3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P47 GENOTyPE VARIAbILITy OF FATTy ACIDS
IN CEREAL GRAINS
DALIBOR JEŠKO a and MILAn ČERTíK b
a Slovak Agricultural Research Centre – Research Institute
of Plant Production Piešťany, Bratislavská 122, 921 68
Piešťany, Slovak Republic,
b Department of Biochemical Technology, Faculty of Chemical
and Food Technology, Slovak University of Technology,
Radlinského 9, 812 37 Bratislava, Slovak Republic,
jeskod@vurv.sk
Introduction
Cereals are important part of human and animal nutrition.
From the view of lipids, cereal grains are quite low in
fats (averaging 3.6 %) that consist of mainly palmitic, oleic
and linoleic acids. Oat (Avena spp) includes many species
of which Avena sativa L is the most commonly cultivated 1 .
It is mainly grown for feed use, but due to its high nutritional
value, much interest is now focused on expanding its food
applications. Among cereal grains, oat has the best protein
quality and quantity and is a valuable source of minerals and
vitamins, especially thiamine and pantothenic acid 2 . Moreover,
the lipid content of oat is high with very good balance
between polyunsaturated and saturated fatty acids 3,4 and,
therefore it is important crop from the nutritional point of
view 5 . Significant levels of other lipid compounds, such as
phospholipids, glycolipids, and phytosterols, may also find
application in various pharmaceutical, medical, food, and
industrial fields.
Buckwheat is annual melliferous crop. For many years
cultivation of buckwheat declined, but recent interest in old,
traditional foods have led to resurgence in its cultivation.
Buckwheat belongs to pseudo-cereals together with amaranth
and millet. These grains have been important food crops in
various parts of the world and have potential for much greater
and more widespread use 6 .
Because lipids are essential compounds of cereal grains,
this study was focused on genotype variability of fatty acid
composition in following cereal grains: oat, millet, amaranth
and buckwheat. The research in this field could significantly
help in cereal classification.
Experimental
Oil content and fatty acid composition in following
cereal grains have been determined in this study: oat (85 varieties),
millet (29 varieties), amaranth (20 varieties) and buckwheat
(10 varieties).
Total lipids were extracted from oat grains 2-times by
100 ml chloroform/methanol (2 : 1, v/v) for 60 min at laboratory
temperature with occasional stirring. After extraction the
mixture was filtered and 0.97% KCl (1.2-fold of total extract
volume) was added. The mixture was stirred vigorously for
1 min and centrifuged (5 min, 3,000 g) to effect phase separation.
The chloroform – lipid containing layer was filtered
through anhydrous na 2 SO 4 and evaporated under vacuum 7 .
s675
Table I
Average amounts (AV), standard deviation (SD) and variation
coefficient (VC) of lipid content and fatty acids in studied
cereal grains
Cereals
(number)
Lipids Fatty acids [%]
[%] C16 : 0 C18 : 0 C18 : 1 C18 : 2 C18 : 3
Oat
(79)
AV 4.5
SD 1.2
VK 26.9
16.0
0.8
4.9
1.7
0.4
22.2
37.8
2.5
6.6
38.5
2.2
5.6
1.6
0.4
21.9
Millet
(29)
AV 3.8
SD 0.57
VK 14.9
7.5 1.9 21.3 63.6 1.2
0.35 0.63 1.83 2.65 0.25
4.6 33.5 8.6 4.2 20.7
AV 2.3 13.3
Buckwheat
SD 0.54 0.52
(10)
VK 23.5 3.9
2.1 36.3 35.2
0.07 0.97 0.53
3.4 2.7 1.5
1.9
0.07
3.5
AV 5.2 17.1 2.7 23.6 43.0 0.7
Amaranth
SD 0.79 2.50 0.29 4.34 6.34 0.11
(10)
VK 15.1 14.6 10.8 18.4 14.8 15.3
Fatty acids of total lipids were analyzed as their methyl
esters by gas chromatography (GC-6890 n, Agilent Technologies)
using a capillary column DB-23 (60 m × 0.25 mm,
film thickness 0.25 μm, Agilent Technologies) and a FID detector
(constant flow, hydrogen 35 ml min –1 , air 350 ml min –
1 , 250 °C) under a temperature gradient (130 °C for 1 min;
130–170 °C at program rate 6.5 °C min –1 ; 170–215 °C at
program rate 2.7 °C min –1 ; 215 °C for 7 min; 220–240 °C at
program rate 2 °C min –1 ) with hydrogen as carrier gas (flow
2.1 ml min –1 , velocity 49 cm s –1 , pressure 174 kPa) and a
split ratio of 1/50 (Inlets: heater 230 °C, total hydrogen flow
114 ml min –1 , pressure 174 kPa) 8 . The fatty acid methylester
peaks were identified by authentic standards of C 4 –C 24 fatty
acid methylesters mixture (Supelco, USA) and evaluated
by ChemStation 10.1 (Agilent Technologies). The variation
coefficient (VC) of individual fatty acids was calculated
from the equation: VC = (δ n-1 /average value of selected fatty
acid) × 100, where δ n-1 is a decisive deviation.
Results
C18:2c-n6 [%]
70
65
60
15 20 25
C18:1c-n9 [%]
Fig. 1. Relationship between oleic and linoleic acid in millet
lipids