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How the honey bee uses invertase

Honey bees produce a number of different enzymes that are important to their survival. One of these is invertase, the very same enzyme that is used in the baking industry. So what is invertase and what does it do?

First, let’s define a few words. In biochemistry, an enzyme is a substance that helps a biological process along. It’s a helper of sorts. Usually, an enzyme speeds up a reaction, so we call it a catalyst.

When you see the letters “ase” at the end of the word, it often means the thing is an enzyme. Sometimes enzymes are named after the substance they help to break apart. For example, lactase and lipase break down lactose and lipids. But sometimes enzymes are named after the things they do. Invertase, for instance, is named for the process of inverting (or separating) sucrose back into its component parts.

No invertase = no chocolate cherries

Invertase is very common in the natural world, especially in plants and various microorganisms. Plants like Japanese pear fruit, the common garden pea, and cereal oats are good sources of invertase. But the most common source by far is Saccharomyces cerevisiae, also known as ale yeast, bread yeast, or wine yeast.

So why do we want it? Well, invertase is an important ingredient in the production of candies and frostings. When added to regular sugar syrup, it breaks down (or inverts) the disaccharide sucrose into two monosaccharides, glucose and fructose. The resulting mixture, called invert sugar or invert syrup, helps keep baked good soft and moist.

Invertase is also the magic ingredient in chocolate-covered liquid cherries. Cherries are covered in a fondant that has been treated with a small bit of invertase and then coated with chocolate. Slowly, in a process that spans several days, the invertase breaks down the sucrose into the transparent, sweet, syrupy confection that surrounds the cherry and fills the hard chocolate shell. Awesome!

Honey bees produce their own invertase

The other big producer of invertase is the honey bee. And for good reason. To store honey in its runny liquid form, the bees use invertase to break down the sucrose portion of nectar. Sucrose is a common ingredient of nectar, but after the bees add invertase, the nectar is inverted into its two main components.

In addition, the inverted product becomes acidic because the fructose donates a proton during the reaction, causing it to behave like an acid. That is part of the reason honey is so acidic. Acidity is also enhanced by other bee-produced enzymes including glucose oxidase, which forms gluconic acid (among other things).

You don’t need to invert sugar for bees

I mention the acidity piece of this process because many times you will hear beekeepers say that table sugar isn’t good for bees because the pH of sugar is neutral whereas honey is acidic. Others say you have to invert the sugar with vinegar or lemon juice before it can be palatable to bees.

In truth, as soon as honey bees begin to eat sugar, the invertase they secrete both inverts and acidifies the food. They don’t even have to think about it. Just in the last ten years, I’ve seen a large shift in practice. Many beekeepers have gone from feeding concoctions of cooked sugar with added acids to feeding plain refined sugar straight out of the bag.

Don’t increase HMF if you don’t have to

One of the arguments for feeding plain sugar is that both heat and acid increase the production of hydroxymethylfurfural (HMF), a substance that is poisonous to bees. With that in mind, if we must feed a supplement due to a poor honey year, we’re better off feeding plain sugar (dry or in syrup) than feeding sugar we’ve tried to “improve.”

Sucrose has a bad name, I think, because we tend to focus on the relative amounts of glucose and fructose in our honey. Meanwhile, we forget that, until the bees began processing it, the nectar they collected may have been up to 55% sucrose. Sucrose is not a bad word in the honey bee world; it’s just one we’re not used to hearing.

Rusty
Honey Bee Suite

Chocolate-covered-cherries-are made with invertase.
Chocolate cherries are made with invertase which converts the sucrose into glucose and fructose, making a soft, runny, delicious mess. Pixabay public domain photo.

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Comments

Dan Stoffel
Reply

Speaking as a former biochemist, it’s nice to see an accurate and clear description of a biologic process. Congrats.

Rusty
Reply

Phew! I maintained credibility one more day! Thanks, Dan.

john connery
Reply

Wow, fascinating. And not just because now I know how those unsuspecting cherries are drown in that nasty goo before entombed in a chocolate prison, but because now I know how honey bees perform another miraculous and beautiful feat. Thanks

Bruce
Reply

Great post Rusty, thanks. I know you prefer to receive questions via the comment process. I have several questions about this topic. Shall I submit all questions in one comment, each question as a separate comment, or send an email? Thanks.

Rusty
Reply

Bruce,

The danger with email is the questions get buried. I just get too many for one person to handle. I almost always get to the comments, although I admit to answering the easier ones first. But if the overall length is intimidating, I put them off as long as possible. So if your questions are really long, you might want to split them up. I guess I’m sounding unreasonably picky, but I just know how I react to these things.

Donald
Reply

Thanks for the really cool article. You have a great talent for not over simplifying things, but just enough that I can read along comfortably with a dictionary. 🤙🏼 Seriously though, ChE here and really enjoy your articles.

Rusty
Reply

Donald,

Hmm. I have to think about this. But thanks, I think.

Donald
Reply

Sorry Rusty . . . the darned auto correct changed what I was trying to say, and my fingers hit send before I noticed. I was just trying to thank you for making thing so easy to read, and teaching me something new.

Rusty
Reply

Donald,

No problem, I thought your comment was funny. Made me think you were from UK.

John
Reply

Excellent article — very succinct and factual. Quick question: since nectar that the bees collect from flowers is mostly sucrose, and that syrup gets converted by way of this process into honey, which is mostly glucose and fructose, should I worry about harvesting frames that may have been on a hive when I was feeding sugar (sucrose) syrup? In other words, since nectar is mostly sucrose syrup and sugar syrup is all sucrose syrup, is there any reason to try avoiding honey that was made from artificial feeding?

Rusty
Reply

John,

Glucose and fructose from refined sugar is not honey because, by definition, honey is made from the bee-collected nectar of flowers. Nectar has hundreds or perhaps thousands of plant chemicals that impart the nuanced flavors and aromas that we recognize as honey. Refined sugar has none of those. So I would go out of my way to keep frames that contain syrup separate from those that contain honey/nectar. Plus, you don’t want to accidentally sell any honey with syrup in it as it’s totally illegal, as least in the US.

Tim
Reply

Hi Rusty,

If the enzyme invertase converts the sucrose into glucose and fructose please explain why some honey usually later in the season(wild flower) will crystallize overtime and honey collected in the spring ( Tulip poplar) will not? Also, I will liquify the crystallized honey back to liquid by putting jars in a 160 degree F water bath; does this temp harm the honey? Hope you have a great day!

Thanks,

Tim

Rusty
Reply

Tim,

The relative amounts of glucose and fructose determine whether honey crystallizes. Nectar contains sucrose, glucose, fructose and some other sugars like maltose. But after the sucrose is inverted, you would need to figure out the total amount of glucose and fructose in the honey. Glucose crystallizes quickly, but fructose does not. So if yours has lots of glucose, it will crystallize quickly. Lots of fructose, and it stays liquid. As a general rule, tree honey has more fructose and stays liquid longer than herbacious plants like wildflowers.

Regarding heat, here’s a quote from Extension.org: “Excessive heat can have detrimental effects on the nutritional value of honey. Heating up to 37°C (98.6 F) causes loss of nearly 200 components, part of which are antibacterial. Heating up to 40°C (104 F) destroys invertase, an important enzyme. Heating up to 50°C (122 F) for more than 48 hrs. turns the honey into caramel (the most valuable honey sugars become analogous to sugar). Heating honey higher than 140 degrees F for more than 2 hours will cause rapid degradation. Heating honey higher than 160 for any time period will cause rapid degradation and caramelization.” -John Skinner, University of Tennessee

I’ve also read that honey used as a wound dressing cannot be heated at all or it loses the main component that heals wounds, which is hydrogen peroxide. As a rule of thumb, heat and honey is a bad combination.

Mike Riter
Reply

There’re a lot of college entomology professors that don’t have the honey bee-related knowledge that you have.

Rusty
Reply

Mike,

Well, it’s easier to specialize in one bug than in zillions, right?

Mike Riter
Reply

In fact, very few do!

MarianA
Reply

Thanks for the chemistry refresher.

I have one quick question for you. At the local Beekeepers meeting someone stated “My sister told me I needed to use only organic white sugar when feeding my bees.”

Unless I’m mistaken, isn’t white sugar so completely processed as to be almost pure sucrose? How organic can it be (or not be)?

Rusty
Reply

Marian,

It’s been a few years since I researched this in depth, but if sugar is bleached and refined in the normal way, it cannot be called organic because they use chemicals (bleaching agents) in the process. So when we see organic sugar it is not refined in the traditional sense, and it is not completely white. Instead, it is made from cane juice from which the water has been evaporated out. In fact, it is called evaporated cane juice. Unless this has changed since I wrote about it, there is no such thing as pure white organic sugar (although it is close to white).

Evaporated cane juice is harder on bees than refined sugar because it has a higher ash content than standard bleached and refined sugar. The refining process removes virtually all impurities and that makes it the best thing you can feed your bees, especially when they are confined for the winter.

Maybe the person was confusing non-gmo refined sugar with organic sugar? I don’t know, but anything is possible. A lot of beekeepers are experts on sugar, it seems.

See “Is organic sugar better for bees?

MarianA
Reply

Thank you. I’ll pass this on.
As always, I learn something when I open your blog.

Tim
Reply

Rusty,

Thanks for the info on heat and honey; is there a way to turn crystalized honey back to liquid without causing degradation?

Thanks,

Tim

Rusty
Reply

Tim,

None that I know of. If I have some, I just use it as is. People pay to have their honey crystallized (creamed honey) so I don’t see an issue. Yes, the crystals are bigger when it crystallizes naturally, but it’s basically the same stuff. Or I feed it to bees. In the comb or out, it can really get a colony going in the spring. It’s a cultural preference more than anything, and Americans are particularly weird about it.

Tim
Reply

Thanks Rusty,

I’ll keep using it to make my bragget.

Tim

Moya
Reply

Hi Rusty,

Thank you for another informative article. Reading Johns comment regarding sugar syrup in honey frames… is there away to tell which frames the bees would have stored the sugar syrup in? Sorry it may be a dumb questions but I have often wondered that myself 🙂 Those chocolate covered cherries look delicious.

Rusty
Reply

Moya,

There is no easy way to tell. A chemical analysis can tell you if the honey contains cane sugar or corn syrup, but it is difficult to identify beet sugar. For a further explanation, see “Is your honey cut with sugar syrup?

The rule most beekeepers follow is that you never place honey supers meant for human consumption on a hive that is being fed syrup. The syrup comes off, before the supers go on. Since honey bees don’t seem to distinguish between syrup and nectar, we have to manage the placement of the honey supers.

Robert Holcombe
Reply

Happy New Year Rusty. I read your article with great appreciation for it’s clarity. I have been trying to understand the benefits of invert sugars versus white sugar or sucrose. I particularly like the introduction of bees using multiple enzymes. Your discussion left out the role of water in the invert process, whether by enzymes or low acid methods. I seem to be zeroing in on sugar syrups as the best alternate feed to honey. It supplies water without foraging under poor weather conditions. Can you provide your view of water’s role?

Rusty
Reply

Robert,

Bees need water to digest foods, just like any other animal. Syrup contains plenty of water. Hard sugar or crystals require additional water which, in winter, forms on the surface of the sugar, due to condensation of the bees’ breath. Syrup has limited usefulness in winter because the bees won’t consume it if the temperature of the syrup drops below 50 degrees F. If your area is not too cold syrup will work well in winter. If the weather is really cold, syrup is a gamble.

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