Swordfish steaks vacuum-packed with Rosmarinus officinalis

In order to investigate the shelf life of swordfish steaks vacuum-packed with Rosmarinus officinalis, microbiological, chemical and sensorial analyses were carried out after 1, 3, 6, 8, 12 and 16 days of storage. In the treated samples, total volatile bases ranged from 7.35 to 13.05 mg/100 mL and trimethylamine from 1.21 and 7.9 mg/100 g. No significant change in the levels of ninhydrin- positive substances was observed. As regards the biogenic amines (BA), cadaverine increased linearly to 5.6 and 4.8 mg/100 g, and histamine to 4.9 mg/100g and 3.9 mg/100 g in the control and treated sample respectively. As regards the other BAs, no significant differences between the two samples were found. The effects of rosemary were reflected by a lower peroxide value of 2.72 mEq/kg in the treated steaks compared to 3.33 mEq/kg in the control sample at the end of the trial. The initial H2S-producing bacteria and psychrotrophic counts of 3 and 5 log10 cfu/g increased to 5 and 6.2 log10cfu/g after 16 days of storage in the treated samples. Salmonella, Staphylococcus aureus, Escherichia coli and Listeria monocytogenes were not detected in any sample. The addition of rosemary in combination with vacuum packaging extended the shelf life of swordfish steaks by four days.