by Michael Hawkins
Once opened, a jar of pesto lasts in the fridge for three days without any dramatic loss of quality. It will be perfectly safe for another two days, but leave it any longer, and its quality will decline to the point that it will no longer be enjoyable to eat.
A fridge's temperature affects how long your pesto lasts
Once opened, pesto's shelf life depends on several factors, but providing you follow the following conditions, an opened jar of pesto will remain perfectly safe for up to five days.
1.) Your fridge is set to the recommended temperature of 5°C or below.
2.) Your pesto is not already past its expiration date.
3.) The jar hasn't been left standing at room temperature for more than two hours.
4.) It has a thin layer of oil over the top to prevent air from turning the sauce brown.
If you can't remember how long your pesto has been in the fridge, don't risk it
If you can't remember how long a jar of pesto has been sitting in your fridge, don't rely on a sniff test. You cannot detect botulism by sight or smell, so it's simply not worth the risk.
Similarly, if you can see mould starting to form on the surface of your sauce, don't be tempted to scrape it off and eat the rest. The mould could have already permeated all parts of the sauce, and the whole batch should be thrown away without a second thought.
A fridge can keep your pesto safer for longer, but it can't stop the inevitable decline in quality
Safety is only one part of the equation. Even though keeping pesto in the fridge makes it last longer, all sauces begin to deteriorate as soon as you twist the lid. So, even if you don't need to worry about food poisoning, you should be aware that your five-day-old pesto won't taste nearly as good as a freshly opened jar.
Use oil to maximise your pesto's fridge life
Pouring a thin layer of oil on top to restrict the sauce's exposure to oxygen will help keep your pesto looking (and tasting) better for longer and is the most effective way to ensure your pesto doesn't turn brown or become bitter.
Consider switching from the fridge to the freezer
If you don't plan to eat any more of your pesto in the next five days, be mindful that it freezes remarkably well. We like to freeze pesto in an ice cube tray so that we always have some tasty nuggets at our disposal whenever we think a dollop of pesto could improve our dinner.
