Metabolizem fenolnih spojin v pivovarskih kvasovkah

Bajc, Rok (avtor), Čadež, Neža (mentor), Tome, Miha (komentor)

Fenolne spojine spadajo med najpomembnejše senzorično zaznavne molekule v pivu, njihova vsebnost se giblje med 500 in 1000 mg/L in je sestavljena iz različnih skupin. 70-80 % fenolnih spojin izvira iz sladu, približno 20-30% pa jih v pivo prispeva hmelj. Med fermentacijo je večina teh spojin podvrženih biotransformaciji. Pri pivovarskih kvasovkah je podrobneje raziskana encimatska pretvorba hlapnih fenolov. Večinoma gre za pretvorbo hidroksicimetnih kislin, kot sta ferulna in p-kumarna kislina, v 4-vinil gvajakol in 4-vinil fenol. V pivovarskih kvasovkah je pretvorba katalizirana z dekarboksilazo ferulne kisline (Fdc1) in dekarboksilazo fenilakrilnih kislin (Pad1). Poleg hidroksicimetnih kislin se v pivu nahajajo tudi druge fenolne spojine, kot so enostavni fenoli, derivati benzojske kisline, kumarini, katehini, di-, tri- in oligomerni proantocianidini, halkoni ter flavonoidi. Nekatere med njimi so v relativno visokih koncentracijah; fenol tirozol, p-hidroksibenzojska kislina, vanilinska kislina, vanilin, katehin in epikatehin, proantocianidni dimeri in flavanon izoksantohumol. Cilj diplomskega dela je spoznati proces fermentacije in sestavo piva, razumeti evolucijo in evolucijske razlike med pivovarskimi sevi kvasovk in kako te vplivajo na metabolizem fenolnih spojin ter spoznati pristope, s katerimi izboljšujemo industrijske seve kvasovk.

• Jezik: Slovenski jezik
• Ključne besede: Saccharomyces cerevisiae, pivovarstvo, fenoli, metabolizem, evolucija
• Vrsta gradiva: Diplomsko delo/naloga
• Tipologija: 2.11 - Diplomsko delo
• Organizacija: BF - Biotehniška fakulteta
• Založnik: [R. Bajc]
• Leto izida: 2020
• PID: 20.500.12556/RUL-119429
• UDK: 663.4:543.92:602.3:582.282.23:602.42:577.152.3(043.2)
• COBISS.SI-ID: 31214083
• Datum objave v RUL: 09.09.2020

BAJC, Rok, 2020, Metabolizem fenolnih spojin v pivovarskih kvasovkah [na spletu]. Diplomsko delo. R. Bajc. [Dostopano 14 avgust 2025]. Pridobljeno s: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=slv&id=119429

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Metabolism of phenolic compounds by brewer's yeast

Izvleček

Phenolic compounds are among of the most important flavor and aroma molecules in beer, where their concentration ranges from 500 to 1000 mg/L, and is made of several different phenol groups. 70-80% of phenolic compounds are derived from malt and 20-30% are derived from hops. During the process of fermentation they are susceptible to biotransformation. Among the brewing yeast the enzymatic transformation of volatile phenols is researched more into detail. It mainly refers to the transformation of hydroxycinnamic acids, e.g. transformation of ferulic and p-cumaric acid, to 4-vinylguaiacol and 4-vinylphenol. Transformation is catalysed by ferulic acid decarboxylase (FDC1) and phenylacrylic acid decarboxylase (PAD1). Besides hydroxycinnamic acids, other phenolic compoudns like simple phenols, benzoic acid derivatives, coumarins, proanthocyanidins, chalcones and flavonoids, can be found in beer. Some of those are present in relatively high concentrations, e.g. tyrosol, p-hydroxybenzoic acid, vanillic acid, vanillin, catechin and epicatechin, dimeres of proantocianidin and isoxanthohumol. The goal of this thesis is to understand the proces of beer fermentation, beer composition, the evolution and evolutionary differences between different yeast strains, their role in metabolism of phenolic compounds and also get to know the techniques that help us improve the industrial yeast strains.

• Ključne besede: Saccharomyces cerevisiae, beer brewing, phenols, metabolism, evolution