Onion antioxidants

FIGURE 5.9 Response surfaces indicating the effect of high pressure and temperature on (a) onion antioxidant activity (b) total quercetin of onion sample. (From Roldan, M.E. et ah, Lebensm. Wiss. TechnoL, 42, 835, 2009. With permission.)... 

Mincing, cooking and maturing expose meat products to oxidative stress for a long time so that antioxidants added for lipid protection are slowly destroyed on storage. Onion juice is a powerful antioxidant in meat products, more efficient than garlic juice. Lipid hydroperoxides are reduced to inactive hydroxyl derivatives by reaction with sulphur compounds present in those juices. 

Yellow and red onions (Allium cepa) were reported to be poor antioxidants toward oxidation of methyl linoleate (Kahkonen and others 1999) in contrast to their high antioxidant activity toward oxidation of LDL (Vinson and others 1998). Garlic (Allium sativum L) was reported to have four times more antioxidant activity than onions when using the ORAC assay (Cao and others 1996). 

Yang J, Meyers KJ, van der Heide J and Liu RH. 2004. Varietal differences in phenolic content and antioxidant and antiproliferative activities of onions. J Agric Food Chem 52 6787-6793. 

Makris DP and Rossiter JT. 2001. Domestic processing of onion bulbs (Allium cepa) and asparagus spears (Asparagus officinalis) effect on flavonol content and antioxidant status. J Agric Food Chem 49(7) 3216-3222. 

Santas J, Carbo R, Gordon MH and Almajano MP. 2008. Comparison of the antioxidant activity of two Spanish onion varieties. Food Chem 107(3) 1210-1216. 

The experiment with 0.5 g/mL of erode extracts of different parts of Allium plants (bulb, green leaf, white stalk) showed the inhibition of acrosin and trypsin activities, mostiy the red onion and garlic extracts. These results demonstrated that spermicidal effect of Allium extracts is determined also by their capacity of protease inhibition. The red onion extract shows the higher antioxidant capacity and a very low cytotoxicity. 

McAnlis GT, McEneny J, Pearce J, Young IS. Absorption and antioxidant effects of quercetin from onions in man. 1999. Eur J Clin Nutr 53 92-96. 

Murota K, Hotta A, Ido H, Kawai Y, Moon J-H, Sekido K, Hayashi H, Inakuma T, Terao J. 2007. Antioxidant capacity of albumin-bound quercetin metabolites after onion consumption in humans. J Med Invest 54 37-374. 

Ly, T. N., Flazama, C., Shimoyamada, M., Ando, H., Kato, K., and Yamauchi, R. (2005). Antioxidative compounds from the outer scales of onion.. Agri. Food Chem. 53, 8183-8189. 

Roldan, E., Sanchez-Moreno, C., de Ancos, B., and Cano, M. P. (2008). Characterisation of onion (Allium cepa L.) by-products as food ingredients with antioxidant and anti-browning properties. Food Chem. 108(2008), 907-916. 

The subject of flavonoids is taken up in Ebadi s Chapter 29, some of which are said to be effective against breast cancer. Varions subclasses are listed, and then-antioxidant properties are noted, along with their role as enzyme inhibitors. The chemical compound quercetin is singled ont as among the most active, and it is commonly found in onion, apples, kale, red wine, and green/black teas. A rednced risk of not only of breast cancer, but also of prostate, lung, colon, and stomach cancers is associated with an increased intake of fruits, vegetables, and soy prodncts. 

Roldan, M.E., Sanchez, M.C., Lloria, R., Ancos, B., and Cano, M.P. 2009. Onion high-pressure processing Havonol content and antioxidant activity. Lebensmittel-Wissenschaft und-Technologie 42 835-841. 

Fig 24.21. The flavonoid quercetin. All flavonoids have the same ring structure, shown in blue. They differ in ring substituents (=0, -OH, and OCH3). Quercetin is effective in Fe chelation and antioxidant activity. It is widely distributed in fruits (principally in the skins) and in vegetables (e.g., onions). 

Ishikawa, Y., Kubota, T., 1991. Effect of host plant and dietary quercetin on antioxidant enzymes in onion and seedcom maggots, Delia antigua and D. platura (Diptera Anthomyiidae). Appl. Entomol. Zool. 26 (2), 245-253. 

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