What Is the Sweetener Actually Doing?
We often think of sugar as the ingredient that makes a cookie sweet. But sugar contributes much more than sweetness.
One of the properties that matters in baking is hygroscopicity.
What “Hygroscopic” Really Means
A hygroscopic substance attracts and holds water from its surroundings. Sugars do this because their molecular structures contain hydroxyl (–OH) groups, which can form bonds with water.
But the strength of that attraction varies depending on the type of sugar and its molecular structure.
How Sugars Differ
- Fructose — Highly hygroscopic. Readily attracts and retains moisture.
- Glucose — Hygroscopic, but generally less so than fructose.
- Sucrose — Less hygroscopic than fructose and glucose; readily forms crystals.
- Lactose — Relatively low hygroscopicity; readily crystallizes.
Sugar alcohols such as sorbitol can be even more hygroscopic than many common sugars.
These differences affect what happens when sugars become part of a dough. They can influence how moisture is distributed, how much moisture remains associated with the sugar, and how the sugar behaves as the dough is heated and cooled.
Why This Matters in a Cookie
Greater hygroscopicity can contribute to:
- softer or chewier textures
- greater moisture retention
- a softer or tackier surface, particularly in humid conditions
Lower hygroscopicity can contribute to:
- less moisture being held by the sugar
- greater tendency toward crystallization
- different surface and structural characteristics
But hygroscopicity is only part of the story.
The amount of water that comes into the dough with the sweetener matters too.
Honey and Coconut Sugar
Honey contains primarily fructose and glucose, both of which are hygroscopic, and it brings substantial water into the dough.
Coconut sugar is predominantly sucrose, although it also contains glucose, fructose, and other components.
So when we move from coconut sugar to honey, we aren’t simply changing the sweetener. We are changing the types of sugars present, their relative hygroscopicity, and the amount of water entering the dough with the sweetener.
Now consider what that means for the rest of the formula.
With honey:
sugars + substantial water → fluid system
With coconut sugar:
concentrated sugars + much less water → solid system
That difference changes the environment in which the other ingredients have to work.
It can affect:
- how much water enters the dough
- how moisture moves through the dough
- how coconut flour absorbs available water
- how the sugars interact with proteins and other ingredients
- how the dough responds to heat
- how quickly the cookie’s structure develops
- how the finished cookie behaves after cooling
This is why changing a sweetener can require changes elsewhere in the formula.
The interesting question isn’t simply:
Which sweetener tastes better?
It’s:
What did we change when we changed the sweetener—and what does the rest of the cookie have to do differently because of it?