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1.
The effect of prolonged maceration with spontaneous fermentation on chemical and sensorial characteristics of white wine
Tara Seničić, 2024, raz. nal. na višji ali visoki šoli

Opis: The use of prolonged maceration and spontaneous fermentation in white wine production is gaining renewed interest among winemakers, considering rising consumer interest in sustainable and traditional winemaking. This seminar aimed to assess how these approaches influence the sensory and chemical profiles of white wines based on available literature. Additionally, chemical analyses were conducted on three ‘Ribolla gialla’ variety wines from Vipava valley, which were produced using the aforementioned technology. The analyses indicated the presence of a wide range of aromatic compounds including esters and C-6 alcohols found in ‘Ribolla gialla’ wine samples. Spoilage indicators such as 4-ethylguaiacol and 4-ethylphenol were detected in some ‘Ribolla gialla’ samples, highlighting the risks of spontaneous fermentation. Assessing the reviewed literature data, prolonged maceration can enhance the aromatic complexity of white wines as related to the higher content of monoterpenes and phenolic compounds. This study supports the potential of these traditional methods to create unique and complex wines, but further research is needed to optimize these technological approaches and ensure consistent quality.
Ključne besede: white wine, prolonged maceration, spontaneous fermentation, sensorial characteristics
Objavljeno v RUNG: 19.08.2024; Ogledov: 715; Prenosov: 1
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Cider yeasts associated with Hardanger cider during fermentation process
Urban Česnik, Mitja Martelanc, Branka Mozetič Vodopivec, Ingunn Ovsthus, Lorena Butinar, 2022, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: In the Hardanger area in Western Norway, the production of cider has a long tradition that goes back to the 12th century, when monks introduced apple growing in this area. Nowadays, this is also the main area of fruit production in Norway. Despite the strict regulation of the alcoholic beverage production in Norway, traditional cider is still produced on some farms in this area. Therefore, our aim was to study the ecology and biodiversity of the yeasts associated with the cider production in the Hardanger area during fermentation process; especially of traditional cider, which is produced by a spontaneous fermentation of apple juice, performed by naturally occurring indigenous yeasts that originate from the fruit or the surfaces of the processing equipment. In our study, samples of fermenting juice/cider were taken during fermentation process from 12 producers, located in 12 different locations in Hardanger region. Classical cultivation methods using WL (Wallerstein Laboratories) agar medium with added chloramphenicol enable us to isolate a total of 530 yeast isolates that were stored in in-house yeast collection at the NIBIO and included also at the Wine Research Centre collection. Based on the sequencing of the D1/D2 domain of the 26S rDNA we managed to identify 357 isolates and distinguished 27 different yeast species as follows: Aureobasidium pullulans, Candida californica, C. oleophila, C, sake, Hanseniaspora meyeri, H. uvarum, H. valbyensis. Kregervanrija fluxuum, Kregervanrija sp., Metschnikowia andauensis, M. chrysoperlae, M. fructicola, M. pulcherrima, Metschnikowia sp, Pichia fermentans, P. kluyveri, P. membranifaciens, P. nakasei, Piskurozyma capsuligena, Rhodotorula nothofagi, Saccharomyces bayanus, S. cerevisiae, S. paradoxus, S. pastorianus, Saccharomyces sp., S. uvarum and Torulaspora delbrueckii. Even though we were not able to obtain samples in three different fermentation stages (beginning, middle and at the end of fermentation) from all producers, we could observe yeast succession during fermentation progress. Yeast diversity was higher at the beginning comparing to the middle of fermentation, when mostly different non-Saccharomyces yeast species prevailed, while in the middle of fermentation 11 species were detected (Candida californica, H. uvarum, H. valbyensis, Kregervanrija sp., K. fluxuum, Pichia membranifaciens, Metschnikowia pulcherrima, Saccharomyces sp, S. bayanus, S. uvarum and S. cerevisie). On the other hand, at the end of fermentation mainly Saccharomyces species with high ethanol tolerance were present (Saccharomyces sp., S. cerevisiae, bayanus, S. uvarum and P. fermentans). In samples that were collected from three producers in all three fermentation stages also quality parameters were determined (ethanol, organic acids, sugars, biogenic amines) with in-house developed methods using HPLC-UV/RID. The most important sugars in ciders were fructose and glucose, as expected. Two producers added sugar to increase the level of ethanol in the middle of fermentation, which is a common procedure in the Hardanger area. Ethanol and organic acid analysis indicated that fermentations went in the right direction, since all parameters were within normal limits. Including the acetic acid level, an indicator of low cider quality, was very low (average around 0,06 g/L). The alcohol incised from the beginning to end fermentation in all samples analysed and minimum concentration was 2,71 g/L. In ciders we detected four biogenic amines (putrescin, cadaverine, histamine and tyramine). The average amount was 32 mg/L and the most abundant was tyramine.
Ključne besede: indigenous yeasts, biodiversity, spontaneous fermentation, cider-making
Objavljeno v RUNG: 18.10.2022; Ogledov: 2396; Prenosov: 0
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Biodiversity of cider yeasts and their cider-making potential
Eivind Vangdal, Melita Sternad Lemut, Branka Mozetič Vodopivec, Lorena Butinar, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: In the area of Hardanger, a part of the fjord region in Western Norway, the production of apple wine (cider) has a long tradition that goes back to the 12th century, when monks introduced apple growing in this area. Nowadays, this is also the main area of fruit production in Norway. Despite the strict regulation of the alcoholic beverage production in Norway, traditional cider is still produced on some farms in this area. By tradition cider is produced by a spontaneous fermentation process of apple juice, performed by naturally occurring indigenous yeasts that originate from the fruit or the surfaces of the processing equipment. Therefore, our aim was primarily to study the ecology and biodiversity of the yeasts associated with the production of traditional cider in the Hardanger area. For two consecutive years, we sampled at 11 different locations in the observed region, where we collected cider samples and surface swabs of processing facilities from the cideries, and also soil and various parts of apple trees in orchards owned by the same producers. Thus, by enriching collected samples with the selective medium with high sugar and ethanol concentration, we managed to isolate about 1,300 yeasts. Based on the multiplex PCR results the yeasts were grouped into the Saccharomyces sensu stricto complex and non-Saccharomyces yeasts. The isolates were determined to the species level by performing the restriction analysis of ITS PCR products, and in some cases identifications were confirmed by sequencing of the D1/D2 domain of the 26S rDNA and/ or ITS region. As expected, non-Saccharomyces yeasts from the genus Metschnikowia and Hanseniaspora mainly populated the orchards, while the Saccharomyces yeasts were isolated in the orchards from the soil and fruits. In contrast, in ciders the species S. uvarum was predominantly found, occasionally also S. cerevisiae, Torulaspora delbrueckii and P. membranifacies. Indigenous cider yeasts were further on characterized in micro-plate format for the most important cider-making technological parameters (tolerance to ethanol, SO2, growth at low pH), for the presence of glucoside hydrolase activity, H2S production ability, and assimilation of malic acid. Based on this screenings the micro-scale fermentations of apple juice were performed with 13 different indigenous cider yeasts as monocultures. The most promising indigenous yeasts, T. delbrueckii and S. uvarum, were also tested as mixed cultures in sequential fermentations. Since the tested strain of T. delbrueckii as monoculture was not able to complete the alcoholic fermentation, better results were obtained in sequential fermentation with the mixed culture in combination with S. uvarum.
Ključne besede: indigenous yeasts, biodiversity, spontaneous fermentation, cider-making
Objavljeno v RUNG: 08.11.2017; Ogledov: 7428; Prenosov: 0
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Isolation and selection wild yeasts for winemaking
Natalia Mikhaylina, 2017, diplomsko delo

Opis: The aim of this study was to explore the diversity of fermentative yeast species in a non-vineyard and vineyard environment, and exploit their oenological potential. For this purpose we collected plant and soil material in the vineyard (located in Črniče in Vipava Valley) planted with Vitis vinifera L. and in the forest (forest in Vipava Old Castle), and by using a selective medium with high ethanol and sugar content we managed to obtain 35 isolates. By sequencing the D1/D2 domain of the 26S rDNA we identified nine different yeast species. The oenological potential of identified yeasts was further investigated by employing a series of tests, such as growth at low pH values, tolerance to ethanol and sulfur, and H2S production ability. Based on the results of these tests we selected four different yeast species for the microvinification of Vitis vinifera L. cv. ‘Pinot Noir’ grape juice. A commercial strain Saccharomyces cerevisiae Lalvin D47 was also included as a control in the fermentation experiment. Fermentation monitoring was done by measuring daily weight loss and microbiological analysis in the middle of fermentation. For the final wines, sugars were determined and sensorial evaluation performed. Among four tested yeasts, S. paradoxus IVV 32 and Torulaspora delbrueckii IVV 36 appeared to be the most promising for winemaking, but further studies should be carried out.
Ključne besede: wine, Vitis vinifera L. cv. ‘Pinot Noir’, biodiversity, yeasts, fermentation
Objavljeno v RUNG: 10.07.2017; Ogledov: 7095; Prenosov: 290
.pdf Celotno besedilo (2,57 MB)

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Introduction to carbon metabolism in yeast
Jure Piškur, Sofia Dashko, Concetta Compagno, 2014, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Ključne besede: yeast, carbon metabolism, alcohilic fermentation
Objavljeno v RUNG: 09.05.2017; Ogledov: 5537; Prenosov: 27
URL Povezava na celotno besedilo

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Changes in the relative abundance of two Saccharomyces species from oak forests to wine fermentations
Sofia Dashko, Ping Liu, Helena Volk, Lorena Butinar, Jure Piškur, Justin C. Fay, 2016, izvirni znanstveni članek

Opis: Saccharomyces cerevisiae and its sibling species S. paradoxus are known to inhabit temperate arboreal habitats across the globe. Despite their sympatric distribution in the wild, S. cerevisiae is predominantly associated with human fermentations. The apparent ecological differentiation of these species is particularly striking in Europe where S. paradoxus is abundant in forests and S. cerevisiae is abundant in vineyards. However, ecological differences may be confounded with geographic differences in species abundance. To compare the distribution and abundance of these two species we isolated Saccharomyces strains from over 1,200 samples taken from vineyard and forest habitats in Slovenia. We isolated numerous strains of S. cerevisiae and S. paradoxus as well as small number of S. kudriavzevii strains from both vineyard and forest environments. We find S. cerevisiae less abundant than S. paradoxus on oak trees both within and outside the vineyard, but more abundant on grapevines and associated substrates. Analysis of the uncultured microbiome shows that both S. cerevisiae and S. paradoxus are rare species in soil and bark samples, but can be much more common in grape must. In contrast to S. paradoxus, European strains of S. cerevisiae have acquired multiple traits thought to be important for life in the vineyard and dominance of wine fermentations. We conclude that S. cerevisiae and S. paradoxus currently share both vineyard and non-vineyard habitats in Slovenia and we discuss factors relevant to their global distribution and relative abundance.
Ključne besede: Wine, microbiome, yeast, Ecology, Fermentation
Objavljeno v RUNG: 12.02.2016; Ogledov: 6711; Prenosov: 203
.pdf Celotno besedilo (3,21 MB)

10.
EXPLORING BIODIVERSITY POTENTIAL OF WINE ASSOCIATED YEASTS
Sofia Dashko, 2015, doktorska disertacija

Opis: Human exploitation of yeast fermentation dates back to the Neolithic. S. cerevisiae has been the most important yeast used for numerous fermentations of biotechnological interest, including grape fermentation for wine production. Despite its abundant use, the molecular mechanisms controlling alcoholic fermentation are rather unclear and the choice of S. cerevisiae as an inoculum is often the consequence of a mere habit, rather than the result of rational analyses. In this work we focused on the role of different yeasts in the winemaking process. I was interested in understanding how the specific strain used for inoculum could influence the wine aroma formation. Furthermore, I wished to investigate the yeast genetics and ecology by characterizing their population and strain diversity in one of the wine regions of Slovenia. To evaluate the effect of the yeast species on the fermentation outcome, we performed successive fermentations with five different species in combination with the industrial strain S. cerevisiae Lalvin T73. The experiment showed that at least two more yeast species, Kazachstania gamospora and Zygosaccharomyces kombuchaensis have good potential to be applied in the winemaking. , The main conclusions of this study are the possibility of: i) expanding the palette of alternative starters to widen the aromatic components ii) co–fermenting using two different yeast species. Mixed yeast culture fermentations are present in the natural context, but this practice has been neglected in biotechnological processes. Positive results of wine fermentations with non – conventional yeast urged us to explore the diversity of Slovenian wine region natural isolates. The resulting yeast collection counts more than 1200 strains for which phenotype and genotype have been defined. Numerous isolates, including non – Saccharomyces species, showed promising oenological and biotechnological traits because of their capacity of rapid utilization of various carbon sources, growth at low pH and at presence of copper sulfite and potassium metabisulfite. Sampling also revealed sharp discrimination between the ecological niches of S. cerevisiae and S. paradoxus, which is a striking feature of European vineyards. While S. cerevisiae habitats are strongly associated with human activity, S. paradoxus was mainly isolated from the forest sources. Profound analysis of the collected data could give some explanations to the driving forces of S. cerevisiae domestication and S. paradoxus geographic isolation population structure.
Ključne besede: Yeasts, biodiversity, molecular biology, alcoholic fermentation
Objavljeno v RUNG: 02.11.2015; Ogledov: 9894; Prenosov: 171
.pdf Celotno besedilo (41,27 MB)

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