Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

New quality monitoring and prediction systems for production management (QIM, indole and other chemical indices)

The production of high-quality Crustaceans requires the definition of quality standards, which allow the producer the placement of the crustaceans. Indole level is used by the U.S. FDA to validate the sensory evaluation of shrimp decomposition and a level of less than 250 µg/kg has been established for Class I shrimps. Sensory evaluation and indole level of fresh shrimps has been demonstrated to show a good correlation. Though, in the present study a very low level of indole was detected during sensory shelf life of pink shrimps at all storage temperatures. Furthermore, all samples presented at shelf life lower indole levels than the limit suggested by the FDA.
In contrast, when these limits were attained, TVB-N, TMA-N, TVC and Enterobacteriaceae had increased in the same period to unacceptable levels and pink shrimps considered spoiled by the test panel. The present study confirms that findings of others that indole levels indicated decomposition. However, decomposed shrimp may not necessarily contain indole.

In conclusion, indole should be used in conjunction with other quality indices when evaluating the quality of fresh shrimp.

Thus, in order to classify a sample of acceptable the following limits could be suggested for
Pink shrimp:
Total viable counts: 9.10E+5 cfu/g
Total Volatile Basic Nitrogen: ≤ 30 mg/100g
TMA-N: ≤ 11 mg/100g
Indole: ≤ 88 µg/kg
Putrescine: ≤ 6 mg/100g
Cadaverine: ≤ 7 mg/100g
Agmathine: ≤ 7 mg/100g
For Penaeus monodon the following limit values could be determined.

Change from good to poor quality
Total Viable Counts: 5.00E+5 CFU / g
Total Volatile Basic Nitrogen: 40-45 mg / 100 g
pH value: 7.9 - 8.0
Tyramine: < 7 mg/kg
Putrescine: < 6 mg/kg
Cadaverine: < 6 mg/kg

Change from poor quality to not marketable
Total Viable Counts: 1.00E+7 CFU / g
Total Volatile Basic
Nitrogen: 45-50 mg / 100 g
pH value: 7.9 - 8.0
Tyramine: < 7 mg/kg
Putrescine: < 6 mg/kg
Cadaverine < 6 mg/kg

Reported by

Cardiopeixe
Av. Brasilia, Porto de Pesca de Pedrouços, Bloco de Escritorios - 93B Gab. 1
1400 Lisboa
Portugal
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