Reducing diacetyl content in lager rice beer by high valine supplementation

Name: Sreymom Tith

LCSH: Kasetsart University -- Theses. M.S. (Food Science) 2019

Classification :.LCCS: TP577

LCSH: Kasetsart University. -- Department of Food Science and Technology -- Theses

LCSH: Lager beer

LCSH: Rice beer

LCSH: Diacetyl

LCSH: Valine

Abstract: The wort composition is important for yeast growth and determines beer quality; furthermore, valine is an essential amino acid known to reduce diacetyl, undesirable flavor compound giving buttery character in lager beer. Thus, supplementation with synthetic valine (SV), defatted soybean meal (DSB) and defatted sunflower meal (DSF) was used to minimize diacetyl in 30% rice grit lager beer fermented with the isolated yeast, Saccharomyces cerevisiae LPST01. The results of wort analysis showed that SV wort contained 463.20 mg/L of valine higher than those found in DSBW, DSFW, and control (CW) as 113.90 mg/L, 109.00 mg/L, and 115.70 mg/L valine respectively. Whereas after fermentation at 10o C for 13 days, SV supplementation could reduce diacetyl content in green beer to 0.72 mg/L that was significantly lower than that found in CW (1.96 mg/L), DSBW (2.09 mg/L) and DSFW (2.22 mg/L). Thus, supplementation of valine resulted in a significantly lower diacetyl content in the green beer. Furthermore, poor diacetyl reduction ability with natural defatted protein supplementations (DSB and DSF) in sweet wort was due to low valine and free amino nitrogen (FAN) liberated from the hard structure of DSB and DSF during mashing step. To achieve sufficient valine content in wort of DSB supplementation, adding commercial protease enzyme (Neutrase® ) was conducted since the mashing process using RSM with CCD design. Fifteenth treatments resulted high valine and FAN content, but the highest was in 10 g of DSB and 32 mL Neutrase® per kilogram of rice grit. Whereas, the predicted model and actual values were no significantly difference. After fermentation at 10o C for 8 days, wort DSB with enzyme (DSBNW) reduced diacetyl content in green beer to 0.51 mg/L that was significantly (p< 0.05) lower than the control (0.71 mg/L). Thus, the optimum condition from RSM could provide high valine and FAN content in wort, resulted in a significantly lower diacetyl content in the beer product. Finally, this research can prove that valine supplementation in beer brewing could directly impact on diacetyl reduction during fermentation without any impact on fermentation performance, reduced maturation time, and provided good flavor profile to beer production as well, especially the natural valine supplementation (DSB).

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Siree Chaiseri

Role: Thesis Advisor

Name: Yaowapa Lorjaroenphon

Role: Thesis CO-Advisor

Name: Ulaiwan Withayagiat

Role: Thesis CO-Advisor

Created: 2019

Modified: 2025-07-04

Issued: 2025-07-04

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2562/sreymom-tit-all.pdf

CallNumber: TP577 .S64

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Food Science

Grantor: Kasetsart University

©copyrights Kasetsart University

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