Quality parameters and storage stability of the Norwegian red sea cucumber (Parastichopus tremulus)

Abstract

Quality parameters and storage stability were evaluated through biochemical, textural, and microbial analyses of the Norwegian red sea cucumber Parastichopus tremulus at two different storage temperatures (0 °C and 4 °C) over 17 days. During storage, the pH decreased from 7 to 6.3, the texture became softer decreasing from 47.3 to 0.3 N, while K-value increased from 4 to 52 %, microbial counts increased from 2 to 8 log cfu/g and formation of volatiles increased. After storage for 7 days at 0 °C and 5 days at 4 °C, the microbial counts exceeded the acceptability for consumption (7 log cfu/g). Microorganisms such as Flavobacterium and Psychrobacter were the main specific spoilage organisms contributing to the deterioration. Prolonged storage favored the Polaribacter and Marinomonas proliferation regardless of storage temperatures. The free amino acid concentration increased from 24 to 86 mg/100 g at both storage temperatures, probably resulting from the autolysis degradation. The pH decrease could be attributed to the production and dissolution of volatile compounds during storage. Odor-active compounds such as aldehydes (decanal, 2,4-decadienal, nonanal), ketones (1-octen-3-one, 1-penten-3-one), alcohols (1-octen-3-ol, 2-heptanol), aromatics (p-cresol and phenol), indoles (indole) and sulfides (dimethyl disulfide and trisulfide) showed increasing levels with storage time, with the highest levels found in the samples stored at 4 °C. This is the first study that demonstrate the quality changes on molecular and microbial level occurring during cold storage of sea cucumber P. tremulus. These results can be used for evaluating the shelf-life limiting factors of such species.