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31.
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: 6304; Downloads: 212
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Simple and fast HPLC-DAD method for determination of HCDC activity and formation of vinylphenol in Saccharomyces and non-Saccharomyces yeast
Jelena Topič, Lorena Butinar, Dorota Korte, Branka Mozetič Vodopivec, published scientific conference contribution abstract

Abstract: Conventionally, alcoholic fermentation in the production of wine is performed by yeast species Saccharomyces cerevisiae. There are numerous starters available, however due to the growing demand for wines with specific characteristics, other Saccharomyces and non-Saccharomyces species are being investigated for potential use as starters. [1]. Yeast selection has involved the development of techniques for detecting strains that might improve wines in terms of aroma, structure, colour and other technological properties [2]. Colour of the wine can be affected as some metabolites produced by yeast during fermentation may react with grape anthocyanins to produce highly stable pyranoanthocyanins. For the facilitation of formation of vinylphenolic pyranoanthocyanins, yeast strains with high hydroxycinnamate decarboxylase activity are used (HCDC). The mechanism of reaction is decarboxylation of hydroxycinnamic acids and formation of vinylphenols that condense with grape anthocyanins and form stabile vinyphenolic pyranoanthocyanin adducts [3]. It has been demonstrated that some non-Saccharomyces strains (Pichia guillermondii, Schizosaccharomyces pombe) have positive HCDC activity and they can produce vinylphenolic pyranoanthocyanins in higher concentrations than S. cerevisiae. A simple way of determining whether the yeast strain has HCDC activity or not, is the use of fermentation media with the addition of hydroxycinnamic acids, such as p-coumaric acid. The degradation of p-coumaric acid and transformation into 4-vinylphenol (and possibly in 4-ethylphenol) can be checked by LC-DAD. Most of the published data has been done on smaller number of strains. The goal of our work was to develop simple method for the screening of Slovenian in-house yeast collection, comprising of native isolates that mostly originated from Vipava valley and Karst region, and therefore try to determine strains with high HCDC activity. These strains can be used for wine fermentations in order to produce more stable pyranoanthocyanins; which is especially important in wines that has less anthocyanin concentration already from the grape, such as Pinot Noir. 103 different yeast strains belonging to 28 species were selected for the assessment of HCDC activity. In some cases the difference in p-coumaric acid metabolism rate between two strains exceeded 90%. All tested S. paradoxus strains showed higher than 40% degradation rate of p-coumaric acid. HCDC activity of S. cerevisiae strains which is the species most commonly used in fermentation, varied between 5.1 and 66.1%. The commercial strains tested, FPC and EC118 showed 43.9 and 21.5% conversion rate, respectively. It was observed that some native strains had higher HCDC activity than commercial tested ones. Three strains produced vinylphenol in concentration higher than 50 ppm, two of them being P. guillermondii and another strain being S. paradoxus (Sut85). In general strain with high HCDC activity also produced high concentration of 4-vinylphenol. The results showed that HCDC activity is highly strain dependent, which correlates with the literature data available. The proposed method is very simple and does not require special sample preparation prior to HPLC analysis. Furthermore, the proposed fermentations in deep-well microtiter plates allow the screening of high number of strains. The method could be used for routine screening, to determine which strain has high HCDC activity and produces high concentration of vinylphenols and can therefore be used in future for determination of strains ability to synthesize vinylphenolic pyranoanthocyanins.
Keywords: yeast, hydroxycinnamate decarboxylase, 4-vinylphenol
Published in RUNG: 18.06.2018; Views: 3981; Downloads: 0
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Biodiversitet i naturleg gjær i siderproduksjonen i Hardanger
Lorena Butinar, Eivind Vangdal, Melita Sternad Lemut, Branka Mozetič Vodopivec, 2017, professional article

Keywords: biodiverziteta, kvasovke, jabolčno vino, fermentacija
Published in RUNG: 01.02.2018; Views: 4500; Downloads: 0
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40.
BIOTSKA RAZNOVRSTNOST KVASOVK POVEZANIH S PROIZVODNJO JABOLČNEGA VINA
Eivind Vangdal, Melita Sternad Lemut, Branka Mozetič Vodopivec, Lorena Butinar, 2017, published scientific conference contribution abstract

Abstract: Na območju fjorda Hardanger, del zahodne Norveške, ima proizvodnja jabolčnega vina dolgo tradicijo in sicer sega v 12. stoletje, ko so menihi na tem območju začeli uvajati sadjarstvo. Danes je to glavno območje pridelovanja sadja na Norveškem. Kljub strogi regulativi proizvodnje alkoholnih pijač, pa se je na tem območju na nekaterih kmetijah ohranila tradicionalna proizvodnja jabolčnega vina. Namen naše študije je bil predvsem preučiti ekologijo in biotsko raznovrstnost kvasovk, ki so povezane s proizvodnjo tradicionalnega jabolčnega vina na območju Hardanger. Na tem območju smo tekom dveh zaporednih let vzorčili na 11-ih različnih lokacijah, kjer smo pri proizvajalcih vzorčili jabolčno vino, tla in različne dele jablan v sadovnjakih. Tako smo s pomočjo bogatitve v gojišču s povišanim sladkorjem in etanolom osamili približno 1300 izolatov kvasovk. Kvasovke smo s pomočjo multipleks PCR testa ločili na skupino kompleksa Saccharomyces sensu stricto in ne-Saccharomyces kvasovke. Nadalje smo izolate določili do nivoja vrste z izvedbo restrikcijske analize ITS PCR produktov, v nekaterih primerih smo za potrditev identifikacij opravili še določitev nukleotidnih zaporedij D1/D2 domene 26S rDNA. Kot pričakovano smo ugotovili, da sadovnjake naseljujejo predvsem ne-Saccharomyces kvasovke iz rodov Metschnikowia in Hanseniaspora, v tem okolju so bile Saccharomyces izolirane iz tal in jabolk. V jabolčnem vinu pa je bila pretežno izolirana vrsta S. uvarum, občasno pa tudi S. cerevisiae, Torulaspora delbrueckii in P. membranifacies.
Keywords: kvasovke, biotska raznovrstnost, jabolčno vino
Published in RUNG: 09.11.2017; Views: 5071; Downloads: 0
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