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The chemical secrets that help keep honey fresh for so long

bbc.com

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Re: The chemical secrets that help keep honey fresh for so long

#21

Post by kragen »

gerdesj wrote: post #19
kragen wrote: post #11

This story can be summarized as "Low water activity and low pH keep honey fresh permanently." The other 14 paragraphs are just filler. Moreover, even that summary is factually incorrect; low water activity and low pH don't come close to explaining honey's astounding shelf life, which amounts to centuries in many cases. https://en.wikipedia.org/wiki/Honey#Preservation in particular mentions gluconic acid and hydrogen…

"which amounts to centuries in many cases." Pretty sure I read about honey found in a Pharaoh's tomb - that's millennia, not centuries. Quick search: https://www.smithsonianmag.com/science-nature/the-science-be...

I edited "millennia" into "centuries" in my comment above because the Wikipedia article claimed those claims didn't pan out:

> (However, no edible honey has been found in Egyptian tombs; all such cases have been proven to be other substances or only chemical traces.[29])

...but the citation is from 01975.

The Smithsonian page is a great link! It mentions that the pH of honey is 3–4.5 (another crucial fact omitted from the BBC article) and mentions the peroxide, but not the methylglyoxal.

The Smithsonian article contains this link:

> Modern archeologists, excavating ancient Egyptian tombs, have often found something unexpected amongst the tombs’ artifacts: pots of honey, thousands of years old, and yet still preserved

which goes to a Google Books page I can't see (perhaps because I'm in Argentina) of a book from 02006 that is apparently about beekeeping, not archaeology, called "Letters from the Hive", published by Random House Children's Books.

The copy of the book that I've been able to get does talk extensively about the uses of honey in ancient Egypt, but, unless I missed it, doesn't mention pots of honey being found in tombs at all.

Even if so, it's unclear whether the book would have evidence posterior to Wikipedia's 01975 citation; it isn't the kind of book that cites its sources.

Re: The chemical secrets that help keep honey fresh for so long

#22

Post by jfengel »

kragen wrote: post #11

This story can be summarized as "Low water activity and low pH keep honey fresh permanently." The other 14 paragraphs are just filler. Moreover, even that summary is factually incorrect; low water activity and low pH don't come close to explaining honey's astounding shelf life, which amounts to centuries in many cases. https://en.wikipedia.org/wiki/Honey#Preservation in particular mentions gluconic acid and hydrogen…

I don't see why anything other than low water and pH are necessary. Stories about ultra long lasting honey come from the desert, which will dessicate it further.

(The stories about pyramid honey always imply that it's fresh and liquid. It's not. It's dried out and usually completely crystallized.)

There may be other effects on top of that, but if you made a sucrose solution thick enough it too will last forever.

Re: The chemical secrets that help keep honey fresh for so long

#23

Post by jfengel »

bdamm wrote: post #17
quibono wrote: post #15

Earlier quoted context omitted.

I've often wondered about this - is sunlight really all that's needed?

You can zap it in the microwave for 10-15 seconds, but I always feel terribly guilty for some inexplicable reason.

If you're looking to have a reason.... That's probably going to over-heat the honey, which comes at a cost to flavor.

But your grocery store honey is already pasteurized. That's more controlled than your microwave, so if you were looking to feel guilty about something, save it for when your neighbor gives you some from her hive next door.

Re: The chemical secrets that help keep honey fresh for so long

#24

Post by gerdesj »

kragen wrote: post #21
gerdesj wrote: post #19

Earlier quoted context omitted.

"which amounts to centuries in many cases." Pretty sure I read about honey found in a Pharaoh's tomb - that's millennia, not centuries. Quick search: https://www.smithsonianmag.com/science-nature/the-science-be...

I edited "millennia" into "centuries" in my comment above because the Wikipedia article claimed those claims didn't pan out: > (However, no edible honey has been found in Egyptian tombs; all such cases have been proven to be other substances or only chemical traces.[29]) ...but the citation is from 01975. The Smithsonian page is a great link! It mentions that the pH of honey is 3–4.5 (another crucial fact omitted fro…

I'm so sorry but I can't help myself: 01975 is the dialling code for somewhere in Aberdeenshire!

WP: "(However, no edible honey has been found in Egyptian tombs; all such cases have been proven to be other substances or only chemical traces.[29])"

[29] is https://gwern.net/doc/history/1975-leek.pdf - this does not look like a peer reviewed paper. They do look to be reputable and they refute some rubbish documented cases of ancient honey but not all of them.

I'm going to call out the WP article as being factually wanting on that point.

Re: The chemical secrets that help keep honey fresh for so long

#26

Post by kragen »

jfengel wrote: post #22
kragen wrote: post #11

This story can be summarized as "Low water activity and low pH keep honey fresh permanently." The other 14 paragraphs are just filler. Moreover, even that summary is factually incorrect; low water activity and low pH don't come close to explaining honey's astounding shelf life, which amounts to centuries in many cases. https://en.wikipedia.org/wiki/Honey#Preservation in particular mentions gluconic acid and hydrogen…

I don't see why anything other than low water and pH are necessary. Stories about ultra long lasting honey come from the desert, which will dessicate it further. (The stories about pyramid honey always imply that it's fresh and liquid. It's not. It's dried out and usually completely crystallized.) There may be other effects on top of that, but if you made a sucrose solution thick enough it too will last forever.

If you can get an aqueous solution of solids to completely crystallize (and sucrose does like to crystallize), it won't support microorganisms, but if it doesn't crystallize, it will have a critical "deliquescence relative humidity". When the relative humidity of the air is above the DRH†, the solution absorbs water from the air rather than giving up water to the air, and if there are crystals in it, they tend to shrink instead of growing.

Different solutes have different DRHs, but there are many of them whose affinity for water is so strong that their DRH is so low that under normal circumstances they never completely dry out. Some of them are commonly used as desiccants, such as lye, calcium chloride, and magnesium chloride. In general, mixing solutes tends to impede crystallization, so more heterogeneous mixtures like honey tend to have lower DRH than more homogeneous mixtures like pure sucrose.

(This is an engineering reason to add something like lemon juice when you make simple syrup: the citrate hydrolyzes some of the sucrose into glucose and fructose, greatly impeding crystallization and greatly improving your chances of having a pourable syrup when you want to use it next month.)

Under many circumstances, honey will eventually absorb enough water from the air by this mechanism to permit the growth of yeasts and bacteria. But it takes a remarkably long time.

______

† The DRH does vary with temperature, but in most cases only slightly over the human-survivable range, so you can say "CaCl₂ has a DRH of about 40%" and be correct enough for many purposes.

Re: The chemical secrets that help keep honey fresh for so long

#27

Post by kragen »

gerdesj wrote: post #24
kragen wrote: post #21

Earlier quoted context omitted.

I edited "millennia" into "centuries" in my comment above because the Wikipedia article claimed those claims didn't pan out: > (However, no edible honey has been found in Egyptian tombs; all such cases have been proven to be other substances or only chemical traces.[29]) ...but the citation is from 01975. The Smithsonian page is a great link! It mentions that the pH of honey is 3–4.5 (another crucial fact omitted fro…

I'm so sorry but I can't help myself: 01975 is the dialling code for somewhere in Aberdeenshire! WP: "(However, no edible honey has been found in Egyptian tombs; all such cases have been proven to be other substances or only chemical traces.[29])" [29] is https://gwern.net/doc/history/1975-leek.pdf - this does not look like a peer reviewed paper. They do look to be reputable and they refute some rubbish documented ca…

Ha, I had no idea about Aberdeenshire!

I agree that in 01975 peer review was not a given, but it does seem to be academic work, as opposed to a children's book.

Re: The chemical secrets that help keep honey fresh for so long

#28

Post by cypherpunks01 »

This article is missing what I think is a pretty important PSA on the topic of bacteria in honey:

Honey commonly contains small amounts of the anaerobic bacteria Clostridium botulinum, which causes botulism.

This is why you should not feed honey to infants, because their immune systems cannot safely handle any amount of it yet. Even though the levels apparently are small enough for the rest of humans to consume worry-free.

Re: The chemical secrets that help keep honey fresh for so long

#30

Post by Jun8 »

Same principle, reducing water activity (aw), is how Nutella keeps fresh for so long without refrigeration: its water activity is even lower than honey. Most bacteria need an aw of around 0.85 to thrive, Nutella’s aw is around 0.4, honey’s around 0.5-0.6. Peanut butter is 0.7, so it stays fresh for relatively long, too.

Here’s the definition of water activity from FDA:https://www.fda.gov/inspections-compliance-enforcement-and-c...

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