Rapid Electrochemical Method for the Evaluation of the Antioxidant Power of Some Lipophilic Food Extracts

• Published in: Journal of agricultural and food chemistry Vol. 49; no. 11; pp. 5136 - 5141
• Main Authors: Buratti, Susanna, Pellegrini, Nicoletta, Brenna, Oreste V, Mannino, Saverio
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.11.2001
• Subjects: Antioxidants - pharmacology; Biological and medical sciences; Chromatography, High Pressure Liquid - methods; Electrochemistry - methods; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; General pharmacology; Medical sciences; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Vegetables - chemistry; Chlorophyll; Vegetables; Capsaicin; Electrochemical method; Foodstuff; Antioxidant; Biological activity; Lipophilic compound; Rapid technique; Health food; Pigments; Measurement method; Measurement accuracy; Tocopherol; Carotenoid; Protection; Comparative study
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf010731y

In this paper, a novel electrochemical method to evaluate the antioxidant power of lipophilic compounds present in vegetables, such as carotenoids, chlorophylls, tocopherols, and capsaicin, is reported. The method is based on a flow injection system with an electrochemical detector equipped with a glassy carbon working electrode operating amperometrically at a potential of + 0.5 V (vs Ag/AgCl). The proposed method is selective for lipophilic compounds having antioxidant power. When applied to pure compounds, the order of antioxidant power resulted as follows:  lycopene > β-carotene > zeaxanthin > α-carotene > β-cryptoxanthin > lutein > α-tocopherol > capsaicin > chlorophyll a > chlorophyll b > astaxanthin > canthaxanthin. Results obtained on five vegetable and two fruit extracts were compared to those obtained by the 2,2‘-azinobis(3-ethylbenz-thiazoline-6-sulfonic) acid (ABTS) radical cation decolorization assay, one of the most used methods to evaluate the total antioxidant capacity of foods. A good correlation between the two methods was found, except for spinach, because of the different antioxidant powers assigned by the two methods to chlorophylls. In conclusion, results suggest that the proposed electrochemical method can be successfully employed for the direct, rapid, and reliable monitoring of the antioxidant power of lipophilic food extracts. Keywords: Antioxidant power; carotenoids; chlorophylls; capsaicin; electrochemical method; amperometric detection