Why should I throw out the floating beans?

July 26, 2009 9:54 AM

Quite a few times in recipes I've seen directions to put beans in water and discard any that float after a period of soaking (I've even heard this from you, AskMeFi). Now, I like beans. My question is: why can't I eat those?
posted by evhan to food & drink (9 answers total)

According to this you remove the "floaters" because they're gassy.
posted by dogmom at 10:08 AM on July 26, 2009 [1 favorite]

Does that mean you could collect all the floating ones and save them for a weapons-grade serving? Might be useful for farting contests. Or revenge.
posted by MsMolly at 10:19 AM on July 26, 2009

I discard those because it seems they are extra resistant to absorbing water (or else they wouldn't still be floating after all that soaking), which suggests that they will not cook at the same rate as the others, remaining hard even when the others are done.
posted by redfoxtail at 10:31 AM on July 26, 2009 [1 favorite]

Yeah, you throw them out because they've failed to de-gassify. Redfoxtail's explanation is actually the same point from a different direction.

I also endorse an televised experiment to confirm this per MsMolly's idea, mainly because I really want to see Adam and Jamie do it, so evhan, please forward this myth to asavage post-haste.

"Up next, an EXPLOSIVE television event."
posted by rokusan at 10:42 AM on July 26, 2009

Gas? That's bullshit.

If by gas you mean farting, the fart gas is produced by bacteria in your gut as they digest the oligosaccharides in the bean. Nothing to do with any sort of gas in the bean, or anything that correlates with floating.

Personally, I've never ever seen any beans float that haven't been held up by surface tension. I push the stragglers under, and I don't seem to suffer any problems thereby.

In fact, sometimes I cook beans without soaking (eg in a slow cooker, or when I have an extra hour up my sleeve). No way to detect floaters then, and it doesn't matter.

I do rinse them and pick them over, mind.
posted by i_am_joe's_spleen at 12:26 PM on July 26, 2009

Floaters remain floating because they're hollow to some degree. They can end up hollow because worms have bored into them and eaten the insides.

(This is excluding the occasional surface-tension floaters mentioned by i_am_joe's_spleen .)
posted by jocelmeow at 12:37 PM on July 26, 2009

Not saying it's necessary, just answering the part of the question on why people throw out floaters.

I agree you don't actually need to soak at all, though getting them all hydrated sure cuts down on cooking time. I sometimes don't either (though I wash them well) if I have extra cooking time or they're being cooked in some all-day simmer anyway (soup, rather than chili, for example). But that wasn't the question.

And I really do want to see Mythbusters deal with this.
posted by rokusan at 1:10 PM on July 26, 2009

To elaborate on several previous answers, Alton Brown puts it like so:

Typically, dried beans don't have to soak before they're cooked. But if the don't, they'll take twice as long to cook as soaked beans will. And if they're old beans it will take, like, three times longer. They only exception, really, are lentils and split peas which are small and fast cooing anyway. And of course, black beans can get by with a 3 to 4 hour soak, but everything else gets the long soak.

Dried beans, in this case a pound of Great Northerns, will double in volume during soaking. So, start with enough liquid to cover by a couple of inches. The actual amount of liquid does not matter as long as the beans stay submerged. If they swell up above the water line, they will explode. [pause] Okay, they won't explode. But it will be impossible to cook every bean in the batch evenly because the beans on the bottom will be more hydrated than the beans on the top.

Later in that episode's transcript, he explains that while the soaking liquid probably does extract some of the oligosaccharides, it also extracts the flavors you want, so you're much better off just cooking with the soaking solution and using alphagalactosidase (Beano) to combat the gas.
posted by jbrjake at 7:12 PM on July 26, 2009

You know how you can test eggs for rottenness by seeing if they float? I've always assumed that floating beans were a similar situation---they float because microbes were eating their insides.

Some websites also claim that floating beans are old, and thus take longer to cook (so they'll still be uncooked when most of your beans are done). That makes sense too.
posted by goingonit at 6:52 AM on July 28, 2009