Title: The Mysterious Chocolate Cookies
Author: Hody, Sherby, Liv, Canny
Introduction
Most traditional chocolate chip cookie recipes start with some of the basic ingredients and technique: butter and sugar (a mixture of white sugar and brown sugar). Different results will be shown when different techniques are in used. It is suggested that different proportion of different types of sugar will lead to different structure and texture of the cookies. Therefore, in this experiment, we are going to investigate the effect of the sugar in the cookies, like the spreading of the cookies, the rise of the cookies and the texture of the cookies.
As mentioned before, sugar is one of the vital ingredients of the cookies, the type of sugar we use and its method of incorporation can have a significantly effect on the finished cookies. There are two main types of sugar and they are white sugar and brown sugar which have some structurally different. White sugar is crystallised sucrose, a disaccharide which consists of a fructose and a glucose linked together. It is also mildly hygroscopic which can retain moisture in their structure, and relatively has a neutral pH. On the other hand, brown sugar is mostly crystallised sucrose, bit it also contains a good amount of glucose and fructose, and trace minerals will present in it and give it flavour, and a slightly acidic pH. As it contains glucose and fructose, they are far more hygroscopic than sucrose, which means they have a higher ability to trap water in their structure relatively. So in this experiment, we will mainly focus this effect on the results of cookies.
The rise and spreading of the cookies
The rising of the cookie mainly due to the air bubbles produced in the baking process. As in this experiment, we are going to use baking soda as the "rising tool" for the cookies, the chemical reaction between the baking soda and the sugar matters. in the brown sugar, as it is slightly acidic, it will react with the baking soda to create more bubbles that leaven the cookies, so as to make it rises higher than the white sugar. Therefore, it is expected to have a cakier and tall cookie when brown sugar is in used. As the rise of cookies and the spreading of cookies is relative, if the spreading is large, the cookie will become thinner thus less rising.
sodium bicarbonate+acid --> carbon dioxide+water+salt
Texture and the appearance of the cookies (browning, cracking, chewiness and softness)
As mentioned before, the structure of white sugar is more difficult to hold moisture, compare to the ability to brown sugar. So it is expected that the white sugar-based cookies give up moisture more readily in the baking process, which end up more crisp.
Science behind cookies
X-ray microfocus computed tomography porosities and cell sizes increased with fat level, but cell size distribution, cell wall thickness and distribution were not affected by fat level, indicating that fat primarily incorporates air. In contrast, the sugar level influenced porosity, cell size, cell wall thickness and their relative distributions. Thus, the sucrose level, probably by affecting dough viscosity during baking, largely influences the baked cookie structure.
Sucrose is the most important sugar in cookie making. It delivers sweetness, influences the structural and textural properties of cookies, and is presumed to incorporate air into the fat during cookie dough preparation. Furthermore, in cookies, sucrose decreases dough viscosity (Maache-Rezzoug et al., 1998). During baking, the undissolved sugar progressively dissolves, and hence contributes to cookie spread (Hoseney, 1994). Other parameters that are influenced by the recipe’s sugar (level) include cookie hardness, crispness, colour, and volume.
Several authors ( Manohar and Rao, 1997 and Maache-Rezzoug et al., 1998) also observed a decrease in cookie dough hardness when more sugar was added. This can be related to an increase in the liquid-like character of the dough when more sucrose is present
Hypothesis
We hypothesise that more brown sugar we use, the cookies will rise higher when baking, and the texture will be more soft and moist. Also, we also hypothesise that more white sugar we use, the cookies will spread wider.
Amount of Sugar ( same amount in total)
|
More White sugar and Less Brown sugar
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Less white sugar and More Brown sugar
|
Spreading of the cookie
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More spread
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Less spread
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Rising of the cookie
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No obvious rising, thin
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Tall
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Browning of cookie
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Less browning
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More browning
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Texture of the cookie
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Crisp
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Moist and soft
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Method and materials
Materials:
• Unsalted butter: 225g
• Ice cube: 2 tablespoons
• All-purpose flour: 280g
• Baking soda: 3g
• Salt: 3 teaspoons
• Sugar: 280g
• Eggs: 2
• Vanilla extract: 2 teaspoons
• Chocolate chips: 225g
Method:
The cookies will be done in the following step:
1. Melt butter in a medium saucepan over medium-high heat. Cook, gently swirling pan constantly, until particles begin to turn golden brown and butter smells nutty, about 5 minutes. Remove from heat and continue swirling the pan until the butter is a rich brown, about 15 seconds longer. Transfer to a medium bowl, whisk in ice cube, transfer to refrigerator, and allow to cool completely, about 20 minutes, whisking occasionally. (Alternatively, whisk over an ice bath to hasten the process.)
2. Meanwhile, whisk together flour, baking soda, and salt in a large bowl. Place white sugar (the amount of sugar should be follow the table below), eggs, and vanilla extract in the bowl of a stand mixer fitted with the whisk attachment. Whisk on medium-high speed until mixture is pale brownish-yellow and falls off the whisk in thick ribbons when lifted, about 5 minutes.
White sugar (g)
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Brown sugar (g)
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Sample 1
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280
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0
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Sample 2
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140
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140
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Sample 3
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0
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280
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3. Fit paddle attachment onto mixer. When brown butter mixture has cooled (it should be just starting to turn opaque again and firm around the edges), add brown sugar and cooled brown butter to egg mixture in stand mixer. Mix on medium speed to combine, about 15 seconds. Add flour mixture and mix on low speed until just barely combined, with some dry flour still remaining, about 15 seconds. Add chocolate and mix on low speed until dough comes together, about 15 seconds longer.
4. When ready to bake, adjust oven racks to upper- and lower-middle positions and preheat oven to 325°F. Using a 1-ounce ice cream scoop or a spoon, place scoops of cookie dough onto a nonstick or parchment-lined baking sheet. Each ball should measure approximately 3 tablespoons in volume, and you should be able to fit 6 to 8 balls on each sheet. Tear each ball in half to reveal a rougher surface, then stick them back together with the rough sides facing outward. Transfer to oven and bake until golden brown around edges but still soft, 13 to 16 minutes, rotating pans back to front and top to bottom halfway through baking.
5. Remove baking sheets from oven. While cookies are still hot, sprinkle very lightly with coarse salt and gently press salt down to embed. Let cool for 2 minutes, then transfer cookies to a wire rack to cool completely.
6. Repeat steps 3 through 5 for remaining cookie dough. Allow cookies to cool completely before storing in an airtight container, plastic bag, or cookie jar at room temperature for up to 5 days.
7. Repeat step 2 to 6 with white sugar. Other portion of white and brown sugar can be used for further investigation.
8. Compare for the result for the appearance and the texture of the cookie.
Measurement:
Spreading of the cookies
Measure the diameter of each cookie by using a high accuracy ruler
The rise of the cookies
Measure the height of the cookie by using a high accuracy ruler
Texture and the appearance of the cookies (browning, cracking, chewiness and softness)
By observation and tasting
Reference
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