Changes in 4-hexylresorcinol residues during processing of deepwater pink shrimp (Parapenaeus longirostris)

Hexylresorcinol has been used as an alternative to sulphites for prevention of melanosis or black-spot of the shrimp carapace. In order to estimate consumption of 4-hexylresorcinol, residual levels have been evaluated in deepwater pink shrimp (Parapenaeus longirostris) following dip treatments and different processing technologies (freezing, cooking and washing). The effect of 4-hexylresorcinol on the microbial growth in the dipped shrimp as well as change in the inhibitory solution during repeated utilization was also followed. The use of 4-hexylresorcinol at concentrations of 0.10 or 0.25 mg/kg led to the detection in pink shrimp of residue levels considerably higher than the limit level of 2 mg/kg. Furthermore, the processing technologies studied also showed a very low efficiency in the reduction of residues from the initial loads to acceptable values. Though the tested initial bacterial load of the shrimp was higher than it is normally expected onboard the solution of 4-hexylresorcinol did not evidence any tendency for an increase of the bacterial counts even after 29 h of utilization. No decrease in the 4-hexylresorcinol concentration is visible even after 8 dips and 29 h of solution use.