Sugar in Muffins

In an effort to be health-conscious, it’s tempting to just reduce the sugar in a recipe when we bake. Often, the result is still plenty sweet. But sugar is not just a sweetener, and merely using less sugar will lead to drastic changes in a baked good’s texture and structure. In this post, we’ll explore some of these changes in muffins.

Experiment Overview

Goal: To see and taste differences in structure, texture, and color in muffins with different amounts of sugar
Recipe: Best Ever Muffins from AllRecipes
Method: Mix and divide the dry ingredients except for sugar. Add half, two-thirds, or twice the sugar called for in the recipe to each portion and combine. Add the wet ingredients to each batch of dry ingredients. Bake, cool, and taste.
Results: As sugar content increased, we noticed
– More batter
– Darker color
– Sweeter taste
– Bigger muffins, smoother tops, and a more open crumb
– More tender, then chewy texture
– Moister muffins
– Longer shelf life
Conclusions: Sugar plays crucial roles in the structure and texture of baked goods. Removing sugar from a recipe with no other alterations will drastically change the bake.

Testing Method

Ingredients and Equipment

• 2 c (250 g) Baker’s Corner bleached all-purpose flour
• 1 Tbsp Baker’s Corner double-acting baking powder
• 1/2 tsp Stonemill iodized salt
• 3/4 c (157 g) sugar, divided
• 1 c (244 g) Friendly Farms Vitamin D whole milk
• 1 Goldhen large egg, beaten
• 1/4 c (56 g) Carlini vegetable oil
• Whisk
• Rubber spatula
• 12-cup muffin pan lined with cupcake liners

Baking the muffins

1. Preheat oven to 400°F.
2. Whisk the flour, baking powder, and salt together in a large bowl (265 g total). Divide into four portions (66 g each). To each portion, add 19, 25, 38, or 75 g of sugar and whisk well. These contain one-half, two-thirds, equal, and double the sugar written in the recipe, respectively. (Baker’s percentages are 30%, 40%, 60%, and 120%.)
3. In a separate bowl, whisk the milk, egg, and vegetable oil together (348 g total). Pour one-fourth (87 g) of the wet ingredients into each portion of dry ingredients. Fold the wet and dry ingredients together until just combined.
4. Divide each portion of batter into three muffin cups. Muffins from each condition each weigh 56, 58, 63, and 74 g, respectively.
5. Bake for 21 minutes. Cool on a wire rack for 5 minutes, then remove muffins from pan to cool completely.

Results

To better understand some of these results, I suggest reading through the last few posts about sugar: the introduction, its roles in baking with water, and its other roles in baking.

More batter

The more sugar the batter contained, the greater its mass and volume. As you can see in the muffin pan below, when I divided each portion of batter equally among its three muffin cups, the batters containing more sugar filled the cups higher. They also weighed more. Sugar adds physical substance to the batter, and the more batter there is, the bigger the muffins.

Darker color

After baking, the muffins also differed in their color. As shown below, the more sugar the muffins contained, the darker their color. Sugar contributes to browning through the chemical reactions of caramelization and Maillard reactions, so the more sugar in the muffins, the more browning reactions occurred, and the darker the color.

Sweeter taste

Unsurprisingly, the more sugar the muffins contained, the sweeter they were. While the double-sugar muffins were definitely sweeter than the controls, they weren’t overpowering. I enjoyed the taste of both the double-sugar and the control muffins. The two-thirds-sugar muffins were bland, and the half-sugar muffins were actually salty—not what I would expect from a muffin.

Although I preferred the control and double-sugar muffins in this batch, a typical muffin recipe contains other flavorings and mix-ins that change the taste of the muffin. For example, if I’d added chocolate chips, the double-sugar muffin might have been too sweet. Ultimately, the sweetness of the sugar should balance the other flavors.

Bigger muffins, smoother tops, and a more open crumb

As you can see, after baking, the more sugar the muffin contained, the bigger it became. This difference was not merely a consequence of having more batter: notice how much more the muffins rose and expanded. The double-sugar muffins even developed a nice lip over the edge of the pan.

As we discussed, sugar prevents baked goods from setting. As the muffin batter bakes, sugar’s chemical structure makes it attract water molecules so strongly that it steals them away from proteins and starch. Structure molecules such as gluten, egg proteins, and starch need water to coagulate, gelatinize, and solidify the baked good. With less water available to them, these processes cannot occur at lower temperatures, and the batter must get hotter before it sets. The longer the batter takes to set, the more it rises as gases and expand. Thus, the more sugar the muffin batter contains, the more it expands before it solidifies, and the bigger the muffin.

We can also see this delayed structure in the crumb of the muffins, shown below. The less sugar the muffin contained, the tighter its crumb. Because the air bubbles didn’t have time to expand before the structure around them solidified, they didn’t create many air pockets large enough for us to see. The irregular ones we do see are actually like the tunnels we saw in overmixed muffins, where air bubbles trapped in tough gluten build up so much pressure that they explode through the solidifying muffin, leaving tunnels in their wake. On the other hand, the double-sugar muffin has lots of air pockets that form an intricate, almost lace-like crumb. The extra sugar gave the air bubbles plenty of time to expand in the batter before it set.

We can also see sugar’s tenderizing effect in the cracks on the muffin tops. The double-sugar muffins are barely cracked, while the other ones have dramatic splits. These formed when the uncooked interiors of the muffins expanded and burst through the top after the top of the muffin had already set. In the double-sugar muffins, the top crust set later, so when the muffin rose, the insides did not have a top crust to crack open.

More tender texture, then chewy with extra crunch

The timing of structure formation in the muffins also affected the muffins’ textures. Interestingly, the double-sugar muffin was not tender and fluffy. It was chewy. The extra sugar most likely held on to so much water that the muffin developed a chewy consistency, much as the high hygroscopicity of honey lends it to chewy baked goods. Furthermore, the double-sugar muffin had a crunchy crust, not just on top, but all around the sides, suggesting that sugar crystals had formed there. Before I baked the batter, I rubbed it between my fingers, and I hadn’t felt any rough undissolved sugar crystals. It is more likely that the muffin lost so much water as it baked that some sugar crystallized as it cooled.

When the muffins were fresh out of the oven, the textures of the half- and two-thirds-sugar muffins weren’t too different than that of the control muffin. They were pleasantly loose, like a warm biscuit. However, as the muffins sat through the afternoon, the muffins with less sugar toughened in texture. Their structure molecules hadn’t been separated by expanding air bubbles as the muffin baked. Biting through a compacted muffin is much harder than biting through a light and airy muffin, like the difference between a squished and normal slice of bread. The reason this difference was not immediately apparent is because muffins (and all baked goods) continue to undergo chemical changes as they cool and stale. These changes include the bonding and solidifying of starch molecules, which changes the muffin texture from soft to hard.

Moister muffins

These differences in texture were exacerbated as time passed, especially because the muffins began to dry out. Even though the muffins sat in airtight containers, some water evaporated. The low-sugar muffins became chalky and dry by the next morning. The control and double-sugar muffins, though drier than they were the day before, maintained a pleasant texture.

Sugar attracts water even as the muffins sit. The double-sugar muffins had plenty of sugar to keep its water molecules for a nice, moist muffin, but without sugar, the half- and two-thirds-sugar muffins did not keep well.

Longer shelf life

Not only did the low-sugar muffins stale more quickly, but they also molded before the control and double-sugar muffins. I left the muffins in an airtight container on the kitchen counter at a warm room temperature, and after about two weeks, I glanced inside and found mold on the low-sugar muffins. I threw them out (I wasn’t trying to grow mold), so I didn’t follow the progression of the mold, but the double-sugar muffins probably would have lasted the longest. (As I write this, I wonder if I should have continued to observe the mold for the sake of science.)

High concentrations of sugar inhibit microbial growth because the sugar attracts water. Microbes like mold and disease-causing bacteria need water to live, but if it’s held by the sugar, they can’t access it. The low-sugar muffins left more water available to the mold, so it reproduced and grew there first.

Conclusions

Sugar plays a critical role in the chemical reactions that make muffins. Although the loss of volume, color, and sweetness in the two-thirds-sugar muffin did not make it unpalatable, its texture was undesirable. Batters with reduced sugar will still set into a muffin, but the resulting bake will be drastically different than the one intended by the recipe developer. Without any other changes to the recipe, the loss of sugar makes a tougher, drier muffin with a shorter shelf life.

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References

Corriher, S. O. Bakewise; Scribner: New York, 2008.

Figoni, P. How Baking Works, 3rd ed.; John Wiley & Sons, Inc.: Hoboken, 2011.