Possibilities of reducing microbial contamination of common carp (Cyprinus carpio) meat

Sterniša, Meta (author), Smole Možina, Sonja (mentor), Mraz, Jan (comentor)

Common carp aquaculture is one of the most important in the world but only a small part of the production is tied to Europe, where carp is not yet fully exploited due to its sensory characteristics and despite its good nutritional value and economic accessibility. We have shown that bleeding as an additional processing step improves the carp meat quality with improved sensory characteristics and slowed down lipid oxidation and bacterial growth. Spoilage of fresh fish meat is defined by microbial activity, especially by representatives of the genus Pseudomonas. These are often resistant to antimicrobials, but we have demonstrated anti-Pseudomonas activity by inhibition of their growth and enzymatic activity by commercially available natural additives based on rosemary extract and buffered vinegar as well as ethanolic extracts of oregano and nettle. Pseudomonas are also found in biofilms on surfaces in fish processing. We show that Pseudomonas can easily adhere and form biofilm on stainless steel and polystyrene at 5 °C, 15 °C and 30 °C, but this was more pronounced on stainless steel. These Pseudomonas produced protease and lipase, and their activity increased with increasing temperature from 5 °C to 15 °C. Pseudomonas can thus form a biofilm in which they harbour bacterial cells and their spoilage enzymes. Fish meat can therefore easily be contaminated from surfaces during processing. We further show that the transfer of Pseudomonas from a biofilm formed on stainless steel as a donor surface depends on the amount of lipids and proteins in the recipient surface. The dynamics from the first to the last succession contact showed that the higher the rate of decline, the faster the transfer rate decreases. But, if the rate is lower, the difference in transfer rates between successive contacts is smaller and could represent a longer lasting constant contamination of the food.

• Language: English
• Keywords: microbiological quality, fish meat, common carp, Cyprinus carpio, spoilage, shelf-life, natural compounds, antimicrobial effect, Pseudomonas, bacterial adhesion, biofilm, surface contamination, transfer of contamination
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: BF - Biotechnical Faculty
• Publisher: [M. Sterniša]
• Year: 2020
• PID: 20.500.12556/RUL-121766
• UDC: 579.67:579.24/.25:597.551.214:547.9
• COBISS.SI-ID: 36039427
• Publication date in RUL: 28.10.2020

STERNIŠA, Meta, 2020, Possibilities of reducing microbial contamination of common carp (Cyprinus carpio) meat [online]. Doctoral dissertation. M. Sterniša. [Accessed 12 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=121766

Secondary language

• Language: Slovenian
• Title: Možnosti zmanjšanja mikrobiološke kontaminacije mesa navadnega krapa (Cyprinus carpio)

Abstract

Akvakultura navadnega krapa je ena izmed najpomembnejših na svetu, a le majhen del proizvodnje je vezan na Evropo, kjer krap zaradi svojih senzoričnih lastnosti – kljub dobri hranilni vrednosti in cenovni dostopnosti – ostaja neizkoriščen. Pokazali smo, da dodatni procesni korak izkrvavitve izboljša kakovost mesa navadnega krapa z zavrtjem oksidacije maščob in rasti bakterij, kar izboljša senzorične lastnosti in upočasni kvar. Kvar svežega mesa rib povzročijo predvsem bakterije, med njimi prevladujejo vrste rodu Pseudomonas. Te bakterije so pogosto odporne proti protimikrobnim snovem, a smo pokazali dobro proti-Pseudomonas aktivnost komercialnih naravnih dodatkov na osnovi izvlečka rožmarina in puferiranega kisa ter pripravljenih etanolnih izvlečkov origana in koprive. V sprejemljivih koncentracijah so zavrli rast bakterij in njihovo encimsko aktivnost. Bakterije Pseudomonas najdemo tudi v biofilmih na površinah v obratih predelave mesa rib. Pokazali smo, da se bakterije Pseudomonas adherirajo in tvorijo biofilm na nerjavnem jeklu in polistirenu pri 5 °C, 15 °C in 30 °C. Bakterije Pseudomonas lahko tvorijo biofilm na površinah materialov, ki se uporabljajo v predelovalni industriji rib, v njem so bakterijske celice in encimi kvara. Meso rib se lahko dodatno kontaminira med predelavo, kar smo preučili v nadaljevanju raziskave. Pokazali smo, da je prenos bakterij Pseudomonas s površinsko tvorjenega biofima na nerjavnem jeklu odvisen od količine beljakovin in maščob modelne kontaktne površine. Dinamika od prvega do zadnjega zaporednega kontakta je pokazala, da čim višja je hitrost padanja prenosa biofilmskih celic, hitreje se prenos zniža. A če je hitrost manjša, je razlika v stopnji prenosa med zaporednimi stiki manjša in lahko predstavlja dolgotrajnejšo kontaminacijo.

• Keywords: mikrobiološka kakovost, meso rib, navadni krap, Cyprinus carpio, obstojnost živil, kvar, naravne snovi, protimikrobno delovanje, Pseudomonas, bakterijska adhezija, biofilm, kontaminacija površin, prenos kontaminacije