The Only Knife You Should Be Using To Cut Avocados

Whether you're making a simple avocado toast or a homemade batch of guacamole, the first thing you probably do is reach for a knife to cut the avocado. The size and sharpness are usually the main characteristics most people take into consideration when deciding what knife to use, however, when it comes to cutting avocados, the material of the blade matters just as much. As it turns out, most metal knives can cause avocados to brown prematurely.

While this browning is entirely superficial, and not a sign that the avocado has immediately gone bad, if you want the flesh to retain its vibrant green color, it's best to avoid using any knife made with copper, iron, or stainless steel. Instead, opt for either a ceramic or plastic knife. Both are effective at preventing excessive browning from occurring; a plastic knife, on the other hand, particularly a disposable one, may not be sharp enough to cut through the thicker outer layer.

While you might assume that the browning caused by a metal knife has something to do with bruising the flesh, the truth is that certain metals trigger a chemical reaction when they come in contact with the enzymes in the avocado. This reaction, called enzymatic browning, is inevitable, as it also occurs whenever avocado flesh is exposed to oxygen for an extended time. It simply gets expedited when you use a metal knife to cut the fruit.

What this means, therefore, is that as soon as you cut into an avocado and introduce oxygen to it, enzymatic browning is already underway. However, you're able to slow this process down and help your avocado stay greener longer if you use ceramic or plastic because neither material reacts with the enzymes in the avocado. Instead of the avocado browning immediately after you cut it, you'll be in the clear for several hours.

When cutting an avocado, no matter the material of the knife blade, avoid removing the pit too soon as it can help prevent browning too. The longer the pit stays in contact with the flesh of the avocado, the longer it'll stay green. Avocado pits naturally produce a chemical that offsets the browning caused by oxygen exposure.

The sharpness of the knife also plays a role in browning, which is why ceramic is generally a better choice than plastic. Not only is it easier to pierce through avocado skin with a ceramic knife, but a cleaner cut also yields less browning. If you plan to let your avocado sit for a little bit after cutting it, you can also sprinkle a bit of lemon or lime juice on top of it since citrus can also help counteract browning. 

If you plan to eat your avocado immediately after cutting it though, using a ceramic knife instead of a metal one should give you the most time to enjoy a vibrant green avocado before it goes brown.