How To Keep Pesto Green – The Best Way

Fresh, classic basil pesto is a stunning shade of emerald green that is almost too beautiful to eat. Almost. 

Unfortunately, it doesn’t stay this verdant color nearly long enough, unless you take precautions. Like many other fruits and vegetables, basil will start to oxidize once it’s exposed to air after cutting or crushing, which turns it a much less appetizing dark army green, nearly black color over time.

There are a few secrets to help you learn how to keep pesto green.

So what is the best way to keep pesto green? The best way to keep pesto green is to blanch your basil leaves before making the pesto. Blanching the basil prevents oxidation and prevents your pesto from turning brown.

In this article, we’ll explain exactly how to blanch your basil leaves to keep your pesto green, and we’ll also share 2 other solutions for extending the color-life of your pesto if blanching isn’t a convenient option for you.

The 3 Best Ways To Keep Pesto Green

Keeping pesto green is all about preventing oxidation. This can be done either by eliminating the enzyme that reacts with oxygen and causes your basil to brown, or it can be accomplished by protecting your basil from exposure to air, stopping the oxidation before it happens. 

We’ve found that blanching basil leaves before making pesto is the most effective solution for preventing browning, but topping your pesto with either olive oil or lemon juice before storing it in your fridge is also useful.

Keep reading to find out which solution is the best choice for your pesto.

1. Blanching The Basil Leaves

Blanching basil leaves neutralizes the enzyme in basil that reacts with oxygen and turns your green leaves brown. If you blanch your basil before making the pesto, it doesn’t darken at all, or at least not much.

This is the best method because it protects your pesto completely, not just on the very surface. It also protects your pesto at all times, not just when it goes into cold storage.

How To Blanch Basil

When you blanch anything, it’s important to prepare your kitchen because it’s a fast-paced process.

1. Fill a pot with water and bring it to a boil
2. Next to the pot, prepare a large bowl of ice water
3. Fill a large skimmer spoon or metal skimmer basket with your basil and parsley, if you’re using parsley in your pesto as well. Make sure your skimmer spoon or basket has small holes that your basil won’t slip through
4. Plunge the basil into the rapidly boiling water for 15 seconds
5. Pull the basil out of the boiling water and immediately immerse it in the ice water for 15 seconds
6. Drain the basil immediately and squeeze as much water out of it as you can
7. Make your pesto as per your normal recipe instructions

The purpose of blanching is not to cook your basil, but just to deactivate the enzymes that cause browning. 15 seconds is not a long time and you will want to move quickly to keep your basil from cooking or becoming waterlogged. Don’t let your leaves sit in either the hot or cold water any longer than necessary.

2. Pouring Olive Oil On Top When Storing It In The Fridge

Most pesto calls for olive oil in the recipe, which in itself will help protect your basil from browning to a certain degree. The oil creates a protective barrier around everything it touches, preventing air exposure from penetrating and causing oxidation. 

When olive oil is blended into your pesto, it can only prevent so much browning. However, when you create a thin oil slick on the surface of your pesto, it creates a much more effective barrier against air contact. 

Before you store your pesto, pour a light layer of olive oil over the surface. Follow this with an air-tight seal, either in a Tupperware container with an appropriate lid or by covering your serving bowl tightly with plastic wrap.

Keep your pesto in the fridge, undisturbed, and it will stay green.

Unfortunately, as soon as you break the surface protection, the olive oil becomes less effective of a protector and your basil may start to brown as it’s left out. If you eat it within 30 minutes to an hour, however, it should stay nice and bright green.

3. Squeezing Lemon On Top Before Storing It In The Fridge

Lemon juice contains citric acid and ascorbic acid, both of which prevent oxidation. You may have heard that spraying a bit of lemon juice over sliced apples helps keep them from browning. It works the same way for basil leaves.

If you don’t mind a bit of citrus tang in your pesto, you can add some freshly squeezed lemon juice to the recipe itself. This will help protect your pesto more thoroughly, as it’s worked through the entire batch.

If you are not a great fan of lemon, you can try simply spritzing or pouring a small amount on the surface of your pesto before you seal and refrigerate it.

This will protect the surface while it’s being stored but, similar to the olive oil previously mentioned, as soon as you disturb the surface your pesto will be at risk of oxidizing, so eat it soon after.

It is also possible to keep your pesto green by adding vitamin C powder, but we found that this left a much more sour flavor than fresh lemon juice did, and it’s less convenient overall, so we don’t actually advice trying this method if you can avoid it. 

How Long Does Pesto Last?

The lifespan of pesto depends heavily on the type of pesto you have and how it is stored. 

You can find shelf-stable jarred or canned pesto that can last nearly indefinitely if it’s kept in a cold, dry location out of sunlight and heat and it’s never opened.

Even shelf-stable pesto will have a recommended use-by date, however, and beyond that date, the taste, texture, and aroma of your pesto may decline, while still remaining safe to consume. Generally, you’ll want to eat it within 3 months of the purchase date.

Fresh pesto, on the other hand, does not last as long though it still varies depending on whether it was commercially produced using preservatives, homemade, or somewhere in between.

Pesto purchased from the refrigerated section of your grocery store will also have a best by date stamped on the packaging. It’s always best to follow this recommendation, but if left unopened and properly refrigerated, it will stay fresh for at least 10 days after purchasing, often longer. 

How Long Does Pesto Last In The Refrigerator?

If you’ve opened a container of fresh, store-bought pesto, it should stay fresh in your fridge for up to 1 week. 

Make sure to always store it in an airtight container and scoop out each serving individually, rather than eating straight from the container. You should use a fresh, clean utensil every time you dip into the pesto to prevent contamination and early spoilage. 

You also want to try to keep your pesto in the fridge as much as possible. If you’re serving up a snack, serve only as much as you’re going to eat and put the rest back in the fridge right away.

If it’s left on the counter, it can be exposed to bacteria and other contaminants that are no good for your pesto.

How Long Does Homemade Pesto Last?

Homemade pesto will typically last 3 – 5 days, depending on the freshness of the ingredients you use and the specific recipe.

As with all other pestos, you want to be sure you keep it refrigerated as much as possible and avoid cross-contamination with other foods.

Related Questions 

Why is my pesto not green?

The primary reason pesto turns dark is because the basil, or other fresh greens used in your recipe, have oxidized. Oxidation happens when a specific enzyme that’s present in most plants is exposed to air.

When a basil leaf is cut or crushed, the enzyme is exposed to air and it starts to turn black. 

Pesto will quickly start to darken because all the leafy greens that have been chopped into minuscule pieces are exposed to oxygen from all angles.

Oxidation isn’t dangerous and it doesn’t change the flavor or texture, it just doesn’t look nearly as visually appealing as a beautiful, bright green pesto.

How do you keep basil green in pesto?

As mentioned, pesto in general turns black because the basil oxidizes. If you follow the instructions in this article to protect your basil from oxidizing, it will keep your pesto bright green, like it was freshly minced.

The most effective solution is to blanch your basil before preparing your pesto. This deactivates the enzyme that oxidizes and keeps your basil from oxidizing almost completely. 

Slightly less effective solutions are to store your pesto with a thin layer of either olive oil or lemon juice on the very surface. This protects the pesto until the surface layer is broken and the underlying pesto is exposed to air.

From that point on, slow oxidation will occur and your pesto will gradually darken over time. 

Why is my pesto bitter?

There could be multiple reasons your pesto is bitter, depending on the recipe and freshness of your ingredients. If you use greens in addition to your basil, it can alter the flavor.

For example, while arugula in pesto is popular, it is more bitter. If you want to add greens without the bitterness, try some spinach.

Another possibility is slightly rancid oil or overly strong fresh garlic. Some pesto creators will temper this type of bitterness by adding some parmesan cheese or extra toasted pine nuts.

Some also simply add sugar, but sweetening a recipe is not the same as counteracting the bitterness, so try this only if you’re open to the possibility of not liking the less traditional flavor.

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