Electron Paramagnetic Resonance Studies Comparing Wort Boiling Temperatures and Various Levels of Sulfur Dioxide in Packaged Beer
MBAA TQ vol. 42, no. 3, 2005, pp. 209-213 |
VIEW ARTICLE
Robert T. Foster II, Eric Johann Samp, Cecil E. Giarratano, Stephen Fletcher,
Michael Miller, and Warren Quilliam. Coors Brewing Company, B.C. 600, Golden,
Colorado, 80401, U.S.A.
Abstract
In brewing applications of the new technology, namely, electron paramagnetic
resonance (EPR), initial investigations have shown promise in wort boiling
studies and packaged beer samples with various sulfur dioxide (SO(2)) levels. In
the wort boiling study of this report, pilot-scale brews were boiled at 95.5,
100.5, and 104.7�C, while wort samples were taken hot every 20 min, cooled, and
frozen for future EPR analyses. EPR profiles showed that high-pressure
(temperature) boiling abused (scorched) the wort and predicted a reduction in
potential flavor stability of the beer with regard to the wort EPR signal
intensity at a constant time of 150 min (T150 values). Several packaged beers
ranging from 2.1 to 10.8 ppm of SO(2) showed a positive trend with EPR lagtime
minutes. In looking at the onset of stale flavors for these beers, we noticed
that, from a sensory perspective, these beers tasted stale at different EPR
lagtimes. Therefore, in order to match the sensory stale score with the EPR
lagtime score with high and low levels of SO(2) in fresh beer, we developed a
predicted staling resistance rating based on sensory validation.
Keywords: electron paramagnetic resonance, EPR, flavor stability,
lagtime, sulfur dioxide, T150
This online article contains color figures.
S�ntesis
De las aplicaciones de la resonancia paramagn�tica de electrones (EPR) en la
industria cervecera, pareciera ser de utilidad en estudios sobre el hervor del
mosto y en estudios de cerveza envasada con diferentes contenidos de di�xido de
azufre (SO(2)). En el estudio sobre el hervor del mosto, mostos de planta piloto
fueron hervidos a 95.5, 100.5 y 104.7�C, extrayendo muestras del mosto caliente
a cada 20 min, enfriadas y congeladas para futuro an�lisis por EPR. Los
perfiles de EPR mostraron que el hervor a alta presi�n y temperatura abusaba
(abrasaba) el mosto, pronosticando que estos mostos dar�an cervezas con menor
estabilidad sensorial con respecto a la intensidad de la se�al EPR de un mosto
a un tiempo constante de 150 min (valor T150). Muestras de cerveza envasadas con
un contenido de SO(2) variando entre 2.1 y 10.8 ppm, mostraron una tendencia
positiva con los minutos de EPR en rezago. Notamos que la apreciaci�n sensorial
de un sabor/aroma a cerveza vieja comenz� a diferentes tiempos de rezago EPR. A
ra�z de esto, desarrollamos una clasificaci�n de resistencia pronosticada al
envejecimiento seg�n el valor de rezago EPR, correlacionado con la validaci�n
sensorial, para as� poder comparar la valoraci�n sensorial de cervezas con
alto y bajo contenido de SO(2).
Palabras claves: resonancia paramagn�tica de electrones, EPR,
estabilidad sensorial, tiempo de rezago, di�xido de azufre, T150
