Antioxidants are defined as compounds that can delay, slow down, and prevent lipid oxidation process. In a special meaning, antioxidants are substances that can delay or prevent the occurrence of antioksidasi reactions of free radicals in lipid oxidation (Kochhar and Rossell, 1990).
Sources of antioxidants can be classified into two groups, namely synthetic antioxidants (antioxidants obtained from the synthesis of chemical reactions) and natural antioxidants (antioxidant extraction yield natural ingredients).
Some examples of synthetic antioxidants permitted for food use and their use has been often used, namely anisol butyl hydroxy (BHA), butyl hydroxy toluene (BHT), propyl gallate, tert-butyl hidoksi quinon (TBHQ) and tocopherols. Antioxidant-these antioxidants are natural antioxidants that have been produced synthetically for commercial purposes.
Natural antioxidants in food can be derived from (a) the existing antioxidant compounds from one or two of food components, (b) antioxidant compounds formed from reactions during processing, (c) antioxidant compounds isolated from natural sources and added to food as a food additive (Pratt, 1992).
Antioxidant compounds isolated from natural sources is derived from plants. Plant Kingdom, Angiosperm has approximately 250 000 to 300 000 species and of these approximately 400 species have been known to be a human food ingredient. Isolation of a natural antioxidant has been made from plants that can be eaten, but not always from the part that can be eaten. Natural antioxidant in several parts of plants, such as in wood, bark, roots, leaves, fruits, flowers, seeds and pollen (Pratt, 1992).
Natural antioxidant plant compounds are usually phenolic or polyphenolic compounds that can form groups of flavonoids, cinnamic acid derivatives, coumarins, tocopherols and polyfunctional organic acids. Flavonoid having antioxidant activity include flavones, flavonols, isoflavones, kateksin, flavonol and kalkon. Meanwhile, cinnamic acid derivatives including kafeat acids, ferulic acid, chlorogenic acid, and others.
Ginger (Zingiber officinale Roscoe) is used as a seasoning or traditional medicine. Pungent components of ginger such as gingerol and 6-6 shogaol known to have antioxidant activity that was enough. Of ginger extract that has been removed by steam distillation volatilnya components, then the fraction of non volatilnya after purification, it was found that there were four derivatives and four kinds diarilheptanoid gingerol which has strong antioxidant activity (Nakatani, 1992).
