Does pesto go bad?

Does Pesto Go Bad? How Long Does Pesto last?

You know that moment when you’re rummaging through your fridge, and you stumble upon that half-used jar of pesto? The vibrant green color beckons, but then the doubt creeps in. “How long has this been here? Does pesto go bad?”

If these questions sound familiar, you’re not alone. Pesto, with its aromatic blend of basil, garlic, cheese, and pine nuts, is a culinary delight. It can elevate a simple pasta dish, make a pizza irresistible, or even jazz up a sandwich. But, like all good things, it doesn’t last forever.

In this guide, we’ll unravel the mystery of pesto’s shelf life, share tips on proper storage, and help you spot when it’s time to let go. Let’s get started!

Does Pesto Go Bad?

Absolutely, pesto does go bad, and its unique composition plays a significant role in determining its shelf life.

Pesto is an uncooked concoction, primarily made of fresh herbs like basil, combined with oil. The freshness of these herbs, especially basil, is what gives pesto its vibrant flavor and color. However, being uncooked means the enzymes and microorganisms in the fresh ingredients remain active, which can lead to quicker degradation.

The oil in pesto acts as a preservative in two ways. Firstly, it creates a barrier that can reduce the exposure of the herbs to air, slowing down oxidation. Secondly, many microorganisms find it hard to grow in oil. However, over time, if water or any contaminants get mixed with the pesto, it can become a breeding ground for bacteria, especially since the mixture is uncooked.

Store-bought versions often contain preservatives to counteract this natural degradation process, granting them a longer shelf life. In contrast, homemade pesto, which usually lacks these preservatives and relies solely on fresh ingredients, can spoil more quickly.

The very essence of pesto—its freshness—while being its strength, is also its Achilles’ heel when it comes to longevity. Proper storage, therefore, becomes paramount to ensure you get the most out of its delightful flavors before it goes bad.

Related: Does Ketchup Go Bad? Opened vs. Unopened Shelf Life

How to Tell if Pesto Is Bad?

Recognizing when pesto has gone bad is crucial for your health and taste buds. Here are some telltale signs to help you determine if your pesto is past its prime:

  1. Appearance: Fresh pesto has a vibrant green color. If you notice any mold growth or if the pesto has turned a darker, brownish hue, it’s a clear indication that it’s spoiled.
  2. Smell: Pesto has a distinctive aromatic scent, thanks to its basil and garlic content. If your pesto emits a sour or off-putting odor, it’s time to toss it.
  3. Texture: A good pesto has a consistent, smooth texture. If it becomes too watery, separated, or has an unusual consistency, it might be going bad.
  4. Taste: While it’s better to rely on the above signs before tasting, if you do take a bite and it tastes off or sour, it’s best not to consume any more.

How Long Does Pesto Last?

The longevity of pesto is influenced by its composition and storage conditions. Let’s delve deeper into the shelf life of different types of pesto:

Store-Bought Pesto Sold Unrefrigerated

  • Composition: This variant often contains preservatives, which are added to prolong its shelf life. These preservatives help in warding off bacteria and mold growth.
  • Storage: When unopened, it can last for several months if stored in a cool, dark pantry away from direct sunlight and heat sources.
  • After Opening: Once you break the seal, its freshness starts to diminish. At this point, it’s crucial to refrigerate it. Typically, it remains good for 1-2 weeks when stored in the fridge.

Store-Bought Pesto Sold Refrigerated

  • Composition: This type of pesto is often fresher and might have fewer preservatives, leaning more on its cold storage to maintain freshness.
  • Storage: Even if unopened, it has a shorter shelf life than the unrefrigerated version due to its fresher ingredients.
  • After Opening: Once opened, the clock starts ticking faster. It’s best to consume this pesto within 5-7 days to enjoy its optimal flavor and texture.

Homemade Pesto

  • Composition: Homemade pesto is typically free from the commercial preservatives found in store-bought versions. Its freshness comes from the ingredients you use, like fresh basil, pine nuts, and olive oil.
  • Storage: Without those preservatives, it’s vulnerable to spoilage. It’s essential to store it in an airtight container to minimize air exposure.
  • Shelf Life: When stored correctly in the refrigerator, homemade pesto usually retains its freshness for 5-7 days. If you’ve added ingredients like fresh lemon juice, it might last a bit longer due to the acidic environment it creates, which can deter bacterial growth.
Type of PestoShelf Life (Unopened)Shelf Life (Opened)
Store-Bought Pesto Sold UnrefrigeratedSeveral months1-2 weeks
Store-Bought Pesto Sold RefrigeratedUp to the ‘best before’ date5-7 days
Homemade PestoN/A5-7 days

Factors Affecting Pesto’s Shelf Life

The longevity of pesto isn’t solely determined by its production date or the label on its container. A myriad of factors come into play, affecting how long this aromatic sauce retains its freshness:

  1. Ingredients: The very essence of pesto lies in its ingredients. Fresh basil, with its vibrant green hue, and aromatic garlic are the heart and soul of the sauce. However, their freshness, while imparting rich flavors, also makes the sauce more perishable. On the other hand, many store-bought pestos incorporate preservatives, which can significantly extend their shelf life.
  2. Packaging: The choice of packaging material and its quality can be a game-changer. While glass jars with airtight seals are champions in retaining freshness, they aren’t foolproof. Plastic containers, especially if they’re not BPA-free, might affect the taste and longevity of the pesto.
  3. Storage Conditions: Pesto, much like a fine wine, prefers cool, dark nooks. It’s sensitive to environmental factors; hence, exposure to elements like heat, light, or even air can hasten its spoilage. This is why an opened jar of pesto feels most at home in the chilly confines of a refrigerator, snugly sealed.
  4. Presence of Contaminants: Using a previously-used spoon or letting breadcrumbs fall into the jar can introduce unwanted bacteria, setting the stage for rapid degradation.
  5. Preparation Method: A homemade pesto, crafted in a pristine environment with freshly sourced ingredients and meticulous techniques, will undoubtedly outlive one whipped up in haste.
  6. Oil Layer: In homemade pesto, adding a thin layer of olive oil on top acts as a protective barrier, shielding the sauce from air exposure and potential contaminants.

How to Store Pesto to Extend Its Shelf Life?

Storing pesto correctly is the key to enjoying its rich flavors for longer. Here’s a guide to ensure your pesto remains as fresh as the day you bought or made it:

  1. Airtight Containers: Whether it’s homemade or store-bought, once opened, transfer your pesto to an airtight container. This prevents air from getting in, which can accelerate spoilage.
  2. Refrigeration: Always refrigerate pesto after opening. Keeping it cold slows down the growth of bacteria and mold. For homemade pesto, it’s best to refrigerate even if you haven’t opened it yet.
  3. Avoid Cross-Contamination: Always use a clean spoon when scooping out pesto. Introducing foreign substances or bacteria can reduce its shelf life.
  4. Layer of Oil: If you’ve made homemade pesto, consider adding a thin layer of olive oil on top before sealing it. This can act as a barrier, reducing exposure to air.
  5. Limit Light Exposure: If possible, store your pesto in a dark place or in a dark container. Light can degrade some of the ingredients, affecting both flavor and freshness.
  6. Freezing for Longer Storage: If you don’t plan on using your pesto soon, consider freezing it. Use ice cube trays to freeze individual portions, then transfer to a freezer bag. This way, you can thaw just the amount you need.

Frequently Asked Questions

Navigating the world of pesto can bring up a lot of questions. Let’s address some of the most common queries to help you make the most of this delightful sauce.

How do you know if pesto is expired?

The best way to determine if pesto has expired is to check its appearance, smell, and taste. Signs of spoilage include mold growth, an off or sour smell, and a change in texture or color. Additionally, always refer to the “best before” or “use by” date on store-bought jars.

Is it bad to eat expired pesto?

Yes, consuming expired pesto can be harmful. Spoiled pesto may contain harmful bacteria that can lead to foodborne illnesses. It’s always safer to discard any food product that shows signs of spoilage.

Is pesto bad when it turns brown?

While a brownish hue doesn’t necessarily mean the pesto is spoiled, it indicates oxidation, which can affect the flavor. It’s safe to eat, but the taste might be slightly different from fresh, vibrant green pesto.

How long does jarred pesto last in the fridge after opening?

Once opened, jarred pesto should be consumed within 1-2 weeks when stored in the refrigerator. Always ensure the lid is tightly sealed and use a clean spoon to prevent contamination.

Does pesto need to be refrigerated?

Yes, after opening, pesto should always be refrigerated to maintain its freshness and prevent spoilage.

Can you freeze pesto?

Absolutely! Freezing pesto is a great way to extend its shelf life. Consider using ice cube trays to freeze individual portions, then transfer them to a freezer bag for longer storage. This way, you can thaw just the amount you need.


Understanding the nuances of pesto storage and recognizing its shelf life is essential for both taste and safety. So, the next time you find yourself pondering, “Does pesto go bad?”, you’ll be well-equipped with the knowledge to answer confidently.

Remember, proper storage not only ensures you’re consuming safe, delicious pesto but also helps you make the most of every jar. Enjoy your pesto dishes with the assurance that they’re as fresh and flavorful as they can be!

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