaminetetraacetic acid and di-sodium di-hydrogen pyrophosphate); four commercial formulae based on sulphites (alone or accompanied by gluconic acid, chitosan or glucose), and a commercial blend based on 4-HR and NaCl. Non-treated shrimp were used as control. 4-HR-based treatments, as well as the joint use of sulphites and D-gluconic acid, were very effective in preventing melanosis during storage without affecting sensory parameters. All formulations assayed did not alter the water holding capacity of muscle protein during frozen storage. In general terms, shrimp hardness increased after a melanosis-inhibiting blend treatment and remained more or less constant during storage. From the microbiological point of view, experimental formulations with 4-HR reduced the total microbiota after treatment, especially at 0.1% (w/w). After 6 months of frozen storage, for most microbial groups studied counts were lower than the limit of detection, except in shrimp treated with the commercial 4-HR-based formulation, where counts were close to 3 log cfu/g. The melanosis-inhibiting blends assayed were useful to preserve sensory, functional and microbial quality in shrimp after six months of frozen storage.