The primary acid present in garlic is 2-propene-1-sulfinothioc acid S-2-propenyl ester, also known as allicin.
Allicin (diallyl thiosulphate) is the compound responsible for garlic's characteristic pungent smell and taste. It's not present in intact garlic cloves; rather, it's produced when alliin, a sulfoxide, comes into contact with the enzyme alliinase. This occurs when garlic cloves are crushed, chopped, or damaged.
Here's a more detailed breakdown:
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Alliin: This is a naturally occurring sulfur-containing amino acid derivative found in garlic. It is odorless.
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Alliinase: This is an enzyme also present in garlic. It is normally separated from alliin within the plant's cells.
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Allicin Formation: When garlic is crushed, alliinase is released and comes into contact with alliin. This enzymatic reaction converts alliin into allicin.
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Allicin's Instability: Allicin is unstable and quickly breaks down into other sulfur-containing compounds, such as diallyl disulfide, diallyl trisulfide, and diallyl tetrasulfide, which contribute to garlic's flavor and odor profile after it has been cooked or processed.
Therefore, while allicin is the key compound responsible for the pungency and antimicrobial properties of garlic, it is technically a sulfenic acid derivative formed enzymatically from alliin rather than a pre-existing free acid within the intact garlic clove.
