Graz University of Technology Austria Institute of Biochemistry ...

Trilinolein
263
288
O
O
O
O
O
O
599
896
901
1-Oleoyl-2-linoleoyl-3-linoleoyl glycerol
288
O
O
O
O
O
O
599
601
O
O
O
O
O
898
+
881
O
872
+
903
Triolein
263
O
O
O
O
O
O
1-Oleoyl-2-oleoyl-3-stearoyl glycerol
+
883
+
O
O
O
O
O
O
Stability of triacylglycerols decreases with the increased formation of the oxidation products
of β-carotene.
100
1-Oleoyl-2-linoleoyl-3-oleoyl glycerol
[ M + Na]
+
905
603
[ M + ] + NH4
100 OO +
902
80
80
Intensity
60
OL +
601
[ M + NH4]
+
900
Intensity
60
[ M + Na]
+
907
40
20
288
263
0
200 300 400 500 600 700 800 900
m/z
OO +
603
[ M-O +H+ Li]
+
874
+ [ M + H]
883
40
20
[ M + H]
0
200 300 400 500 600 700 800 900
m/z
[ M- O+ H + Li]
876
100
+ [ M + Na]
100
+ [ M + Na]
100
[ M + NH4 ] +
909
[ M + Na]
+
904
80
Intensity
80
60
40
20
[ M + NH 4]
+
+ [ M + H]
879
0
200 300 400 500 600 700 800 900
m/z
LL +
Intensity
80
60
40
20
LL +
[ M + NH4]
+
[ M-O+ Li]
H+
[ M + H]
0
200 300 400 500 600 700 800 900
m/z
OL +
Intensity
60
OO +
603
887
40
20
288 [ M + H
+
]
0
200 300 400 500 600 700 800 900
OS +
605
DAGs
HPLC-MS
0 5 10 15 20 25 30
Time (min)
Figure 1. Separation and Identification of Triacylglycerols using HPLC-ESI-MS.
Doctoral Thesis completed
Alam Zeb: Carotenoids and Triacylglycerols Interactions during Oxidation
Carotenoids (β-carotene and astaxanthin) were oxidized in high oleic model triacylglycerols
(TAGs) and edible oils such as corn and olive oils. The main techniques used in this
dissertation were HPTLC and HPLC coupled to DAD and mass spectrometry. The previous
literature on the uses of TLC suggests that HPTLC have the potential to be the first choice in
the analysis of carotenoids in foods. We also found that HPTLC is a useful tool in the study of
degradation of β-carotene in model TAGs and edible oils. The isocratic HPLC-ESI-MS
method was very useful for the fast screening and identification of TAGs in edible oils. We
correctly identify and separated thirteen, fourteen, fifteen and sixteen TAGs in refined olive
oil, rapeseed oil, corn oil and sunflower oil, respectively. The oxidation products of TAGs
were also studied using this method. Epoxy epidioxides, hydroxy bis-hydroperoxides and
epidioxy bishydroperoxides were identified as major oxidized compounds that have been
identified for the first time in model TAGs and edible oils under similar conditions. Other
triacylglycerols oxidized species were hydroxy hydroperoxides, mono-hydroperoxides, bishydroperoxides,
epoxy-epidioxides, and epoxides. Significant degradation of β-carotene was
observed in sunflower oil. In high oleic model TAGs, β-carotene degraded significantly in the
first three hours, however, in olive oil of relatively similar TAG composition, β-carotene
degraded slowly. Astaxanthin degradation was much slower than β-carotene in olive oil. The
HPLC method for the degradation and oxidation of carotenoids reveal a total of eight oxidized
compounds of β-carotene in corn oil. The degradation of all-E-β-carotene in corn oil was
relatively similar to model TAGs and olive oil. The interactions of carotenoids and TAGs
reveal the pro-oxidant action of both β-carotene and astaxanthin. The pro-oxidant action of β-
carotene was much stronger than astaxanthin. These findings help us to understand the
34