Effect of beta-glucan and environmental factors on the physical and chemical properties of wort and beer.
Date
2002
Authors
Jin, Yulai.
Journal Title
Journal ISSN
Volume Title
Publisher
Dalhousie University
Abstract
Description
Behaviour of barley beta-(1 → 3)(1 → 4)-D-glucans in wort and beer was examined to investigate their effect on brewing process and beer quality. Beta-glucans at 0--1000 mg/L increased wort and beer viscosity linearly with MW and concentration. The Arrhenius relationship governed the effect of temperature on wort viscosity. Beta-glucan viscosity in wort was lowered after shearing although shearing increased the apparent wort viscosity (p < 0.001). Shearing decreased beer viscosity (p < 0.001) but did not affect the beta-glucan viscosity in beer (p > 0.05). Shearing temperature did not affect the viscosities of wort or beer (p > 0.05). Increasing pH raised wort viscosity (p < 0.001) but did not affect beer viscosity (p > 0.05). Maltose in wort and ethanol in beer enhanced the viscosity of beta-glucan polymers (p < 0.001). Beta-glucan-caused viscosity was found to be an indicator of potential technical problems. Beta-glucans had higher intrinsic viscosities (5°C) in beer than in wort (p < 0.001). The critical overlap concentration (C*) for beta-glucans (31--443 kDa) in beer and wort was found to vary in the range of 1.3--8.3 g/L.
Apparent particle size of beta-glucans in wort and beer increased with their MW and concentration (p < 0.001). Beta-glucans had greater particle size in beer (mainly 0.01--0.1 mum in diameter) than in wort (even distributed in <0.01 mum and >0.01 mum fractions) (p < 0.001). Beta-glucan particles were larger at higher pHs of wort and beer (p < 0.001). Maltose did not affect the beta-glucan particle size distributions in wort (p > 0.05). High ethanol concentrations increased the 0.01--0.1 mum fraction and decreased the >0.1 mum fraction of the 443 kDa beta-glucan in beer (p < 0.001). Shearing of wort and beer resulted in a decrease in the <0.01 mum fraction of beta-glucans and an increase in 0.01--0.1 mum beta-glucan fraction (p < 0.001) but shearing temperature did not affect the particle size distribution (p > 0.05).
Wort and beer turbidity increased with higher MWs and concentrations of beta-glucans (p < 0.001), shearing (p < 0.001), lower maltose and ethanol levels and lower pHs (p < 0.001). Shearing (20--76°C) at high temperatures resulted in lower wort turbidity values than low temperatures (p < 0.001) but shearing temperature (0--10°C) did not affect beer turbidity (p > 0.05). (Abstract shortened by UMI.)
Thesis (Ph.D.)--DalTech - Dalhousie University (Canada), 2002.
Apparent particle size of beta-glucans in wort and beer increased with their MW and concentration (p < 0.001). Beta-glucans had greater particle size in beer (mainly 0.01--0.1 mum in diameter) than in wort (even distributed in <0.01 mum and >0.01 mum fractions) (p < 0.001). Beta-glucan particles were larger at higher pHs of wort and beer (p < 0.001). Maltose did not affect the beta-glucan particle size distributions in wort (p > 0.05). High ethanol concentrations increased the 0.01--0.1 mum fraction and decreased the >0.1 mum fraction of the 443 kDa beta-glucan in beer (p < 0.001). Shearing of wort and beer resulted in a decrease in the <0.01 mum fraction of beta-glucans and an increase in 0.01--0.1 mum beta-glucan fraction (p < 0.001) but shearing temperature did not affect the particle size distribution (p > 0.05).
Wort and beer turbidity increased with higher MWs and concentrations of beta-glucans (p < 0.001), shearing (p < 0.001), lower maltose and ethanol levels and lower pHs (p < 0.001). Shearing (20--76°C) at high temperatures resulted in lower wort turbidity values than low temperatures (p < 0.001) but shearing temperature (0--10°C) did not affect beer turbidity (p > 0.05). (Abstract shortened by UMI.)
Thesis (Ph.D.)--DalTech - Dalhousie University (Canada), 2002.
Keywords
Agriculture, Food Science and Technology.