What Does Cookie Dough Resting Do?
What Does Cookie Dough Resting Do?
Salted Rye Chocolate Chip Cookies and An Experiment on Cookie Dough Resting
It’s been a crazy couple of days in LA with the weather. We’ve had rain and hail and even snow! Okay, the snow that fell in front of the house was a tablespoon; even that amount, I’ve exaggerated a little. The scene was a little different, a few blocks from the house. Our local park had some snow; most melted or were washed away by the rain. The hills and mountains are painted white with snow. Paddington got close to the snow at the park, but he was baffled, and unlike my previous dog, who would run out to play in it and eat it, he shook his head and walked away.
This week’s big recipe is my version of the famous Salted Rye Chocolate Chip Cookies from the now-shuttered San Francisco Cooking School. Everyone has their favorite chocolate chip cookie, and when I lived in Oakland, this was a cookie I looked forward to every time I visited the school. It’s got the earthy and nutty goodness of rye flour with a bit of rye whiskey as a flavor booster with a few sprinkles of flaky salt to play with the deeper flavors of the chocolate. BTW, you can use bourbon here, but unlike rye whiskey, bourbon is made from 51% corn and doesn’t provide the same flavor.
Now that we’re talking about cookies, it’s time to discuss the results of a cookie experiment I recently ran.
In many cookie recipes, including mine, there’s often a request to let freshly made cookie dough in the refrigerator “rest.” This rest is supposed to help with two things; improve flavor and texture.
Let’s look at the first claim – resting improves the flavor of cookie dough. The premise behind this claim assumes that this rest lets the flavor molecules inside the cookie distribute uniformly. Here’s the thing for molecules to move, they need energy. When we make cookie dough at room temperature, the heat produced during mixing and the mechanical process of folding the ingredients helps distribute the flavor molecules throughout the dough. Once the dough is prepared, it sits undisturbed in the refrigerator (or freezer, depending on the recipe). Refrigerating or freezing cookie dough significantly reduces the energy supplied to the molecules, and their movement slows down, and they don’t travel as much. Based on this, flavor molecules are unlikely to get redistributed significantly enough to make a noticeable difference in taste while the cookie dough rests at colder temperatures in the refrigerator or freezer without mechanical mixing. For these reasons, I’m not convinced by this claim.
Let’s look at the second claim – resting improves the texture of cookies.
This one makes more sense. Cookies have high quantities of sugar and fat and low quantities of water. Sugar makes cookies taste sweet, and fat improves the perception of flavor in the cookie by enhancing texture. At a more granular level, sugar and fat help reduce gluten formation in cookies by inserting themselves between the gluten-producing substances in the flour and improving the volume of the cookie. Sugar also reduces the gelatinization of starch (gelatinization is a fancier way of describing the swelling of starch granules in the presence of water and heat) during baking by raising the temperature at which this occurs. During baking, the undissolved sugar starts to dissolve, and the fat becomes more fluid; together, they help the cookie spread, and the diameter of the cookie will increase. Sugar also positively contributes to the cookie's color and crispiness and is responsible for the cracked pattern on baked cookies. Water acts as the solvent; it brings the ingredients together and provides moisture.
Some cookie recipes, like the one I tested in this experiment, use baking soda as a leavening agent. Baking soda also helps with browning by accelerating the caramelization and Maillard reactions during baking.
One more thing, rested cookie dough is usually baked straight from the refrigerator to the oven; this low temperature helps the cookie dough spread more slowly during baking.
Keeping all of this in mind, I wanted to see if and how resting time influenced the texture of the cookie.
First, I picked a cookie recipe to experiment with and selected this salted rye chocolate chip cookie to play around with. I didn’t fiddle with anything in the recipe; I kept everything the same to get a clearer picture of the effect of time. I used the same brand of flour and ingredients and made three sets of cookie dough, so I could also look at statistical significance (p values tend to give me a sense of comfort). I prepared the cookie dough, portioned it out and let it rest, wrapped it tightly in cling film in the refrigerator at 39F/4C, and pulled out batches to bake at different times; 0 hour (no rest), 1 hour, 3 hours, 16 hours, 1 day (24 hours) and 2 days (48 hours). I let the cookies cool (a challenging thing to do when it’s chocolate chip cookies) entirely to room temperature. Then I measured the cookies' diameter and the cookie dome's height (the height from the bottom to the top of the cookie at the center). I also made notes of the cracking pattern on the surface of the cookies. Here’s what I learned.
Cookie diameter: The average cookie diameter keeps increasing for up to 16 hours; after that, the diameter decreases and plateaus.
Cookie dome height: The average cookie dome height decreases at 16 hours. After that, it rose slightly and plateaus out. That rise at 16 hours was not statistically significant.
Cracking Patterns on the Cookie Surface: This is purely observational and subjective (it’s a little tricky to calculate this without proper lab equipment). Take a close look at the tray with the cookies. (BTW, I didn’t report the zero-hour (no rest time) values cracking patterns here, but they’re the same as the 1 hour. There was no difference).
The 48-hour/2-day rested cookie appears to show the most cracks, with many tiny cracks.
The 1-hour and 3-hour rested cookies show larger cracks, but they are fewer.
The 16-hour and 24-hour rested cookies show a balance of larger and tinier cracks.
What do the numbers mean?
As the cookie diameter increases, the cookie will be flatter and crispier, and a taller dome-shaped cookie should help with chewiness. Chocolate chip cookies are typically eaten warm within a few minutes straight out of the oven, and it made sense to test out the textures while they were warm. As predicted, the wider cookies had crispier edges, and the taller domed cookies had soft and chewier centers. The cracked pattern on the surface of the cookies is known to be directly affected by the amount of sugar in a recipe. The cracking pattern didn’t affect the taste perception, and my taster test group’s preferences lay in the middle – an equal divide – between the 16-hour and 24-hour/1-day rested cookie dough samples. From a taste and texture perspective, 16 hours appeared slightly crispier and less chewy. Shorter rest periods created chewier cookies, and longer extended rest periods over 16 hours produced a good balance of both textures.
Cookie dough is a complex mixture of different players in the form of ingredients. They’re all trying to work together and adapt to new conditions. In this case, they reach a critical point at 16 hours and then begin to move into a relaxed cookie texture bliss phase.
How long should you rest your cookies?
It will all depend on your preference and the recipe. Cookies are so personal to us, and so is our perception of textures. Some like crispy chocolate chip cookies, others prefer chewy, while others want both. Based on what these results demonstrated for this chocolate chip cookie recipe, for crispier cookies, aim for a 16-hour rest period or longer, and a shorter rest period for chewier cookies. For a good balance of both textures, a rest period of more than 16 hours works well.
There you have it! Cookie science.
P.S. A LOT of cookies were sacrificed for this.
More on cookies:
Have a great week, and stay tuned for this week’s menu suggestions.
xx
Nik