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Adesida Rowland, Melita Sternad Lemut, Lorena Butinar, 2020, published scientific conference contribution abstract

Abstract: A number of indigenous yeast strains isolated from vineyard / cellar-associated samples and non-vineyard sites, from forests with oak trees (a known habitat where Saccharomyces species resides) from existing in-house yeast collection and from ZIM culture collections (Slovenia) were screened for enzymatic activities with enological importance. The yeasts were screened for glycosidase enzymes connected to terpene aroma release, the β-lyase activity responsible for the volatile thiol release, and sulfite reductase activity involved in off-flavours. Yeast strains that showed positive results for qualitative and quick detection of glucoside hydrolase activity on plates were selected for further studies. The glucoside hydrolase activity of 20 selected strains belonging to 15 different species was quantitatively characterized by determinations of the activity on pNPG. All strains demonstrated hydrolase activity, especially strain H. uvarum 116 which showed the highest value of specific activity 6.32 mU/mg for cell-associated activity and T. delbrueckii Sut 94 with highest value of specific activity 1.36 mU/mg for extracellular activity. Increased growth of tested yeast on medium containing substrate S-methyl-L-cysteine indicated β-lyase activity, and by this approach a moderate activity was recorded throughout our tested strains with immense intraspecific inconsistency. Noticeable H2S production was observed in P. manshurica strain whereas, H. uvarum, L. thermotolerance, S. bayanus and S. cerevisiae demonstrated weak/slight H2S-producer strains in our study. Therefore, our screening indicates the importance of strain selection for enological application due to intraspecies differences, as well as the introduction of non-Saccharomyces yeast starters with interesting potential to enhance wine aroma.
Keywords: wine yeasts, non-Saccharomyces, enzymatic activities
Published in RUNG: 08.05.2023; Views: 1225; Downloads: 0
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Novel analytical approaches in quality and safety control in production of fermented beverages : dissertation
Jelena Topić, 2022, doctoral dissertation

Abstract: The exploitation of microorganisms for fermentation goes back centuries. Two types of fermentation are usually used in the winemaking process – alcoholic fermentation and malolactic fermentation. Nowadays, inoculated fermentations with the use of starter cultures are commonly used in order to produce wine with more consistent quality. However, wines can lack in flavour complexity, so scientists and the industry are constantly looking for new and improved starters that can be adapted to different types of wine. In this work we focused on the development and implementation of novel analytical methods for wine quality control. In the course of method development native yeasts and lactic acid bacteria isolates were characterized for wine starter properties. We focused on the determination of biologically active compounds that determine wine quality and safety. Yeasts can influence wine colour through their adsorption capacity and synthesis of stable colour pigments pyranoanthocyanins and lactic acid bacteria can produce biogenic amines which can have adverse detrimental health effects on sensitive consumers when they are present in wines.
Keywords: Saccharomyces yeasts, non-Saccharomyces yeasts, pyranoanthocyanins, thermal-lens spectrometry, lactic acid bacteria, biogenic amines, thin layer chromatography, dissertations
Published in RUNG: 18.02.2022; Views: 3080; Downloads: 127
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Yeasts and wine colour
Jelena Topić Božič, Olga Butinar-Čeh, Dorota Korte, Branka Mozetič Vodopivec, 2019, review article

Keywords: yeast, Saccharomyces, non-Saccharomyces, wine colour, pyranoanthocyanins
Published in RUNG: 20.12.2019; Views: 4463; Downloads: 0
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Uporaba različnih kvasovk v pridelavi jabolčnega vina
Luka Koporec, 2018, undergraduate thesis

Abstract: Kemijske in senzorične lastnosti vina so poleg genetskih danosti ter geo-klimatskih okoliščin odvisne tudi od strategije tehnologije pridelave, ki jo izbere vinar. V to strategijo spada tudi izbira seva kvasovke. Vinski trg postaja vse bolj zahteven in željan nečesa novega, zato vse več vinarjev poskuša pridobiti drugačne lastnosti vin z uporabo drugačnih sevov kvasovk, oziroma z uporabo kombinacij različnih vrst kvasovk. V diplomski nalogi smo preučevali vpliv različnih kombinacij kvasovk na potek fermentacije ter na osnovne kemijske in senzorične lastnosti pridelanega jabolčnega vina. Poskus je bil izveden na laboratorijski skali. Rezultati poskusa so pokazali, da različne vrste kvasovk različno vplivajo na senzorične lastnosti vina, nekoliko manj pa na kemijske lastnosti. Rezultati nakazujejo, da različne kvasovke različno hitro porabljajo sladkorje, kar vpliva tudi na hitrost poteka fermentacije. Ob opazovanju osnovnih kemijskih lastnostih smo opazili razlike med kvasovkami oz. kombinacijami kvasovk pri parametrih kot so hlapne kisline in reducirajoči sladkorji, medtem ko v vsebnosti alkohola in pH vrednostih končnih jabolčnih vin med obravnavanimi fermentacijami nismo opazili razlik. Senzorična analiza vonja in barve jabolčnih vin je potrdila vpliv kvasovk na barvo, intenzivnost, trajnost in vrsto vonja.
Keywords: jabolčno vino, ne-Saccharomyces kvasovke, potek fermentacije, kvasovke, senzorična analiza
Published in RUNG: 26.10.2018; Views: 7131; Downloads: 218
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Gabrijel Cernigoi, 2017, undergraduate thesis

Abstract: The aim of the study was to investigate and select indigenous yeasts Saccharomyces cerevisiae and non-conventional yeasts that were isolated during this and previous studies, and than evaluate them for wine production by performing micro-scale vinification experiment
Keywords: Saccharomyces, non-conventional yeasts, wine, fermentations
Published in RUNG: 17.07.2017; Views: 6041; Downloads: 318
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