Repozitorij Univerze v Novi Gorici

Iskanje po repozitoriju
A+ | A- | Pomoč | SLO | ENG

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju


1 - 8 / 8
Na začetekNa prejšnjo stran1Na naslednjo stranNa konec
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, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: 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.
Ključne besede: Cider, yeast, biogenic amines, Hardanger, biodiversity
Objavljeno v RUNG: 23.06.2023; Ogledov: 377; Prenosov: 4
URL Povezava na datoteko

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: 624; Prenosov: 0
Gradivo ima več datotek! Več...

Facilitating green care improvements in viticulture
Melita Sternad Lemut, Lorena Butinar, Adesida Rowland, Urban Česnik, Tjaša Jug, Paolo Sivilotti, Urška Vrhovšek, 2019, objavljeni znanstveni prispevek na konferenci

Opis: 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).
Ključne besede: sustainable viticulture, Botrytis cinerea, yeasts, biocontrol, canopy microclimate manipulation, metabolomics, grapevine metabolites
Objavljeno v RUNG: 28.02.2020; Ogledov: 3157; Prenosov: 0
Gradivo ima več datotek! Več...

Prisotnost biokontrolne aktivnosti pri kvasovkah, osamljenih iz vinogradniškega okolja
Urban Česnik, 2019, magistrsko delo

Opis: Opravili smo dve hitri molekularni tehniki za identifikacijo enoloških kvasovk, ki so bile izolirane iz vinogradov z ekološko in intergrirano pridelavo grozdja. Najprej smo določili 15 Saccharomyces kvasovk s pomočjo analize multipleks PCR med zbranimi 131 izolati, nato smo s pomočjo ribotipizacije ITS določili približno 98 kvasovk do nivoja vrste, ki so bile potrjene tudi s sekvenciranjem regije ITS. Določili smo 16 vrst vinskih kvasovk: Hanseniaspora uvarum, H. valbyensis, H. opuntiae / H. uvarum, Lachancea thermotolerans, Candida tropicalis, Candida sp. / Starmerella sp., Metschnikowia pulcherrima, Pichia kudriavzevii, P. terricola, P. kluyveri, Wickerhamomyces anomalus, Kodamaea ohmeri, S. bacillaris, Saccharomyces cerevisiae, Saturnispora diversa in Torulaspora delbrueckii. Ugotovili smo, da so najdene kvasovke običajne naseljevalke grozdne mikroflore ter da je način pridelave grozdja vplival na pojavljanje določenih vrst v obravnavanih vinogradih. Nadalje smo testirali kvasovke na tvorbo sideroforov, tvorbo protiglivnih hlapnih organskih spojin (HOS), hidrolitično aktivnost in toleranco kvasovk na fungicide, kot so baker, iprodion, fluazinam ter kombinacijo ciprodinil / fludioksonil. Za kvalitativno detekcijo hidrolitične aktivnosti smo uporabili presejalne teste na osnovi trdnega gojišča z dodanim hitinom ali β-D-glukozidi kot substratom in ugotovili, da je veliko testiranih kvasovk sposobnih proizvajati litične encime, ki bi lahko bili odgovorni za razgradnjo celičnih sten fitopatogenih gliv in potencialno sposobni proizvajati HOS s hidrolizo grozdnih glikozidov zaradi prisotnosti β-glukozidaz. Prav tako smo opazili, da so te encimske aktivnosti običajno odvisne od seva. Na splošno so kvasovke tudi tolerantne na testirane fungicide. Ugotovili smo tudi, da je odpornost biofungicidnih kvasovk na fungicide koristna lastnost za razvoj biofungicidov v prihodnosti pri aplikacijah v strategijah z zmanjšanim vnosom pesticidov.
Ključne besede: Kvasovka, biološki nadzor, fitopatogen, Botrytis cinerea, vinogradništvo
Objavljeno v RUNG: 01.12.2019; Ogledov: 3785; Prenosov: 119
.pdf Celotno besedilo (1,57 MB)

Study of yeast biodiversity potential in the development of biological control agents against phytopathogenic fungi in viticulture
Melita Sternad Lemut, Adesida Rowland, Urban Česnik, Lorena Butinar, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Despite public’s growing concerns for human health and environmental pollution, synthetic fungicides are still preferred and massively used for the protection of agricultural crop plants against fungal diseases. However, more and more research is focused on finding potential alternatives in the form of effective biological control agents. Although there are reports of yeast’s biocontrol activity, they are up to date 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 Botrytis cinerea in viticulture. With this aim we tested biocontrol activity of various strains / species of indigenous wine yeasts that were isolated from the vineyard environment in Slovenia and cross-border Italy. The yeasts were tested for the presence of siderophores, hydrolytic enzymes (chitinase, β-glucosidase and β-glucanase) and sensitivity to fungicides (copper, iprodion, cyprodinil + fludioxonil combination). The tests of phytopathogenic fungi growth inhibition in the presence of antagonistic yeast were also performed. The double Petri dish test was used to verify the inhibition of conidia germination by the formation of antifungal volatile organic compounds (VOC), synthetized by the antagonistic yeasts. The presence of hydrolytic enzymes was confirmed in many wine yeasts, particularly in the strains of Hanseniaspora uvarum and Metschnikowia pulcherrima species and in some strains of the Pichia genus. Using a medium, based on natural diluted grape juice in a double Petri dish test, we found that yeasts of the Debaryomyces hansenii, Lachancea thermotolerans, P. kudriavzevii, Saccharomyces kudriavzevii, S. cerevisiae and Torulaspora delbrueckii species were able to inhibit the germination of fungal conidia at the expense of the VOC formation. However, none of the up to date tested yeasts formed siderophores. On the other hand, the yeasts were generally resistant to the tested fungicide concentrations, thus they could be used as potential biofungicides in the combination with chemical fungicides.
Ključne besede: yeasts, biocontrol, Botrytis cinerea, viticulture
Objavljeno v RUNG: 08.11.2017; Ogledov: 4026; Prenosov: 0
Gradivo ima več datotek! Več...

Urban Česnik, 2016, diplomsko delo

Opis: Goriška regija z Novo Gorico je zaradi milega podnebja in prehodne lege ugodno okolje za tujerodne vrste, tako rastlinske kot živalske. V zadnjih letih je invazivna vrsta tigrastega komarja (Aedes albopictus Skuse, 1894) na tem območju naselila areal, v katerem se nemoteno razmnožuje in vzdržuje stalno populacijo. V diplomskem delu smo se odločili spremljati letno dinamiko pojavljanja jajčec in ličink komarjev na različnih lokacijah mestnega, primestnega in gozdnega okolja. S preverjanjem prisotnosti ličink tigrastega komarja na različnih lokacijah smo poskušali dobiti odgovor na to, kje se nahajajo za to vrsto ugodni mikrohabitati. Rezultati so bili pridobljeni s pomočjo pasti, s katerimi smo spremljali številčnost ličink v okolju. Ob zaključku smo preverili še razmerje med številom ličink avtohtonih vrst komarjev in ličink tigrastega komarja. Dobljene vrednosti smo primerjali med seboj, ugotavljali dinamiko razmnoževanja in določali območja, ki jih ta vrsta v večjem številu naseljuje. Iz raziskave smo ugotovili, da tigrasti komar na tem območju naseljuje predvsem urbane habitate, manj pa je zastopan v gozdovih. Začetek pojavljanja prvih ličink smo zabeležili v drugi polovici maja, njihovo število je strmo naraščalo do julija, ko smo raziskavo tudi zaključili. Največje število ličink na vseh vzorčnih mestih je pripadalo tigrastemu komarju, manj pa je bilo avtohtonih vrst komarjev. Med preučevanimi potencialnimi razmnoževalnimi habitati smo daleč največjo številčnost ličink tigrastega komarja zaznali v peskolovih.
Ključne besede: Nova Gorica, invazivne vrste, Aedes albopictus, ličinke tigrastega komarja, razmnoževanje, reprodukcijska dinamika
Objavljeno v RUNG: 30.09.2016; Ogledov: 6922; Prenosov: 282
.pdf Celotno besedilo (3,62 MB)

Iskanje izvedeno v 0.06 sek.
Na vrh