VIEW ARTICLE DOI: 10.1094/ASBCJ-54-0216
Arabinoxylan Composition in Barley, Malt, and Beer. Jee Yup Han (1) and P. B. Schwarz, Department of Cereal Science, North Dakota State University, Fargo, ND 58105. (1) Author to whom correspondence should be addressed. Present address: Department of Crop Science and Plant Ecology, University of Saskatchewan, Saskatoon, SK, S7N 5A8 Canada; 306/966-5008, Fax 306/966-5015. J. Am. Soc. Brew. Chem. 54(4):216-220. Accepted August 1, 1996.
Arabinoxylans
comprise 4-8%
of the barley
kernel and are
major constituents
of both aleurone
and endosperm
cell walls.
They are partially
water soluble,
high-molecular-weight
polymers that
contribute to
viscosity. Both
arabinoxylan
and beta-glucan
content of barley
were found to
be significantly
related to beer
viscosity. Therefore,
arabinoxylan
may be involved
in some of the
undesirable
effects normally
attributed to
the beta-glucans
in the brewing
process. A study
was made of
three malting
barley samples
to determine
the composition
of non-starch
polysaccharide
(NSP) fractions,
total and insoluble,
and to observe
the change in
their content
during both
commercial malting
and pilot-brewing.
The NSP fractions
were isolated
by a combination
of enzyme treatments
and fractional
precipitation
and then analyzed
by gas chromatography.
The NSP fractions
were significantly
(P < 0.05)
decreased during
malting and
brewing. Arabinose
and xylose,
at a ratio of
0.70-0.72, accounted
for 70% of total
NSP in pilot-brewed
beer. Thus highly
substituted
arabinoxylan
alone, or synergistically
with beta-glucan,
could result
in lautering
and/or filtering
problems during
brewing. Further
investigations
on the structural
characteristics
of arabinoxylan
in barley, malt,
and beer are
a priority.
Keywords: Arabinoxylan,
beta-Glucan,
Brewing, Filtration,
Lautering, Viscosity.
Los
arabinoxilanos
representan
el 4-8% del
grano de cebada
y son de los
principales
constituyentes
de las paredes
celulares de
la a leurona
y del endospermo.
Son polímeros
de alto peso
molecular, parcialmente
solubles en
agua, que contribuyen
a la viscosidad.
Se encontró
que el nivel
de arabinoxilanos
y beta-glucanos
en la cebada
está
muy relacionado
a la viscosidad
de la cerveza.
Por lo tanto,
los arabinoxilanos
pudieran estar
involucrados
en algunos efectos
indeseables
en el proceso
cervecero y
que normalmente
se atribuyen
a los beta-glucanos.
Se realizó
un estudio con
tres muestras
de cebadas malteras
para determiner
la composición
de las fracciones
de polisacarldo
no-almidón
(NSP), total
e insoluble,
y observar los
cambios en su
contenido durante
el malteo, a
nivel piloto
y a escala comercial.
Las fracciones
NSP se aislaron
con una combinacion
de tratamiento
enzimático
y precipitación
fraccionada
y luego analizadas
por cromatografía
de gases. Las
fracciones NSP
se redujeron
significativamente
(P < 0.05)
durante el malteo
y proceso cervecero.
La arabinosa
y la xilosa,
en una relación
de 0.70-0.72
representaron
el 70% del total
de NSP en la
cerveza elaborada
en la planta
piloto. Por
lo tanto, los
arabinoxilanos
sustituidos,
solos o en sinergía
con beta glucanos,
pueden causar
problemas durante
el filtrado
de mosto y/o
cerveza. Es
necesario seguir
investigando
las características
estructurales
de los arabinoxilanos
en cebada, malta,
y cerveza.