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Composition of tomatoes and tomato products in antioxidants (WG1) page 81
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significant losses of xanthophylls (37% for lutein) but not carotenes (Khachick et al. 1986,
Scott 1992). Granado et al. (1992) reported that these losses could be partially corrected if the
sample was quantified on the basis of a calibration curve, which was also subjected to a
process of saponification. Similarly, tocopherol from biological tissues and tocol (internal
standard) were shown to be largely degraded during saponification (Sommerburg et al. 1997).
However, when mild conditions of saponification were used, no marked losses of lutein levels
from brocoli were observed (Heinonen et al. 1989). Recently, an enzymatic digestion
alternative was proposed (Lietz and Henry 1997, Sommerburg et al. 1997). Hence, plasma
samples were saponified by ethanolic KOH (30%) at 60°C for 30 min or were incubated with
lipase and cholesterol esterase at room temperature in the dark for 1h. Without saponification
or lipid digestion, lutein and α-tocopherol were well extracted whereas lycopene, β-carotene
and γ-tocopherol were only moderately extracted by hexane. The enzymatic digestion of
lipids resulted in higher recoveries for all analytes than the KOH saponification (Table 28).
Because tocol and BHT were degraded during the chemical hydrolysis, the enzyme digestion
was preferred.
Table 28. Effect of saponification and lipolysis enzymes on the recovery of plasma
vitamin E and carotenoids.
Direct KOH Enzymes
n=5 n=6 n=6
Lycopene 80.7+ 0.3 91.7+ 10.8 96.7+ 4.2
β- Carotene 66.1+ 1.8 92.7+ 3.9 99.1+ 4.5
α- Tocopherol 99.9+ 0.9 96.4+ 7.1 104.7+ 4.2
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(Adapted from Sommerburg et al. 1997)