Kvantificiranje fiziološke aktivnosti i flokulacijske sposobnosti kvasca Saccharomyces uvarum

master's thesis

• Title (english): Quantification of physiologycal activity and flocculation ability of yeast Saccharomyces uvarum
• Author: Lucija Kusalić
• Mentor: Sunčica Beluhan (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for Biochemical Engineering, Industrial Microbiology and Malting and Brewing Technology); Zagreb
• Defense date and country: 2011-07-09, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Kvantificiranje fiziološke aktivnosti i flokulacijske sposobnosti pivskog kvasca Saccharomyces uvarum pri točno definiranim uvjetima može pomoći boljem spoznavanju fizikalnih mehanizama procesa flokulacije koja se primjenjuje u pivarstvu. Nakon odgorčavanja kvasca s Tweenom 80 (20 % v/v), smanjena je gorčina kvasca za 87 % bez negativnih učinaka na životnost kvasca ili udjel proteina. Fiizološka aktivnost odgorčenog kvasca bila je vrlo zadovoljavajuća, što je potvrđeno određivanjima broja mrtvih stanica, te udjela glikogena i volutina. Flokulacijaska sposobnost je kvantificirana mjerenjem veličine flokula i brojem pojedinačnih stanica. U radu su proučavane metode taloženja, odnosno flokulacije pivskog kvasca S. uvarum, putem Helmovog i Stratfordovog testa. Kod obje je metode proučavan utjecaj početne koncentracije stanica (inokuluma), miješanje, uzorkovanje i određivanje postotka istaloženih stanica. Rezultati dobiveni Helmovim testom nisu se razlikovali značajno od onih dobivenih sa Stratfordovim testom. Prikazani rezultati jasno su pokazali da su obje metode pouzdane za kvantificiranje sposobnosti flokulacije pivskog kvasca S. uvarum.

Abstract (english)

Quantification of brewer’s yeast Saccharomyces uvarum physiological activity and flocculation ability under defined conditions will help to understand the physical mechanisms of the flocculation process used in beer production.After yeast debittering with Tween 80 (20 % (v/v) a bitterness reduction of 87 % was obtained without affecting yeast viability or protein content. Physiological activity of debittered yeast seems to be quite satisfactory, according to microbiological viability determinations (dead cells, glycogen and volutine content). Flocculation was quantified by measuring the size of yeast flocs and the number of single cells. The sedimentation/flocculation methods of brewer’s yeast S. uvarum based on Helm’s and Stratford’s tests were investigated. In both methods, all steps were optimised: initial cell concentration, agitation, sampling and determination of settled cells. The results obtained with the Helm’s test do not differ significantly from those obtained with Stratford’s test. The results presented clearly demonstrated that the both methods are rigorous for quantification of brewer’s yeast S. uvarum flocculation.

• Keywords: flokulacija; kvantifikacija; pivski kvasac; Saccharomyces uvarum; taloženje
• Keywords (english): flocculation; brewer’s yeast; quantification; Saccharomyces uvarum; sedimentation
• Language: croatian
• URN:NBN: urn:nbn:hr:159:122397
• Study programme: Title: Bioprocess Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva (magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2017-05-30 11:10:57