Wild Edible Plants as Potential Antioxidants in Vegetables Oils

The effect of the addition of fruits of Rosa canina and Quercus ballota and leaves of Sanguisorba minor to sunflower, seed, and olive oils on lipid oxidation during the frying process was analyzed. The three underutilised edible plants increased the oxidative stability of the sunflower oil, since the malondialdehyde (MDA) content was significantly decreased with respect to values of the control sunflower oil after the heating process. However, in olive oil, the effect of these edible plants on decreasing the lipid peroxidation was only evident for the highest concentration, while in seed oil the addition of the edible plant showed a prooxidant effect. Thus, these wild edible plants could be used to enrich vegetable oils with low content of natural antioxidant, such as sunflower oil, and avoid or decrease the use of synthetic antioxidant. 1. Introduction Edible vegetable oils such as sunflower oil, seed oil, and olive oil have an important place in human diet, since their use in culinary processes is a constant. However, during frying, a gradual deterioration of oil quality occurs due to lipid oxidative decomposition reactions leading to lowering quality and nutritional value of foods, with consequences for the health of the consumer, causing aging, membrane damage, and numerous diseases, such as chronic inflammation, neurodegenerative diseases, adult respiratory distress syndrome, atherogenesis, diabetes, and different types of cancer [1]. Synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tert-butyl hydroquinone (TBHQ), are widely used in the food industry to avoid oxidation [2] due to their low cost and good performance, although their safety has been questioned due to carcinogenic effect [3]. According to the European Bulletin (order of 24 August 2007) [4] the maximum dose that allowed for these artificial additives in frying oils is 200？mg？kg？1 of oil. Under these circumstances, research on development of safe natural antioxidants is therefore essential. Recently it has been shown that Nigella sativa seed extract could be an interesting alternative to the use of synthetic antioxidants, since the addition of Nigella seed extract to sunflower oil improved their thermal stability and shelf-life [5]. Accordingly, Cordeiro et al. [6] have shown that extract of Rosmarinus officinalis added to sunflower, corn, and soybean oils displayed a more effective antioxidative action than TBHQ and it was stable at the frying temperature of the oils, unlike the majority of the antioxidants commonly used. Moreover, even