How Long Does Opened Pesto Last?

Every home cook should know how to make pesto or have a jar of high-quality pesto handy in their pantry or fridge. Pesto is incredibly easy to make (particularly if you have a food processor) and incredibly versatile: Toss it with some pasta, spread it on a sandwich or pizza, or layer it in your lasagna. The options are only limited by your creativity. However, the last thing you want is for this delicious mixture of basil, cheese, and nuts to go bad before you can eat it all, which begs the question, how long will your pesto last?

While you can keep unopened store-bought pesto in your pantry until the best-by date listed on the jar (which will usually be a few months from the purchase date), it's advised you refrigerate the pesto after opening. From that point, you'll have a week or two to use the pesto before things start to get a little iffy. If you're right on the cusp of that two-week mark, and you're wondering if your pesto is still good, look for two things: mold or oxidation. If you see mold, throw the pesto away immediately. If you see oxidation, which shows up as brown or gray discoloration, it's unlikely to be harmful, but it's not appetizing, so you may want to throw the pesto away. (If your pesto is homemade, you'll want to eat it in just a few days.)

Let's say you opened up a big jar of pesto for a single serving of a simple recipe or to make one sandwich, or maybe you made a big batch of pesto and have lots of leftovers. If you're worried about your pesto oxidizing (which happens pretty quickly) before you can eat it all, there are some things you can do. Similarly, if you're worried you simply won't eat all your pesto in time, you can freeze it.

To prevent store-bought pesto from oxidizing, cover the pesto with a thin layer of olive oil before storing it in the fridge for the first time. To prevent homemade pesto from oxidizing, do the same, but consider blanching your basil before making it, and add an acid like lemon juice to your recipe, as both can help prevent oxidization. To freeze pesto, which will ensure it lasts up to six months, you can do so in either an ice cube tray or glass jars, or spread homemade pesto out on a baking sheet, freeze it, and cut it into portions to store in air-tight freezer bags.