Effect of cinnamon essential oil on bacterial diversity and shelf-life in vacuum-packaged common carp (Cyprinus carpio) during refrigerated storage

- High-throughput sequencing was used to assay bacterial diversity in carp samples
- Macrococcus and Aeromonas dominated the bacterial flora of fresh carp
- Aeromonas followed by Lactococcus were predominant in spoiled vacuum-packed carp
- Cinnamon essential oil inhibited Aeromonas in vacuum-packed carp during storage
- Cinnamon essential oil treatment extended shelf-life of vacuum-packed carp

The present study investigated the effect of cinnamon essential oil on the quality of vacuum-packaged common carp (Cyprinus carpio) fillets stored at 4 ± 1 °C in terms of sensory scores, physicochemical characteristics (total volatile basic nitrogen (TVB-N), biogenic amines, and color), and presence of spoilage microbiota. A total of 290,753 bacterial sequences and 162 different genera belonging to 14 phyla were observed by a high-throughput sequencing technique targeting the V3-V4 region of 16S rDNA, which showed a more comprehensive estimate of microbial diversity in carp samples compared with microbial enumeration. Before storage, Macrococcus and Aeromonas were the prevalent populations in the control samples, but cinnamon essential oil decreased the relative abundance of Macrococcus in the treated samples. Variability in the predominant microbiota in different samples during chilled storage was observed. Aeromonas followed by Lactococcus were the major contaminants in the spoiled control samples. Microbial enumeration also observed relatively higher counts of Aeromonas than other spoilage microorganisms. Compared with the control samples, cinnamon essential oil inhibited the growth of Aeromonas and Lactococcus were the predominant components in the treated samples on day 10; plate counts also revealed a relatively high level of lactic acid bacteria during refrigerated storage. However, there were no significant differences (P > 0.05) in the composition of dominant microbiota between these two treatments at the end of the shelf-life. Furthermore, cinnamon essential oil treatment was more effective in inhibiting the increase of TVB-N and the accumulation of biogenic amines (especially for putrescine and cadaverine levels). Based primarily on sensory analysis, the use of cinnamon essential oil extended the shelf-life of vacuum-packaged common carp fillets by about 2 days.