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4. Variations of phenolic compounds and sensory properties of virgin olive oils from the variety 'Istrska belica'Milena Bučar-Miklavčič, Terezija Golob, Vasilij Valenčič, Erika Bešter, Bojan Butinar, Ana Miklavčič Višnjevec, 2016, original scientific article Keywords: olive oil, phenolic compounds, sensory properties, Istrska belica
Published in RUP: 07.08.2016; Views: 4123; Downloads: 125
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6. Antioxidants in virgin olive oils produced from two olive cultivars of Slovene IstriaBojan Butinar, Milena Bučar-Miklavčič, Metoda Lipnik-Štangelj, 2006, original scientific article Keywords: olive oil, virgin olive oil, biophenols, tocopherols, extraction process, HPLC, Slovene Istria
Published in RUP: 10.07.2015; Views: 3998; Downloads: 29
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7. Evaluation of the acidity in samples of virgin olive oil for the 1995-2005 period and correlation between the collected data and the performed sensory analysisVasilij Valenčič, Erika Bešter, Milena Bučar-Miklavčič, Bojan Butinar, 2007, original scientific article Abstract: The acidity and organoleptic characteristics of virgin olive oil produced in Slovenian Istra were studied. The acidity of 4,871 samples of virgin olive oils was determined for the 1995-2005 period. 135 samples produced in crop year 2002/2003 with acidity below 0.2% (w/w) and 291 samples of crop year 2005/2006 were sensory evaluated. According to sensory evaluation in crop year 2002/2003, 128 out of 135 samples were classified as extra virgin olive oils, while 7 samples did not reach the specified requirements. In crop year 2005/2006, it was established that 71.5% of the analysed samples complied with extra virgin category, 24.4% with virgin and 4.1% with lampante. Time of harvest, storage conditions before processing, and time from picking to processing all influenced the oil quality, whereas olive cultivars did not. Chemical and sensory analyses were performed according to the Commission Regulation (EEC) No 2568/91 and added annexes.
Keywords: olive oil acidity, grading of oil, harvest, storage, processing, sensory analysis
Published in RUP: 10.07.2015; Views: 4513; Downloads: 32
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8. Evaluation of measurement uncertainty for the methods of analysis used to assess the characteristics of olive oil and olive-pomace oil from commission regulations EEC 2568/91 and EC 1989/2003 : a case sample evaluating the measurement uncertainty for peroxide valueBojan Butinar, Milena Bučar-Miklavčič, Erika Bešter, Vasilij Valenčič, 2007, original scientific article Abstract: Metrology has been present in our scientific knowledge for a long time, but mostly in physical measurements. Chemical measurement can be defined as a comparison of a quantity of measurand and relating it to a unit (e.g. mol/kg).When expressing a result of a measurement, the problem of traceability, validation and the measurement uncertainty (MU) evaluation must be challenged. It is well known that MU is a parameter associated with the result of a measurement that characterizes the dispersion of the values that could reasonably be attributed to the measurand. The EEC document 2568/91 with its annexes gives the methods of analysis to assess the characteristics of olive oils and olive-pomace oils with given limits. The EC document 1989/2003 gives the scheme, the algorithm, the pathway, the decision tree to differentiate between various types of olive oils using the particular determinations based on limits. The major lack of these EC methods is the non-existence of validation parameters, which are crucial in determining the MU (and in accreditation of a laboratory). There are several ways of evaluating (better term than calculating) the MU: with model equation, with use of a certified reference material (CRM) and with participation in a proficiency testing (PT) scheme. MU for a method of analysis is inherent to a laboratory and can serve as a tool for 'measuring' the quality of a laboratory. Unfortunately, there are practically no CRM's in the olive oil testing field. The only way to achieve a usable MU is through participation in PT schemes.
Keywords: CRM, EEC 2568/91, EC 1989/2003, metrology, olive oil, PT scheme
Published in RUP: 10.07.2015; Views: 4937; Downloads: 47
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10. Dynamics of oil quality parameters changes related to olive fruit fly attackOlivera Koprivnjak, Ivana Dminić, Urška Kosić, Valerija Majetić, Sara Godena, Vasilij Valenčič, 2010, original scientific article Abstract: In order to evaluate the role of intrinsic characteristics of olive cultivars on dynamics of oil quality parameters changes related to the olive fruit fly (Bactrocera oleae (Gmelin)) attack, two specific olive cultivars were compared, Istarska bjelica and Buža. I. bjelica is characterised by late ripening, a lower flesh/stone mass ratio and higher oleic/linoleic ratio, the total phenols content and oil mass fraction compared to Buža. Oil samples were obtained at two harvesting dates, from fruit lots with 0, 25, 50, 75 and 100% of infestation degree, expressed by mass. Oil and water content in olive paste, as well as total phenols, fatty acids composition and standard chemical and sensorial oil quality parameters were determined. At equal maturity level, the cultivar with a higher oil (24 +- 1% vs. 16 +- 1%) and lower water content (54 +- 2% vs. 61 +- 4%) was more susceptible to hydrolytic degradation, while the one with the lower total phenols content (231 +- 32 vs. 575 +- 124mg/kg) and oleicžlinoleic fatty acid ratio (5.7 vs. 9.1) was more liable to oxidative deterioration of oil. Lower susceptibility to negative flavours formation could be related to the absence of ripening induced by fly attack and less favourable environment for larvae growth (higher total phenols content, lower water content and flesh/stone mass ratio)
Keywords: Bactrocera oleae, Olive cultivars, Olive fruit fly, Olive oil quality
Published in RUP: 15.10.2013; Views: 4739; Downloads: 166
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