21. Spremljanje, ugotavljanje in zagotavljanje kakovosti: poročilo za študijsko leto 2019/2020 : Univerza v Novi Gorici. : poročilo za študijsko leto 2019/2020 : Univerza v Novi Gorici.Iztok Arčon, Jana Beguš, Blaž Belec, Martina Bergant Marušič, Lorena Butinar, IMRE CIKAJLO, Saša Dobričič, Sandra Gardonio, Renata Kop, Martin Knez, Boštjan Potokar, Branka Mozetič Vodopivec, Egon Pavlica, Samo Stanič, Tea Stibilj Nemec, Željko Oset, VERONIA Piccinini, Peter Purg, Arthur Stepanov, Aljaž Rener, Nives Štefančič, Ana Toroš, Tanja Urbančič, Vanesa Valentinčič, NIKA VODOPIVEC, treatise, preliminary study, study Keywords: samoevalvacijsko poročilo
Published in RUNG: 23.12.2020; Views: 4509; Downloads: 0
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22. Determination of biogenic amine-forming potential of naturally occuring lactic acid bacteria (LAB) strains isolated from the grapes of Vitis vinifera cv. Refošk grape varietyJelena Topić, Lorena Butinar, Martina Bergant Marušič, Dorota Korte, Branka Mozetič Vodopivec, 2020, published scientific conference contribution abstract Abstract: Biogenic amines are naturally occurring compounds that have been reported in variety of food, such as fish, meat, cheese, vegetables, and wines. When biogenic amines are formed by microorganisms such as lactic acid bacteria (LAB) they may have adverse effect on human health. The most common biogenic amines found in foodstuff are histamine, tyramine, putrescine and cadaverine. LAB are used as starters in the production of several foods and beverages. In wines they are used in malolactic fermentation, where the conversion of malic acid to lactic acid occurs. The aim of this work was to determine biogenic amine-forming capacity of indigenous LAB strains isolated from grapes which were PCR positive and screening medium positive for biogenic amines. Three methods for the confirmation of LAB biogenic amine-forming potential were developed and compared: HPLC-DAD and TLC methods both using derivatization agent dansyl chloride and enzymatic method using horseradish peroxidase (HRP) and diamine oxidase (DAO) enzymes. The applicability of methods was tested on the three known biogenic amine-producing LAB strains: 0006, 9809, 9906 (IOEB, France). The limit of detection (LOD) of the methods was <1 mg/L for HPLC-DAD, 5 mg/L for TLC and 25 mg/L for enzymatic method. Although the LODs between the proposed methods differed, all of the three methods confirmed BA-forming potential of the three strains. Furthermore, the proposed methods were applied for the analysis of three indigenous strains: MKBT-282 (BA+), MKBT-307 (BA-) and MKBT-325 (BA+). The positive or negative BA-forming potential was confirmed with all of the three proposed methods.
Keywords: lactic acid bacteria, biogenic amines, histamine, grape
Published in RUNG: 10.07.2020; Views: 4049; Downloads: 0
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23. Implementation of high performance liquid chromatography coupled to thermal lens spectrometry (HPLC‑TLS) for quantification of pyranoanthocyanins during fermentation of Pinot Noir grapesJelena Topič Božič, Lorena Butinar, Natka Ćurko, Karin Kovačević Ganić, Branka Mozetič Vodopivec, Dorota Korte, Mladen Franko, 2020, original scientific article Abstract: In this work high performance liquid chromatography coupled to thermal lens spectrometry (HPLC-TLS) was applied for monitoring of vinylphenolic pyranoanthocyanins formation during the fermentation of Pinot Noir wines. Vinylphenolic pyranoanthocyanins are wine pigments, present in low concentrations, but very important for wine colour stability.
Fermentation process was conducted with four different yeast strains, used as starters, either in sequential fermentation of non-Saccharomyces with S. cerevisiae yeast or as single fermentation with S. cerevisiae yeasts in order to test the applicability of developed method for monitoring of selected compounds in real wine fermentation experiments. The
developed HPLC-TLS method showed higher sensitivity compared to HPLC coupled to diode array detection (DAD) technique for particular wine colour compounds. Obtained limits of detection (LODs), were 6- and 22-times lower in comparison to HPLC–DAD in gradient and isocratic elution mode, respectively, whereas limits of quantification (LOQs)
5 and 18-times lower. Lower LODs enabled earlier observation of vinylphenolic pyranoanthocyanins formation during fermentation (already at day 7) in the case of HPLC-TLS method in gradient mode, while by using HPLC–DAD in gradient elution mode the formation of vinylphenolic pyranoanthocyanins was noticed only after 12 days of fermentation.
Keywords: Thermal lens spectrometry (TLS), High performance liquid chromatography (HPLC), Pyranoanthocyanins, Wine, Yeasts
Published in RUNG: 18.06.2020; Views: 4459; Downloads: 0
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24. Synthesis of pyranoanthocyanins from Pinot Noir grape skin extract using fermentation with high pyranoanthocyanin producing yeasts and model wine storage as potential approaches in the production of stable natural food colorantsJelena Topić, Natka Ćurko, Karin Kovačević Ganić, Lorena Butinar, Alen Albreht, Irena Vovk, Dorota Korte, Branka Mozetič Vodopivec, 2020, original scientific article Keywords: Pyranoanthocyanins, Anthocyanins, Food colorants, Yeasts, Fermentation
Published in RUNG: 03.04.2020; Views: 4978; Downloads: 0
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25. Facilitating green care improvements in viticultureMelita Sternad Lemut, Lorena Butinar, Adesida Rowland, Urban Česnik, Tjaša Jug, Paolo Sivilotti, Urška Vrhovšek, 2019, published scientific conference contribution Abstract: The growing demand of consumers for environment-friendly and safe food products already forced many winemakers to restrict the application of synthetic fungicides to earlier season, trying to reduce the risk of residues being detected in wines. Main risk for infection by B. cinerea, however, occurs later in the season. To support an improvement in whole-season B. cinerea green care, the potential of yeasts as biocontrol agent (PBA) was studied. Selected yeasts were tested for their antifungal activities. Furthermore, a field experiment in Pinot noir and Pinot gris vineyards was designed to study different combinations of optimized canopy microclimate manipulation (CMM) techniques and PBA application. In experimental conditions, PBA's ability to maintain appropriate population density for disease prevention was observed. Grape and wine quality parameters were evaluated. Analytical approach of metabolomics was applied to upgrade the understanding of potentially induced changes in plant metabolism.
Based on yeasts testing results, biocontrol yeast P. guilliermondii ZIM 624 was selected and after its field application, we were able to detect its suitable density on grapes until harvest. In case of early defoliation for both varieties smaller grape compactness was confirmed together with lower yield. Among grape basic quality parameters, optimized techniques showed positive effect on sugar content, but unexpectedly, in the treatments with biocontrol yeasts the trends toward higher acidity were noticed in Pinot gris. CMM and PBA introduction indicated some effects on grapevine biosynthetic behaviour but the differences in content of these metabolites compared to control were poorly detected in final wines with exception of mainly some flavonols, stilbenes and flavan-3-ols (and consequently total phenolic content).
Keywords: sustainable viticulture, Botrytis cinerea, yeasts, biocontrol, canopy microclimate manipulation, metabolomics, grapevine metabolites
Published in RUNG: 28.02.2020; Views: 5047; Downloads: 0
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26. The impact of Saccharomyces and non-Saccharomyces yeasts on wine colour: a laboratory study of vinylphenolic pyranoanthocyanin formation and anthocyanin cell wall adsorptionJelena Topić, Lorena Butinar, Alen Albreht, Irena Vovk, Dorota Korte, Branka Mozetič Vodopivec, 2020, original scientific article Keywords: Non-Saccharomyces yeast, Hydroxycinnamate decarboxylase activity, Sequential fermentation, Vinylphenolic pyranoanthocyanins, Anthocyanin adsorption
Published in RUNG: 23.01.2020; Views: 4238; Downloads: 0
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29. Occurence of biogenic amine - producing lactic acid bacteria in Refošk grape and wineJelena Topić Božič, Jan Reščič, Martina Bergant Marušič, Darja Lisjak, Branka Mozetič Vodopivec, Lorena Butinar, 2019, published scientific conference contribution abstract Abstract: Lactic acid bacteria (LAB) are naturally present in grapes, musts and wines. During malolactic fermentation, besides the beneficial conversion of L-malic to L-lactic acid, LAB can form also other compounds like biogenic amines (BAs). BAs are formed through decarboxylation of corresponding amino acids, through the action of enzymes. Consumption of food containing BAs can lead to food poisoning such as histamine poisoning. Histamine, the most studied BA, is known to cause headaches, oedema, vomiting.
In the last years, BAs associated pathways have been described as strain dependent and not as species dependent. Because of the high variability of microorganisms to decarboxylase amino acids, the detection of bacteria that have the possibility to transform precursor amino acid into BAs is very important in order to estimate the risk of BAs accumulation in wines. Since in previous years during project AGROTUR I we detected the higher BA content in some wines, we decided to focus on the presence of BA-producing LAB in Refošk grapes and wines. Therefore, during AGROTUR II project LAB collection of autochthonous lactic acid bacteria was set-up by isolating LAB from Refošk grapes and wines, originated from the grape growing cross-border region Karst (Slovenia). Over 600 isolates were obtained using MRS medium with added cycloheximide and 2% tomato juice. In parallel, also selective enrichment was performed using MRS medium described above with additionally added 5% ethanol. BA-producing LAB were primarily detected in microtiter-plate format using the decarboxylase screening medium with added amino acids (histidine, lysine, ornithine or tyrosine), which enable us to identify histamine-, cadaverine-, ornithine and tyrosine-producing LAB. Selected representatives from each BA-producing LAB groups were further on confirmed with chromatographic analysis (HPLC) and molecular methods (multiplex PCR method). BA-producing LAB were in majority represented by thyramin-producers, thereafter followed cadaverine-producers, with putrescine and histamine producers being the least presented. This screening of the BA-producing LAB is also incorporated in our on-going accurate selection of LAB starters for potential production of Refošk wines.
Keywords: biogenic amines, lactic acid bacteria, refošk, grape, wine
Published in RUNG: 22.01.2020; Views: 4348; Downloads: 0
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