Bioelektrička svojstva odmrznutog brancina skladištenog na -18°C sa fluktuacijom temperature

master's thesis

• Title (english): Bioelectrical properties of thawed sea bass stored at -18°C with fluctuations in temperature
• Author: Iva Vidaković
• Mentor: Sanja Vidaček (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Meat and Fish Technology); Zagreb
• Defense date and country: 2012-09-25, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Cilj ovog rada bio je ispitati bioelektričke parametre na odmrznutom brancinu skladištenom u smrznutom stanju 30 odnosno 90 dana na – 18 °C sa fluktuacijom i bez fluktuacije temperature. Fazni kut i impedancija mišićnog tkiva mjereni su na 35 uzoraka i to pri frekvencijama u rasponu od 100 Hz do 100 MHz. Visoke frekvencija mjerenja (iznad 1 MHz) korištene su kako bi se umanjio utjecaj anizotropije, inače izraženiji pri niskim frekvencijama. Rezultati su pokazali da se utjecaj anizotropije značajno smanjio povišenjem frekvencije kod mjerenja impedancije mišićnog tkiva, no ne i kod faznog kuta. Usporedbom sa fizikalno-kemijskim karakteristikama, skladištenje na – 18 ºC utječe na promjenu kvalitete brancina, pojedinih funkcionalnih (pH, sposobnosti vezanja vode, boja) i bioelektričkih parametara (impedancije i fazni kut), dok fluktuacija temperature ne utječe značajno na navedene karakteristike. Izmjeri električkih svojstava pri frekvencijama iznad 1 MHz nisu pouzdani pokazatelji razlika u kvaliteti smrznutih fileta kada uzorci ribe nisu smrznuti odmah nakon ulova.

Abstract (english)

The aim of this study was to investigate the bioelectrical parameters in thawed sea bass stored in a frozen state for 30 and 90 days at -18 °C with and without temperature fluctuations. Phase angle and impedance of muscle tissue were measured in 35 samples at frequencies ranging from 100 Hz to 100 MHz. High frequencies (above 1 MHz) were used to diminish the impact of anisotropy, which is more expressed at low frequencies. Results showed that the effect of anisotropy at elevated frequency is significantly reduced in impedance measurements, but not in phase angle. Comparing with the physico-chemical characteristics, storage at - 18 °C changes the quality of bass, some functional (pH, water binding capacity, color) and bioelectric parameters (impedance and phase angle), while temperature fluctuations do not significantly affect these characteristics. Measurement of electrical properties at frequencies above 1 MHz is not a reliable indicator of differences in quality of frozen fish fillets when samples are not frozen immediately after catch.

• Keywords: brancin (Dicentrarchus labrax); smrzavanje; anizotropija; impedancija; fazni kut
• Keywords (english): sea bass (Dicentrarchus labrax); freezing; anisotropy; phase angle; impedance
• Language: croatian
• URN:NBN: urn:nbn:hr:159:523640
• Study programme: Title: Food Safety Management; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka upravljanja sigurnošću hrane (magistar/magistra inženjer/inženjerka upravljanja sigurnošću hrane)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-09 09:25:15