Which type of apple turns brown the fastest?
October 22, 2006 10:00 PM   Subscribe

Calling all cooks: Which type of apple turns brown the fastest when sliced?

I could post this whole long explanation, but the short version is: I'm preparing a science experiment for a short school visit, and am looking for an apple that will turn as grossly brown as possible within an hour after being sliced in half! The Golden Delicious I just tried only got a few brown streaks, and I need more brown...
posted by easternblot to Food & Drink (15 answers total)
I'm sure someone will disagree but I don't think there's a real answer to this question as there are too many variables: how ripe the fruit is, what the air is like (temperature, amount of oxygen), even what the instrument you cut it with is made out of--all of these things will effect the process (which is known as oxidation, should you want to do more research).
posted by dobbs at 10:14 PM on October 22, 2006

Best answer: Try some of the sweeter red apples. It also seems to me that the apples that feel light for their size (as opposed to dense) have browned quickly for me in the past, but it's entirely possible I'm making that up.
posted by Addlepated at 10:15 PM on October 22, 2006

The yellow ones seem to go faster. Have you tried refridgerated vs. air temp?
posted by Pollomacho at 10:28 PM on October 22, 2006

Smack it once on a flat surface, it should turn brown faster. You could also see if salt or baking soda help the process along.
posted by BrotherCaine at 10:50 PM on October 22, 2006

Best answer: I've made two apple crisps in the past few weeks, and after slicing, Macintoshes seemed to brown up really quickly. I didn't get the full effect since I drizzled them in lemon juice, but they seemed to go quicker than Granny Smiths (the other kind I tried).
posted by anjamu at 10:56 PM on October 22, 2006

Best answer: As a kid, I remember eating wild macintoshs fresh off the tree, and they would brown immediately after biting into them, before you even took a second bite. Try some different kinds of macintoshs, maybe organic ones?
posted by stray at 11:06 PM on October 22, 2006

Also, the wild macintoshs were always quite small, so maybe size makes a difference.
posted by stray at 11:07 PM on October 22, 2006

Response by poster: Dobbs, good points. I'm actually going to be using the apple to explain the process of why it turns brown and why lemon juice stops it. Eventually I will be talking about melanin in skin, but melanin in apples is so much easier to show, and kids will be intrigued (I hope!) that the processes of tanning and rotting fruit are related.
So, because it's a quick demo, I will have the apples at room temperature, and cut them only once. I have no time to have 30 kids cut apples into many pieces, so it will all be chopchop in half, and one half will get lemon juice and the other half won't. I know it will be browner if I cut it more, but there is no time!
posted by easternblot at 11:08 PM on October 22, 2006

Response by poster: That's two votes for Macintoshes so far. I guess I'll put those on the grocery list for Tuesday and try it again with those and some others.
posted by easternblot at 11:09 PM on October 22, 2006

Best answer: Older apples brown faster. If they don't feel super-hard, they're older.
posted by flabdablet at 11:14 PM on October 22, 2006

Quote from fantastic book: "On Food and Cooking, the Science and Lore of the Kitchen".

A different kind of phenolic compound is responsible for the discolouration of fruits and vegetables when the tissue is cut or bruised. We are all familiar with the way apples, bananas, pears, eggplants, avocados and raw potatoes turn brwon when they are sliced or bitten into. This discoloration is the work of an enzyme konwn as polyphenoloxidase which oxidises phenolic compounds in the tissue and causes them to condense into brown or grey polymers. A similar kind of enzyme acting on a similar kind of compound is responsible for the browning of humans in the sun. Polyphenoloxidase is also present in mushrooms, apricots, pears, cherries, peaches and dates but it is missing from citrus fruits, melons and tomatoes. These fruits will eventually turn brown simply by the action of oxygen in the air, but the chemical reactions are much slower without polyphenoloxidase and it takes days for their color to change. In intact tissues, the enzyme and the phenolic compounds are segregated but when the cells are disrupted they come into contact with each other and react to form the dark pigments.

Here's the good bit.

Enzymatic browning can be discouraged by several means. Chilling the bood below about 40F (4C) will slow the enzyme down. Even better, boiling temperatures will destroy it, but this means cooking and so altering the flavor and texture of the fruit or vegetable. Chroide ions inihibit the enzyme, so that salt solutions will retard discolouration but again at the cost of flavour. Immersing hte cut pieces in cold water limits the enzyme's access to oxygen adn slows browning somewhat. VArious sulphur compounds combine iwht the phenolic substances and block their reaction with the enzyme, they are often applied commercially to dried fruit. The single handiest method is the old standby, lemon juice. The enzyme works only very slowly in highly acidic conditions. Apparently malic acid, which is found in apples and grapes is even more effective than the citric acidd of lemons but those fruits are not as concentrated source of of acid as lemons are, and tier own distinctive flavours would interfere more with the food to be protected.

Therefore, I suggest, the sweetest apples are more prone to browning than the sourer ones.
posted by b33j at 11:17 PM on October 22, 2006

Have you considered using a pear? They seem to go brown pretty quick. And a ripe, soft one.

What the heck - it would be cool if you'd buy one each of a bunch of different apples and see which browned fastest, seeing if you could find a relationship between sweetness and browiness. But maybe you have other things to do...

Side issue - there's a scene in the play "The Nerd" (by Larry Shue?) where the main characters are all sitting around a table, watching an apple core turn brown. Sometimes, we'll say to each other "Come on, apple core!" (a line from the play) remembering that scene. It was a funny play... I'll think of your project next time.
posted by amtho at 7:02 AM on October 23, 2006

You could slice the apple on a tray with a little H2O2 in it. Turn the cut side of the apple face down in the tray briefly. No one will know you've done anything, and if I'm correct, that would accelerate the oxidation of the phenolic compounds and make it brown almost instantly. The inhibitors of this(temp, Cl-, Na+, H+) should still work.

Generally, you want the apples with the lowest acidity.
posted by Mr. Gunn at 7:11 AM on October 23, 2006

My apple bakin' wife says that tart apples turn brown faster and something like Gravenstein could turn brown when cut within an hour (at least all our organic, ripe Gravensteins seem to go brown before a dish is even done being prepared).
posted by mathowie at 9:23 AM on October 23, 2006

Response by poster: Late, late follow up. I did the class visit a few weeks ago, and used a red delicious apple that I bought about 4 or 5 days before the visit to make sure it wouldn't be too fresh. I cut it open, put lemon juice on one half, and by the time I got to that point in my presentation the apple had been cut for an hour, and was already visibly turning brown on the unlemoned half. I showed them again at the end of our visit, when another hour had passed, and it was even browner at that point, while the lemoned half was still okay. I tried it at home before that, and waiting longer than two hours is pointless, because once the apple is dried out it doesn't get any browner.
They liked it, because a lot of them knew about the lemon juice trick, but never really compared what happened if you don't add lemon juice. I also did a banana-pigment experiment, where you scratch in a banana peel and within minutes the scratches turn brown, showing that pigment needs oxygen to be formed.
posted by easternblot at 6:00 PM on December 29, 2006

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