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
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