The presence of off-flavor compounds in fish represents one of the significant economic problems encountered in aquaculture. These off-flavor compounds are due to the absorption of substances produced by microorganisms. Currently, a number of strategies have been employed to prevent or limit the growth of these microorganisms in recirculating aquaculture system. Therefore, it is important to evaluate the effectiveness of these strategies by monitoring the concentrations of off-flavor compounds in fish. In-vivo solid phase microextraction (SPME), a rapid and simple sample preparation method, allows the monitoring of concentrations of off-flavor compounds in live fish. In this research, geosmin and 2-methylisoborneol (2-MIB), which are produced by cyanobacteria and actinomycetes being the major sources for “earthy” and “muddy” flavors in fish, were selected as representatives. In order to accurately quantify these compounds in fish muscle, two kinetic calibration methods, on-fibre standardization and measurement using pre-determined extraction rate, were used. Results obtained were validated by traditional methods. The detection limit of in-vivo SPME in fish muscle was 0.12 ng/g for geosmin and 0.21 ng/g for 2-MIB, both below the human sensory threshold. Additionally, the binding effect of geosmin and 2-MIB in fish muscle was investigated in details. Facilitated by the agarose gel model, it was proven that binding did not impact the extraction rate under the pre-determined sampling time. Furthermore, an optional sampling position was undertaken by inserting the fibre into the fat tissue found under the fish belly, the results indicating that this method could decrease extraction time by up to two-thirds of its usual time.

The presence of off-flavor compounds in fish represents one of the significant economic problems encountered in aquaculture. These off-flavor compounds are due to the absorption of substances produced by microorganisms. Currently, a number of strategies have been employed to prevent or limit the growth of these microorganisms in recirculating aquaculture system. Therefore, it is important to evaluate the effectiveness of these strategies by monitoring the concentrations of off-flavor compounds in fish. In-vivo solid phase microextraction (SPME), a rapid and simple sample preparation method, allows the monitoring of concentrations of off-flavor compounds in live fish. In this research, geosmin and 2-methylisoborneol (2-MIB), which are produced by cyanobacteria and actinomycetes being the major sources for “earthy” and “muddy” flavors in fish, were selected as representatives. In order to accurately quantify these compounds in fish muscle, two kinetic calibration methods, on-fibre standardization and measurement using pre-determined extraction rate, were used. Results obtained were validated by traditional methods. The detection limit of in-vivo SPME in fish muscle was 0.12 ng/g for geosmin and 0.21 ng/g for 2-MIB, both below the human sensory threshold. Additionally, the binding effect of geosmin and 2-MIB in fish muscle was investigated in details. Facilitated by the agarose gel model, it was proven that binding did not impact the extraction rate under the pre-determined sampling time. Furthermore, an optional sampling position was undertaken by inserting the fibre into the fat tissue found under the fish belly, the results indicating that this method could decrease extraction time by up to two-thirds of its usual time.

Στην παρούσα διατριβή, αναπτύχθηκαν και εφαρμόστηκαν πρωτοποριακές διεργασίες, με σκοπό την απολύμανση και την απόσμηση των φλοιών φελλού και των φυσικών φελλών. Στόχος της απολύμανσης του φελλού είναι η μείωση του μικροβιακού του φορτίου, τόσο σε βακτήρια όσο και σε ζύμες-μύκητες, ενώ με την απόσμησή του επιχειρείται η μείωση της άμεσα απελευθερούμενης 2,4,6-Τριχλωροανισόλης (2,4,6-TCA) που περιέχεται σε αυτόν. Η εφαρμογή της διεργασίας του απλού οζονισμού αποδείχθηκε ιδιαίτερα ικανοποιητική στην επεξεργασία των φλοιών φελλού, ενώ συγκρίσιμα αποτελέσματα λήφθηκαν και μέσω της απλής ή παλμικής έκθεσής τους στον ατμό. Στην περίπτωση των φυσικών φελλών, είτε πρόκειται για τεχνητά ή φυσικά μολυσμένους και με βάση τεχνοοικονομικά κριτήρια, επιλέχθηκε ως βέλτιστη διεργασία, η παλμική διεργασία με έκθεση στον ατμό (SPP). Για την πληρέστερη περιγραφή της απόσμησης των φελλών, υλοποιήθηκε κατάλληλο μαθηματικό μοντέλο, του οποίου οι κρίσιμες παράμετροι προσδιορίστηκαν μετά από προσομοίωση των αποκτηθέντων πειραματικών αποτελεσμάτων. Στο δεύτερο μέρος της παρούσας διατριβής, μελετήθηκε η απόσμηση των φυσικών φελλών με χρήση εμπορικών προσροφητικών μέσων, διαμέσου της υγρής και αέριας φάσης και ως καταλληλότερο επιλέχθηκε το πολυμερές Tygon. Τέλος, προκειμένου να λάβει χώρα η διαχείριση της 2,4,6-TCA που αποβάλλεται από τους φελλούς κατά την απόσμησή τους στην υγρή και αέρια φάση, δοκιμάστηκε η χρήση διάφορων οξειδωτικών μέσων. / Novel processes for sterilization and deodorization of cork stoppers and cork barks have been developed and evaluated. Cork sterilization targets to microbial load reduction, either for bacteria or yeasts-moulds, while the reduction of rapidly releasable 2,4,6-trichloroanisole (2,4,6-TCA) of cork is achieved via their deodorization. The application of the plain ozonation process proved to be particularly efficient in cork barks treatment, while similar results were achieved using their plain or pulsed steam exposure. In the case of naturally or artificially contaminated cork stoppers, the steam pulsed process (SPP) was chosen as the optimum, based on techno economical criteria. The detailed description of cork deodorization was based on an appropriate mathematical model and the determination of its critical parameters was carried out via the simulation of the obtained experimental results. In the second part, the cork deodorization using commercially available adsorption materials via gas or liquid phase was studied and the polymer Tygon was chosen as the optimum. Finally, the management of 2,4,6-TCA, as a waste from cork deodorization in liquid and gas phase was tested using various oxidizing agents.