http://blogs.smithsonianmag.com/science/2013/08/the-science-behind-honeys-eternal-shelf-life/
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. Through millennia, the
archeologists discover, the food remains unspoiled, an unmistakable
testament to the eternal shelf-life of honey.
There are a few other examples of foods that keep–indefinitely–in their
raw state: salt, sugar, dried rice are a few. But there's something
about honey; it can remain preserved in a completely edible form, and
while you wouldn't want to chow down on raw rice or straight salt, one
could ostensibly dip into a thousand year old jar of honey and enjoy it,
without preparation, as if it were a day old. Moreover, honey's
longevity lends it other properties–mainly medicinal–that other
resilient foods don't have. Which raises the question–what exactly makes
honey such a special food?
The answer is as complex as honey's flavor–you don't get a food source
with no expiration date without a whole slew of factors working in
perfect harmony.
The first comes from the chemical make-up of honey itself. Honey is,
first and foremost, a sugar. Sugars are hygroscopic, a term that means
they contain very little water in their natural state but can readily
suck in moisture if left unsealed. As Amina Harris, executive director
of the Honey and Pollination Center at the Robert Mondavi Institute at
Univeristy of California, Davis explains, "Honey in its natural form is
very low moisture. Very few bacteria or microorganisms can survive in an
environment like that, they just die. They're smothered by it,
essentially." What Harris points out represents an important feature of
honey's longevity: for honey to spoil, there needs to be something
inside of it that can spoil. With such an inhospitable environment,
organisms can't survive long enough within the jar of honey to have the
chance to spoil.
Honey is also naturally extremely acidic. "It has a pH that falls
between 3 and 4.5, approximately, and that acid will kill off almost
anything that wants to grow there," Harris explains. So bacteria and
spoil-ready organisms must look elsewhere for a home–the life expectancy
inside of honey is just too low.
But honey isn't the only hygroscopic food source out there. Molasses,
for example, which comes from the byproduct of cane sugar, is extremely
hygroscopic, and is acidic, though less so than honey (molasses has a pH
of around 5.5). And yet–although it may take a long time, as the sugar
cane product has a longer shelf-life than fresh produce, eventually
molasses will spoil.
So why does one sugar solution spoil, while another lasts indefinitely?
Enter bees.
"Bees are magical," Harris jokes. But there is certainly a special
alchemy that goes into honey. Nectar, the first material collected by
bees to make honey, is naturally very high in water–anywhere from 60-80
percent, by Harris' estimate. But through the process of making honey,
the bees play a large part in removing much of this moisture by flapping
their wings to literally dry out the nectar. On top of behavior, the
chemical makeup of a bees stomach also plays a large part in honey's
resilience. Bees have an enzyme in their stomachs called glucose oxidase
(PDF). When the bees regurgitate the nectar from their mouths into the
combs to make honey, this enzyme mixes with the nectar, breaking it down
into two by-products: gluconic acid and hydrogen peroxide. "Then,"
Harris explains, "hydrogen peroxide is the next thing that goes into
work against all these other bad things that could possibly grow."
For this reason, honey has been used for centuries as a medicinal
remedy. Because it's so thick, rejects any kind of growth and contains
hydrogen peroxide, it creates the perfect barrier against infection for
wounds. The earliest recorded use of honey for medicinal purposes comes
from Sumerian clay tablets, which state that honey was used in 30
percent of prescriptions. The ancient Egyptians used medicinal honey
regularly, making ointments to treat skin and eye diseases. "Honey was
used to cover a wound or a burn or a slash, or something like that,
because nothing could grow on it – so it was a natural bandage," Harris
explains.
What's more, when honey isn't sealed in a jar, it sucks in moisture.
"While it's drawing water out of the wound, which is how it might get
infected, it's letting off this very minute amount of hydrogen peroxide.
The amount of hydrogen peroxide comes off of honey is exactly what we
need–it's so small and so minute that it actually promotes healing." And
honey for healing open gashes is no longer just folk medicine–in the
past decade, Derma Sciences, a medical device company, has been
marketing and selling MEDIHONEY, bandages covered in honey used in
hospitals around the world.
If you buy your honey from the supermarket, that little plastic bottle
of golden nectar has been heated, strained and processed so that it
contains zero particulates, meaning that there's nothing in the liquid
for molecules to crystallize on, and your supermarket honey will look
the same for almost forever. If you buy your honey from a small-scale
vendor, however, certain particulates might remain, from pollen to
enzymes. With these particulates, the honey might crystallize, but don't
worry–if it's sealed, it's not spoiled and won't be for quite some time.
A jar of honey's seal, it turns out, is the final factor that's key to
honey's long shelf life, as exemplified by the storied millennia-old
Egyptian specimens. While honey is certainly a super-food, it isn't
supernatural–if you leave it out, unsealed in a humid environment, it
will spoil. As Harris explains, " As long as the lid stays on it and no
water is added to it, honey will not go bad. As soon as you add water to
it, it may go bad. Or if you open the lid, it may get more water in it
and it may go bad."
So if you're interested in keeping honey for hundreds of years, do what
the bees do and keep it sealed–a hard thing to do with this delicious treat!
Read more:
http://blogs.smithsonianmag.com/science/2013/08/the-science-behind-honeys-eternal-shelf-life/#ixzz2dA4bsbEc
Follow us: @SmithsonianMag on Twitter
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. Through millennia, the
archeologists discover, the food remains unspoiled, an unmistakable
testament to the eternal shelf-life of honey.
There are a few other examples of foods that keep–indefinitely–in their
raw state: salt, sugar, dried rice are a few. But there's something
about honey; it can remain preserved in a completely edible form, and
while you wouldn't want to chow down on raw rice or straight salt, one
could ostensibly dip into a thousand year old jar of honey and enjoy it,
without preparation, as if it were a day old. Moreover, honey's
longevity lends it other properties–mainly medicinal–that other
resilient foods don't have. Which raises the question–what exactly makes
honey such a special food?
The answer is as complex as honey's flavor–you don't get a food source
with no expiration date without a whole slew of factors working in
perfect harmony.
The first comes from the chemical make-up of honey itself. Honey is,
first and foremost, a sugar. Sugars are hygroscopic, a term that means
they contain very little water in their natural state but can readily
suck in moisture if left unsealed. As Amina Harris, executive director
of the Honey and Pollination Center at the Robert Mondavi Institute at
Univeristy of California, Davis explains, "Honey in its natural form is
very low moisture. Very few bacteria or microorganisms can survive in an
environment like that, they just die. They're smothered by it,
essentially." What Harris points out represents an important feature of
honey's longevity: for honey to spoil, there needs to be something
inside of it that can spoil. With such an inhospitable environment,
organisms can't survive long enough within the jar of honey to have the
chance to spoil.
Honey is also naturally extremely acidic. "It has a pH that falls
between 3 and 4.5, approximately, and that acid will kill off almost
anything that wants to grow there," Harris explains. So bacteria and
spoil-ready organisms must look elsewhere for a home–the life expectancy
inside of honey is just too low.
But honey isn't the only hygroscopic food source out there. Molasses,
for example, which comes from the byproduct of cane sugar, is extremely
hygroscopic, and is acidic, though less so than honey (molasses has a pH
of around 5.5). And yet–although it may take a long time, as the sugar
cane product has a longer shelf-life than fresh produce, eventually
molasses will spoil.
So why does one sugar solution spoil, while another lasts indefinitely?
Enter bees.
"Bees are magical," Harris jokes. But there is certainly a special
alchemy that goes into honey. Nectar, the first material collected by
bees to make honey, is naturally very high in water–anywhere from 60-80
percent, by Harris' estimate. But through the process of making honey,
the bees play a large part in removing much of this moisture by flapping
their wings to literally dry out the nectar. On top of behavior, the
chemical makeup of a bees stomach also plays a large part in honey's
resilience. Bees have an enzyme in their stomachs called glucose oxidase
(PDF). When the bees regurgitate the nectar from their mouths into the
combs to make honey, this enzyme mixes with the nectar, breaking it down
into two by-products: gluconic acid and hydrogen peroxide. "Then,"
Harris explains, "hydrogen peroxide is the next thing that goes into
work against all these other bad things that could possibly grow."
For this reason, honey has been used for centuries as a medicinal
remedy. Because it's so thick, rejects any kind of growth and contains
hydrogen peroxide, it creates the perfect barrier against infection for
wounds. The earliest recorded use of honey for medicinal purposes comes
from Sumerian clay tablets, which state that honey was used in 30
percent of prescriptions. The ancient Egyptians used medicinal honey
regularly, making ointments to treat skin and eye diseases. "Honey was
used to cover a wound or a burn or a slash, or something like that,
because nothing could grow on it – so it was a natural bandage," Harris
explains.
What's more, when honey isn't sealed in a jar, it sucks in moisture.
"While it's drawing water out of the wound, which is how it might get
infected, it's letting off this very minute amount of hydrogen peroxide.
The amount of hydrogen peroxide comes off of honey is exactly what we
need–it's so small and so minute that it actually promotes healing." And
honey for healing open gashes is no longer just folk medicine–in the
past decade, Derma Sciences, a medical device company, has been
marketing and selling MEDIHONEY, bandages covered in honey used in
hospitals around the world.
If you buy your honey from the supermarket, that little plastic bottle
of golden nectar has been heated, strained and processed so that it
contains zero particulates, meaning that there's nothing in the liquid
for molecules to crystallize on, and your supermarket honey will look
the same for almost forever. If you buy your honey from a small-scale
vendor, however, certain particulates might remain, from pollen to
enzymes. With these particulates, the honey might crystallize, but don't
worry–if it's sealed, it's not spoiled and won't be for quite some time.
A jar of honey's seal, it turns out, is the final factor that's key to
honey's long shelf life, as exemplified by the storied millennia-old
Egyptian specimens. While honey is certainly a super-food, it isn't
supernatural–if you leave it out, unsealed in a humid environment, it
will spoil. As Harris explains, " As long as the lid stays on it and no
water is added to it, honey will not go bad. As soon as you add water to
it, it may go bad. Or if you open the lid, it may get more water in it
and it may go bad."
So if you're interested in keeping honey for hundreds of years, do what
the bees do and keep it sealed–a hard thing to do with this delicious treat!
Read more:
http://blogs.smithsonianmag.com/science/2013/08/the-science-behind-honeys-eternal-shelf-life/#ixzz2dA4bsbEc
Follow us: @SmithsonianMag on Twitter
Comments
Post a Comment