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Organic storage for organic apples

(article, Rebecca Kessler)

Despite being harvested only in autumn, apples are a year-round staple of the American fruit bowl, thanks to a post-harvest combination of refrigeration and chemicals. That’s great for conventionally grown apples, but what about organics? Come spring, their numbers dwindle. A new, cheap storage method could help keep the fruit bowl stocked with organic apples throughout the year.

Refrigeration is essential for extending the life of an apple. Trouble is, in cold storage many apple cultivars suffer scald, a skin discoloration that renders them unmarketable. To prevent scald, many growers rely on chemicals: diphenylamine, an antioxidant, or 1-methylcyclopropene, which inhibits production of the ripening hormone ethylene. The chemies do a good job keeping apples scald-free for up to a year in cold storage — but they don’t square with organic standards.

[%image apples float=left width=350 credit="Photo: iStockphoto/WoodyUpstate" caption="How apples are stored makes all the difference in their shelf life."]

Without the chemicals, organic apples last only about three months in cold storage. If they want to sell their apples later in the year, organic growers must store their fruit in special airtight “controlled atmosphere” storage chambers that maintain a cold, low-oxygen environment. That can keep apples marketable for more than 10 months, depending on the cultivar, but it’s mighty expensive.

Now Edna Pesis, a postharvest physiologist at the Israeli government’s Volcani Center in Bet Dagan, and several colleagues have come up with a cheap, organic way to store apples for up to eight months. They pre-treated Granny Smiths by subjecting them to a low-oxygen environment for one week at 20 degrees Celsius (68 degrees Fahrenheit) before putting them into regular cold storage. After eight months, only 10 percent of the apples had developed scald, compared to 100 percent of the apples that went into cold storage with no pre-treatment.

The technique was nearly as effective in preventing scald as treating apples with 1-methylcyclopropene. 

On the other hand, Pesis and her team conducted a taste test and found that 41 percent of the tasters preferred the chemically treated apples, saying the texture was better — though there was no difference in flavor. (The study was published in the Journal of the Science of Food and Agriculture.)

Because only nitrogen — which makes up most of the air we breathe — is used to create the low-oxygen environment, the apples are still perfectly organic. And because the technique is simple and cheap, it could help reduce the cost of organic apples. What’s more, Pesis says, variations on the method should be applicable to avocados, tomatoes, and perhaps other organic produce.

Anything that helps make organic food more affordable and available has got to be a good thing. But freshness is half the fun of organic food, and consumers may balk at the notion that their organic apples have been sitting around for eight months.

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