Peeling garlic releases enzymes that interact with allicin precursors, intensifying its pungent and spicy flavor. The more finely you chop or crush peeled garlic, the stronger the flavor will be.
Garlic's flavor is largely determined by a compound called allicin, which isn't present in intact garlic cloves. When you peel and especially when you cut or crush garlic, you break open cells, releasing an enzyme called alliinase. This enzyme converts alliin (a sulfur-containing amino acid derivative) into allicin. Allicin is responsible for the characteristic pungent aroma and flavor of garlic. The more you damage the garlic cells, the more alliinase is released, and the more allicin is produced. Therefore, minced or crushed garlic will have a much stronger flavor than whole cloves added to a dish. The intensity of the flavor also depends on how long the garlic sits after being peeled and chopped before being cooked. Letting it sit for about 10 minutes allows for maximum allicin production. Cooking garlic deactivates the alliinase enzyme and reduces the pungency of the allicin, resulting in a milder, sweeter flavor.
To mellow the flavor of garlic, especially if you've accidentally minced it too finely, sauté it gently in oil over low heat. This helps to temper the sharpness and prevent it from burning, which can create a bitter taste.