Playing with Emulsifiers- Analyzing the effects of switching between bananas and eggs

L.Berndt

AP Biology, Period 1

Miramonte High School, Orinda, CA

Abstract

I hypothesized that emulsifiers would change the cookies. Ultimately they did not change

the cookies quantitatively but they did change the taste (qualitative change).

Introduction

        Eggs and bananas are emulsifiers used in baking; emulsifiers help water and oil mix together. They are in many processed foods.The most common emulsifiers in manufactured foods are monoglycerides. Emulsifiers are in almost everything we eat, including but not limited to baked goods, sauces, salad dressings etc. Without emulsifiers our food would be significantly less appatizing. 

During emulsification, lipids are broken-up (the surface tension created between the opposing substances is destroyed) and dispersed throughout the water, while both of the substances, fat and water, keep their chemical makeup and characteristics. In some cases, this can happen by shaking- ie vinaigrette; the fat and water will mix together temporarily and quickly separate back out after sitting for a short period of time. It also happens more permanently when strongly mixed together with a whisk; however, if allowed to sit for a long period of time the ingredients will separate back out. That is why we keep things in the refrigerator (other than to keep food from spoiling) because the cold of the refrigerator keeps the dispersed bubbles of oil (fat) suspended in the water (Stella). Some think emulsification occurs because of the Surface Tension theory where emulsifiers work to surround the oil molecules and preventing them from joining together and conjugating at on top of the water. The emulsifier essentially breaks the surface tension that separates the liquids to begin with (Ansari).  

Emulsifiers are also used in medicine and to help fight fires. During fires, fighters use a aqueous surfactant solution to trap flammable fuels laying around the burning object (Dunlap).

        In this experiment, I tested the effect emulsifiers have on cookies. I hypothesized that using bananas as an emulsifier would make the cookies sweeter and more dense (aka greater mass). I also assumed that people would enjoy the cookies made with eggs significantly more, this being what they are used to.

Materials

Materials:                                                                                Quantity:

• Mixer with General Attachment (KitchenAid Standing Mixer)                        1
• Metal Bowl (Attachment to the KitchenAid Mixer)                                1
• Cookie trays (Aluminum)                                                        2
• Measuring cups (Glass)                                                        3
• Assortment of glass bowls (Different sizes. Only used to hold                 10

measured out ingredients)  

• Oven (Wolf Range)                                                                1

Ingredients:                                                                                Quantity:

With Egg:

• Butter (Pantry Essentials)                                                        227 g
• Sugar          (C&H)                                                                         250 g
• Brown Sugar (C&H)                                                                250 g
• Eggs (Lucerne)                                                                 2
• Vanilla        (MB Spices)                                                                15 mL
• All-Purpose Flour (King Arthur Flour)                                                281.25 g
• Salt (Baleine)                                                                        2.85 g
• Baking soda (Arm & Hammer)                                                2.85 g
• Chocolate chips (Kirklands)                                                         276.6 g

With banana:

• Butter (Pantry Essentials)                                                        277 g
• Sugar (C&H)                                                                        250 g
• Brown Sugar (C&H)                                                                250 g
• 1 Pureed Banana (Dole)                                                        122 g (without peel)
• Vanilla (MB Spices)                                                                15 mL
• Flour (King Arthur Flour)                                                        281.25 g
• Salt (Baleine)                                                                        2.85 g
• Baking soda (Arm & Hammer)                                                2.85 g
• Chocolate chips (Kirklands)                                                         276.6 g

Procedure

(must make two separate batches of cookies)

1. Preheat oven to 176.67 Degrees Celsius
2. Beat butter until smooth
3. Mix in both sugars
4. Mix in Emulsifier and vanilla
5. Mix in Dry ingredients (Flour, Salt and Baking Soda)
6. Mix in Chocolate Chips
7. Use a Tablespoon measure to make equal sized balls; place them two cm apart
8. Bake for 11 minutes

1. Note: cookies will not look finished, take them out regardless and let them cool

9. Use a ruler to measure the height and width of five cookies from each batch. Record your data.
10. Weigh each of those cookies and record your data
11. Repeat the experiment for the different emulsifier (either Banana or Eggs)

Results

Observations

Quantitative: 5 cookies made by the same dough scooper. Almost exactly the same size

• Diameter measured to longest point
• Height measured to the tallest point

Qualitative:

• Banana:

• Oily
• Looks lighter
• Looks less dense

• Eggs:

• Fluffier
• Looks denser
• Not oily

(Banana on the Left and Egg on the right)

• Essentially Taste Tests asked to a group of people

• They were asked to answer the following questions without knowing what the difference was (I knew which was which and wrote down their respective answer)

Summary:

When leaving the oven, both batches of cookies appeared to be the same. The two different emulsifiers didn’t affect their masses (they both averaged 18.714 grams). They also had relatively small impact of their height and diameter: Average height: Eggs: 1.38cm, Banana: 1.3cm;  Average diameter: Egg: 5.78cm, Banana: 6.12 cm. There was minor difference between the diameters (only 6%); however, this is most likely due to the inability to create perfectly exact cookie dough ball. Although the cookies appeared the same, they did not taste the same. When told that there was banana in the second batch, people could taste it’s presence; however, without knowing, many people just explained that it had a “fuller aftertaste.” It was surprising that more people thought the banana cookie was the better cookie. However, that may very well be due to the fact that I did not test a large enough group of people. I thought the banana cookie would be regarded as sweeter by everyone (due to the extra sugar the banana adds to the mix) but there were no telling or compelling results that showed this.  

Discussion

In the ead, my hypothesis was not correct. I assumed the bananas would have great impact on the cookies and they really didn’t qualitatively. Their masses, however, were exactly the same on average. The only difference my data shows me is that people tended to like the banana cookies more than the egg cookies. I predicted the opposite, but it is possible that because I handed everyone the banana cookie second it was the taste that was in their mouth and they therefore thought it was the better cookie. This is an example of potential error and could be fixed by testing one group with banana going first and another group with banana handed to them second. My experimenters also thought the banana cookies were crunchier (however this could have to do with error in the lab; see next paragraph). Ultimately, my experiment shows that the emulsifier will only affect taste, not even look, of a cookie. This is important to know because it allows cooks to use emulsifiers interchangeably in all their recipes without worrying about it changing the chemical makeup; however, it will change the taste.

I believe if I could perform this experiment without error, I would be able to make the cookies exactly the same when it comes to Quantitative reasoning. Some of the error that occurred during the lab I will now explain. One main problem was lack of unification. I didn’t stir the batters the same number of times or use the same aluminum pan to back them; at the same time the butter for the banana experiment was slightly more melted than the egg batch (because it sat out while the egg batch cooked) and could be apart of the reason the banana batter appeared more oily and shiny. These errors could be easily fixed by simply unifying all my materials. The measuring was also very imprecise. I used measuring cups instead of setting the ingredients on a scale and weighing them; a much more accurate way of collecting all the ingredients necessary. This error is also an easy fix; simply start weighing versus measure. The oven could also have distributed the heat unevenly while cooking. This definitely would affect my qualitative results; if the oven was hotter for the banana cookies because they were cooked second, the fact that they are crunchier means nothing (and its qualitative so it already means almost nothing). I also needed to test a larger group of people if I want to get more concrete qualitative data. It is possible that because my data pool was so small, the results I got are completely off of the actual qualitative answers.

A following experiment would need to have a negative control. This experiment didn’t test what would happen if there was no emulsifier at all, which would give insight to the importance of emulsifiers and

References

Ansari, Hamid V. A deliberation on the surface tension theory. Issue brief no.

16. Isfahan,: Department of Physics, Isfahan University, Isfahan, IRAN,

2007. Print.  

Berndt, Debbie. "Cookie Recipe." 1950. Raw data.

Dunlap Wilson, Peggy M., and Carl F. Brandner. "Aqueous surfactant solutions

which exhibit ultra-low tensions at the oil-water interface." ScienceDirect.

ScienceDirect, July 1977. Web. 17 Sept. 2013.

<http://www.sciencedirect.com/science/article/pii/0021979777903113>.

Stella Culinary. Stella Culinary, n.d. Web. 16 Sept. 2013.

<https://stellaculinary.com/podcasts/video/what-is-an-emulsion-a-cooks-guide>.