Learn the harmless chemical reaction that can cause your garlic paste to turn green or blue, and find out that it's still perfectly safe to eat.
1 Answer
Garlic paste turns green in storage due to a reaction between sulfur compounds in the garlic and amino acids, particularly when exposed to acidity and heat. This reaction produces blue and yellow pigments that combine to create a green color.
Detailed Explanation:
The greening of garlic paste is a natural chemical reaction and is generally harmless. Garlic contains alliinase, an enzyme that, when garlic is crushed or cut, converts alliin into allicin. Allicin then breaks down into various sulfur-containing compounds. These sulfur compounds can react with amino acids present in the garlic, especially under acidic conditions (like when lemon juice or vinegar is added) and with heat (which can occur during processing or storage).
This reaction forms pyrroles, which are ring-shaped molecules. These pyrroles can link together to form larger molecules that absorb light in the yellow and blue regions of the spectrum. When yellow and blue pigments are present together, they appear green. The intensity of the green color depends on factors like the garlic variety, storage temperature, acidity, and the presence of certain metal ions.
The greening is more likely to occur in older garlic or garlic that has been stored improperly. It's also more common in garlic paste or minced garlic because the crushing process releases more of the enzyme and sulfur compounds.
Pro Tip:
To minimize greening, store garlic paste in the refrigerator in an airtight container. Adding a small amount of baking soda (an alkaline substance) can help neutralize acidity and inhibit the reaction, but be careful not to add too much, as it can affect the flavor.