Monday, February 27, 2012

Apples, Potatoes, Storage and Gas?

About two years ago I read about a Korean industrial designer (Jihyun Ryou - her project website) who researched methods of storing vegetables with out a fridge. She referred to traditional oral knowledge and found many interesting ways that her ancestors used to keep fruit from going bad. One of her concepts was keeping apples and potatoes together and she explained that the ethylene gas that the apples produce while ripening delayed the sprouting of the potatoes. Was this true?

The biggest class we took this semester was Plant Physiology and of the many topics we studied in the course, one was plant hormones. As it turns out ethylene gas is a plant hormone involved in many physiological processes. I immediately remembered the designer and her concept and sought to find out if the oral knowledge on which she based her project had any scientific basis - will storing apples with potatoes really stop them from sprouting?!

Ethylene is used in ripening many fruits before we find them on our store shelves. Oranges, tomatoes, bananas and more are all picked green (it's easier to ship them that way) and gas-ripened to the desirable color. In this case it seemed that ethylene should make the potatoes go bad quicker as with other fruits, vegetables and even flowers.  So now the question was why does word of mouth Korean traditional knowledge contradict science? Do potatoes react differently to ethylene than other fruit? As my teacher was talking, I started Googling.

Soon enough I found this paper published in HortScience in 2003. Surprisingly the researchers deducted that ethylene can actually increase potatoes' shelf life, but only if they were kept in extremely low concentrations. This made sense to me - all the hormones we were studying about in class work in very low concentrations. I was getting closer.

I continued my search and discovered another paper that found that 1 kilogram of apples released about 1.7 ml of ethylene gas in 24 hours. This would mean that, if these apples and potatoes were stored in a sealed box, this would be WAY to much ethylene for what the original experiment called for, like 10,000 times more.

So what is a struggling plant science student to make of all this? Basically, it seems that storing apples with most fruits, especially in a sealed box or bag, will make them go bad quicker. Potatoes will also sprout quicker if surrounded by high concentrations of this gas, but, in the open kitchen air, the ethylene released by apples could just be the perfect low concentration of ethylene required to delay the potatoes from sprouting.

More than anything, the science behind all of this proves to me that students on a tight budget need to keep apples away from all their other fruits or do as I've been increasingly doing over this hellish finals period -  stick to pizza.

Jihyun Ryou and her concepts:


Photo credit Donna

4 comments:

  1. I tried posting a comment earlier, though the system had a difficulty determining what identity of mine to attribute the comment to.
    I just wan`ted to say, that science aint necessarily the only way to get results. working in the garden and in the kitchen supplies plenty of opportunities to learn about different effects caused by different circumstances. To me it`s obvious though, that if your potatoes sprout, and it`s rainy season - plant them, and let them complete their entire growth cycle!

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  2. I was just reading about the same designer and had the exact same question. I am glad you reference peer-reviewed research as all I have found so far have been anecdotes!

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  3. This old paper is worth a read. I'm pretty sure in the artists experiment, she used half exposed apples with ventilation for the potatoes. It seems possible this could have had the reduced sprouting. Apparently in the many research studies in this paper, ethylene had both effects on sprouting.

    Dual Effects of Ethylene on Potato Dormancy and Sprout Growth: http://www.plantphysiol.org/content/53/4/658.full.pdf

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  4. I've been finishing off my tomatoes in a paper bag with an apple ( from a friends garden) as much to keep them from the slugs as anything. Not only are the tomatoes ripening off nicely but the apple has outlasted all the others. Fluke or a two way effect?

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