Water in Shortbread

Shortbread is a delicious cookie. Buttery and rich, it’s a treat whose decadence belies its simplicity. A basic shortbread contains only butter, sugar, and flour, but these ingredients create a crumbly dough that can be difficult to work with. To give our dough more structure, we can add a touch of water to the flour to develop gluten before it’s combined with the butter. In this post, we’ll explore how the extra water affects the cookie, from mixing bowl to oven into our mouths.

Experiment Overview

Goal: To make shortbread cookie dough more cohesive without significantly changing the cookie’s texture
Recipe: 3 Ingredient Shortbread Cookies from Bigger Bolder Baking
Method: Cream the butter and sugar together and divide into six. Add water to six portions of flour, combine flours with butter mixtures, roll into logs, and chill. Slice, chill again, bake, and eat.
Results: As we added more water to the flour, we noticed
– Less mixing time
– Stiffer, then stickier dough
– More spread during baking
– Uneven surfaces
– Chewier cookies
Conclusions: We can encourage gluten development in shortbread cookies by adding water. Ultimately, the amount to add will depend on other ingredients in the recipe and the desired texture.

Testing Method

Ingredients and Equipment

  • 2 c (300 g) Baker’s Corner all-purpose flour, divided
  • 1 c (240 g) Countryside Creamery unsalted butter, softened
  • 1/2 c (60 g) Domino’s confectioner’s sugar
  • Water
  • 5-speed KitchenAid hand mixer
  • Baking sheet lined with parchment

Baking the Cookies

  1. Measure out 6 portions of all-purpose flour, each 1/3 c (50 g).
  2. Cream the butter and sugar together until pale and fluffy. Divide the total (274 g) into 6 portions (45 g each).
  3. To each portion of flour, add the following volumes of water and stir right before combining the flour with the butter: 0 tsp, 1/4 tsp, 1/2 tsp, 1 tsp, 2 tsp, 1 Tbsp.
  4. Beat the flour with the butter mixture until a dough forms.
  5. Turn out each portion of cookie dough onto plastic wrap and roll into a log with a diameter of 1 1/2 inches.
  6. Refrigerate logs for 50 minutes.
  7. Preheat oven to 350°F. Slice each log into 4 rounds about 1/2-inch thick and place on prepared baking sheet. Refrigerate the cookies until the oven reaches temperature.
  8. Bake for about 17 minutes. Remove to rack to cool.

Results

To better understand some of these results, I suggest reading the introduction to gluten and the section on fats in “Gluten in the Kitchen.”

Dough with 1/4 tsp water partway through mixing
Shortbread cookie dough with 1/4 tsp additional water became sandy before coming together into a dough.

Less mixing time

As the amount of water increased, the cookie dough formed more quickly. The control (no water) and 1-tsp doughs first became very sandy before coming together into doughs. The photo above shows the small bits in the 1/4-tsp dough right before it started to come together. As the water increased beyond 1 tsp, the flour maintained noticeably larger chunks before forming a cohesive dough.

Dough forms when the gluten network extends across flour chunks to hold them together. As we discussed in the introduction, gluten forms when we hydrate proteins in the flour and they form bonds to each other. In the control cookies, butter is the sole source of water (butter contains about 16-18% water), but it is also about 80% fat. When the dry flour meets the butter, it’s more likely to come into contact with the fat. So before the flour absorbs much water, the fat coats the flour particles and separates them from each other, forming the sandy mixture shown in the picture above. It is only after the flour is separated that the proteins develop more gluten. The fine, separated flour particles have a lot more surface area, which gives them a greater chance of finding the water molecules from the butter around them. When this finally happens, enough gluten forms to bring the separate particles together into a cohesive dough.

As we add more water to the flour, the flour becomes less dependent on butter for water. In fact, it’s already formed some gluten by the time it’s added to the butter. The flour doesn’t need as much surface area to absorb water, so the dough forms more before the mixture becomes sandy.

Cookie doughs containing different amounts of water
Shortbread cookie dough became stiffer, then sticker with the addition of more water.

Stiffer, then stickier dough

The doughs’ consistencies also changed as we added more water. The doughs with 1/2 and 1 tsp additional water were noticeably stiffer than the control and quite nice to work with. Beyond 1 tsp, however, the doughs became soft, more like bread dough than cookie dough. As you can see in the photo above, the 1-Tbsp dough was a little shaggy.

The more water we add to the flour, the more gluten forms in the dough. With 1/2 and 1 tsp water, enough gluten developed to lend the dough noticeable structure and strength. Beyond that, the additional gluten started to render the dough sticky and soft.

Baked cookies
Cookies with more water spread more.
Insides of shortbread cookies
Cookies with more water retained more water inside.

More spread during baking

As you can see in the photos above, the cookies with water spread more as they baked. The spread was more obvious in earlier tests that added more than two tablespoons of water to each third-cup portion of flour, but you can see the spread in the angled edges and flatness of the 1-Tbsp cookies. The spread is consistent with the stickier dough we observed. Wetter dough tends to spread more because it flows a little bit, like liquid. The more water in the dough, the more it has spread by the time the cookies have set. You can also see the difference inside the cookie, with the darker coloring inside the cookies with more water. The color homogenized disappeared after a day or so, suggesting that the cookies with more water hadn’t dried as much as the control cookies in the oven.

Baked cookies
Cookies with more water had pockmarked, uneven surfaces.

Uneven surfaces

The cookies with more water, especially with 2 tsp and 1 Tbsp, also developed pockmarked surfaces as they baked. As discussed above, as we added more water, the flour particles stayed in larger chunks before coming together to form a cohesive dough. This may have resulted in uneven incorporation of the flour and butter. In the oven, as the dough warmed up, the larger chunks of butter melted and soaked into the surrounding cookie, leaving holes where there was butter without much flour to hold it in place.

Chewier cookies

As more water was added to the cookies, the cookies developed a different texture. Some tasters described it as “mushy” as opposed to the crunchy crumbliness of the control cookies. I found the texture almost bread-like and doughy by the 1-Tbsp dough. In fact, the first time I tried this experiment, I added more than 2 Tbsp water to a portion of flour. Those cookies were tough, rubbery, and awful.

Compared against the control, the textural difference was noticeable (though not egregious) by the 1/2-tsp dough, though when one tester went straight down the line of increasing water content, she could not determine any differences among the cookies. It was only after comparing the control to the 1-Tbsp cookies that she knew what to look for.

As we discussed in the introduction, gluten contributes structure and texture to the final baked good. The control cookies, with minimal gluten, crumble and melt in the mouth. As water and gluten increase, however, the cookies develop a noticeable chew. The taste testers loved the texture of the control cookies. Not so much the ones with more water.

Conclusions

The original recipe we tested created a delicious shortbread cookie that did not need the structural help from additional water. However, some crumbly doughs could use a drop of extra water to be easier to work without sacrificing texture. Shirley Corriher uses this strategy in her wedding cookies, which are essentially shortbread cookies with lots of nuts. Since mix-ins hinder gluten structure, the water helps hold the dough together while still producing a wonderfully crumbly cookie. Or, if you wanted to try making shortbread cookies with brown butter, you might consider adding water to replace the water lost from the butter.

From our taste tests, we’d feel comfortable adding up to 1/2 tsp water to 1/3 c flour for minimal change in texture (make sure to scale up—that’s 1 1/2 tsp for every cup of flour). But ultimately, the amount depends on the texture you’re aiming for. I will say that adding 7 tsp of water to 1/3 c dough (that’s 3/8 c water per cup of flour) in my first attempt at this experiment was way too much. The result was dense and tough. The cookie (if you could call it that) probably would have bounced it I threw it on the ground.

References

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

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



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