Herbs and spices have been used not only as food preservatives and flavoring, but also as traditional medicines for thousands of years. Two-thirds of the world's population still relies on traditional medicines with herbal medicines the most common form. The World Health Organization (2010) estimates that 80% of the population in some Asian and African countries depends on traditional medicines for primary health care. In the United States, the Centers for Disease Control and Prevention estimates ≈38% of adults use complementary and alternative medical treatments. Scientific evidence increasingly supports the potential health benefits of herbs with plant extracts displaying antioxidant, anti-inflammatory, antibacterial, analgesic, and antitumor activities.
Oxygen-free radical induced oxidation of cellular components is believed to be one of the major factors in the development of heart disease and cancer (Berger, 2005). Oxidizing agents, often in the form of free radical compounds, can cause damage to numerous cellular components, including membranes, proteins, and nucleic acids (Knight, 2000). Dietary intake of herbs and spices with high antioxidant contents may improve our resistance to free radical damage and thus reduce risk of heart disease and cancer (Kaefer and Milner, 2008). Studies show that herbs generally contain higher levels of antioxidant content than fruits, vegetables, and nuts (Konczak et al., 2010; Zheng and Wang, 2001). More and more people have realized the health benefits of herbs and the use of herbs is increasing (Kaefer and Milner, 2008).
The drying of spices has been used for disinfestations, microbial decontamination, and long-term preservation (Schweiggert et al., 2007). Although reports are limited, studies indicate that drying conditions can impact the chemical and biological activities of herbs (Capecka et al., 2005; Lim and Murtijaya, 2007). The Mint family, Lamiaceae, is a group of ≈210 genera and some 3500 species. Many members of the family have high phenolic and antioxidant content such as basil (Ocimum basilicum), lemon balm (Melissa officinalis), sweet marjoram (Origanum majorana), oregano (Origanum vulgare), peppermint, rosemary, sage (Salvia officinalis), and thyme (Thymus vulgaris) (Dragland et al., 2003; Yi and Wetzstein, 2010). Systematic evaluations of drying and extraction conditions on biochemical activities of this group are lacking. The objectives of this study were to evaluate the effects of drying conditions and extraction protocols on total phenolic content and antioxidant capacity of selected herbs.
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