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

Abstract

Zaradi porasta z glutenom povezanih bolezni se je pokazala potreba po izdelavi brezglutenskih piv. Ena izmed možnosti proizvodnje brezglutenskih piv je uporaba brezglutenskih surovin, kot sta ajda in proso, ki pa potrebujeta na novi surovini prilagojene seve kvasovk. V magistrski nalogi smo preverjali, kako učinkovito različni sevi kvasovk uporabljajo ajdovo in proseno pivino, v primerjavi z ječmenovo pivino, in ali imajo končni produkti zadovoljiv organoleptični profil. Uporabili smo štiri različne seve Saccharomyces pastorianus in dva seva iz rodu Saccharomyces spp., izolirana iz jabolčnega vina. Med potekom fermentacije smo gravimetrično določali kinetiko in hitrost fermentacije. Sevi so najuspešneje izkoriščali ječmenovo pivino, pivini na osnovi prosa in ajde pa so sevi izkoriščali primerljivo učinkovito. Najvišje hitrosti fermentacije so kvasovke dosegle v ječmenovi pivini, najnižje pa v proseni pivini. V mladem pivu smo z analizo HPLC določili količino preostalih sladkorjev in količino nastalega etanola in glicerola. V vseh pivinah so sevi S. pastorianus porabili več sladkorjev in proizvedli več etanola kot seva izolirana iz jabolčnega vina. Največ etanola so kvasovke proizvedle v ječmenovi pivini, v proseni in ajdovi pivini pa se bile koncentracije medsebojno podobne. Z analizo GC-MS smo v mladem pivu določili še vrsto in količino nastalih aromatičnih spojin. Pri določanju aromatičnih spojin smo ugotovili, da so v ječmenovem pivu sevi proizvedli več različnih aromatičnih spojin kot v ostalih dveh pivih in tudi koncentracija teh spojin je bila v ječmenovem pivu največja, najmanjša pa je bila v prosenem pivu.

Keywords

pivo;kvasovke;Saccharomyces pastorianus;Saccharomyces cerevisiae;hibridi;ječmen;ajda;proso;fermentacija;arome;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [U. Rajniš]
UDC: 663.45:582.282.23
COBISS: 86161667 Link will open in a new window
Views: 205
Downloads: 42
Average score: 0 (0 votes)
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Other data

Secondary language: English
Secondary title: Kinetics of fermentable substrates consumption in buckwheat and millet worts by different yeast strains
Secondary abstract: The increase in gluten-related diseases has caused the need to produce gluten-free beers. One way to produce gluten-free beers is to use gluten-free raw materials such as buckwheat and millet, but these require brewing yeast strains adapted to the new substrate. In this master's thesis we investigated how effectively different yeast strains use buckwheat and millet wort, compared to barley wort, and whether the finished products have a satisfactory organoleptic profile. We used four different Saccharomyces pastorianus strains and two Saccharomyces spp. strains, isolated from cider. During fermentation, kinetics and fermentation rate were determined gravimetrically. All strains were most successful in utilisation of barley wort, whereas millet and buckwheat worts were utilised with a similar efficiency. The highest fermentation rates were obtained in the barley wort and the lowest in the millet wort. Using the HPLC method we determined the concentrations of non-utilised sugars, ethanol and glycerol present in the green beer. In all worts, S. pastorianus strains consumed more sugars and produced more ethanol than the strains isolated from cider. Most ethanol was produced in the barley wort, while concentrations were similar between the millet and the buckwheat worts. We also used GC-MS analysis to determine the type and quantity of aromatic compounds produced in green beer. We found that the strains in the barley beer produced more aromatic compounds than in the other two beers, and the concentrations of these compounds were the highest in the barley beer and the lowest in the millet beer.
Secondary keywords: beer;yeasts;Saccharomyces pastorianus;Saccharomyces cerevisiae;hybrids;barley;buckwheat;millet;fermentation;aromas;
Type (COBISS): Master's thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Študij mikrobiologije
Pages: X, 62 f.
ID: 14010135