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Cholesterol and long chain fatty acids such as DHA are prone to oxidation during heating or cooking. Chemical products formed due to their oxidation may be causes of deterioration of the food flavor and quality. But more importantly, when the the oxidation products are ingested in high quantity, they can cause health problems including heart disease.
Researchers at the Louisiana State University (USA) and Catholic University of Daegu (Korea) investigated the role of sweet bell peppers in reducing oxidation of cholesterol and omega 3 fatty acid DHA during heating and cooking.
The researchers evaluated antioxidant activity, free-radical scavenging capability, in four sweet bell pepper types (green, yellow, orange and red) and compared the extent of cholesterol and DHA oxidation treated with extracts from the four different sweet bell peppers.
They reported that yellow, orange and red sweet bell peppers had significantly higher antioxidant activity compared to the green colored one. There was no statistically significant difference in antioxidant activity (free radical scavenging capability) among the yellow, orange and red sweet peppers.
Table 1: Antioxidant activity in sweet bell peppers (as measured by their ability to scavenge the DPPH-free radical).
Sweet bell pepper type
|
Antioxidant activity (µmol TE/g fresh pepper) |
| Red |
3.9 ± 1.0 |
Orange
|
3.5 ± 0.5
|
| Yellow |
3.2 ± 0.5
|
| Green |
2.1 ± 0.6
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All sweet bell pepper types significantly reduced the oxidation of cholesterol and DHA during heating. With sweet bell pepper extract, only about 40% of the omega 3 fatty acid DHA and 50% of the cholesterol was oxidized, as compared to about 80% and 90% of the DHA and cholesterol, respectively, in the control. However, the peppers were not significantly different from each other in preventing cholesterol oxidation. The green pepper was however more potent in reducing free-radical damage (oxidation) to DHA during heating than the yellow and red pepper types.
Table 2: Percentage of DHA and cholesterol remaining unoxidized during cooking with or without sweet bell peppers.
Sweet bell pepper type
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Percentage of DHA remaining unoxidized
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Percentage of DHA remaining unoxidized
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| Red |
53.1 ± 8.4 |
84.4 ± 8.4
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| Orange |
56.6 ± 10.1
|
62.0 ± 12.1
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| Yellow |
48.5 ± 8.0
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66.1 ± 27.4
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| Green |
67.8 ± 8.9
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71.3 ± 12.0 |
Control
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9.0 ± 0.1
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19.0 ± 2.9
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According to the researchers, sweet bell peppers, due to their ability to prevent degradation of cholesterol and DHA and reduced production of their toxic and harmful byproducts during cooking, can help lower dietary risk factors for heart disease and cancer formation.
Source:
T. Sun, Z. Xu, C.-T. Wu, M. Janes, W. Prinyawiwatkul, and H. K. No. 2007. Antioxidant Activities of Different Colored Sweet bell Peppers (Capsicum annuum L.). Journal of Food Science 72(2): 98 - 102 .
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