Analytical Session
Liisa P Otama, Thermo Fisher Scientific, Vantaa, Finland
Co-author(s): Liisa Otama, Sari Hartikainen, and Annu Suoniemi-Kahara, Thermo Fisher Scientific, Vantaa, Finland
ABSTRACT: In the beer malting and brewing process, one
important analyte is beta-glucan. Beta-glucans are polysaccharides of
D-glucose monomers linked by beta-glycosidic bonds. Beta-glucans are
present in the cell walls of cereals and are capable of clogging process
filters. Excessive amounts of beta-glucan may cause haze in the end
product and impair the taste of beer. For these reasons it is important
to determine the concentration of beta-glucan, in particular the part of
the beta-glucan polymer that has a molecular mass of about 10,000 Da or
more. The aim of this study was to provide a robust automated
photometric analysis method that is suitable for liquid samples derived
from processing of cereals. A rapid two reagent method was developed for
automated discrete analyzers. The method is easily adapted to a manual
spectrophotometer as well. The use of blank buffer eliminates sample
color interference. In preliminary testing of beer and wort samples,
this method correlates well with the results obtained by a fluorometric
method using Calcofluor fluorescence dye. The Calcofluor method is
recommended by the European Brewery Convention in EBC Methods 8.13.2,
4.16.2, and 3.10.2 and by the American Society of Brewing Chemists in
ASBC Method Wort-18. Thus, this study presents an alternative rapid
method especially suitable for routine use. A method performance study
was done by Thermo Scientific Gallery and Arena discrete analyzers at
wavelength of 405 nm. Method linearity was determined between 15 and 500
mg/L with aqueous beta-glucan standard solutions. Beer and wort samples
tested showed excellent repeatability and reproducibility, with typical
variation being 2% or less. Total analysis time for 9 samples with 10
replicates (total 90 results) was less than 40 min. As an improvement on
the existing fluorometric method, the open on-board stability of these
novel non-hazardous reagents was tested to be at least 30 days.
Sari
Tikanoja received a Ph.D. degree in biochemistry from Kuopio
University, Finland, in 1991. She started her professional career in
clinical laboratories and has a diploma of hospital laboratory
management. In 1989, she became R&D director in Medix Biochemica, a
Finnish company producing monoclonal antibodies and products thereof. In
2007 she joined Thermo Fisher Scientific Finland, a provider of
automated analytical instruments and systems for clinical,
environmental, and industrial markets. She started as a senior manager
and in 2009 became R&D director, diagnostics.
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