Abstract Deepwater pink shrimp (Parapenaeus longiros- tris) is an important commercial species in Portugal with a catch volume over 1000 tons and a high market value, estimated in 2000 as being equivalent to 11 million Euros. Indole levels have been used to confirm the sen- sory evaluation of shrimp decomposition and a limit of 250 μg/kg has been used in several countries to differen- tiate passable shrimp from shrimp in the first stage of decomposition. No data exist on indole levels in this spe- cies and taking into account that a considerable amount of the catches are exported as fresh to Spain, it was necessary to evaluate the indole production in order to identify the usefulness of this index as an indicator of temperature abuse in this species. Biochemical, physico- chemical, microbiological and sensory changes were evaluated in fresh deepwater pink shrimp stored at 2 °C and at room temperature (22 °C). Cooked deepwater pink shrimp chill-stored was studied too. The results indicated that indole was produced at levels of 167 μg/kg when raw shrimp was chill-stored for 7 days, while levels around 7400 μg/kg were produced after 32 h in raw shrimp stored at room temperature. Indole production of deepwater pink shrimps, showed a close parallel with microbiology data, mainly with Enterobacteriaceae pro- duction. We concluded that, in the conditions studied, the indole could be considered a useful indicator in assessing the history of shrimp if high temperature is suspected or bad hygiene conditions have been applied. Nevertheless, a low content of indole does not necessarily imply good quality. Keywords Indole · Deepwater pink shrimp · Temperature abuse Introduction Deepwater pink shrimp (Parapenaeus longirostris) is an important commercial species in Portugal with a catch volume over 1000 tons and a high market value, estimated in 2000 as being equivalent to 11 million Euros [1]. This species is normally landed iced in the fresh state after a 3-day fishing period, but is also frozen onboard and landed after a 30-day period. Though shrimps are gener- ally kept in refrigerated hulls on ice or immediately frozen onboard, deficient processing of catches either by poor washing of bottom mud, inadequate hygiene condi- tions onboard or temperature abuse during the chilled or frozen storage chain may enhance microbial contamina- tion of the products. Shrimps are extremely sensitive to deterioration due to their high concentration of water- soluble non-protein compounds, which may be degraded to sensorially unacceptable compounds. Indole is formed by bacterial degradation of the amino acid tryptophan and has been used to confirm the sensory evaluation of shrimp decomposition [2, 3, 4]. Trypto- phan is present in the protein structure and can be freed and degraded by the enzyme tryptophanase of some mesophilic microorganisms. These microorganisms, fre- quently Gram-negative, have been determined to exist in shrimps [5] and show considerable development at rela- tively high temperatures (20–40 °C). Enterobacteriaceae in particular, show a significant production of indole at high temperature and a good correlation has been shown to exist between the levels of Escherichia coli and the production of indole [5, 6]. In contrast to bacterial counts, indole content is re- ported to be relatively constant during cooking and during frozen storage, except when high levels of indole are present [7, 8]. On account of this, a limit of 250 μg/kg is currently used by the United States of America Food and Drug Administration (FDA) [9] to differentiate passable shrimp from shrimp in the first stage of decomposition [7]. At the moment no data exist on indole levels in deepwater pink shrimp. Taking into account the fact that a considerable amount of the catches are exported as R. Mendes ( ✉ ) Instituto de Investigação das Pescas e do Mar, Avenida de Brasília, 1449–006, Lisboa, Portugal e-mail: mendesr@ipimar.pt Tel.: +351 21 302 7036, Fax: +351 21 301 5948 A. Huidobro · E.L. Caballero Instituto del Frío (CSIC), Ciudad Universitaria, 28040 Madrid, Spain Eur Food Res Technol (2002) 214:125–130 DOI 10.1007/s00217-001-0419-4 ORIGINAL PAPER Rogério Mendes · Almudena Huidobro Elvira López Caballero Indole levels in deepwater pink shrimp (Parapenaeus longirostris) from the Portuguese coast. Effects of temperature abuse Received: 11 June 2001 / Revised version: 31 August 2001 / Published online: 25 October 2001 © Springer-Verlag 2001