A banana would have made it perfect

January 30, 2007 6:08 AM

I just ate a peanut butter and honey sandwich on soft white bread. The bread on the honey side developed a kind of rough texture, almost like the bread had been lightly toasted on one side. Not unpleasant, but kind of odd. I noticed this when I was a kid and I've always wondered about it, and just now realized that someone here might know what's going on (I grew up in the South, and I have been known to eat molasses and butter sandwiches - the rough-texture thing doesn't happen with molasses, only honey. I don't know about other sugary syrup products).
posted by cilantro to food & drink (30 answers total)

Honey is hygroscopic, meaning it attracts water. I would assume that it's pulling water from the bread, which is essentially what a very light toasting will do. I'm a huge PB+H fan, and I've noticed this a number of times. I love it the texture.

Molasses is also hygroscopic, so I'd expect to see the same effect with molasses sandwiches, but if you're not, maybe it just doesn't attract water as well as honey does.
posted by uncleozzy at 6:26 AM on January 30, 2007

The bread was rough on the outside, immediately?

Sometimes with honey sandwiches that have been sitting for a while the honey kind of crystalizes, which leads to a texture I can best describe as a tooth. It's not quite crunchy, but it provides more resistance to your bite than it did before. I've always attributed this to a partial crystallization of the honey, although I've never known why the honey crystallizes in an hours old sandwich but not in the jar.
posted by OmieWise at 6:33 AM on January 30, 2007

My guess is that the bread absorbed water from the honey, leaving the honey supersaturated with sugar, which crystalized.
posted by cmiller at 6:34 AM on January 30, 2007

This is from Yahoo! Answers, but it makes sense anyway:

"It could be that the moisture in the honey is 'soaking' into your waffles. I have noticed similar effects using honey on white bread. Dextrose, a major sugar in honey, can spontaneously crystallize from any honeys in the form of its monohydrate. This sometimes occurs when the moisture level in honey is allowed to drop below a certain level."
posted by amro at 6:45 AM on January 30, 2007

I always figured it was the honey crystallizing, too, but I've got no proof. (best sandwich ever! - thanks for asking this.)
posted by vytae at 7:31 AM on January 30, 2007

Omie: I've had honey crystallize in the jar, although it takes place over months, not hours.

I find it interesting that the respondents so far pick up on the fact that honey is a highly concentrated sugar solution, but don't agree on what happens then: does the bread draw moisture from the honey, causing sugar to crystallize? Or does the honey draw moisture from the bread?

I don't know for sure. My gut is with the uncleozzy's answer. But I propose an experiment which might be able to determine which draws moisture from the other. Place a slice of bread and a small dish of honey in an airtight container, but do not place the honey on the bread. Whichever one is more hygroscopic should still be able to draw water from the other via water vapor. Leave for a day or so, then see whether a) sugar has crystallized in the honey, indicating that the bread is drawing moisture from the honey; or b) the bread has dried out to some extent, indicating that the honey is drawing moisture from the bread. To be really thorough, set up two other airtight containers as controls: one with bread only, and one with honey only.
posted by DevilsAdvocate at 7:37 AM on January 30, 2007

Omiewise - the bread is only rough on the inside, where it touches the honey.
As I am currently unemployed and often a little bored, I am considering performing the experiment laid out by DevilsAdvocate. If so, I will report back.
posted by cilantro at 8:05 AM on January 30, 2007

On the inside, then I vote for the crystallization, and I'll tell you why: taste! The reason what I've always thought of as a crystallized honey and pb sandwich is so good is because it tastes just a little bit of crystallized better than the already sublime honey and pb sandwich.

DA-I've had honey in the jar crystallize, too. I was talking more about the specific situation. I'm not sure the experiment will be conclusive (although it's worth a try) because of the moisture in the air inside the jar.
posted by OmieWise at 8:15 AM on January 30, 2007

Oops. Posted too fast. I would guess that the air will supply the honey with the moisture it needs to keep from crystallizing, but won't be enough for the bread to keep from getting stale (which, in any case, is not only a process of drying out).

I think you might get closer if you start to play around with lightly toasted bread and honey spread on it, leaving it to sit for various times in order to observe what happens.
posted by OmieWise at 8:19 AM on January 30, 2007

Of the two given scenarios, my guess is that the honey draws water from the bread. My rationale is that bread is fairly moist to begin with. In fact, many people throw a slice of bread in a bag with old cookies to soften them up. This occurs because the bread loses moisture that is absorbed by the cookies. Also consider what happens to bread after just an hour sitting out on the counter - it gets dry and stale very quickly, even in humid climates.
posted by chrisamiller at 8:37 AM on January 30, 2007

Chrisamiller, wouldn't you say that bread left on the counter for an hour gets wayyy drier than honey left on the counter for an hour?

Bread is spongey and absorbent. Honey is usually purchased in liquid form. I don't understand how anyone could suggest that it is the honey drawing moisture from the bread in this equation.

When honey is put on bread, the bread absorbs as much of its liquid content as possible, leaving a sugary residue. Once the moisture is in the bread, it evaporates more easily because the sponginess of the bread allows it greater exposure to the air.

While it certainly may be more complex than that, it is preposterous that the honey is actually absorbing moisture.
posted by hermitosis at 8:56 AM on January 30, 2007

In other words, bread is moist, but not moister than a liquid.
posted by hermitosis at 8:57 AM on January 30, 2007

I don't think crystalization or absorbing moisture has anything to do with it.

I think it comes from honey filling the cut open bubbles at the surface of the bread. When you then bite into the bread, your teeth have to squeeze the honey out of those bubbles, and as any one knows who's tried to squeeze honey out of a plastic bottle when you've cut the opening too small, the amount of pressure (force per square inch) needed rises very dramatically when you try to squeeze a viscous liquid through a smaller hole, particularly when the liquid 'wets' the material of the hole.
posted by jamjam at 9:42 AM on January 30, 2007

hermitosis-The fact that honey is a liquid doesn't really have anything to do with it. At issue is how honey acts around water, and it's definitely hygroscopic, which means that it's water attracting, even though it's a liquid.
posted by OmieWise at 9:47 AM on January 30, 2007

*head splode*

Well then sorry for my condescending tone. Is the honey really so hygroscopic that it could have this effect on bread within a few minutes? I still think there's a simpler answer.
posted by hermitosis at 10:04 AM on January 30, 2007

I'm arguing for the honey crystallization answer, too, so I'm with you on that. I'm not sure if honey is hygroscopic enough to "toast" bread or not, but no one else seems to be sure either.
posted by OmieWise at 10:19 AM on January 30, 2007

hermitosis, honey has been used to mummify small animals it is so good at drying things out.
posted by Megafly at 11:28 AM on January 30, 2007

I don't know what's happening, but it tasts sooooo gooood.

That is my favorite snack:

Fill up a glass of milk and place in freezer
Lightly toast some bread
Honey goes on now

wait 10 minutes for the honey to 'activate'

Put on butter and/or supercrunchy peanut butter (and more nuts on top)

Remove ice cold milk from freezer.

Enjoy!
posted by Monkey0nCrack at 11:58 AM on January 30, 2007 [1 favorite]

Honey is already a supersaturated solution of sugar, it's the other compounds from the bee spit (most of which came from the original pollen and nectar) that stops it crystallising. It also depends on the type of honey, mine isn't liquid so reacts with bread differently. The more solid the honey the more liquid it can absorb, but even liquid honey can suck up a great deal of water because the sugar content is so high.

Honey is not only hygroscopic, it's thixotropic (particularly the more solid honeys). This means that it changes from a solid to a liquid under pressure, which is why I can scrape some out and spread it despite it being solid in the jar. It turns back to more stable form on the bread because the pressure is removed, and this interaction is probably also involved in what you're describing. During that second physical change the honey may be removing water from the bread or adding water to the bread or crystallising or just incorporating breadcrumbs into it's honeyness (this is what seems to happen to mine, but again my honey is solid so there's a lot of pressure going on) or whatever is happening to create that interface that has such good mouth feel. Just putting bread and honey into a jar takes away all these physical interactions and isn't a good model.

The temperature of the honey also makes a big difference, since it's supersaturated and all. Heating it makes more sugar go itno solution, so putting honey onto warm toast is different than putting it on bread (I only ever eat it on toast). Too much heating, i.e. microwaving to make it more spreadable, changes the structure of the honey altogether and can't be undone (the sugars change, the bee spit stuff changes, enzyme activity is destroyed, and taste is very different). So if you're in the habit of warming your honey then that's another factor to consider.

So I'm not sure what is creating the change you describe. But I think it's more complex than just movement of water and there are a number of factors to consider.
posted by shelleycat at 2:21 PM on January 30, 2007 [1 favorite]

I think jamjam has the right idea. It seems similar to the way turgor pressure makes non woody plants stiff, except that instead of rigid cell walls full of water held in by osmotic pressure, you've got little cavities full of honey, held in by adhesion/friction. I don't know how much of an impact the thixotropic property of the honey would have, but it seems like it could be a factor.

Are there any physicists in the house? I JUST finished eating some peanut butter and honey on rye and I really want to know now...
posted by benign at 2:21 PM on January 30, 2007

Just putting bread and honey into a jar takes away all these physical interactions and isn't a good model.

Taking away all those physical interactions is exactly the point of putting bread and honey, not touching, in an airtight container! It allows us to separate potential "movement of water" explanations, which we would expect to still happen in such an experiment, from other physical causes, which would not happen. If the bread doesn't harden, and the honey doesn't crystallize, then the other factors you suggest are still on the table as possible explanations (or parts thereof).
posted by DevilsAdvocate at 3:43 PM on January 30, 2007

Just to throw something else into the mix : I've only ever noticed this with highly-processed honey e.g. the creamed plastic tub stuff. I've never noticed it with real honey.

Don't know exactly what that indicates, except that it supports the theory that it's due to honey crystallising at the honey-bread interface.

Damn you, now I want a honey and peanut paste sandwich. And I have no honey, peanut paste, or bread...
posted by Pinback at 3:49 PM on January 30, 2007

I don't know about other sugary syrup products

I can attest that the same delightful effect occurs with Fluffernutter.
posted by ottereroticist at 3:52 PM on January 30, 2007

Pinback, I can attest that it happens with "pure" honey. I get my honey from my father, who gets it straight from his two dozen hives. He slings it out, filters out the macroscopic chunks, and puts the honey in jars.

To others: Prithee, is bread more or less hygroscopic than honey? Which is more likely to give up water in a few seconds?
posted by cmiller at 8:12 PM on January 30, 2007

There has been formal research done about honey's water carrying capacity in the context of its use as a wound dressing. Sadly I lost the stack of papers I had about this a couple of years ago and haven't had time to look them up again (a quick search now shows I need better keywords and some time to think about it better, neither of which I have). I can no longer remember the actual numbers of how much liquid it can suck up. But it was a lot and I'm betting that honey is way more hygroscopic than bread. It would depend on the type of honey used as their sugar:water ratio differs, but probably not by enough to change this.
posted by shelleycat at 9:40 PM on January 30, 2007

MetaTalk Don't worry it's not bad
posted by Brainy at 10:46 PM on January 30, 2007

In the interests of science and breakfast, I just made two sandwiches - a Fluffernutter and a PB&H. Same peanut butter, same bread (Stop & Shop Light Italian, FWIW - a thin, white bread). At about the 5 minute mark neither sandwich demonstrates the toasty texture cilantro is talking about (and I am also familiar with). I will give the sandwiches another 30 minutes to "ripen" as I figure staleness of the bread will begin to be a factor after that.

Stay tuned for updates.
posted by Rock Steady at 6:41 AM on January 31, 2007

At about 10 minutes the bread facing the honey and the fluff was significantly drier than the bread facing the peanut butter. No palpable difference between the honey and the fluff though.

About the same situation at 15 minutes.
posted by Rock Steady at 6:55 AM on January 31, 2007

At 20 minutes neither sandwich has attained that crunchiness that we are talking about, and I am familiar with (in both PB&Hs and Fluffernutters). Perhaps there is some missing environmental factor? A humid environment? Sunlight? Being crammed into a lunch box for 4 hours?
posted by Rock Steady at 7:06 AM on January 31, 2007

Well, the bread is beginning to get stale around the edges now, so I'm eating my experiments. There was some definite crystallization of the honey within the PB&H sandwich, but little effect on the bread. Back to the cutting board, I guess.
posted by Rock Steady at 7:09 AM on January 31, 2007