The Best Ways to Keep Fruit From Browning
Slices of fresh fruits and vegetables are delicious and healthy snack, but some of them really burn me away, turning brown and soft. This struggle is nothing new and the internet is full of ways to prevent it, but it’s hard to know which method is worth your precious time, so you’re lucky to have me around.
The brown spots that spoil an otherwise beautiful fruit are mostly “fruit rust” caused by oxygen in the air that reacts with a plant enzyme called “polyphenol oxidase.” This article explains the science in more detail, but to prevent enzymatic browning, you either need to stop the oxygen or the enzyme (or both). Most prevention methods involve a physical barrier (water) and a chemical inhibitor (such as ascorbic acid). but we wanted to see which solutions provide the best solution to this ugly problem.
How we tested
To find the best way to keep your apples, pears, and other easily oxidizing fruit slices fresh, I prepared four different solutions (lemon water, parsley water, honey water, and plain tap water) along with a control (just apple wedges in a bowl) …
I chopped up a few fresh apples and placed them in each of the above solutions. After about fifteen minutes, all slices except the control, which had a few brown spots, were completely white with no signs of darkening. This is all good, but apple slices are useless to me, sitting in bowls of water. To see how long each solution would last, I took them out of their respective bowls and let them sit outdoors for about an hour.
Lemon water
Theory: Lemon juice has two things: vitamin C (ascorbic acid) and a low pH. Oxygen reacts with vitamin C earlier than polyphenol oxidase, delaying browning, but when it is completely used up, oxygen begins to act on the enzyme in the fetus, and the flesh begins to brown. Fortunately, as long as the environment is acidic enough (pH 3), the enzyme is deactivated and no browning occurs.
The surest way to apply this theory is to coat the apple slices with pure lemon juice, but then your apples will taste like lemon, not apples. Yummy Life recommends diluting lemon juice with water (two tablespoons for one cup) and soaking apple slices in this solution.
Results: The apples were fine while dipped in the acidic solution, but after an hour on a cutting board, they were almost as brown as the control, which makes me think you should only use pure lemon juice or powder. ascorbic acid if you want to go this route.
Parsley water:
Theory: Like lemons, parsley is also rich in vitamin C, so all of the above applies. However, this article from Kitchn claims that parsley stalks work even better than lemons (which is a kind of low bar given above), although I can’t find anything to substantiate why this would be other than the presence of ascorbic acid ( culinary author Harold McGee seems to think water does all the work, but we’ll get to that in a minute.)
Results: The slices stayed fresh in the solution, but after removal and exposure to air, they begin to brown a little, although not nearly as much as the slices that were in the lemon water. It should be noted, however, that the apple slices now had a slight parsley flavor.
Pure water:
Theory: As mentioned above, Harold McGee seems to believe that the lack of browning is less due to the parsley stalks than to the water physically blocking oxygen from reaching the pulp:
I’ve heard of many good chefs in a number of great restaurants using parsley stalks to prevent browning of chopped artichokes. A couple of times I did a simple experiment: in one bowl I chopped artichokes in plain water, in the second I chopped artichokes in water with chopped parsley stalks, on a plate – artichokes. I saw no difference in the two underwater artichokes, which held their color fairly well for an hour or more, much longer than the outdoor sample. I’ve come to the conclusion that water itself is quite effective at blocking contact with oxygen, and parsley does little.
Results: As predicted by Mr. McGee, no browning occurred while the slices were submerged. But what was more interesting was that after they were taken out of the water, these slices were browned a little, but much less than those in the lemon water solution.
Honey water:
Theory: According to the video from the American Test Kitchen below, honey contains a peptide compound that prevents polyphenol oxidase from activating the browning reaction. According to ATK, just thirty seconds of exposure to the honey solution is supposedly enough to keep the apple slices from darkening for a full twenty-four hours. We’ve covered this method before , and many of you have reported using it successfully.
Results: An hour after removing the honey from the solution, the apple slice was still flawless. However, after three hours, one brown spot appeared on the cut.
Conclusions:
A solution of honey was by far the best method for preventing browning on apple slices, followed by parsley stalks. (Parsley stalks are useless, however, unless you want the fruits or vegetables you cook to have a slight parsley flavor.) Oddly enough, slices soaked in plain water are better than those soaked in lemon water, which ultimately proved to be just as effective. how to leave slices outdoors.
So use honey, honey, and your apples will stay beautiful for several hours (but not twenty-four of them).