Microbiological spoilage and volatiles production of gutted European sea bass stored under air and commercial modified atmosphere package at 2 °C

• Microbiological spoilage analysis of gutted European sea bass was performed.
• Volatile compounds profile was determined during spoilage of gutted sea bass.
• Storage conditions affected shelf-life, spoilage microbiota and volatile profile.
• TVB-N and TMA-N proved non-suitable for chemical spoilage indices.
• Various microbial origin volatiles confirmed as potential chemical spoilage indices.

Microbiological, sensory, TVB-N and TMA-N changes and Volatile Organic Compounds (VOCs) detection using the SPME/GC–MS technique, were performed to evaluate potential chemical spoilage indices (CSI) of gutted sea bass (Dicentrarchus labrax) stored at 2 °C under air and in modified atmosphere packaging (MAP CO2: 60%, O2: 10%, N2: 30%). Shelf-life, determined by sensory evaluation, of gutted sea bass stored at 2 °C under air and MAP was 9 and 13 d respectively. Pseudomonas and H2S producing bacteria were among the dominant spoilage microorganisms under both storage conditions, while Lactic Acid Bacteria (LAB) and Brochothrix thermosphacta were co-dominant with Pseudomonas and H2S producing bacteria under MAP. The traditional CSIs such as TVB-N and TMA-N were increased substantially only at the late stages of storage or after rejection of the products, making them unsuitable for freshness/spoilage monitoring throughout storage. A substantial number of VOCs attributed to microbiological action or chemical activity, were detected including alcohols, aldehydes, ketones, organic acids and esters. The level of microbial origin VOCs such as ethanol, 2-ethyl-1-hexanol, 3-methyl-1-butanol, 2-methyl-1-butanol, 3-methylbutanal, 2-methylbutanal and some ethyl esters increased during storage, suggesting their potential as CSIs.