21. Study of yeast biodiversity potential in the development of biological control agents against phytopathogenic fungi in viticultureMelita Sternad Lemut, Adesida Rowland, Urban Česnik, Lorena Butinar, 2017, published scientific conference contribution abstract Abstract: 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.
Keywords: yeasts, biocontrol, Botrytis cinerea, viticulture
Published in RUNG: 08.11.2017; Views: 4564; Downloads: 0
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22. Preučevanje potenciala biotske raznovrstnosti kvasovk za razvoj alternativnih biofungicidov v vinogradništvuMelita Sternad Lemut, Adesida Rowland, Ajda Lemut, Urban Česnik, Lorena Butinar, 2017, published scientific conference contribution abstract Keywords: biotska raznovrstnost, kvasovke, biokontrolna aktivnost, biofungicid, Botrytis cinerea, trajnostno vinogradništvo
Published in RUNG: 28.09.2017; Views: 5084; Downloads: 0
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23. Study of grapevine early leaf removal sustainability potential by means of targeted metabolomic approachMelita Sternad Lemut, Paolo Sivilotti, Lorena Butinar, Ajda Lemut, Urška Vrhovšek, 2017, published scientific conference contribution abstract Keywords: Pinot gris, early leaf removal, sustainable viticulture, grape compactness, targeted metabolomics, phenolic compounds
Published in RUNG: 21.09.2017; Views: 5172; Downloads: 0
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24. Combined effects of early season leaf removal and climatic conditions on aroma precursors in ‘Sauvignon blanc’ grapesPaolo Sivilotti, Rachele FALCHI, Jose Carlos Herrera, Branka Škvarč, Lorena Butinar, Melita Sternad Lemut, Marijan Bubola, Paolo SABBATINI, Klemen Lisjak, Andreja Vanzo, 2017, original scientific article Abstract: Early leaf removal around the cluster zone is a common technique applied in cool climate viticulture, to regulate yield components and improve fruit quality. Despite the increasing amount of information on early leaf removal and its impact on total soluble solids, anthocyanins and polyphenols, less is known regarding aroma compounds. In order to verify the hypothesis that defoliation, applied before or after flowering, could impact the biosynthesis of thiol precursors, we performed a two year (2013 and 2014) experiment on Sauvignon blanc. We provided evidence that differential accumulation of thiols precursors in berries is affected by the timing of defoliation and this impact was related to modifications in biosynthetic pathway. Furthermore, the possible interaction between leaf removal treatment and seasonal weather conditions, and its effect on the biosynthesis of volatile precursors are discussed. Our results suggested that in Sauvignon blanc the relative proportion of 4-S-glutathionyl-4-methylpentan-2-one (G-4MSP) and 3-S-glutathionylhexan-1-ol (G-3SH) precursors can be affected by defoliation, and this could be related to the induction of two specific genes encoding glutathione-S-transferases (VvGST3 and VvGST5), while no significant effects on basic fruit chemical parameters, polyphenols and methoxypyrazines were ascertained under our experimental conditions.
Keywords: early leaf removal, cluster exposure, thiol precursors, methoxypyrazines, glutathione S-transferase, Vitis vinifera
Published in RUNG: 31.08.2017; Views: 4346; Downloads: 0
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25. Alternativne vinogradniške in vinarske tehnologije: kakovostni, trajnostni in senzorični potencial : /Melita Sternad Lemut, Paolo Sivilotti, Lorena Butinar, Jana Laganis, Urška Vrhovšek, 2017, published scientific conference contribution abstract (invited lecture) Keywords: odstajevanju listov v predelu grozdov, trajnostno vinogradništvo, Botrytis cinerea, mikrobna ekologija vinske trte, alternativne vinarske tehnologije, senzorika vina.
Published in RUNG: 29.06.2017; Views: 5094; Downloads: 252
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26. Vpliv karbonske maceracije na vsebnost fenolov in aromatične značilnost vina MerlotIris Lisjak, 2017, undergraduate thesis Abstract: Kakovost vina je prvi vrsti odvisna od lastnosti uporabljenega grozdja, njegova
kakovost in stil pa sta močno odvisna tudi od vinarjevih odločitev glede uporabljenih
vinifikacijskih postopkov. Zahteve vinskega trga spodbujajo k izboljšanju klasičnih kot
tudi k uvajanju alternativnih vinarskih strategij.
V sklopu diplomskega dela smo preučevali vpliv postopka karbonske maceracije v
predelavi grozdja sorte 'Merlot' na vsebnosti prostih aromatičnih spojin, skupnih
antocianov ter skupnih polifenolov v vinih in sicer v primerjavi s kontrolnim, klasičnim
postopkom pridelave mladega rdečega vina. Kemijske analize vzorcev smo opravili
spektrofotometrično ter s pomočjo naprednih analitskih pristopov metabolnega
profiliranja in tehnike GC-MS-MS. Preučili smo tudi senzorične lastnosti
eksperimentalnih vin.
Rezultati enoletnega poskusa so pokazali, da lahko s karbonsko maceracijo v vinu
Merlot povečamo vsebnost skupnih prostih aromatičnih kislin, estrov in norizoprenoida
damascenona. Nasprotno smo več aromatičnih alkoholov določili v kontrolnih vinih.
Uporaba karbonske maceracije je povzročila slabši izplen skupnih antocianov, ne pa
tudi skupnih polifenolov. Senzorične analize barve so potrdile več češnjevo rdečih
odtenkov pri vinih, pridelanih s karbonsko maceracijo ter več vijoličnih in rubinastih pri
kontrolnih vinih. Karbonska maceracija je povzročila boljšo intenzivnost ter kakovost
vonja, vendar slabšo trajnost in intenzivnost okusa vina. Degustatorji so pri vinih,
pridelanih s karbonsko maceracijo, zaznali več svežega sadja in mehkega rdečega sadja
v vonju ter več svežine in nekoliko boljšo harmoničnost v okusu. Kontrolna vina so
imela močnejše zaznave gozdnih sadežev v vonju, v okusu pa več grenkobe in
astringence, a so degustatorjem delovala polnejše.
Keywords: 'Merlot' (Vitis vinifera L.), tehnologije pridelave rdečega vina, karbonska maceracija, proste aromatične spojine, polifenoli, antociani, senzorika vina
Published in RUNG: 19.06.2017; Views: 6748; Downloads: 328
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30. Vpliv različnih tehnoloških postopkov predelave grozdja sorte Zelen (Vitis vinifera L.) na aromatične značilnosti vinaFranko Fabjan, 2017, undergraduate thesis Abstract: Poleg sorte, geo-klimatskih pogojev in vinogradniških strategij v vinogradu so tudi vinarjeve odločitve glede izbora vinifikacijskih postopkov tiste, ki lahko odločilno vplivajo na končno kakovost vina, vključno z njegovimi aromatskimi značilnostmi. Z različnimi prijemi ali postopki pred alkoholno fermentacijo in med njo lahko vplivamo predvsem na ekstrakcijo in ohranitev primarnih ter na tvorbo sekundarnih aromatskih spojin.
V okviru diplomskega dela smo s pomočjo modernih analitskih pristopov metabolnega profiliranja in tehnike GC/MS/MS preučevali vpliv različnih tehnoloških postopkov predelave grozdja (krioekstrakcija s suhim ledom, stik s celimi jagodami med fermentacijo, klasični pristop-kontrola) na vsebnost prostih in vezanih aromatičnih spojin v mladih vinih Zelen, letnik 2014. Preučili smo tudi vpliv obravnavanih tehnologij na senzorične lastnosti, vezane na zaznave vonja v mladih vinih.
Rezultati enoletnega poskusa so nakazali, da lahko s pomočjo krioekstrakcije v vinih Zelen povečamo izplene skupnih prostih aromatičnih kislin, estrov in terpenov, po drugi strani pa smo zaznali le trend povečanja vsebnosti skupnih višjih alkoholov pri vzorcih iz postopka dodajanja jagod med fermentacijo.
V primeru vezanih aromatskih spojin smo s pomočjo postopka dodajanja jagod v primerjavi s kontrolo opazili trende povečanja vsebnosti nekaterih vezanih estrov, norizoprenoidov in višjih alkoholov, krioekstrakcija pa je večinoma povzročila trende k niţjim vsebnostim vezanih aromatskih spojin glede na kontrolne vzorce.
Nazadnje so se tudi senzorična opazovanja z vonjem povezanih lastnosti vin zaključila preteţno v prid postopku z dodajanjem jagod med fermentacijo.
Keywords: 'Zelen' (Vitis Vinifera L.), alternativni pristopi v predelavi grozdja, krioekstrakcija, dodajanje sveţih jagod med alkoholno fermentacijo, proste aromatične spojine v vinu, vezane aromatične spojine v vinu, senzorika vina
Published in RUNG: 23.01.2017; Views: 7656; Downloads: 316
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