Monday, October 3, 2011

The Great Apple Browning Experiment

At last! I finally got around to doing an apple browning prevention experiment!  In order to see what works best to prevent the oxidization browning of sliced apples, I treated 6 Granny Smith apple slices each with a different thing suggested to prevent browning - plain water, apple juice, orange juice, lemon juice (in water), ginger ale, and Fruit Fresh, and left 1 alone. I labeled them and left them exposed to the air, photographing them throughout an 8 hour period. Here are the results:

Freshly cut. 
The apple I did nothing to has already started to brown. The one dipped in orange juice hasn't started browning, it just looks a bit like it because it has a slight tinge from the juice itself.


1 hour exposed to the air. 
The apple I did nothing to is quite browned, the one dipped in water slightly less. The apples dipped in juices have about the same degree of browning. Surprisingly, the apple dipped in ginger ale has browned as much as if not more than the one dipped in water! The Fruit Fresh apple has not changed.



4 hours exposure. 
This is probably what an apple I sliced in the morning would look like by lunch time for my kids. The apple I did nothing to has browned considerably - no surprise there. The apple dipped in ginger ale is a close second though! My kids wouldn't want to eat either of those. The apple dipped in water has browned less than the ginger ale one, but more than those dipped in juices. The juice apples are very similar - the lemon juice apple does seem to have browned a little bit less than the apple juice and orange juice ones - all 3 would probably still appeal to my sproutlets. The Fruit Fresh apple is almost unchanged :)



8 hrs after being sliced. The Fruit Fresh apple is the clear winner - it's still very fresh-looking 8 hours later, as advertised. The orange juice apple comes in second place, it browned visibly less than the lemon and apple juice ones. The apples dipped in water and ginger ale did not fare very well, by now they are nearly as browned as the apple that had nothing done to it.


Here are the apples in order of browning, most to least. Fruit Fresh wins!


In conclusion, I'd say that the best way to keep apples from browning is to use a product made to keep produce fresh. My jar of Fruit Fresh was pretty inexpensive (about $3),  can be stored in the cupboard, and leaves no taste on the fruit. If I didn't have that, a juice containing citric acid would be my next choice. Soda pop containing citric acid (like ginger ale or Sprite) would not be my choice - dipping the apple slices in plain water worked better, without adding any sugar, and is more practical for me since we don't regularly have soda pop in our fridge - but  even if we did I wouldn't want to open a whole bottle/can just to brush a little on my kids' fruit ;)

* I should also add that these apple were dipped, not soaked, in the product used. I have soaked apples in just plain water for 10 minutes or more and then sealed them in an airtight container and had them look perfectly fresh hours later. Preventing any air exposure - by soaking then sealing the apples in an airtight container -  is the best way - I don't always have time to soak though - sometimes I want to slice, pack, and go - and sometimes I am multi-tasking while making lunch and the apple slices may be exposed to air for a bit - and not all my containers keep all the air out either. That's why I tested these in open air.

9 comments:

  1. this is really interesting, I'm glad you shared this. I wonder if the type of apple makes a difference as well. My kids never eat granny smith's for lunch. I"d be curious which *type* does the best. Suggested flavors to try: gala, red/golden delicious, whatever else is in season now :)

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    1. Anonymous4/26/2014

      I did a project on this very recently.

      There is no indication that one kind of apple has more iron (which when combined with oxygen causes oxidation). The enzyme polyphenol oxidase (AKA phenolase or tyrosinase) comes in contact with oxygen. Browning is the reaction.

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    2. I thought read somewhere that darker-peeled apples browned more than lighter. If it's not because of iron content, might it be that some apple varieties bruise more easily? I have found that apples brown less when cut with a sharp knife vs a serrated one - less damage is done to the fruit - so less browning that way. I've still not tested different apple varieties - I'm a poor apple scientist :)

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  2. I hear that crushed vitamin C in some water works great like Fruit Fresh, with out all the extra preservatives.... I haven't tried it though

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  3. Kendra, I think I read somewhere that the dark-skinned apples like red delicious and macintosh brown more than the lighter gala and granny smith... that will be my next experiment I guess :)

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  4. Anonymous3/10/2015

    I keep a small spray bottle on my counter filled with Seasoned Rice Vinegar. I cut my apple, spritz the cut sides and put them in baggies. The seasoned rice vinegar is sweeter (which is why I use it), but you use so little it seems inconsequential. 1 tablespoon of seasoned rice vinegar is 25 calories, and you won't even come close to using that much.

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    1. Anonymous6/22/2017

      that is so cool, I will try that

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  5. Anonymous12/11/2016

    so good I am in fith grade and doing the same thing for science fair. you are helping me out alot

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