If Your Pesto Is Bitter, This Might Be The Culprit

A classic pesto sauce delivers a vibrant flavor that enhances any dish with its perfectly balanced ingredients. Whether tossed with pasta, spread on sandwiches, or drizzled over your favorite foods, it adds a delicious burst of freshness to every bite. Made from basil, pine nuts, olive oil, garlic, parmesan, and salt, the recipe is simple, but the combination of ingredients creates a complex flavor that is rich and herbaceous. However, whether it is freshly made or store-bought pesto, it shouldn't be bitter. If it is, you'll want to put on your detective cap so your pesto can live up to expectations.

There are many possible reasons why your pesto might have a bitter twang, but one of the most obvious culprits, and the first place you'll want to look, is the olive oil. This heart-healthy ingredient actually should have a touch of bitterness to it, especially if it is high-quality oil, thanks to the polyphenols (polyphenols are a plant-based compound that is great for heart health and immunity). The more polyphenols your olive oil has, the better it is for you, but that also increases the bitterness.

Despite its natural bitterness, as olive oil ages that flavor will intensify, bordering on rancid if it has passed its prime. The best way to avoid letting old olive oil affect your pesto sauce (and any other dish you are using the oil for) is to test the olive oil before you add it. This is especially important if you know it's been sitting around in your kitchen for a while since olive oil will start to oxidize once opened and exposed to air. A small taste should do the trick — if the bitterness is overpowering, you might want to buy a new bottle before you make your next pesto.

Although your oil will bring a note of bitterness, it should be balanced out with the other ingredients. If not, you have a couple of options. You can add more of some of the other ingredients, namely the cheese, nuts, or salt to help combat the bitterness, and you can even try adding a splash of lemon (but avoid adding sugar or honey), or you can keep investigating to find out if there is another cause.

One of the other most common causes of bitter pesto has to do with technique and how it affects the olive oil. To make a good pesto, you want your basil, nuts, garlic, and cheese to all be chopped very finely so they blend together for a smooth finish. This is often accomplished using a food processor or blender, but pesto is a delicate sauce and doesn't take well to overprocessing. The high speed of the blades gets you the consistency you want but has the unfortunate effect of cutting through the olive oil too quickly, which releases even more polyphenols and increases the potential for a bitter-tasting pesto.

There is hope though! When it comes to mixing your ingredients together you can still use your trusty food processor to get the desired texture. Simply add your basil, nuts, garlic, parmesan, and salt and blend away. Once everything is thoroughly chopped you can then add the mixture to your olive oil and stir it briskly to incorporate it into the dry ingredients. The result will be just as good and the flavor should be spot on.