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Lipids, especially unsaturated fatty acids, belong to very reactive compounds present in food. Unsaturated fatty acids are usually slowly oxidized to hydro peroxides at lower temperatures (storage of food). Aldehydes, aldehydic fatty acids, and other products are consequently formed (B i l e k , 2000; F r a n k e l , 2005; C h r p o v a et al., 2010). Plant materials containing phenolic constituents are increasingly of interest because they inhibit oxidative degradation of lipids and therefore improve quality and nutritional value of food. Phenolics are vital substances that possess the ability to protect the body from damage caused by free radical-induced oxidative stress (K h a l i l et al., 2007). Medicinal plants are traditionally used in folk medicine as natural healing remedies with therapeutic effect. Pharmacological industry utilizes medicinal plants for their content of active chemical substances. Due to their preservative effects caused by the presence of antioxidant and antimicrobial constituents, they are valuable additives used also in food and cosmetic industry. Plants from several families, especially Lamiaceae (rosemary, sage, oregano, marjoram, basil, thyme, mints, balm), Apiaceae (cumin, fennel, caraway), and Zingiberaceae (turmeric, ginger) belong to commonly used medicinal plants with antioxidant activity known worldwide (Z e u t h e n , B o g h S o r e n s e n , 2003; B o u a y e d et al., 2007; V i u d a M a r t o s et al., 2010; S k o v r a n k o v a et al., 2012). Culinary herbs are considered to be rich sources of antioxidants in direct consumption and in processed stage as well. Processing can cause degradation of many groups of biologically active chemical substances, which leads to their content reduction (V a b k o v a , N e u g e b a u e r o v a , 2011). Plant antioxidants consist of a wide range of different substances such as ascorbic acid, tocopherols, polyphenolic compounds, or terpenoids. They perform several important funcions in plants and humans (G r a s s m a n n , 2005). ANTIOXIDANT ACTIVITY OF LAMIACEAE HERBS GROWN UNDER ORGANIC AND CONVENTIONAL FARMING* |
