Evaluation of the effect of natural antimicrobials on the preservation and safety of semi-cooked coated chicken fillets

In the present study, the effect of natural antimicrobials- EDTA, lysozyme and the essential oils of rosemary and oregano- on the shelf-life, natural microflora, sensory and physicochemical characteristics of the semi-cooked coated chicken fillets stored at 4 °C, was examined. The organoleptic shelf-life, was determined 10, 11, 12 and 15 days for the A, AEL, AR/ AO και AELR/ AELO samples, respectively, whereas for the VP chicken fillets the shelf-life was 14 for the VPEL, 16 for the VP/ VPR/ VPO and 18 days for the VPELR/ VPELO chicken samples. Additionally, it was found that the most effective treatment against TVC, Brochothrix thermosphacta, Lactic acid bacteria and Yeasts/ Moulds was VPELR, whereas against Pseudomonas spp. and Enterobacteriaceae was the VPELO. These two treatments were also the most effective ones in preserving both sensory and physicochemical characteristics of the semi-cooked coated chicken fillets.Additionally, the survival/ growth of Listeria monocytogenes, Salmonella enterica serotype Montevideo and of a 4-strain cocktail of Bacillus cereus inoculated onto the samples and subsequently stored at 4 °C was examined. Results showed that population of both L. monocytogenes and Salmonella Montevideo was either reduced or maintained at the initial inoculation levels. On the contrary, the cocktail of Bacillus cereus managed not only to survive but to grow and increased to 6-9 log CFU/ g population, with storage time.Furthermore, the effect of the aforementioned natural antimicrobials on the survival/ growth of the pathogens was also examined, inoculated onto the fillets and stored either at 4 or 8 °C. Our results showed that the combination of EDTA, lysozyme and oregano essential oil was more effective against the growth of L. monocytogenes (VPELΟLm) and Bacillus cereus (VPELΟB), whereas the combination of EDTA, lysozyme and rosemary essential oil was effective against Salmonella Montevideo (VPELRS). The antimicrobials added were more effective when used at rather 4 than at 8 °C. Furthermore, it was noted that counts of L. monocytogenes and Salmonella Montevideo were maintained at its initial levels. As far as Bacillus cereus was concerned it was found that counts increased throughout the storage period. Finally, the effect of the microwave heating against the survival/ growth of the pathogens was determined at 4 και 8 °C. Results showed that the combination of EDTA, lysozyme and essential oils might have reduced the initial counts of the pathogens for 2 (Lm), 3 (Sm) and 4 (Β) min, but for the final inactivation of the microorganisms only microwaves were responsible. It is noteworthy that when the semi-cooked coated chicken fillets were inoculated with L. monocytogenes, Salmonella Montevideo and Bacillus cereus, they should be microwave cooked until the product’ s internal temperature reaches 76-78, 84-85 και 97-98 °C, respectively, so as for the product to be considered safe for consumption.Στην παρούσα μελέτη εξετάστηκε η επίδραση των φυσικών αντιμικροβιακών παραγόντων- EDTA, λυσοζύμη και αιθέρια έλαια δενδρολίβανου και ρίγανης- στο χρόνο ζωής, τη μικροχλωρίδα, τα οργανοληπτικά και φυσικοχημικά χαρακτηριστικά των ημι-μαγειρεμένων σνίτσελ κοτόπουλου που διατηρήθηκαν στους 4 °C. Ο χρόνος ζωής των μεταχειρίσεων που συσκευάστηκαν υπό αερόβιες συνθήκες ήταν 10, 11, 12 και 15 ημέρες για τα δείγματα A, AEL, AR/ AO και AELR/ AELO, αντίστοιχα, ενώ αυτών υπό κενό ήταν ίσος με 14 για τα VPEL, 16 για τα VP/ VPR/ VPO και 18 ημέρες για τα VPELR/ VPELO δείγματα, αντίστοιχα. Η μεταχείριση VPELR ήταν πιο αποτελεσματική έναντι της ανάπτυξης της ΟΜΧ, του Brochothrix thermosphacta, των Οξυγαλακτικών βακτηρίων και των Ζυμών/ Μυκήτων, ενώ η μεταχείριση VPELO ανέστειλε περισσότερο την ανάπτυξη των Ψευδομονάδων και των Εντεροβακτηριοειδών. Παρατηρήθηκε ότι μόνο οι μεταχειρίσεις VPELR και VPELO διατήρησαν τα αρχικά φυσικοχημικά και βελτίωσαν τα οργανοληπτικά χαρακτηριστικά των δειγμάτων.Επίσης, μελετήθηκε η ανάπτυξη/ επιβίωση των Listeria monocytogenes, Salmonella enterica serotype Montevideo και μίγμα 4 στελεχών Bacillus cereus, που ενοφθαλμίστηκαν στα ημι-μαγειρεμένα σνίτσελ κοτόπουλου που διατηρήθηκαν στους 4 °C. Τα αποτελέσματα έδειξαν ότι οι πληθυσμοί των βακτηρίων L. monocytogenes και Salmonella Montevideo μειώθηκαν ή διατηρήθηκαν στα επίπεδα που αρχικά ενοφθαλμίστηκαν στα δείγματα, ενώ το μίγμα του Bacillus cereus, όχι μόνο κατάφερε να επιβιώσει, αλλά και να αναπτυχθεί σε πολύ υψηλούς πληθυσμούς της τάξης των 6-9 log CFU/ g.Με βάση τη μελέτη της επίδρασης των προαναφερθέντων αντιμικροβιακών παραγόντων έναντι της ανάπτυξης/ επιβίωσης των παθογόνων μικροοργανισμών στα δείγματα κοτόπουλου στους 4 ή/ και 8 °C, βρέθηκε ότι ο συνδυασμός των EDTA, λυσοζύμης και ριγανέλαιου και ήταν αποτελεσματικότερος έναντι της ανάπτυξης των L. monocytogenes (VPELΟLm) και Bacillus cereus (VPELΟB), ενώ ο συνδυασμός EDTA, λυσοζύμης και αιθέριου ελαίου του δενδρολίβανου ανάστειλε την ανάπτυξη της Salmonella Montevideo (VPELRS). Οι αντιμικροβιακοί παράγοντες που εξετάστηκαν ήταν πιο αποτελεσματικοί στους 4 έναντι των 8 °C. Επιπλέον, παρατηρήθηκε ότι οι πληθυσμοί των L. monocytogenes και Salmonella Montevideo διατηρήθηκαν στα αρχικά επίπεδα, ενώ ο Bacillus cereus αυξήθηκε με το χρόνο διατήρησης των ημι-μαγειρεμένων σνίτσελ κοτόπουλου.Τέλος, μελετήθηκε η επίδραση των μικροκυμάτων στην ανάπτυξη/ επιβίωση των ενοφθαλμισμένων παθογόνων μικροοργανισμών στα δείγματα κοτόπουλου που διατηρήθηκαν στους 4 και 8 °C. Τα αποτελέσματα έδειξαν ότι οι συνδυασμοί EDTA, λυσοζύμης και αιθέριων ελαίων δενδρολίβανου ή ρίγανης, μπορεί να ελάττωσαν τον αρχικό πληθυσμό των παθογόνων για 2 (Lm), 3 (Sm) και 4 (Β) min αλλά δεν φαίνεται να είναι ικανός να επιφέρει την πλήρη αδρανοποίηση αυτών, η οποία επιτυγχάνεται με τη χρήση των μικροκυμάτων. Επιπλέον, όταν τα δείγματα εμβολιαστούν με L. monocytogenes, Salmonella Montevideo και Bacillus cereus, η εσωτερική θερμοκρασία των δειγμάτων να φτάσει μετά το ψήσιμο τους 76-78, 84-85 και 97-98 °C, αντίστοιχα, για να θεωρηθούν ασφαλή προς κατανάλωση

Surface Decontamination and Shelf-Life Extension of Gilthead Sea Bream by Alternative Washing Treatments

The efficacy of washing and the investigation of alternative sanitizing treatments for the reduction of microbial population are major issues for fresh fish and seafood. Limited work on the effect of alternative washing media on fish, particularly gilthead sea bream, one of the important popular fish species, has been published and no industrial scaling-up has been reported. The objective of this study was to systematically evaluate the effect of surface decontamination treatments on the microbial load of fish and the quality and shelf life during subsequent chilled storage. Citric acid (200 ppm for 0–10 min), lactic acid (200 ppm for 0–10 min), and peracetic acid (0–200 ppm for 0–4 min) were tested as alternative washing media by immersion of gutted gilthead sea bream by evaluating their effect on microbial growth and physicochemical and organoleptic degradation of fish. The results of the study indicated that washing with citric (200 ppm, 10 min) and peracetic acid (200 ppm, 4 min) significantly delayed the growth of spoilage microorganisms (total viable count, Pseudomonas spp., Enterobacteriaceae spp., and H2S-producting bacteria) in gutted fish and extended the shelf life to 18 days at 0 °C, compared to 11 days without washing treatment. Appropriate handling and processing of fish and shelf-life extension may enable longer transportation and thus open new distant markets, as well as contribute to reduce food waste during transportation and storage

Slurry ice as an alternative cooling medium for fish harvesting and transportation: Study of the effect on seabass flesh quality and shelf life

The objective of the study was to investigate the efficiency of slurry ice during harvesting and transportation of European sea bass (Dicentrarchus labrax) to retain flesh quality and extend shelf life, compared with conventional flake ice. Fish was slaughtered and transported in different mixtures of slurry ice and conventional flake ice (C: slaughtered and transported in 100% flake ice-Control samples, SC: slaughtered in 100% slurry ice and transported in 100% flake ice, S50: slaughtered and transported in 50% slurry ice-50% flake ice, S100: slaughtered and transported in 100% slurry ice) and subsequently stored under controlled isothermal conditions at 0 °C for shelf life modelling and flesh quality evaluation (proteolytic enzymes). The replacement of conventional flake ice with slurry ice as a slaughtering method led to improved quality stability during subsequent refrigerated storage and shelf life extension, in terms of microbial growth, flesh quality and sensory degradation of fish. Based on microbial growth, the shelf life of C samples was found to be 19 days, whereas the shelf life of S50/S100 and SC was 21 and 25 days, respectively, showing that the replacement of flake ice with slurry ice resulted in 2–6 days shelf life extension of whole sea bass stored at 0 °C. The use of slurry ice at slaughter and flake ice in transportation was accompanied by low activities and late peaks of all four enzymes that is expected to lead to delayed proteolytic degradation and extended freshness