Utjecaj kvasaca na kvalitetu žitnog destilata

master's thesis

• Title (english): Effect of yeast on cereal spirit quality
• Author: Ivan Počepan
• Mentor: Marin Mihaljević Žulj (mentor)
• Committee member: Marin Mihaljević Žulj (predsjednik povjerenstva)
• Committee member: Nenad Jalšenjak (član povjerenstva)
• Committee member: Sanja Sikora (član povjerenstva)
• Committee member: Marko Viskić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Agriculture; (Viticulture and Enology); Zagreb
• Defense date and country: 2019-09-26, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Agronomy

Abstract

Izbor kvasca za proizvodnju žitnog destilata može uvelike utjecati na prinos etanola i konačnu kvalitetu proizvoda, a činjenica kako vrsta i soj kvasca nije propisan regulativama ostavlja prostor za mnoga istraživanja u ovom području. Cilj rada je ispitati utjecaj dvaju sojeva kvasaca različitih namjena na kvalitetu destilata dobivenog dvostrukom destilacijom fermentirane sladovine na jednostavnom destilacijskom uređaju. Prvi korišteni kvasac (A, Saccharomyces cerevisiae) komercijalnog je naziva FERMOALE AY4 američke proizvodnje. Drugi kvasac (B) je soja Saccharomyces cerevisiae (ex. bayanus) pod imenom EC-1118 proizvođača Lalvin. Kemijskom analizom utvrđeno je kako kvasac A očekivano ima bolji prinos u etanolu (3 % više etanola), nižu titracijsku kiselost, dok su koncentracije etil acetata bile malo više u uzorku kvasca B. Na plinskom kromatografu SRI 8610C utvrđene su povišene koncentracije acetaldehida, uzorak A imao je 274 mg/L a.a., a uzorak B 356 mg/L a.a. Nadalje, koncentracije viših alkohola u oba su uzorka bile povišene. Uzorak A imao je 2161 mg/L a.a, dok uzorak B, sa 3571 mg/L a.a. ukupnih viših alkohola, već ulazi u kategoriju destilata niže kvalitete. Uzorak B bio je bogatiji etil acetatom, dok je uzorak A imao više koncentracije ostalih estera što je rezultiralo kompleksnijom aromom i punijim okusom destilata A. Interesantno bi bilo ispitati utjecaj ovih kvasaca u uvjetima fermentacije prilagođenim onima u destileriji; brza fermentacija u uvjetima visoke temperature u mediju visoke specifične težine.

Abstract (english)

The choice of yeast for cereal spirit production can greatly affect ethanol yield, as well as final product quality. In addition, the fact that yeast type and variety aren’t regulated, leaves great room for research in this field. The aim of this study was to evaluate the effect of two different yeast types on the quality of spirit produced by double distilling a fermented cereal wash on a simple still. The first used yeast (A, Saccharomyces cerevisiae) is called FERMOALE AY4 and is produced in USA. The other yeast (B) Saccharomyces cerevisiae (ex. bayanus) is called EC1118 and is made by Lalvin. Chemical analysis proved that yeast A, as expected, has a better ethanol yield (3 % more ethanol), lower titratable acidity, while ethyl acetate concentrations were slightly higher in sample B. Gas chromatography on chromatograph SRI 8610C identified higher acetaldehyde concentrations, sample A had 274 mg/L a.a. and sample B had 356 mg/L a.a.. Furthermore, larger amounts of higher alcohols were produced in both samples, sample A had 2161 mg/L a.a. while sample B, with 3571 mg/L a.a. total higher alcohols, enters the lesser quality spirit rank. While sample B was richer with ethyl acetate, sample A had higher concentrations of other esters which made sample A a distillate with more complex aroma and fuller flavour. Future experiments could yield interesting results if the fermentation conditions would match those in a distillery; rapid, high temperature fermentation in high gravity medium.

• Keywords: žitni destilat; kvasac; hlapivi spojevi; kromatografija; esteri; viši alkoholi
• Keywords (english): cereal spirit; yeast; flavour congeners; chromatography; ester; higher alcohols
• Language: croatian
• URN:NBN: urn:nbn:hr:204:538357
• Study programme: Title: Horticulture; Study programme type: university; Study level: graduate; Academic / professional title: magistar/ magistra inženjer/inženjerka hortikulture (magistar/ magistra inženjer/inženjerka hortikulture)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-12-02 09:21:21