Authors: Roy, Molay Kumar; Takenaka, Makiko; Isobe, Seiichiro

Source: Journal of the Science of Food and Agriculture, Volume 87, Number 12, September 2007 , pp. 2259-2265(7)

Publisher: John Wiley & Sons, Ltd.

Abstract:

Both the pro- and antioxidant activities were found in water-soluble components contained in onion, leek and garlic samples, and effects of thermal treatment on such activities were investigated. Raw vegetable extracts were prepared by squeezing vegetable homogenates followed by centrifugation at 4 °C. The extracts were subjected to thermal treatment at 75 or 100 °C for 30 and 60 min. The water-soluble extracts were assayed for antiradical activity using both a chemical and a cellular system. Heating onion and leek extracts at 100 °C for 60 min, and garlic extract at 100 °C for 30 min, yielded strong antioxidant components that are able to scavenge free radicals, in either system, significantly. Measuring total phenolic content by the Folin-Ciocalteu method, we observed that thermal treatment significantly decreased the phenolic contents in leek and garlic extract. In addition, we estimated pro-oxidant activities in the vegetable extracts, using reactive oxygen species (ROS)-sensitive 2′,7′-dichlorofluorescin diacetate; we found that extracts of raw alliums have strong ROS activity, and that thermal treatment destroyed most of the ROS activity present in the raw extracts. These findings indicate that thermal processing enhanced the nutritional value of alliums by increasing the total antioxidant activity, and reducing the pro-oxidant elements. Copyright © 2007 Society of Chemical Industry

Keywords: onion; garlic; leek; thermal processing; antioxidant; pro-oxidant; HL-60 cells

Document Type: Research article

DOI: http://dx.doi.org/10.1002/jsfa.2981

Publication date: 2007-09-01

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