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Salmon with brown rice, nutmeg spinach and carrot and apple salad

April 25, 2010

…and some ways to stop your apple from browning


Serves two, or one for dinner and then a bento lunch box (very handy for when you forget to take a picture of your dinner)

Why do those apples go brown anyways?

Ingredients

2 salmon fillets

100- 200 g fresh spinach (looks like a lot, but remember that it shrinks)

Nutmeg

Salt and pepper

Butter

1 apple

2 medium sized carrots

Bring some lightly salted water to the boil. If you like some extra flavour, add some whole pepper corns and a bay leaf. When it boils, turn down the heat, plop the fish in and let it simmer for 10-ish minutes. Do not boil it, as that may cause the fish to break apart. I sprinkled the salmon with gomashio, a Japanese condiment made from roasted sesame seeds and salt.

Rinse the spinach and drain. Heat a little butter or oil in a deep frying  pan or a pot. Add the spinach, stir occasionally. The spinach is done when it has wilted completely, which should only take a minute or two. Season with salt, pepper and nutmeg.

Peel the apple and carrots and grate them. If you want a bit more flavour to it, you can add some lemon juice.

Serve with brown rice – I used short grain brown rice.

Lemon juice in the salad not only tastes good, it will also stop the grated apple from browning. Many people are aware of this trick – but do you know why it works?

Apples (as well as pears, bananas, avocado and potatoes to mention a few more) contain an enzyme called polyphenol oxidase and something called phenols. Normally these stay inside the apple’s cells, separated by membranes. Cutting the apple breaks the cells, and the enzymes and phenols start reacting with the oxygen in the air. It’s pretty much the same process that causes rust on metals.  This is the apple’s self defense system, as the brown surface is anti-bacterial and poisonous to insects, thus preventing nasty little microbes and bugs from OM NOM NOM-ing the fruit. Neat, huh?

We all know apples are pretty good at self defence anyways:

(badass apple shamelessly stolen from myfoodlooksfunny.com)

Now, there are two ways you can avoid the problem: reducing the availability of the oxygen or inactivating the enzymes.

The oxygen can be reduced by keeping the apple under water, by vacuum packing it or by wrapping it tightly in plastic wrap. Or even covering it with something else that will limit the oxygen availability, such as mayo if you’re making a Waldorf salad. (idea stolen from prof. Wolke’s article, see link below)

The enzymes can be inactivated by heat, i.e. cooking the apple, or by adding something acidic – which is where the lemon juice comes in. In short, the acid deforms the enzyme molecules, thus preventing them from hooking up with the phenols.

The browning can also be reduced by minimizing the destruction of the cells. Using a sharp knife will be better than using a blunt one, as well as making as few cuts as possible since that would make fewer surfaces. Grating makes the browning of epic proportions, something I saw when I opened the bento box the next day.

Sources and fun:

Lemon Juice Keeps the Brown Away – an article in The Washington Post by Robert L. Wolke, professor emeritus of chemistry at Pittsburgh University

This reply to a question by Barry Shell, creator of science.ca

Why Do Cut Apples Pears Bananas and Potatoes Turn Brown? By Anne Marie Helmenstine, Ph.D.

The food industry has other ways of reducing browning; there is an interesting article about that here: The control of enzymic browning in food

Favourite pseudoscience explanation found:

From Yahoo!Answers, a reply to the question

“Dude- why does an apple’s inside ‘meat’ stuff turn brown when exposed to the air?”:

[No, seriously! That really was the question]

– because microscopic bacteria eat it. thats why an apple with chemicals sprayed all over it doesn’t turn brown; because the natural bacteria are smart enough to stay away from it. hours go by, and its still crisp and white!

…what?

There are so many things wrong in this, I could go on forever. I am not even sure where to start!

The main issue I am having, is that this is a good example of how people tend to misunderstand the terms “chemical” and “natural”. Firstly, just about everything is chemical. Water is a chemical substance. So is air.

I guess what many people mean when they use the word “chemical” is something artificial and unnatural. And for some reason that must automatically mean that it’s a bad thing. I don’t get it. Sure, there are a lot of harmful substances that are made in a lab, but that goes for nature too. You wouldn’t eat an organically grown, un-fertilized, un-sprayed toadstool, would you?

Next question I guess would be how on earth bacteria could be “smart enough” to know the difference between natural and artificial chemicals? And then there’s the point about the brown colour actually not being caused by bacteria but rather being a defence against them.

I could go on. But I’m not going to. However, there might just be a follow-up to this post. Stay tuned!

Update

Yeah… I couldn’t stay away from this silly discussion. I actually decided to do a little experiment to see whether it is true that conventionally grown apples won’t go brown because “natural bacteria are smart enough to stay away from it”.

So I bought two apples; one organic and one conventional. Both were Royal Gala, imported from Chile. One was a tiny bit more ripe then the other, but the difference wasn’t large. Both were thoroughly rinsed and cut with the same blunt knife in order to mess up as many cells as possible. The knife and cutting board was cleaned before cutting the second apple. I diced 3/4 of the apple into cubes and kept the the remaining quarter. Then I waited to see if both would go brown.

The results?

This is the organic apple:

And this is the conventionally grown one:

…the organic apple actually stayed white longer, and was less brown after 10 minutes. Myth busted. Scary chemicals do not turn your apple into some sort of super mutant fruit that stays shiny and white forever.

Why there was such a difference between them I don’t know, but I’m tempted to think that it has nothing to do with being organic or conventional, but rather about the degree of ripeness or how it’s been stored during transport and in the shop. That’s just speculation though.

And of course: one little experiment done on two little apples does not mean that this is scientifically proven. You need a much larger sample and a more controlled environment in order to get proper, valid scientific results. However, I think this works very well as a reply to a pretty random and drastical statement about bacteria and chemicals and how the world works. Remember kids: it’s always a good idea to investigate things first and then make a statement about them. 😉

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3 Comments leave one →
  1. Tine permalink
    April 25, 2010 10:41 pm

    Hey, I would eat an organically grown, un-fertilized and un-sprayed toadstool. Or was that irony? I can never tell. (Nice blog)

  2. April 25, 2010 11:27 pm

    Haha, OK, feel free to do that, but do it outside my blog. You are ruining my point! 😉 (thanks!)

Trackbacks

  1. Post about apple browning updated! « Noms and Sciunce

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