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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. [ABSTRACT FROM AUTHOR]

Abstract Indole levels have been used to confirm the sensory evaluation of shrimp decomposition and a limit of 250 μg/kg has been used in several countries to differentiate passable shrimp from shrimp in the first state of decomposition. However, no data exist on the correlation between sensory quality and indole content in deepwater pink shrimp (Parapenaeus longirostris) which validate the use of this defect level. The sensory, microbiological and biochemical changes were determined in microbiologically contaminated (4 and 7 log cfu/g ) deepwater pink shrimp stored at 0, 5, 10 and 15°C. Indole, TMA-N, TVB-N, pH, TVC, Enterobacteriaceae and Pseudomonas spp. increased with time and temperature. At low temperature storage, final indole levels in severely decomposed shrimp (TVB > 60 mg/kg) were much lower than the suggested defect level of 250 μg/kg shrimp. Increased microbiological contamination (7 log cfu/g) induced faster and higher indole production at all temperatures. At higher storage temperatures, indole formation was greatly accelerated resulting in very high indole levels. High indole levels indicate decomposition; however decomposed shrimp may not necessarily contain indole. The shelf life of shrimp ranged from 15 h at 15°C to 6 days at 0°C. An indole defect level >90 μg/kg shrimp should be used for deepwater pink shrimp. [ABSTRACT FROM AUTHOR]

Abstract Fresh Atlantic horse mackerel (Trachurus trachurus) were gamma irradiated at 1 and 3 kGy, and stored in ice for 23 days. Quality changes during ice storage at 0±1 °C were followed by sensory analysis and the determination of total viable count, histamine, cadaverine, putrescine, tyramine, agmatine, spermidine, trimethylamine and volatile basic nitrogen contents. The control lot had a sensory shelf life of 8 days, whereas those of the irradiated lots were extended by 4 days. TVC’s and levels of amines increased in all lots with storage time, their contents being significantly reduced by irradiation, even when the lower level (1 kGy) was used. Histamine in the irradiated lots was undetectable when the fish was spoiled at the end of 23 days, whereas in the control lot, the concentration did not exceeded the maximum allowed in fresh fish (100 mg/kg). Presumptive identification of microorganisms gave a majority aerobic or facultative Gram-negative anaerobic rods being Gram-positive bacteria circa 10–18% in irradiated samples. Chemical indices were shown to be unsuitable for the determination of the quality changes in irradiated fish. [ABSTRACT FROM AUTHOR]