3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
G C A n a l y s i s
GC conditions (for FAMEs): gas chromatograph SHI-
MADZU GC-17-A equipped with FID detector and capillary
column Alltech ATWAX (30 m × 0.25 mm × 0.25 µm)
with temperature programme 150 o C held for 5 min, ramp
4 o C min –1 up to 235 o C, held for 5 min. The flow rate of the
carrier gas helium was 1.8 ml min –1 (split ratio 1 : 20). The
injector and the FID temperature was 260 o C. The identification
of FAMEs was based on retention times and comparison
with those of standard FAMEs.
GC conditions (for derivatized sterols): GC-FID apparatus
was the same. An RTX-5 fused silica capillary column
(30 m × 0.25 mm × 0.25 µm) was used. The temperature programme
was: 200 o C held for 5 min, ramp 10 o C min –1 up to
300 o C (held 20 min); injector temperature 280 o C; detector
temperature 300 o C. The flow rate of the carrier gas helium
was 0.58 ml min –1 (split ratio 1 : 17). Identification of sterols
was based on comparison of their relative retention times
(RR t to β-sitosterol) with data from the literature 4, 5 . A mixture
of sterol standards was studied in the same conditions
and the retention times (R t ) were used to assist the peak identification.
The sterol concentrations were calculated using the
area of the internal standard peak.
All extractions and GC-FID runs were performed in triplicate.
The mean values and standard deviations were calculated.
Results
The fatty acid and sterol compositions reported in this
study are in good agreement with those reported in the literature.
3,4,6,7
Table I
Total sterol concentrations after direct saponification of the
oils (mg 100g –1 )
Sterols Walnut Sesame Peanut Poppyseed RRt
1.
1.01
± 0.12
n.d. n.d. n.d. 0.80
2. n.d. n.d. n.d. n.d. 0.83
3.
13.10
± 0.74
71.00
± 0.32
23.90
± 0.34
41.18
± 0.25
0.90
4.
0.60
± 0.07
1.11
± 0.11
1.53
± 0.06
4.09
± 0.11
0.91
5.
0.42
± 0.05
34.10
± 0.63
14.60
± 0.32
11.44
± 0.57
0.94
6.
147.00
± 1.03
345.00
± 0.66
114.00
± 0.86
187.40
± 0.56
1.00
7.
7.15
± 0.23
2.71
± 0.15
2.46
± 0.10
2.33
± 0.08
1.02
8.
28.00
± 0.94
50.70
± 0.50
15.30
± 0.49
23.29
± 0.70
1.03
Total
197.28
± 3.18
504.62
± 2.37
171.79
± 2.17
269.73
± 2.27
s620
Fig. 2. Free and esterified sterol concentrations in four edible
oils: (a) walnut, (b) sesame, (c) peanut and (d) poppysed oil
F a t t y A c i d C o m p o s i t i o n
Fig. 1. illustrates the fatty acids compositions of edible
oils used in this study. Three fatty acids were predominant in
the analyzed oils (TLE) and theirs subfractions (ESF): linoleic
acid (37.27–71.41 %), oleic (11.58–40.36 %) and palmitic
acid (6.54–24.62 %).The unsaturated fatty acids/saturated