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1.
Aromatic characterization of Graševina wines from Slavonia and Podunavlje sub-regions
Mitja Martelanc, Guillaume Antalick, Tatjana Radovanović, Branka Mozetič Vodopivec, Melita Sternad Lemut, Ahmad Hosseini, Valentina Obradović, Josip Mesić, Lorena Butinar, 2024, original scientific article

Abstract: This study investigated the chemical aromatic profiles of 60 volatile organic compounds (VOCs), including 21 terpenes, 6 norisoprenoids, 6 volatile phenols, 4 C-6 alcohols, and 23 esters, in Graševina wines originating from Slavonia and Podunavlje sub-regions (Croatia). Headspace solid-phase microextraction gas chromatography coupled with mass spectrometric detection (HS-SPME-GCMS) was used to assess 60 VOCs, and a novel HS-SPME-GCMS method for the determination of terpenes and norisoprenoids was developed and validated. Statistical analysis also found no significant differences between VOCs present in Graševina wines and others wines (Chardonnay and Pinot gris); nonetheless, comparison of VOC fingerprints between different wines from the same producer showed that four terpenes (α-terpinene, γ-terpinene, 1,4-cineol, and 4-terpineol) were present in higher amounts in Graševina wines when compared to other wines. By exclusively examining VOCs within Graševina wines through the utilization of a heatmap and hierarchical clustering, a distinct visualization of samples and VOCs emerged, highlighting the vintage effect. Simultaneously, a partial least squares discriminant analysis model was developed with a confidence interval of 95%, demonstrating a noticeable distinction between samples originating from the western and eastern regions. Furthermore, by employing the heatmap using only VOCs from the terpene and norisoprenoidic groups, a clear separation of samples into two groups was observed based on geographical origin; namely, higher concentrations of norisoprenoids and terpenes were observed in the Slavonia sub-region. These results suggest that terpenes and norisoprenoids to a lower extent may be valuable aromatic markers for the regional typicality of Graševina wines.
Keywords: Graševina–Welschriesling, aromatic profiling, HS-SPME-GCMS, terpenes
Published in RUNG: 08.04.2024; Views: 389; Downloads: 6
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2.
Uporaba lesa v vinarstvu : diplomski seminar
Matija Gregorič, 2023, research project (high school)

Keywords: les, sodi, zorenje vina, vpliv lesa, senzorične lastnosti vina
Published in RUNG: 17.11.2023; Views: 768; Downloads: 0
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3.
Upočasnjena ali ustavljena alkoholna fermentacija : možni vzroki in rešitve
Maruša Mulej, 2023, research project (high school)

Keywords: alkoholna fermentacija, upočasnjena fermentacija, ustavljena fermentacija
Published in RUNG: 17.11.2023; Views: 751; Downloads: 0
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4.
SCREENING AND EVALUATION OF ENZYMATIC ACTIVITIES OF WINE RELATED YEAST SPECIES
Adesida Rowland, Melita Sternad Lemut, Lorena Butinar, 2020, published scientific conference contribution abstract

Abstract: A number of indigenous yeast strains isolated from vineyard / cellar-associated samples and non-vineyard sites, from forests with oak trees (a known habitat where Saccharomyces species resides) from existing in-house yeast collection and from ZIM culture collections (Slovenia) were screened for enzymatic activities with enological importance. The yeasts were screened for glycosidase enzymes connected to terpene aroma release, the β-lyase activity responsible for the volatile thiol release, and sulfite reductase activity involved in off-flavours. Yeast strains that showed positive results for qualitative and quick detection of glucoside hydrolase activity on plates were selected for further studies. The glucoside hydrolase activity of 20 selected strains belonging to 15 different species was quantitatively characterized by determinations of the activity on pNPG. All strains demonstrated hydrolase activity, especially strain H. uvarum 116 which showed the highest value of specific activity 6.32 mU/mg for cell-associated activity and T. delbrueckii Sut 94 with highest value of specific activity 1.36 mU/mg for extracellular activity. Increased growth of tested yeast on medium containing substrate S-methyl-L-cysteine indicated β-lyase activity, and by this approach a moderate activity was recorded throughout our tested strains with immense intraspecific inconsistency. Noticeable H2S production was observed in P. manshurica strain whereas, H. uvarum, L. thermotolerance, S. bayanus and S. cerevisiae demonstrated weak/slight H2S-producer strains in our study. Therefore, our screening indicates the importance of strain selection for enological application due to intraspecies differences, as well as the introduction of non-Saccharomyces yeast starters with interesting potential to enhance wine aroma.
Keywords: wine yeasts, non-Saccharomyces, enzymatic activities
Published in RUNG: 08.05.2023; Views: 957; Downloads: 0
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Exploration of yeast biodiversity potential for development of alternative biofungicides in viticulture : dissertation
Rowland Adesida, 2022, doctoral dissertation

Abstract: Botrytis cinerea Pers., the fungal plant pathogen and the causal agent of gray mould diseases in grapevine, is vastly responsible for substantial economic losses in table and wine grapes production worldwide by negatively affecting plant growth and causing the reduction of grape and wine quality. The conventional approach for pathogen control has been up to date based on synthetic fungicides with good effectiveness against pathogens but a negative impact on the environment. The growing level of harmful residues in the environment and some also detected in wines have led the European Union and many winemakers to limit the application of synthetic fungicides to earlier season. However, with a high risk of disease also late in the season, the need for other solutions is clear. Consequently, more and more research is focused on finding potential alternatives in the form of effective biological control agents. Although there are several reports of yeast’s biocontrol activity, they are up to date still poorly commercialized for such purposes. As the yeasts represent an important part of the grape microflora, competing with other microorganisms (including pathogens) for nutrients and space, we decided to examine the potential of autochthonous yeasts as "green" alternatives in fighting against phytopathogens such as B. cinerea in viticulture. With this aim, we tested the biocontrol activity of 119 different indigenous yeasts belonging to 30 different species of 17 genera against filamentous fungus B. cinerea, the causal agent of grey mould or botrytis bunch rot in grape. The yeasts were screened for putative multidimensional modes of action such as antifungal volatiles (VOC), in vitro inhibition of fungal mycelial growth, competition for nutrients, hydrolytic enzyme activities, and yeast tolerance to fungicides like copper, iprodione and cyprodinil/fludioxonil combination. With a qualitative detection of the hydrolysis activity by using screening methods based on solid medium with chitin or βD-glucosides as substrates, we found that many tested yeasts were capable of producing lytic enzymes with the ability to degrade the cell wall of phytopathogenic fungi and are potentially also able to produce VOCs via hydrolysis of grape glycosides as a result of β-glucosidase presence. Furthermore, we observed the capability of tested yeast to inhibit fungal mycelia growth on plate and assimilation of a wide variety of carbon sources; however, no siderophore producers were detected. In general, the yeasts under observation were tolerant to the tested fungicides. Their fungicide resistance can indeed be regarded as a beneficial trait for potential biofungicide agent (PBA) candidates due to open possibilities of applications and combinations within low input pest management strategies in the vineyard. Finally, a field experiment in Pinot noir and Pinot gris vineyards was designed to study different combinations of optimized canopy microclimate manipulation (CMM) techniques and potential biocontrol agent (PBA) application. In experimental conditions, the ability of PBA’s to maintain appropriate population density for disease prevention was observed. In addition, the grape and wine quality parameters were analysed to observe the possible impact of implemented biocontrol yeast on final products. The biocontrol yeast Pichia guilliermondii ZIM 624 was selected and applied in experimental vineyards based on yeast testing results. We were able to detect and confirm PBA yeast’s suitable density on grapes until harvest. In the case of early defoliation for both varieties lower grape compactness was observed together with lower yield/ plant, regardless of PBA yeast/ no yeast application. Among grape basic quality parameters, the optimized techniques showed a positive effect on sugar content. Still, unexpectedly, in the treatments with biocontrol yeasts some trends toward higher acidity were noticed in Pinot gris.
Keywords: sustainable viticulture, Botrytis cinerea, gray mould, yeasts, biocontrol, canopy microclimate manipulation, grapevine metabolite, dissertations
Published in RUNG: 07.07.2022; Views: 1934; Downloads: 137
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8.
Univerza v Novi Gorici, Fakulteta za vinogradništvo in vinarstvo
2020, other monographs and other completed works

Keywords: študijski programi, Univerza v Novi Gorici, Fakulteta za vinogradništvo in vinarstvo
Published in RUNG: 23.02.2021; Views: 2147; Downloads: 0
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9.
e-Klet
Guillaume Antalick, Marko Lesica, Melita Sternad Lemut, Lorena Butinar, Erika Jež, Branka Mozetič Vodopivec, 2020, other educational material

Keywords: interaktivno učno gradivo, pridelava vina, posamezne faze pridelave, sveže belo vino
Published in RUNG: 23.02.2021; Views: 2319; Downloads: 0
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10.
Facilitating green care improvements in viticulture
Melita 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: 3897; Downloads: 0
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