Combined effect of vacuum-packaging and oregano essential oil on the shelf-life of Mediterranean octopus (Octopus vulgaris) from the Aegean Sea stored at 4 degrees C.

The present study evaluated the use of vacuum packaging (alone) or with addition of oregano essential oil (EO), as an antimicrobial treatment for shelf-life extension of fresh Mediterranean octopus stored under refrigeration for a period of 23 days. Four different treatments were tested: A, control sample; under aerobic storage in the absence of oregano essential oil; VP, under vacuum packaging in the absence of oregano essential oil; and VO1, VO2, treated samples with oregano essential oil 0.2 and 0.4% (v/w), respectively, under VP. Of all the microorganisms enumerated, Pseudomonas spp., H2S-producing bacteria and lactic acid bacteria (LAB) were the groups that prevailed in octopus samples, irrespective of antimicrobial treatment. With regard to the chemical freshness indices determined, thiobarbituric acid (TBA) values were low in all octopus samples, as could have been expected from the low fat content of the product. Both trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values of oregano treated under VP octopus samples were significantly lower compared to control samples during the entire refrigerated storage period. Based primarily on sensory evaluation (odor), the use of VP, VO1 and VO2 extended the shelf-life of fresh Mediterranean octopus by ca. 3, 11 and 20 days, respectively.

Potential of oregano essential oil and MAP to extend the shelf life of fresh swordfish: a comparative study with ice storage.

The present study evaluated the effect of modified atmosphere packaging (MAP, 5% O(2)/50% CO(2)/45% N(2); treatment M), the addition of oregano oil (0.1%, v/w; treatment AO) as a natural preservative, as well as their combination (treatment MO) on the quality and shelf life extension of fresh Mediterranean swordfish fillets during a refrigerated storage (4 degrees C) period of 18 d. Simultaneously, swordfish fillets were stored under aerobic conditions (control treatment A, 4 degrees C) and on ice (usual commercial method of preservation, treatment I, 0 degrees C). Among the 5 treatments examined in the present study, the most effective one to inhibit the microbial and sensory spoilage proved to be the MO treatment, achieving a shelf life extension of 8 to 9 d. The dominant bacteria in the microflora of swordfish, irrespective of treatment, were the Pseudomonads and the H(2)S-producing bacteria, while both lactic acid bacteria (LAB) and the Enterobacteriaceae produced the lowest populations in swordfish samples kept on ice. Among the chemical indices examined, thiobarbituric acid (TBA) values showed no specific trend of lipid oxidation for swordfish, irrespective of treatment. Final trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for treatments, A, AO, M, and MO ranged between 1.33 and 14.29 mg N/100 g and 14.11 to 55.52 mg N/100 g, respectively, whereas for I samples they remained almost unchanged during storage. Sensory analysis (taste attribute) correlated well with microbiological analysis, indicating a shelf life of approximately 5 to 6 d for control, 10 to 11 d for AO, 12 d for I, 13 d for M, and 14 d for MO samples.

Shelf-life of chilled fresh Mediterranean swordfish (Xiphias gladius) stored under various packaging conditions: microbiological, biochemical and sensory attributes.

The present work evaluated the effect of air, vacuum and modified atmosphere packaging (MAP) on the shelf-life of chilled Mediterranean swordfish (Xiphias gladius). Fresh swordfish slices were stored in air, under vacuum and MAP (40%/30%/30%, CO(2)/N(2)/O(2)) under refrigeration (4 degrees C) for a period of 16 days. Of the three treatments used (vacuum, MAP and air), both MAP and vacuum packaging (VP) were the most effective for inhibiting growth of aerobic microflora in swordfish samples until days 9-10 of refrigerated storage. Of the microbial species determined, both Pseudomonas spp. and H(2)S-producing bacteria (including Shewanella putrefaciens) were dominant in swordfish samples stored in air, whereas growth of these species was partly inhibited under VP and MAP conditions. Lactic acid bacteria (LAB) and Enterobacteriaceae were also found to be members of the final swordfish microbial flora, irrespective of packaging conditions throughout the entire storage period. Of the chemical freshness indices determined, thiobarbituric acid (TBA) values were variable in swordfish samples, indicative of no specific oxidative rancidity trend. Trimethylamine nitrogen (TMA-N) values of swordfish samples stored in air, under VP and MAP exceeded the limit value of 5mgN/100g fish muscle after days 7, 8-9 and 11 days of storage, respectively. In a similar trend, total volatile basic nitrogen (TVB-N) for swordfish samples stored in air, under VP and MAP exceeded the limit value of 25mgN/100g fish muscle after 7-8, 10 and 12 days of storage, respectively. Sensory analyses (odor and taste attributes) indicated a shelf-life of ca. 7 days for air, 9 days for VP and 11-12 days for the MA-packaged swordfish samples.