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1.
2.
Polyphenol profiles in white wines : a ǂcomparative analysis of vinification methods
Magdalina 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: 742; Downloads: 0
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3.
Chemical characterization of cider produced in hardanger : from juice to finished cider
Ingunn 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: 823; Downloads: 6
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4.
Aromatic characterization of Graševina wines from Slavonia and Podunavlje sub-regions
Mitja 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: 1614; Downloads: 16
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5.
Chemical composition of apple cider : a comparative study of Norwegian and French ciders
Ingunn 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: 1762; Downloads: 6
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VSEBNOST POLIFENOLOV V OLJU GROZDNIH PEŠK
Enej 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: 1826; Downloads: 26
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8.
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: 2714; Downloads: 41
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9.
Biogenic amines in Hardanger ciders : the effect of native cider yeasts on biogenic amine production
Urban Česnik, Mitja Martelanc, Branka Mozetič Vodopivec, Ingunn Ovsthus, Lorena Butinar, 2023, published scientific conference contribution abstract

Abstract: The presence of bioactive compounds in food and beverages of plant origin is mainly connected with higher nutritional value and better sensory properties. However, some of them can pose a threat to food product quality and human health. For example, excess biogenic amines (BAs) intake can cause different allergenic responses in individuals who have such intolerances. BAs have been intensively studied in recent years, especially in fermented foods like wine, meat, fish, and cheese. Among fermented beverages is apple cider still rather unexplored from this perspective. Especially since no such data exist for the Norwegian cider. Norwegian cider is becoming more and more popular in Norway in recent years among producers and consumers. Hardanger cider from Western Norway is very different from French, English, or Spanish ciders in terms of sensory characteristics, apple cultivars, and in the fermentation process. In Hardanger, the traditional cider is still produced by spontaneous fermentation of apple juice with naturally occurring yeasts that originate from the fruit or processing equipment surfaces. Lactic acid bacteria are known to be associated with BA formation. However, several studies reported about the BA-producing yeasts in winemaking. Due to the important role of natural yeasts in the production of Hardanger cider, we focused on the ability of BA formation by native yeasts. Thus, in our study, we followed the amounts of BAs in the Hardanger ciders during the fermentation process and characterize isolated yeasts if they have the ability to produce BAs under cidermaking conditions by performing a micro-fermentation experiment. From must/cider samples, taken during the fermentation process at 13 producers in the Hardanger region, we isolated 530 yeast isolates. Based on the sequencing of the D1/D2 domain of the 26S rDNA we identified 25 different yeast species. As expected, yeast diversity was higher at the beginning compared to the middle fermentation stage, when mostly different non-Saccharomyces yeast species prevailed, while at the end of fermentation mainly Saccharomyces species with high ethanol tolerance were present. BAs were analyzed with the HPLC-UV method. In all apple juice/cider samples 4 different BAs (putrescine, cadaverine, histamine, and tyramine) were detected and quantified with external calibration. On average in all cider samples from the producers total BA (summation of all BAs) concentration reached 9,45 mg/L, however in one case even 25 mg/L. Tyramine was the most abundant BA in all fermentation stages. 40 isolated yeast strains were further tested for BA formation in a small-scale experiment by fermenting apple juice. Results show that non-Saccharomyces yeasts mainly form histamine (1,68 mg/L) and tyramine (1,30 mg/L), while Saccharomyces yeasts putrescine (0,48 mg/L) and tyramine (3,53 mg/L). As a general conclusion, the occurrence and distribution of BA concentrations in the small-scale fermentation were lower (2,96 mg/L and 4,01 mg/L) and less variable than in the real ciders (average in final ciders 9,45 mg/L) and with tyramine being the most abundant BA in all samples analyzed.
Keywords: cider, yeast, biogenic amines, Hardanger, biodiversity
Published in RUNG: 23.06.2023; Views: 1861; Downloads: 7
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