Megan+L

Science Fair Literature Review Whether or not people are aware of the importance of proper digestion, the consequences of your bodies inability to successfully break down proteins has a profound effect on the function of your body. The acidity of your stomach acid dictates the speed and quality that the proteins in your digestive tract are broken down. In this experiment, various pH levels will be tested to see which one is the most efficient on dissolving proteins. My hypothesis is that the lower the pH level is, then the proteins will be broken down with more sufficiency and speed.

On average, the stomach is a highly acidic environment. It typically ranks a 2-3 on the pH scale. When reading the pH scale, it is important to note that the lower the number is, then the more acidic it is. The low pH just means that the substance has a higher hydrogen ion concentration. With this in mind, it would make sense that the stronger the acid is, then the more capable the stomach acid will be at digesting proteins. Also, other factors affect the digestion of protein which will need to be controlled during this experiment, such as the preparedness of the food by the mouth through grinding and chewing.

In respect to other molecules, proteins are very complex. Due to their size and complexity, it often takes many steps to completely digest a protein. Thus, the point is proven again that a lower pH level would assist in dissolving the protein faster. The hydrochloric acid in the stomach has the task of breaking the protein bonds. As the food that contains protein enters the stomach, the HCL has to break down the food, and separate the protein.

In order to conduct my experiment, I need to take advantage of the lab equipment. I will need to use a beaker to place the measured hydrochloric acid into. In addition, I will need to be able to determine the pH level of the HCL. A timer will also be needed to measure the amount of time that passes before the protein is dissolved. An adequate variety of protein containing food will also be vital to the experiment. Foods that differ in size and complexity should be tested. To begin my experiment, I will need to measure an exactly 50mL of HCL, with a prerecorded pH level, into a beaker, and place 5g of a food item into a beaker. Then stir the mixture until it is thoroughly dissolved. When the food looks like it has been taken over by the hydrochloric acid I would record the time that passed.

To prove that the lower the pH level of stomach acid, the more efficient the digestion of proteins, my experiment will need to be carefully conducted. According to the data that I have collected, my hypothesis is supported. The more acidic the hydrochloric acid is, then the greater the ability to digest complex proteins will be.

Works Cited

1) Barrons, Richard E. “Stomach Acid.” //Zoology Archives.// 5 Oct 2009. <[|www.newton.dep.anl.gov] >

2) Breffeilh, Cherie. “Protein Digestion.” 3 Oct 2009. <[|www.newton.dep.anl.gov] >

3) Calder, Vince. “Stomach Acid.” //Zoology Archives.// 3 Oct 2009. <[|www.newton.dep.anl.gov]>

4) Gruber, Beth. “Protein Digestion and Absorption.” 5 Oct 2009. <[|www.carbsmart.com.]>

5) Ophardt, Charles E. “pH Scale.” //Virtual Chembook//. 3 Oct 2009. <[|www.elmhurst.edu]>

6) “pH Calculation Lectures.” 5 Oct 2009. <[|www.chembuddy.com]>

7) Reynolds, Sue. “pH Balancing” 5 Oct 2009. <[|www.reynoldsoffice.com] >

8) “The Digestion of Proteins” 5 Oct 2009. <[|www.cix.co.uk.] >

9) “The pH Scale.” 5 Oct 2009. 

10) “What is Acid Stomach?” 4 Oct 2009. <[|www.vitaminuk.com]>

Materials: 1 Hydrochloric acid 2 Beaker 3 Hot Pad 4. Raisins 5. M&Ms

Procedure: 1. Measure 20mL of HCL into a beaker. 2. Place the 2.5 grams of food into the beaker 3. Start the timer 4. Stop after 5 minutes 5. Record the changes in appearence 6. Repeat for 10 trials 7. Move to next pH level and repeat steps 1-7 8. After every pH level is tested, repeat steps 1-8 with a the next food item.

December 8th 2009

Today, I tested my control experiment with distilled water. I measured 2.5 grams of raisons on the balance. I filled 10 beakers with 20mL of distilled water. I placed the beakers on a hot pad on low heat. I started my timer and after five minutes I looked at the raisins. Nothing really happened apart from the raisins increasing in volume due to the water rehydrating them.



I did the exact same experiment with m&ms. Each beaker had another 20mL of distilled water, but this time three m&ms were added instead of raisins. When the time was up and I looked at the changes, the water changed to match the color of the m&ms. So the only thing that happened was that the color candy coating dissolved off of the chocolate inside. No significant change.



December 9th

Today, I completed 2 more trials. First I tested the pH level 2.04 which is the closest to stomach acid. Keeping my experiment the same, the raisins were't affected so much. I could see bubbles forming. Maybe if I allowed the experiment to continue, then more woul'dve happened. There were some layers of the raisins that flaked off but nothing too dramatic. With the m&ms, the color dissolved into the water again. The colors mixed a lot more than in the control. If I looked closely, there were some cracks that appeared in the m&ms. Even though there was no significant dissolving, I could tell that it was more effective than the water.



Afterwards, I tested the pH of 9. This was hardly acidic. The results were identical to those of the control.



December 10th

This morning I finished my last pH level test. I'm done! This acid had a pH of 5. The results were in the middle of what I saw in the control and what I saw in the stomach acid. The coating came off pretty quickly. That seems to be the main difference between all of my trials. It's not necessarily what happens, but how fast it happens.