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What Food Waste Isn't OK to Eat? I Asked a Scientist

Stop eating whole sunflower seeds, you monsters.
Photo via Flickr user Jeff Kubina.

Recently, at a dinner with friends, someone (who will remain unnamed) told me that someone (who will remain unnamed) that she knows eats corn by biting off chunks of the cob, chewing the kernels, sucking the juice (what juice?) out of the cob and then… spitting it out. This sounds, I'm sorry, revolting. And while this person doesn't actually eat the cob, it got us talking about what naturally-occurring food detritus we eat, which got me tweeting about that, which got lots of people to send me their avowed commitment to consuming skins, shells, cores, and other compostables. I don't think I like this very much! Although maybe that's wasteful, even unethical of me? Some people claimed that oft-discarded parts of produce are in fact where all the nutrients (or at least, fiber) reside. Could this be true? I only know how I feel viscerally about it, so I looped in an actual expert in the form of Dr. Bradley Bolling, a professor of Food Science at the University of Wisconsin-Madison.


Item: Apple Cores

Many people mentioned this. None with quite as much fervor as:

I say: Personally, I do sort of feel ashamed about my core queasiness. I steer far clear and recognize the waste in doing so. Fortunately, this is usually balanced out by a healthy dose of self-satisfaction that comes from having chosen an apple as a snack.

Dr. Bolling says: Apples seemed like a softball start; plenty of people eat them and it doesn't seem all that bad. "[The core] is safe to eat," Bolling says. "but not the seeds," Oh. I can't imagine most core-eaters are de-seeding their apples first. "Apple seeds contain cyanogenic glycosides which can cause harm if they are chewed or damaged." Swallowing them whole is fine. You'd need to eat hundreds, if not thousands, of apple seeds for it to be a real problem, but it is an opportunity for us core avoiders to regain some of the moral high ground.

Item: Sunflower seed shells

Somehow this, too, received multiple votes.

I say:

I see how you could get confused, since the shell is salted and baseball players with dexterous tongues

toss handfuls of them

into their mouths, but this sounds like a bunch of mouth splinters to me.

Dr. Bolling says:

"Avoid eating this, as hulls that are not well-chewed could possibly hurt the lining of the esophagus or intestine if they are sharp. Because shells are rich in fiber and have low moisture, there is some risk for clogging the intestine (fecal impaction), particularly in children. If consumed, hulls should be well-chewed, and consumed with adequate water."


Item: Kiwi Skins

Other people pointed out how this made them a more portable snack.

I say: The more kiwi the better. This one gets my vote.

Dr. Bolling says: "Kiwi skins are safe to eat, similar to peaches and apples…Eating the skin could add another 0.5-1.0 grams of fiber."

Item: Orange Peels

I say: My mother makes a lovely cranberry sauce that involves first candying orange rinds in a simple syrup before adding the cranberries, making them a deliciously tart addition to a Thanksgiving meal. But just cold off the counter? Hard pass.

Dr. Bolling says: "This should be safe to eat in moderation. There has been interest in the anti-cancer properties of flavonoids from orange peel. Most studies have been performed with extracts, not whole peels though." Get your flavonoid on, sir.

Item: Cherry Pits

Who doesn't eat peach skins?

I say: This one worries me. It's got a low gross-out factor but the reason cherries don't come with a choking hazard labels is because I'm pretty sure you're not supposed to eat the pits.

Dr. Bolling says: "Not safe without further processing. Similar to apple seed, the cherry seed contains amygdalin, which is a cyanogenic glycoside." Then he sent me a link to this story about a man gave himself cyanide poisoning by eating just three cherry seeds! And I thought choking was the problem.

Item: Shrimp Tails

I say: Shrimp are tiny devils of the sea who should be feared and not eaten.


Dr. Bolling says: "I just started eating shrimp shells last year because I found out they are digestible!" He also said that, just like other insect exoskeletons, shrimp tails contain "digestible chitin," which studies have shown is beneficial for gut health.

Item: Watermelon Rinds

I say: How?

Dr. Bolling says: "This is safe to eat, but make sure to clean thoroughly. The National Watermelon Promotion Board suggests stir-fried, stewed, or pickled rind."

So that's how.

Item: Peanut shells

I say: Out of all of the detritus mentioned this one just seems like it would taste the worst. The peanut to shell ratio is not strong enough to cancel out what I imagine is a chalky, uncomfortably fibrous eating experience.

Dr. Bolling says: "Most likely safe, in moderation. Peanut hulls can be used as animal feed and have high fiber content with low moisture, so GI obstruction would be a concern with high amounts of consumption. Also, since hulls are in contact with the soil, there could be a concern for aflatoxin contamination with improperly handled peanuts."

All of this is probably healthier than the Diet Coke I drank earlier though, so rock on with your gastrointestinal composting.