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master's thesis
Određivanje parametara stresa u bakterije Listeria inoccua nakon tretmana ultrazvukom
Zagreb: University of Zagreb, Faculty of Food Technology and Biotechnology, 2017. urn:nbn:hr:159:772335
Zovko, Josipa
University of Zagreb
Faculty of Food Technology and Biotechnology
Department of Food Engineering
Laboratory for Food Processes Engineering

Institutional repository: Repository of the Faculty of Food Technology and Biotechnology

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Zovko, J. (2017). Određivanje parametara stresa u bakterije Listeria inoccua nakon tretmana ultrazvukom (Master's thesis). Zagreb: University of Zagreb, Faculty of Food Technology and Biotechnology. Retrieved from https://urn.nsk.hr/urn:nbn:hr:159:772335

Zovko, Josipa. "Određivanje parametara stresa u bakterije Listeria inoccua nakon tretmana ultrazvukom." Master's thesis, University of Zagreb, Faculty of Food Technology and Biotechnology, 2017. https://urn.nsk.hr/urn:nbn:hr:159:772335

Zovko, Josipa. "Određivanje parametara stresa u bakterije Listeria inoccua nakon tretmana ultrazvukom." Master's thesis, University of Zagreb, Faculty of Food Technology and Biotechnology, 2017. https://urn.nsk.hr/urn:nbn:hr:159:772335

Zovko, J. (2017). 'Određivanje parametara stresa u bakterije Listeria inoccua nakon tretmana ultrazvukom', Master's thesis, University of Zagreb, Faculty of Food Technology and Biotechnology, accessed 03 September 2024, https://urn.nsk.hr/urn:nbn:hr:159:772335

Zovko J. Određivanje parametara stresa u bakterije Listeria inoccua nakon tretmana ultrazvukom [Master's thesis]. Zagreb: University of Zagreb, Faculty of Food Technology and Biotechnology; 2017 [cited 2024 September 03] Available at: https://urn.nsk.hr/urn:nbn:hr:159:772335

J. Zovko, "Određivanje parametara stresa u bakterije Listeria inoccua nakon tretmana ultrazvukom", Master's thesis, University of Zagreb, Faculty of Food Technology and Biotechnology, Zagreb, 2017. Available at: https://urn.nsk.hr/urn:nbn:hr:159:772335

Metadata
TitleOdređivanje parametara stresa u bakterije Listeria inoccua nakon tretmana ultrazvukom
Title (english)Determination of stress parameters in bacteria Listeria innocua after ultrasound treatment
AuthorJosipa Zovko
MentorAnet Režek Jambrak (mentor)
GranterUniversity of Zagreb
Faculty of Food Technology and Biotechnology
(Department of Food Engineering)
(Laboratory for Food Processes Engineering)
Zagreb
Defense date and country2017, Croatia
Scientific / art field,
discipline and subdiscipline		BIOTECHNICAL SCIENCES
Food Technology
Abstract
Listeria innocua nepatogena je bakterija, široko rasprostranjena u okolišu i hrani, te se zbog sličnosti s patogenom bakterijom Listeria monocytogenes koristi kao modelni organizam u istraživanjima. U ovom radu određivani su mehanički utjecaji ultrazvuka visoke snage na stvaranje parametara stresa bakterijske kulture Listeria innocua ATC33090. Uzorci bakterijske suspenzije tretirani su toplinom te toplinom i ultrazvukom u kombinaciji. Uzorcima koji su tretirani ultrazvučnom sondom frekvencije 20 kHz, mjerene su tri nezavisne varijable: amplituda (75 %, 100 %), temperatura (40 °C, 60 °C) i vrijeme tretmana (5, 10 minuta). Rezultati su analizirani metodom odzivne površine (RSM) koristeći program STATGRAPHICS Centurion. Pri 40 °C i amplitudi od 100 %, postignuta je potpuna inaktivacija već nakon 5 minuta ultrazvučnog tretmana, te najviši stupanj redukcije (4,31 log10 CFU ml-1). Najveći porast koncentracije slobodnih radikala je 30 % od početne vrijednosti, pri 60 °C i 100 %-tnoj amplitudi, nakon 10 minuta tretmana. Kod istih uvjeta tretmana u vremenu od 5 minuta dobivena je najznačajnija redukcija stvaranja biofilma (92,25 %). Primjenom viših temperatura (60 °C) uz ultrazvučno tretiranje dolazi do apoptoze stanica te se one ne mogu revitalizirati. Značajnu ulogu pri inaktivaciji bakterijskih stanica osim uvjeta tretmana ima i kavitacijski efekt ultrazvuka, pri kojem se formiraju slobodni radikali.
Abstract (english)
Listeria innocua is a non-pathogenic bacterium, widespread in the environment and food, and because of its similarity to the pathogenic bacterium Listeria monocytogenes, is used as a model organism in researches. In this paper, the mechanical effects of the high power ultrasound have been determined on the creation of stress parameters of bacterial culture Listeria innocua ATC33090. Samples of the bacterial suspension were treated by heat and ultrasound in combination. Samples were analyzed by ultrasound probe frequency of 20 kHz and three independent variables were measured: amplitude (75 %, 100 %), temperature (40 °C, 60 °C) and treatment time (5, 10 minutes). The results were analyzed by response surface methodology (RSM) using the STATGRAPHICS Centurion program. At 40 °C and 100 % amplitudes, complete inactivation was achieved after 5 minutes of ultrasonic treatment and the highest degree of reduction (4,31 log10CFU ml-1). The highest increase in free radical concentration was 30 %, at 60 °C and 100 % amplitude, after 10 minutes of treatment. At the same treatment conditions, in 5 minutes the most significant reduction in biofilm production (92.25 %) was achieved. Applied to higher temperatures (60 °C) with ultrasound treatment, cell apoptosis occurs and cells can not be revitalized. A significant role in the inactivation of bacterial cells, apart from the condition of the treatment, has the cavitation effect of ultrasound, creating free radicals.
Keywords
Keywords (english)
Languagecroatian
URN:NBNurn:nbn:hr:159:772335
Study programmeTitle: Food Engineering
Study programme type: university
Study level: graduate
Academic / professional title: magistar/magistra inženjer/inženjerka prehrambenog inženjerstva (magistar/magistra inženjer/inženjerka prehrambenog inženjerstva)
Type of resourceText
File originBorn digital
Access conditionsOpen access
Terms of useLicence In copyright icon
Created on2017-11-13 14:35:19