magistrsko delo
Saška Košir (Author), Uroš Petrovič (Reviewer), Neža Čadež (Mentor), Iztok Jože Košir (Co-mentor)

Abstract

Cilj magistrske naloge je bil določiti lastnosti pivskih sevov, ki bodo zagotovile učinkovito fermentacijo pivine na osnovi ajde in prosa v primerjavi z ječmenovo pivino pod pivovarskimi pogoji. V delu smo izbrali trinajst genetsko raznolikih sevov Saccharomyces pastorianus in dvanajst hibridnih sevov rodu Saccharomyces izoliranih iz spontanih fermentacij jabolčnega vina. Slednjim smo z reakcijo PCR z vrstno-specifičnimi začetnimi oligonukleotidi določili hibridni vrsti rodu Saccharomyces. Sevom smo s presejalnimi testi določili kinetiko rasti v fermentabilnih sladkorjih kot edinih virih ogljika in v različnih vrstah pivin v mikrotitrskem formatu. Pivski sevi S. pastorianus so učinkoviteje asimilirali maltotriozo, medtem ko so sevi Saccharomyces spp., izolirani iz jabolčnega vina, hitreje asimilirali maltozo in rafinozo. Prav tako smo določali sposobnost stopnje atenuacije različnih pivin in tvorbo etanola in glicerola v konusnih mini-fermentorjih pri 14 °C. Pivski sevi S. pastorianus so najučinkoviteje fermentirali pivino na osnovi ječmena, medtem ko so sevi Saccharomyces spp., izolirani iz jabolčnega vina, primerljivo učinkovito fermentirali pivini na osnovi prosa in ajde. Po končani fermentaciji smo določili stopnjo flokulacije s testom HELM in ugotovili, da hibridni sevi iz jabolčnega vina bolje flokulirajo v ajdovi pivini v primerjavi s pivskimi sevi. Na podlagi teh rezultatov zaključujemo, da smo lahko izbrali pivske seve in seve iz jabolčnih vin, ki imajo želene tehnološke lastnosti za fermentacijo pivin na osnovi ajde in prosa.

Keywords

pivske kvasovke;Saccharomyces pastorianus;Saccharomyces spp.;pivo;pivu podobna pijača;pivina;ječmenova pivina;prosena pivina;ajdova pivina;tehnološke lastnosti;fermentacija;hlapne fenolne spojine;flokulacija;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [S. Košir]
UDC: 663.4:582.282.23
COBISS: 5171576 Link will open in a new window
Views: 673
Downloads: 259
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Other data

Secondary language: English
Secondary title: Characterisation of Saccharomyces pastorianus strains for efficient consumption of buckwheat and millet wort under brewing conditions
Secondary abstract: The aim of this master thesis was to characterize brewing strains that could effectively ferment buckwheat and millet wort in comparison with barley wort under brewing conditions. In this research we selected thirteen genetically diverse Saccharomyces pastorianus strains and twelve hybrid strains of the genus Saccharomyces isolated from spontaneous fermentations of cider. The hybrid nature of the strains isolated from cider was determined by species-specific PCR primers for the species of genus Saccharomyces. Further, we determined growth kinetics of the strains on different fermentable sugars and types of worts in microtiter plates. S. pastorianus brewing strains were more efficient in maltotriose assimilation, whereas Saccharomyces spp. strains isolated from cider were more efficient in maltose and raffinose assimilation. We also determined the rate of attenuation of different worts and the formation of ethanol and glycerol by the strains in conical mini-fermenters at 14 °C. The S. pastorianus brewing strains most effectively fermented barley wort, whereas Saccharomyces spp. strains isolated from cider more effectively fermented millet and buckwheat worts. After the fermentations were completed, we determined the rate of flocculation using HELM test. The hybrid strains isolated from cider, flocculated better in buckwheat wort in comparison with the brewing strains. Based on the results, we conclude that we were able to select brewing strains and strains isolated from cider that have desirable technological properties for fermentation of buckwheat and millet wort.
Secondary keywords: brewing yeasts;Saccharomyces pastorianus;Saccharomyces spp.;beer;beer-like beverage;wort;barley wort;millet wort;buckwheat wort;technological properties;fermentation;volatile phenolic compounds;flocculation;
Type (COBISS): Master's thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Študij mikrobiologije
Pages: XIII, 70 str., [2] str. pril.
ID: 11412846