Chemical Constituents
摘要
Fresh raw garlic bulbs contain ∼65% water, ∼28% carbohydrate, ∼2% protein, ∼1.2% amino acids, ∼1.5% fiber, fatty acids, phenols, trace elements, and more than 33 (∼2.3%) sulfur-containing compounds [1]. Garlic is well known for its pungent odor, caused by oil-soluble organosulfur compounds (OSCs), including allicin, alliin, and ajoene. The main sulfur compound in both raw garlic and garlic powder is alliin. On average, garlic cloves contain 8 g/kg alliin. When raw garlic is chopped or crushed, alliinase, a key enzyme, is released and converted into allicin. This enzymatic process, a major constituent of solvent-extracted garlic, is a crucial step in the formation of allicin, a key compound in garlic. Allicin is very unstable and rapidly decomposes into a variety of products, including ajoene, dithiins, allyl methyl trisulfide, diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS). This breakdown occurs within hours at room temperature and within minutes during cooking [2]. OSCs are generally classified into two groups: oil-soluble OSCs and water-soluble OSCs. Although water-soluble OSCs comprise a small portion of garlic, they are considered the main bioactive component in cancer prevention [3]. S-allylcysteine (SAC) and S-allylmercaptocysteine (SAMC), metabolites of allyl mercaptan (AM) and allyl methyl sulfide (AMS), are water-soluble OSCs, which are less odorous than the oil-soluble OSCs.