Experiment 1
To test the influence of different types of sugars (Brown Sugar or White Sugar) to the hardness and spreadability of cookies.
Hypothesis: Cookies made with Brown sugar will rise higher, the appearance will be thicker, and the texture will be softer; Cookies made with White sugar will spread wider, the appearance will be thinner, and the texture will be harder and crispier.
Experiment 2
To test the influence of the amount of sugar (Brown Sugar) added to the hardness and spreadability of cookies.
Hypothesis: The more the sugar the cookie contained, the more spreadable and soft the cookie.
Ingredients & Equipment
- Sugar
- Unsalted butter
- All-purpose flour
- Chocolate chips
- Baking soda
- Salt
- Vanilla extract
- Eggs
- Electric mixer
- Electronic balance
- Spatula
- Bowls
- Ruler
- Knife
- Toothpicks
Variables
Experiment 1
Controlled Variables:
Independent variables:
Sample B: All Brown Sugar (80g)
Sample C: White Sugar (40g) + Brown Sugar (40g)
Experiment 2
Controlled Variables:
- Brand, Type and Amount of all the ingredients expect Sugar
- Amount of Sugar added (80 g)
- Size of each dough balls before putting into the oven (1 tablespoon) -diameter of each dough is 2cm
- Duration for Baking (10 mins)
- Temperature of the Oven (180°C)
- The ruler, knife and length of toothpicks used in each measurement
- The force used for inserting the toothpick measured by weight balance(100g force)
Independent variables:
- Types of Sugar (Brown VS White)
Dependent Variable:
- Texture (Harder and Crispier VS Softer)
- Rising (Thinner VS Taller)
- Spreadability
Samples:
Sample A: All White Sugar (80g)Sample B: All Brown Sugar (80g)
Sample C: White Sugar (40g) + Brown Sugar (40g)
Experiment 2
Controlled Variables:
Independent variables:
- Brand, Type and Amount of all the ingredients expect Sugar
- Types of Sugar (Brown sugar)
- Size of each dough balls before putting into the oven (1 tablespoon)-diameter of each dough is 2cm
- Duration for Baking (10 mins)
- Temperature of the Oven (180°C)
- The ruler, knife and length of toothpicks used in each measurement
- The force used for inserting the toothpick measured by weight balance(100g force) and the force of knife by gravity through free fall into the cookies
Independent variables:
- Amount of Sugar (20g, 50g, 80g)
Dependent Variable:
- Texture (Harder and Crispier VS Softer)
- Rising (Thinner VS Taller)
- Spreadability
Samples:
Result of the Experiment
Experiment 1
Measurement of spreadability - measuring the size by ruler
Measurement of spreadability - measuring the size by ruler
1) How the types of sugar affect the spreadability of cookies
Sample A
|
Sample B
|
Sample C
| |
Diameter
|
6.8cm
|
5.4cm
|
5.7cm
|
2) How the types of sugar affect the rising of cookies
Sample A
|
Sample B
|
Sample C
| |
Height
|
0.9cm
|
2.0cm
|
1.3cm
|
Measurement of hardness - measuring the depth of insertion of toothpick through enforcing 100g force by weight balance
PHOTO OF 100g weight balance
3) How the types of sugar affect the texture(hardness)of cookies
Sample A
|
Sample B
|
Sample C
| |
delta H
|
0.45cm
|
1.2cm
|
0.7cm
|
i.e. Hardness: A (0.5)>C(0.53)>B(0.6)
Explanation of the Result
White sugar
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.
Brown sugar
Mostly crystallised sucrose, 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.
Rise and spreading of cookies
Due to the air bubbles produced in the baking process. Baking soda is used as the raising agent for the cookies in this experiment. The baking soda and the sugar will have chemical reaction.
Sodium Bicarbonate + Acid --> Carbon dioxide + Water + Salt
Brown sugar, which is slightly acidic, will react with the baking soda to create more bubbles that leaven the cookies, which is believed to raise the cookies higher than white sugar does. 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.
Texture of cookies
The structure of white sugar is more difficult to hold moisture compared to the ability to brown sugar. Hence it is expected that the white sugar-based cookies give up moisture more readily in the baking process, which ends up more crisp.
Result of the Experiment
Experiment 2
1) How the amount of sugar affect the spreadability of cookies
Sample A
|
Sample B
|
Sample C
| |
Diameter
|
4.4cm
|
5.3cm
|
6.7cm
|
2) How the amount of sugar affect the rising of cookies
Sample A
|
Sample B
|
Sample C
| |
Height
|
1.8cm
|
1.2cm
|
1.1cm
|
3) How the amount of sugar affect the texture of cookies
Sample A
|
Sample B
|
Sample C
| |
Height
|
1.8cm
|
1.2cm
|
1.1cm
|
i.e. Hardness: A(0.22)>B(0.66)>C(1.00)
Explanation of the Result
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.
Generally, an increase in sugar level went hand in hand with increased spread (Finney et al., 1950 and Maache-Rezzoug et al., 1998). Higher sucrose levels in the cookie dough recipe lead to increased sucrose dissolution during baking. This results in higher quantities of solvent phase, and, as a consequence, in higher spread rates. It induced cookie dough setting and postponed to higher temperatures when more sugar is present. The increasing amount of undissolved sugar crystals delayed the spread onset. This would mean that sugar not only delays the action of the chemical leavening (Chevallier et al., 2000), but also influences the degree of vertical expansion during baking.
Conclusion
Generally, an increase in sugar level went hand in hand with increased spread (Finney et al., 1950 and Maache-Rezzoug et al., 1998). Higher sucrose levels in the cookie dough recipe lead to increased sucrose dissolution during baking. This results in higher quantities of solvent phase, and, as a consequence, in higher spread rates. It induced cookie dough setting and postponed to higher temperatures when more sugar is present. The increasing amount of undissolved sugar crystals delayed the spread onset. This would mean that sugar not only delays the action of the chemical leavening (Chevallier et al., 2000), but also influences the degree of vertical expansion during baking.
Conclusion
The experiment results matched our hypothesis, in which cookies made with Brown sugar rose higher when baking, the appearance was thicker, and the texture was softer. While cookies made with White sugar spread wider when baking, the appearance was thinner, and the texture was harder and crispier.
Moreover, the more the sugar the cookie contains, the more spreadable and soft the cookie.
Limitations & Possible Errors
Temperature of oven
Although we have set the temperature of the oven to be 180 degrees Celcius, the actual temperature inside the oven may not be accurate. This may under / over-bake the cookies and affect the result of the experiment.
Size and shape of each baked cookie
Every cookie has different shapes before and after baking though we have tried to make them consistent. They can not be a perfect circle and there may be some angles and maybe more like oval shape. This may affect the accuracy of the measurement of diameter of the cookies, which determines the spread-ability result.
Every cookie has different shapes before and after baking though we have tried to make them consistent. They can not be a perfect circle and there may be some angles and maybe more like oval shape. This may affect the accuracy of the measurement of diameter of the cookies, which determines the spread-ability result.
Loss of reagent in the cooking process
Some of the ingredients may left on the container in the transferring process, leading to the inaccurate of amount of each ingredients. Verification of results are occurred.
Improvements
Put a kitchen thermometer into the oven
The thermometer put inside the oven can ensure the temperature (180 degrees Celcius) inside the oven more accurately, which can ensure the baking process of the cookies.
Use mold and Weigh to get constant cookie doughs
We may use the electronic balance to measure each of the cookie doughs to obtain a constant cookie dough weight an size, so as to keep everything as constant as possible, and to reduce the variation of baking time needed.
Choose the more round and smooth cookies
Although we cannot control the shapes of cookies after baking, we can choose those which are smoother and more circle-like cookies for us to measure the diameter, so as to compare the spreadability.
Reference
de la Barca, A. M. C., Rojas-Martínez, M. E., Islas-Rubio, A. R., & Cabrera-Chávez, F. (2010). Gluten-free breads and cookies of raw and popped amaranth flours with attractive technological and nutritional qualities. Plant foods for human nutrition, 65(3), 241-246. Retrieved from: https://www.researchgate.net/publication/45822202_Gluten-Free_Breads_and_Cookies_of_Raw_and_Popped_Amaranth_Flours_with_Attractive_Technological_and_Nutritional_Qualities
Drewnowski, A., Nordensten, K., & Dwyer, J. (1998). Replacing sugar and fat in cookies: impact on product quality and preference. Food Quality and Preference, 9(1), 13-20. Retrieved from: http://www.sciencedirect.com.eproxy2.lib.hku.hk/science/article/pii/S0950329397000177
Jacob, J., & Leelavathi, K. (2007). Effect of fat-type on cookie dough and cookie quality. Journal of food Engineering, 79(1), 299-305. Retrieved from: http://www.sciencedirect.com.eproxy2.lib.hku.hk/science/article/pii/S0260877406001427
Taylor, T. P., Fasina, O., & Bell, L. N. (2008). Physical properties and consumer liking of cookies prepared by replacing sucrose with tagatose. Journal of food science, 73(3), S145-S151. Retrieved from: http://onlinelibrary.wiley.com.eproxy2.lib.hku.hk/doi/10.1111/j.1750-3841.2007.00653.x/full
Use mold and Weigh to get constant cookie doughs
We may use the electronic balance to measure each of the cookie doughs to obtain a constant cookie dough weight an size, so as to keep everything as constant as possible, and to reduce the variation of baking time needed.
Choose the more round and smooth cookies
Although we cannot control the shapes of cookies after baking, we can choose those which are smoother and more circle-like cookies for us to measure the diameter, so as to compare the spreadability.
Reference
Drewnowski, A., Nordensten, K., & Dwyer, J. (1998). Replacing sugar and fat in cookies: impact on product quality and preference. Food Quality and Preference, 9(1), 13-20. Retrieved from: http://www.sciencedirect.com.eproxy2.lib.hku.hk/science/article/pii/S0950329397000177
Jacob, J., & Leelavathi, K. (2007). Effect of fat-type on cookie dough and cookie quality. Journal of food Engineering, 79(1), 299-305. Retrieved from: http://www.sciencedirect.com.eproxy2.lib.hku.hk/science/article/pii/S0260877406001427
Pareyt, B., Talhaoui, F., Kerckhofs, G., Brijs, K., Goesaert, H., Wevers, M., & Delcour, J. A. (2009). The role of sugar and fat in sugar-snap cookies: Structural and textural properties. Journal of Food Engineering, 90(3), 400-408. Retrieved from: http://www.sciencedirect.com.eproxy2.lib.hku.hk/science/article/pii/S0260877408003464
