Chapter 35 - Composition and functionality of clove (Syzygium aromaticum) extracts

Abstract

In this chapter, the composition and biofunctional characteristics of clove (Syzygium aromaticum) extracts were reviewed. Extraction is a key process for gaining valuable ingredients from plants and plant-derived products. There are several extraction techniques, including conventional and novel methods in the literature. Solvent and Soxhlet extraction, maceration, hydro- or steam-distillation, squeezing, and cold processing are the most known and used techniques. In contrast, microwave, pulsed electric field, ultrasound-assisted extraction, pressurized liquid extraction, and supercritical fluid extraction methods are novel techniques that have been intensively used in the plant extraction process. Syzygium aromaticum (syn. Eugenia caryophyllata Thunb., Eugenia aromaticum), commonly known as clove, is a tree from the Myrtaceae family and the second most important spice in the world trade. The plant has been used as medicine traditionally and flavoring agent in different parts of the world. The leaves, buds, and stems of the cloves can be used to prepare extracts and are generally used as whole plants. The clove extracts comprise the major compounds such as eugenol, eugenyl acetate, and caryophyllene. Among these, eugenol is the active ingredient of clove and is a phenolic and aromatic compound. The antibacterial, antifungal, antioxidant, anticancer, anti-inflammatory, antidiabetic, and antistress potentials of eugenol were reported in several studies. As well as eugenol, clove extracts have also been studied for their health-promoting effects. Clove extracts could also be utilized in the food industry as a natural antioxidant for better oxidative stability of food substances and as an anticarcinogenic agent in dentistry. In this chapter, extraction techniques used for the clove, the compositional and functional properties of clove extracts, and also using the potential for different industries are discussed.