Melted vs. Room Temperature Butter in Chocolate Chip Cookies

J. Shen, K. Sorenson

AP Biology, 2°

Miramonte High School, Orinda, CA

ABSTRACT

        Butter can be found as an ingredient in many cookies. Solid butter effectively traps air bubbles and holds the structure of the cookie. In this experiment, the use of room temperature, solid butter was compared to the use of heated, melted butter in cookies to find the effect on height, diameter, and density. The results obtained support the conclusion that melted butter leads to a shorter height, larger diameter, and higher density.

1. INTRODUCTION

Many cookie recipes call for some sort of fat, often butter, margarine, oil, or another. This is because fats are the components of the cookie that determine structure and create air bubbles, affecting the texture, moisture, and density of the cookie.

Butter is a combination of triglycerides of many different fatty acids. Regular butter is about 30% oleic acid (monounsaturated), CH3(CH2)7CH=CH(CH2)7COOH; about 20% myristic acid (saturated), CH3(CH2)12COOH; about 15% palmitic acid (saturated), CH3(CH2)14COOH; about 15% stearic acid (saturated), CH3(CH2)16COOH; and small amounts of many other saturated and unsaturated fats.4 A large majority of butter is saturated fat, meaning that butter is solid at room temperature.

When sugar and butter are beat together, the sugar crystals cut into the fat, holding in and creating air bubbles. In addition, beating the butter traps small pockets of air within the fat.3 Liquid or melted fats tend not to trap air bubbles as well as solid fats do. When butter is melted, the bonds between the fats are broken. The consistency of melted butter is extremely difficult to incorporate with sugar into something light.1 Solid butter has the ability to trap air that holds the “structure” of the cookie - what bakers call the shape and framework of flour, butter, sugar, and eggs.2

The recipe (Riki’s Chocolate Chip Cookies5) originally calls for room temperature butter. This means that the original recipe was designed to use room temperature butter. To compare the results of melted butter vs. room temperature butter cookies, two sets of batches were made for each melted butter cookies and room temperature cookies. Because melted butter cannot hold air bubbles better, the melted butter cookies should be shorter in height, wider in radius, and denser.

2. MATERIALS

2.1 Edible Materials (x4 because four total batches)5

Butter                                                                225 g                        

White sugar (C&H Sugar)                                        300 mL                

Dark brown sugar (C&H Brown Sugar)                        250 mL                

Egg (Home grown)                                                   1.5 units                

Vanilla        (Kirkland Signature)                                        10 mL                        

White all-purpose flour (Safeway)                                700 mL                

Salt (Safeway)                                                        7.5 mL                        

Baking soda (Arm & Hammer)                                7.5 mL

Chocolate chips (Nestle Toll House)                                700 mL

2.2 Non-edible Materials5 

2 Measuring spoons (Kitchen Aid)                                10 mL each

2 Cookie sheets                                                 50 cm x 40 cm

1 Mixer (Kitchen Aid, Heavy Duty)

1 Convection oven (Thermador)

1 Rubber spatula (Kitchen Aid)        

3 Measuring cups (Kitchen Aid)                                500 mL each

1 Centimeter ruler (Westcott)                                        1 meter long

12 Toothpicks (Diamond brand)

3. PROCEDURE

Adapted from Riki’s Chocolate Chip Cookies5

0)        [melt butter] MELTED BUTTER: 57.6°C, ROOM TEMPERATURE BUTTER: 20.2°C

a)        Beat butter for 30 seconds.

b)        Add eggs and vanilla. Beat for 1.5 minutes.

c)        Add white sugar, dark brown sugar, salt, and soda. Beat for 20 seconds.

d)        Add flour. Beat for 30 seconds.

e)        Add chocolate chips. Beat for 25 seconds.

f)        Make 20 mL dough balls using measuring spoons. Place 6 to 7 cm apart on cookie sheet.

g)        Bake at 165°C for 10 minutes.

h)        Remove from sheet and let cool.

i)        To measure height: Stick toothpick perpendicular to cookie at highest point and push down completely. Make mark where the top of cookie meets toothpick. Remove toothpick and measure from bottom tip to bottom of mark using ruler. See Figure 1a-b.

j)        To measure radius: Place cookie on ruler, with one end of longest diameter at the zero and measure. See Figure 1c.

k)        To measure mass: Place paper towel sheet on scale and tare. Then place cookie on paper towel on scale and record mass. See Figure 1d-e.

4. RESULTS

Figure 2 is a photo comparing a sample of each of the two kinds of cookies.

Table 1 compares the results of baking cookies under the same conditions, with the exception of the state of butter. Results recorded included height, diameter, radius, mass, volume, and density. To find radius, the diameter was divided by two. Assuming the cookie is roughly cylindrical, the volume was found by V=πr2h. The density was found by dividing the mass by the volume (d=m/V).

Table 2 compares the average height, diameter, radius, mass, volume, and density of the solid butter vs. melted butter cookies. Procedures for finding all results are described above.

Figure 3 shows the height of the sample cookies, then the average height of each kind.  Figure 4 shows the densities of the cookies side-by-side, then the average densities. Figure 5 shows the radii of the cookies, then the average radii of each type of cookie.

Figure 2

Quantitative Data on Solid and Melted Butter Cookies

Table 1

Average Quantitative Data of Solid vs. Melted Butter

        Table 2 (units see Table 1)                                                                                                        Figure 3

                        Figure 4

                                                                                                                                Figure 5

        In general, the data supports the original hypotheses. The height of the melted butter cookies was 12.7% shorter (average solid butter cookie height: 1.97 cm vs average melted butter cookie height: 1.74 cm). The radius of the melted butter cookies was 3.3% longer (average solid butter cookie radius: 3.86 cm vs. average melted butter radius: 3.99 cm). Finally, the density of the melted butter cookies was 9.7% larger (average solid butter cookie density: .41 g/cm3 vs average melted butter cookie density: .45 g/cm3).

5. DISCUSSION

        In this experiment, the aim was to measure the difference in height, radius, and density when using two different consistencies of butter. The hypotheses included shorter, wider, and less dense cookies in the melted, heated butter batches.

        As shown in Fig. 3, with the exception of the second cookie trial, each solid butter cookie was taller than its melted butter cookie counterpart. In fact, the average heights of the samples reflect the same conclusion. The average height of the melted butter cookie (1.74 cm) was 12.7% shorter than the average height of the solid butter cookie (1.97 cm).

        The density of the cookies were also quite different between the melted and solid butter cookies. In Fig. 4, samples 1, 2, and 5 show that melted butter produced denser cookies, and this is again reflected in the average densities. The average density of the melted butter cookie (0.45 g/cm3) was 9.7% larger than the average density of the solid butter cookie (0.41 g/cm3).

        Finally, the radii of the cookies are compared in Fig. 5. Out of the six sets of cookies, samples 3, 4, and 6 show that melted butter cookies have larger radii. The average radii of each kind of cookie also portrays this effect. The average radius of the melted butter cookie (3.99 cm) is 3.3% longer than the average radius of its counterpart, the solid butter cookie (3.86 cm).

        These results, in addition to validating the hypotheses, suggest that the reasoning is also correct. Likely, the melted butter, which has historically been shown to trap air bubbles less efficiently than solid butter1, was unable to help the cookies rise, giving them a shorter height. Similarly, since the height could not expand, and the amount of cookie dough was consistent, the volume had to expand the other way, so the radius became larger. Also, the idea that butter is less efficient at trapping air bubbles contributes to the results that show that melted butter cookies are denser. There are less air bubbles, creating a denser cookie.

        Unfortunately, as with any experiment, there are sources of error to consider. For instance, the sample size of the cookies was not substantial. This could be improved by simply measuring more cookies. In addition, the volume is not a perfect calculation. In real life, the surface of a cookie is not a circle, much less the volume a cylinder. Therefore, the volume calculations were not quite as accurate as perhaps they should have been, and thereby, the density was not accurate as it depended on the results of the volume calculation. Using water displacement in a measuring cup or beaker would have been more accurate. Finally, it was a nearly 33°C day, and the air conditioning in the kitchen was not efficient. This could have affected the room temperature butter as we baked and brought it closer to the temperature of the melted butter. In this case, the differences between the cookies will not be as drastic, as the temperatures will be more similar.

        Future baking scientists should focus on the qualitative side of the use of melted and solid butter. The evidence collected for this experiment strongly suggests that melted butter will create shorter, wider, and denser cookies. However, this does not speak for the quality of the cookie. To hone in on the purpose of experimental baking (making things taste good), the next experiments should focus more on qualitative evaluations.

REFERENCES

1"Food for Today." Cookie Chemistry. Web. 10 Sept. 2013.

2Moskin, Julia. "Butter Holds the Secret to Cookies That Sing." New York Times

     [New York] 16 Dec. 2008. Print.

3Paula Deen Test Kitchen. "Creaming 101." Pauladeen.com. 5 Dec. 2010. Web. 10 Sept. 2013.  

4Senese, Fred. "What is the chemical structure of butter?" General Chemistry

     Online! Web. 9 Sept. 2013.<http://antoine.frostburg.edu/>

5Sorenson, Riki. "Riki's Chocolate Chip Cookie."