Freshly minced garlic offers a more potent and nuanced flavor compared to pre-minced jarred garlic, which often has a milder, sometimes even slightly bitter, taste due to preservatives and oxidation.
When you mince garlic fresh, you're releasing all the flavorful compounds, particularly allicin, which is responsible for garlic's characteristic pungent aroma and taste. The act of cutting or crushing the garlic cloves ruptures the cells, allowing enzymes to convert alliin into allicin. This process happens almost immediately, delivering a burst of fresh, intense garlic flavor.
Pre-minced jarred garlic, on the other hand, has already undergone this process and has been sitting in oil or water, often with preservatives like citric acid. Over time, the allicin degrades, leading to a weaker and less complex flavor profile. The preservatives can also contribute to a slightly acidic or bitter taste. Furthermore, the texture of jarred garlic is often softer and mushier than freshly minced garlic.
In terms of convenience, jarred garlic wins hands down. It saves time and effort, especially when you need garlic in a pinch. However, for dishes where garlic is a prominent flavor, such as garlic bread, pesto, or aioli, the difference in taste between fresh and jarred garlic is significant. For recipes where garlic is more subtle, like in a long-simmered sauce, jarred garlic can be an acceptable substitute.
If you must use jarred garlic, try sautéing it gently in olive oil before adding other ingredients. This can help to mellow out any potential bitterness and enhance its flavor. However, always taste and adjust seasonings accordingly, as jarred garlic's flavor intensity can vary.