A STUDY ON SOME AROMATIC PLANT EXTRACTS AT ALGABAL AL AKHDAR IN LIBYA AS NATURAL ANTIOXIDANTS

Abstract

The oxidation of lipids in foodstuffs affects their quality due to the volatile compounds formed. Rancid products are thus less acceptable to consumers and have decreased nutritional value (Belitz and Grosch, 1987). Therefore, antioxidants have been used which scavange the peroxy and oxy free radicals formed during the propagation and the branching steps of autoxidation radical chain. Butylated hydroxyanisol (BHA), butylated hydroxytoluene (BHT), gallats and tert-butylhydroquinone (TBHQ) are synthetic antioxidants commonly used in food processing because they provide good protection for unsaturated fat and oils, and they have low cost and high stability (Tsimidou and Boskou, 1994, Ozcan and Akgill, 1995 and Dapkevicius et al., 1998). However, these substances have been questioned because they show some toxicity and carcinogenecity (Madsen and Bertelsen, 1995, Gamez-Meza et a!., 1999, Ozcan, 1999). Therefore, the demand for natural antioxidants has grown in order to render food products safer for mankind. Tocopherols, carotenoids, flavonoids, ascorbic acid and polyphenols are examples of natural antioxidants isolated from different sources. Plant kingdom is a good source of natural preparations containing effective bioactive compounds which can be used for different applications, particularly as food additives and health promoting ingredients in the formulations of functional foods and nutraceuticals (Shahidi, 1997, Gibson and Williams, 2000 and Mcskin eta!. 2002). fresh and dried aromatic plants have been widely used as flavourings since ancient times, however, during last few decades they also have become a subject for a search of natural antioxidants and antibacterial agents (Evans & Reyhout, 1992, Pokorny, 1991, Madsen & Bertelsen, 1995, Venskutonis, 2004). Among the various kinds of natural compounds, essential volatile oils are receiving attention as potential antioxidants, due to their importance in food preservation. Essential oils from several aromatic plants are known to possess antioxidant activities (Lagouri et a!., 1993, Maestri eta!., 1996, Baratta eta!., 1998 a and b, Dorman eta/., 2000, Ruberto et al., 2000, Teissedre and Waterhouse, 2000, Estevez et al., 2007, Genena eta!., 2008, Rota et al. 2008 and Jamshidi and Afzali, 2009).

The present study aimed to evaluate the chemical composition of essential oils of artemisia (Artemisia herba- alba L.), juniper (Juniperrus phoenicea L.), rosemary (Rosmarinus officina/is L.) and thyme (Thymus capitatus L.) leaves collected from AlGabal Alakdar, Libya by GC/MS and investigate their antioxidant activities in different test systems. On the other hand, the effect of different essential oils on the oxidative stability of soybean oil was investigated. Moreover, the effect of broiler diet supplementation with different essential oils on growth performance in chicken and chicken meat quality and stability was evaluated.