1. Lactic acid bacteria and Brettanomyces bruxellensis in Teran wine : impact on biogenic amines and volatile phenolsTatjana Radovanović Vukajlović, Shanique Walker, Julija Šupljika, Mitja Martelanc, Jan Reščič, Melita Sternad Lemut, Branka Mozetič Vodopivec, Dejan Bavčar, Klemen Lisjak, Lorena Butinar, 2025, published scientific conference contribution abstract Abstract: Yeasts and lactic acid bacteria (LAB) are the main microorganisms involved in wine production, responsible for alcoholic fermentation and malolactic fermentation (MLF), respectively. During MLF, LAB convert L-malic acid into L-lactic acid, which primarily leads to biological deacidification but also results in changes to the wine’s aroma and microbiological stability. While LAB generally improve wine quality, certain strains can cause spoilage and are linked to the production of biogenic amines (BAs)—nitrogenous compounds such as histamine, tyramine, and putrescine. At elevated levels, BAs may pose health risks, especially for sensitive individuals, potentially causing headaches, hypertension, and digestive issues. Likewise, the yeast Dekkera/ Brettanomyces bruxellensis is considered a spoilage organism due to its ability to produce volatile phenolic compounds (e.g., 4-ethylguaiacol and 4-ethylphenol), which impart off-flavors resembling bandages, sweat, and smoke. As part of the AGROTUR+ project, we monitored LAB and B. bruxellensis populations, as well as BA and volatile phenol content, during MLF in Teran - a protected wine made from Refošk grapes in the Karst wine-producing region. The goal was to assess the presence of spoilage-related compounds and support improvements in microbiological quality of this traditional wine. A total of 26 Teran wine samples from the 2024 vintage were analyzed. Volatile phenols were analyzed using HS-SPME-GC-MS, and BAs were determined via HPLC–UV following sample derivatization. Basic quality physicochemical parameters were determined using standard methods. LAB and B. bruxellensis populations were estimated through conventional microbiological techniques and flow cytometry. Regarding BA content, histamine was the most abundant (average 21.9 mg/L), followed by putrescine (3.7 mg/L) and cadaverine (1.6 mg/L). No correlation was observed between total LAB counts and BA levels, indicating the need for further analysis of LAB strain composition. For volatile phenols, 4-ethylphenol was found at concentrations below its sensory threshold (600 µg/L), while 4-ethylguaiacol exceeded its threshold (110 µg/L) in three samples. In these, B. bruxellensis was detected using the CyFlow™ BrettCount flow cytometry kit (Sysmex Partec), though no colonies were observed on selective Dekkera/Brettanomyces differential medium (DBDM). Flow cytometry proved to be a rapid and specific method for detecting spoilage yeasts like B. bruxellensis, with strong potential for early intervention and spoilage prevention in winemaking.
Keywords: lactic acid bacteria, biogenic amines, Teran
Published in RUNG: 17.06.2025; Views: 73; Downloads: 0
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2. Microbiological screening of dried fruits and table grape present on Slovenian marketTatjana Radovanović Vukajlović, Melitta Buzás, Anej Colja, Anuša Skušek, Katarina Mukhina, Laura Smolnikar Štrukelj, Valentina Ratoša, Sara Gregorc, Branka Mozetič Vodopivec, Lorena Butinar, 2025, published scientific conference contribution abstract Abstract: Dried fruits are a popular snack due to their high fiber content, but their production may pose microbiological risks, due to the nature of the processing methods, which can allow various microorganisms and their metabolic byproducts to persist. Among these byproducts are mycotoxins—such as ochratoxin A, patulin, and griseofulvin—which are of particular concern due to their potentially harmful effects on human health (Shahidi (2013)). In this study, samples from raisins, dried apricots, and table grapes available on the Slovenian market were analyzed to assess microbial contamination and potential mycotoxin production. Dried fruits and table grape samples were inoculated on MEA, WL, and PDA media and incubated to isolate yeasts and moulds. Morphological identification was performed using CREA and CYA media. For mycotoxin screening, selected mould cultures were extracted and analyzed using Thin Layer Chromatography (TLC), with standards for ochratoxin A, patulin, and griseofulvin. TLC plates were examined under UV light at 254 nm and 365 nm wavelength. DNA from isolates was also extracted and sent for sequencing to confirm species identification. The results showed that Aspergillus spp. were the predominant moulds in raisin samples, while Penicillium spp. were isolated from table grapes and various yeast strains from dried apricots. TLC analysis suggested the presence of griseofulvin in Aspergillus isolates, and possible traces of patulin and ochratoxin A in Penicillium samples. These findings are consistent with literature data ((Narayana (2021), Tournas et al. (2015)) on typical contaminants of dried fruits. Future studies using quantitative methods such as HPLC are needed to confirm and measure mycotoxin concentrations.
Keywords: mycotoxins, dried fruits, Slovenian market
Published in RUNG: 17.06.2025; Views: 59; Downloads: 0
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3. Exploring innovative approaches in flavored ciders : physicochemical and antioxidative properties of cornelian cherry – apple ciderErika Jež, Marianna Mazur, Tatjana Radovanović Vukajlović, Mitja Martelanc, Bartłomiej Menażyk, Maja Pečarič, Jelena Topić, Melita Sternad Lemut, Guillaume Antalick, Branka Mozetič Vodopivec, Lorena Butinar, 2024, published scientific conference contribution abstract Keywords: Cornelian cherry, apple cider, antioxidative properties
Published in RUNG: 27.11.2024; Views: 1640; Downloads: 1
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4. Polyphenol profiles in white wines : a ǂcomparative analysis of vinification methodsMagdalina Mihajlovska, 2024, research project (high school) Abstract: In our graduation seminar, we studied the effects of extended maceration of grape mash on polyphenol extraction in white wine production. Data from the literature show that grape variety plays an important role in the influence of the skin contact procedure on the extraction of phenolics. The polyphenol content of Chardonnay was improved by 24-hour cryomaceration of the mash at 8.0°C and 6.0°C, whereas no such effect was observed at 4.0°C. In the case of Malvasia, the maximum amount of caftaric and caffeic acid was obtained after 21 days of post-fermentation maceration at 16.0°C. These findings underscore the potential of controlled maceration to enrich white wines with greater complexity and antioxidant capacity. However, polyphenols are very susceptible to oxidation, especially during the initial stage of grape processing, leading to the formation of brown pigments and an amber color in such wines, which may also occur during the aging process if the phenolic-rich white wine is not sufficiently protected by other antioxidants. The changes in phenolics during prolonged maceration or aging of vintage white wines are not yet well understood. Further research is needed to elucidate the chemical reactions and transformations of polyphenols during prolonged skin contact and aging in order to develop targeted approaches to produce high-quality white wines with prolonged maceration of the mash with desirable sensory and health-promoting properties.
Keywords: polyphenols, white wine, skin contact, winemaking procedures
Published in RUNG: 19.08.2024; Views: 2120; Downloads: 0
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5. Chemical characterization of cider produced in hardanger : from juice to finished ciderIngunn Ovsthus, Mitja Martelanc, Alen Albreht, Tatjana Radovanović Vukajlović, Urban Česnik, Branka Mozetič Vodopivec, 2024, original scientific article Abstract: Our investigation delves into the previously uncharted territory of cider composition from Norway. This study aimed to obtain an overview of the qualitative and quantitative compositions of general chemical parameters, polyphenols (individual and total expressed as gallic acids equivalents), selected esters, and selected C6-alcohols in ciders with the PDO label Cider from Hardanger. In total, 45 juice and cider samples from the fermentation process were collected from 10 cider producers in Hardanger in 2019, 2020, and 2021. Individual sugars, acids, ethanol, and 13 individual phenols were quantified using HPLC-UV/RI. Seven ethyl esters of fatty acids, four ethyl esters of branched fatty acids, ten acetate esters, two ethyl esters of hydroxycinnamic acids, and four C6-alcohols were quantified using HS-SPME-GC-MS. For samples of single cultivars (‘Aroma’, ‘Discovery’, ‘Gravenstein’, and ‘Summerred’), the sum of the measured individual polyphenols in the samples ranges, on average, from 79 to 289 mg L−1 (the lowest for ‘Summerred’ and highest for ‘Discovery’ and ‘Gravenstein’). Chlorogenic acid was the most abundant polyphenol in all samples. Ethyl butyrate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl isobutyrate, ethyl 2-methylbutyrate, isoamyl acetate, and hexanol were present at concentrations above the odour threshold and contributed to the fruity flavour of the Cider from Hardanger.
Keywords: cider, volatile aroma, esters, higher alcohols, polyphenols
Published in RUNG: 14.08.2024; Views: 2163; Downloads: 10
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6. Aromatic characterization of Graševina wines from Slavonia and Podunavlje sub-regionsMitja Martelanc, Guillaume Antalick, Tatjana Radovanović Vukajlović, 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: 2953; Downloads: 20
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7. Chemical composition of apple cider : a comparative study of Norwegian and French cidersIngunn Ovsthus, Mitja Martelanc, Tatjana Radovanović Vukajlović, Marko Lesica, Lorena Butinar, Branka Mozetič Vodopivec, Guillaume Antalick, 2024, published scientific conference contribution Abstract: Norwegian apple ciders have recently gained attention at the levels of international competitiveness. Accordingly, a comparative study on the chemical composition of selected Norwegian and French apple ciders was conducted to gain knowledge on what ubiquitous chemical parameters make the Norwegian ciders different from ciders from well-established producing regions. A total of 43 ciders, 24 Norwegian and 19 French, in the category of acidic dominant ciders, were included in the study. Ethanol, individual sugars and organic acids, pH, total phenols, aroma compounds including esters, C6-alcohols, volatile phenols and terpenoids, were analysed. Norwegian ciders showed higher contents in ethanol, malic and citric acids, whereas total phenols, pH, glucose, and fructose were higher in French counterparts. Regarding the aromatic profile, no significant differences were observed for C6-alcohols. In contrast, differences were more expressed in the case of esters and volatile phenols. Norwegian ciders were characterised by higher average concentration for all the groups of esters, with the most important differences measured for higher alcohol acetates. Norwegian ciders also displayed higher contents of 4-vinylphenol and 4-vinylguaiacol while French ciders contained substantially higher levels of 4-ethylphenol and 4-ethylguaiacol. These results are in mutual correlation with the empirical observation reporting Norwegian apple ciders as more acidic, alcoholic and with lighter body but fruitier profile. Whereas French ciders are often perceived with more structure and animalistic profile.
Keywords: alcohol, acidity, total phenols, aroma-compounds, apple cider
Published in RUNG: 25.03.2024; Views: 3559; Downloads: 8
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8. Functional characterization of Saccharomyces yeasts from cider produced in HardangerUrban Česnik, Mitja Martelanc, Ingunn Ovsthus, Tatjana Radovanović Vukajlović, Ahmad Hosseini, Branka Mozetič Vodopivec, Lorena Butinar, 2023, original scientific article Keywords: Saccharomyces, Hardanger, characterization, fermentation, cider, non-volatile compounds, volatile organic compounds, partial least squares regression
Published in RUNG: 18.09.2023; Views: 2706; Downloads: 10
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9. VSEBNOST POLIFENOLOV V OLJU GROZDNIH PEŠKEnej Koron, 2023, undergraduate thesis Abstract: Diplomska naloga obravnava pridobivanje olje iz grozdnih pešk s hladnim stiskanjem. V nalogi smo izvedli postopek izolacije in priprave pešk na stiskanje na kmetiji (ne v laboratoriju), samo stiskanje olja na hladen način oz. brez dodatnega segrevanja v vijačni stiskalnici, ki je bila razvita za tako zahtevna semena kot so grozdne peške. V nalogi smo primerjali stiskanje pešk in tudi olje pešk štirih belih sort grozdja 'Pinela', 'Beli pinot', 'Laški rizling', 'Sauvignon' in dveh rdečih sort 'Cabernet sauvignon' in 'Refošk'. Sorte so se zelo malo razlikovale v izplenu olja, ki je znašal v povprečju 9 masnih %, kar je bilo nekoliko manjše kot pri drugih objavah v literaturi – kar je mogoče posledica sezone, pa tudi mehanskega stiskanja, za katerega je iz literature znano, da ima najmanjši izplen – v primerjavi z drugimi metodami ekstrakcije olja. Analiza olja je pokazala prisotnost raznolikih fenolnih spojin - različnih nizkomolekularnih tanininov – procianidinov B1, B2, C1, fenolnih kislin kot je galna kislina, protokatehinska kislina, kavna kislina, klorogenska kislina, p-kumarna kislina in flavonolov katehina in epikatehina. Seštevek vseh kromatografsko določenih fenolnih spojin je variral od 3,75 μg/g pri olju Pinela pa do 9,98 μg/g v olju Refošk. Pri skupnih fenolih, določenih po metodi Folin-Ciocalteu pa od 14,08 μg (kot galna kislina)/g (olje Sauvignon) pa do 35,23 μg (kot galna kislina)/g (olje Refošk). V olju različnih sort so vsebnosti skupnih in posameznih fenolov zelo varirale, na splošno pa smo ugotovili, da mehansko pridobljeno olje pešk rdečih sort vsebuje v povprečju vsebuje tudi do dvakrat večje koncentracije skupnih fenolov kot olje belih sort. Ugotovili smo, da v povprečju v procesu mehanskega stiskanja prehaja v olje zgolj 0,02 % vseh prisotnih fenolnih spojin, torej večina ostane v pogači, ki bi jo lahko še nadalje uporabili ne le kot vir beljakovin, ampak tudi kot vir polifenolov.
Keywords: olje, grozdne peške, Vitis vinifera L., fenoli, mehansko stiskanje olja
Published in RUNG: 07.09.2023; Views: 3316; Downloads: 40
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10. Fenolni potencial izbranih vin s podaljšano maceracijo sorte "Rebula"Dejan Bavčar, Yelyzaveta Popova, 2023, undergraduate thesis Abstract: V diplomski nalogi smo analizirali 30 vzorcev vin sorte grozdja Vitis vinifera L. cv. 'Rebula' iz Vipavske doline in Goriških brd. Vina smo kupili na trgu, in sicer v specializiranih lokalnih prodajalnah vina, spletnih prodajalnah ali pri vinarjih. Osemindvajset (28) vzorcev vina je bilo pridelanih s postopkom podaljšane maceracije drozge grozdja. Dve vini pridelanih brez maceracije, smo dodali v nabor vzorcev zaradi primerjave fizikalno-kemijskih parametrov z ostalimi vzorci. V vinskih vzorcih smo izmerili naslednje standardne fizikalno-kemijske parametre: skupni in prosti žveplov dioksid, skupne titrabilne kisline, pH, hlapne kisline z destilacijsko metodo, izbrane organske kisline, sladkorje (glukozo + fruktozo), etanol in barvo vina s spektofotometrom - absorbanco pri 420 nm (A420) in barvne parametre v CIE Lab sistemu. Izmerili smo tudi skupne polifenole po spektrofotometrijski metodi Folin-Ciocalteu in izbrane posamezne polifenole (hidroksibenzojske kisline, nezaestrene hidroksicimetne kisline, procianidine) s tekočinsko kromatografijo visoke ločljivosti, sklopljeno z UV detetktorjem (HPLC-UV). Želeli smo določiti polifenolni potencial vin sorte 'Rebula', pridelanih s postopkom podaljšane maceracije drozge grozdja in nato določiti morebiten vpliv časa maceracije na količino polifenolov v vinu. Kemijske analize so pokazale veliko variabilnost v količini skupnih polifenolov, ki pa jih nismo uspeli povezati s časom maceracije. Pomanjkljivi podatki o času in drugih pogojih maceracije drozge grozdja nam tega niso dopuščali. Podatki nakazujejo trend večjih koncentracij skupnih polifenolov vina pri vinih, pridelanih s postopkom podaljšane maceracije drozge grozdja. V določenih vinih smo izmerili tudi preko 1000 mg/L (kot galna kislina) skupnih polifenolov. Med posameznimi polifenoli je bilo v vinih največ galne kisline (tudi do 90 mg/L), procianidina B1 (do 52 mg/L) in katehina (do 18 mg/L). Instrumentalno določena barva filtriranega vina (A420 in parametri CIE Lab) je povezana s količino skupnih polifenolov po metodi Folin-Ciocalteu. Parametri barve dolgo maceriranih vin se močno razlikujejo od vin brez maceracije oziroma od vin, pridelanih s krajšim časom maceracije, zato gre za dobre 'markerje' tovrstnih vin. Opazili smo, da kombinacija običajnega parametra barve belih vin A420 nm s parametri CIE Lab sistema omogoča podrobnejšo analizo barve vina.
Keywords: Vitis vinifera L. cv. ‘Rebula’, belo grozdje, belo vino, postopek maceracije, polifenoli
Published in RUNG: 06.07.2023; Views: 4471; Downloads: 44
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