1. 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: 1571; Downloads: 0
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2. 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: 1590; Downloads: 8
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3. The influence of polyphenolic compounds on anaerobic digestion of pepper processing waste during biogas and biomethane productionGregor Drago Zupančič, Anamarija Lončar, Jasmina Ranilović, Drago Šubarić, Mario Panjicko, 2024, original scientific article Abstract: Pepper processing waste has the potential to be used as a substrate in the process of anaerobic digestion, but because of its high polyphenol content, certain limitations are expected. During the determination of the biodegradability of pepper samples, a biogas potential of 687 L/kg DM was observed, as well as a biomethane potential of 401 L/kg DM. While both the testing of biodegradability and the process in the pilot scale progressed, it was observed that total polyphenol content in both cases decreased. Also, as far as individual polyphenols during the process in the pilot scale are concerned, it can be observed that at the end of the process no procyanidin A2, epicatechin, myricetin, and quercetin were detected. The observed concentration of the ferulic acid on the last
day of the process was 0.09 μg/g. Finally, it can be concluded that the presence of polyphenols did
not significantly affect the biogas potential of pepper waste. Due to its relatively stable biogas production,
as far as biogas production on the pilot scale is concerned, it can be concluded that pepper
processing waste has the potential to be used as a substrate for biogas production.
Keywords: anaerobic digestion, polyphenols, ferulic acid, procyanidins, epicatechin, myricetin, quercetin
Published in RUNG: 06.05.2024; Views: 1578; Downloads: 7
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6. Amélioration de l´extraction des composés phénoliques du Merlot par champ électrique pulséCristèle Delsart, C. Cholet, Rémy Ghidossi, Christian Poupot, Nabil Grimi, Eugène Vorobiev, V. Milisic, Martine Mietton-Peuchot, 2012, other scientific articles Keywords: polyphenols, pulsed electric fields, wine, extraction, distribution
Published in RUNG: 22.01.2015; Views: 8050; Downloads: 36
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7. Effect of pulsed electric field on grape polyphenols extractionCristèle Delsart, C. Cholet, Rémy Ghidossi, Christian Poupot, Nabil Grimi, Eugène Vorobiev, V. Milisic, Martine Mietton-Peuchot, 2010, published scientific conference contribution abstract Keywords: pulsed electric field, red wine, extraction, polyphenols
Published in RUNG: 22.01.2015; Views: 6713; Downloads: 33
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