Changes in Biogenic Amines and Bacteria of Tiger-Toothed Croaker (Otolithes ruber) during Ice Storage

Abstract

Changes in the content of biogenic amines (BA; e.g., putrescine, tyramine, and histamine) and the mesophilic and psychrotrophic bacterial counts of tiger-tooth croaker (Otolithes ruber) were monitored during ice storage for 18 days. BA and bacterial loads gradually increased (p < 0.05) with storage time. On the first day of storage, no amines were detected, and no histamine was detected up to 6 days. The best linear regressions between BA and bacterial counts were found between putrescine and psychrotrophic bacteria. Furthermore, it was found that psychrotrophs were the dominant microorganisms during storage and showed significant (p < 0.05) differences with storage time. The initial concentration of putrescine was 1.27 μg g⁻¹ and reached 18.8 μg g⁻¹ when the psychrotrophic bacterial load was over 10⁸ CFU g⁻¹. The results suggest that the level of putrescine is a suitable indicator of freshness for O. ruber, and the shelf life of O. ruber stored in ice as determined by BA content and microbiological data was 10 days.

Keywords:

• tiger-tooth croaker
• Otolithes ruber
• biogenic amines
• ice storage
• psychotrophic bacteria

Acknowledgments

The authors thank Reza Tahergorabi, from the Department of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV, USA, for assistance in writing the manuscript and making a number of helpful suggestions.