Microbial spoilage analysis and its effect on chemical changes and shelf-life of Norway lobster (Nephrops norvegicus) stored in air at various temperatures

Abstract

P>Microbial activity and spoilage of Norway lobster (Nephrops norvegicus) from Greek temperate waters, stored in air at 20, 5 and 0 degrees C was assessed. Microbial spoilage population, Total Volatile-Base Nitrogen (TVB-N), Trimethylamine-Nitrogen (TMA-N), pH and organoleptic changes were determined. Shelf-life of Norway lobster stored at 20, 5 and 0 degrees C was 24, 72 and 96 h respectively. The product was spoiled due to the development of TVB-N and melanosis of the carapace, as TVB-N was apparent from the early stages of storage and correlated very well with microbial growth and shelf-life. Pseudomonas sp. was the predominant spoilage bacterium. Product rejection coincided with TVB-N levels of 330-400 mg kg-1 and Pseudomonas sp. population level of about 5 x 105 cfu g-1. Pseudomonas sp. and TVB-N are presumably the Specific Spoilage Organism and the Chemical Spoilage Index of the product.