• cultured prawns;
  • melanosis;
  • microbial growth;
  • polyphenoloxidase;
  • 4-hexylresorcinol;
  • sulfites

ABSTRACT: A study was made of the effect on melanosis, biochemical indexes, and microbial growth in tiger prawns (Marsupenaeus japonicus) from aquaculture, using a formulation containing 4-hexylresorcinol (0.1% and 0.05%) in combination with organic acids (citric, ascorbic, and acetic) and chelating agents (ethylenediaminetetraacetic acid [EDTA] and disodium dihydrogen pyrophosphate [PPi]). In vivo and postmortem application of treatment was evaluated. Prawns with no additives or treated with 4% of a commercial formula based on sulfites were used to compare with 4-hexylresorcinol. The formulations based on 4-hexylresorcinol or sulfites inhibited the polyphenoloxidase (PPO) activity under 0.2 (Δoptical density [OD]/min/mL), instead of 1 (ΔOD/min/mL) achieved by prawns without additives, with the consequent delay in the appearance of melanosis during the 1st wk of storage. Prawns treated with sulfites showed initially better protection; however 4-hexylresorcinol proved to be more effective at the end of storage. The formulation based on 4-hexylresorcinol at 0.1% concentration, provided in vivo, inhibited the microbial growth (total bacteria count, H2S-producer microorganisms, lactic acid bacteria, enterobacteria, and pseudomonads), whereas the commercial sulfites inhibited the luminescent bacteria growth.