3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P36 (1→3)(1→4)-β-D-GLuCAN: VARIABILITY AND
FACTORS AFFECTING ITS CONTENT IN OAT
GRAIN
MICHAELA HAVRLEnTOVá, MILAn ČERTíK and Ján
KRAIC
Agricultural Biotechnologies Department, Slovak Agricultural
Research Center – Research Institute of Plant Production
Piešťany, Bratislavská cesta 122, 921 68 Piešťany, Slovak
Republic,
havrlentova@vurv.sk
Introduction
β-D-glucan is major polysaccharide constituent of cell
walls in the Poales, an order that includes cereals as well as
other grass species. It is a linear and partially water-soluble
polysaccharide that consists only of glucose linked through
both β-(1→3)- and β-(1→4)-glykosidic linkages in various
ratios. β-D-glucan plays an important role in cell wall architecture
and plant development 1 . It has a positive impact on
human health in terms of lowering cholesterol and blood glucose
levels 2 , increasing immunity against infection and positive
influencing of bowel function 3 .
Heritability estimates for β-D-glucan content have ranged
from 0.27 to 0.58(ref. 4 ). β-D-glucan content is affected
by environmental factors. Genotype and the environment are
significant sources of variation for its content; the ranking of
genotypes is generally consistent over the environments 5 .
Experimental
Mature grains of 99 oat genotypes were milled and
passed through 0.5 mm sieve. The level of β-D-glucan was
determined using Mixed-linkage Beta-glucan assay procedure,
Megazyme (Ireland) 6 . Samples were suspended and
dissolved in a 0.02M sodium phosphate buffer (pH 6.5),
incubated with purified lichenase enzyme, and an aliquot of
filtrate was reacted with purified β-glucosidase enzyme. The
glucose product was assayed using an oxidase/peroxidase
reagent. The measurement of the amount of β-D-glucan was
performed in three parallel assays and expressed on a dry
weight basis.
Results and Discussion
The β-D-glucan content ranged from 1.73 to 5.70 %,
with 3.44 % as a mean value. The result is consistent with
the determined values of β-D-glucan content in the set of
European oat genotypes (3.90 %, 3.64 %, respectively) 7,8 .
Our results show, likewise the literature 8 , that naked genotypes
dispose of higher levels of this metabolite (4.38 %
on average) in comparison with the hulled oat, where the
mean content was 3.26 % (Table I). The majority (90 %) of
naked genotypes contain higher level of β-D-glucan than is
the average in analysed oat set. The increased value of β-
D-glucan is connected with the presence of gene nud for a
hulless type of grain 9 . naked oats are the feed that provide
the largest welfare benefits 10 and their demand as a food
crop is on a world-wide scale increasing 11 . Genotypes Terra,
s649
Avenuda, SV-5, Arnold, neon, Izak, Salomon, Saul, Bandicoot,
and ábel with the highest level (> 4.00 %) observed can
be therefore used as a convenient material in breeding and
food industry.
In our work a relation between the oat glume colour (yellow,
white, black) and the content of β-D-glucan was found.
Our results indicate that the black genotypes show the lowest
standard deviations in the content of evaluated metabolite.
The degree variance of β-D-glucan level expressed as a coefficient
of variation displayed the highest value in white hulled
oat, next in yellow, and the lowest values were calculated
for the genotypes with black glume colour (Table I). Because
higher value of variation coefficient directly correlates with
lower variance of metabolite biosynthesis within a set, we
could state, that black hulled oat with low variation coefficient
are characterized by markedly stable biosynthesis of
β-D-glucan in the comparison with yellow and white types.
Similarly, biosynthesis of other biochemical parameters (proteins,
fatty acids, and lipids) also shows to by more stabile in
black hulled oat 12 .
Analysis of variance suggested that oat morphological
and biochemical parameters depend on the environment and
the genotype variously 13,14 . Test weight, groat percentage and
weight, protein, and β-D-glucan content were about equally
influenced by the environment and genotype 13 , whereas oat
lipids, total starch, and amylose content were more strongly
influenced by genotype.
The content of monitored parameter according to the
year of genotype registration is documented on the Fig. 1.
The mean value of β-D-glucan in oats with the breeding date
before the year 1960 was 2.53 %, moreover a stabilisation
was observed during the period of years 1961–2000. At the
beginning of the 21 st century a gradually raising of β-Dglucan
content in oat seeds was detected.
Table I
Mean values of the β-D-glucan content in naked and hulled
oat and in individual groups according to the glume colour
Group of Mean value Standard Variation
oat [%] deviation coefficient
naked 4.38 *** 0.96 22.03
Hulled 3.26 0.60 18.34
Yellow 3.28 0.62 18.97
White 3.46 0.71 20.55
Black 3.31 0.46 13.89 ***
*** significant at P ≤ 0.001
Conclusions
naked genotypes dispose of higher β-D-glucan content
in comparison with the hulled. Genotypes Terra, Avenuda,
SV-5, Arnold, neon, Izak, Salomon, Saul, Bandicoot, and
ábel with the highest level of monitored health beneficial
polysaccharide can be used in breeding programs and seed
processing in food industry as its donors. Genotypes with
black colour of the glumes account significantly lower stan-