pH of potatoes in stomach acid


The fries will not be digested properly after intervals of 24 hours

What are we trying to prove?

That fast food fries/tater tots are NOT healthy and should NOT be eaten

background information

We purchased different potato products from different local fast-food chains. We purchased french fries from McDonalds, tater tots from Sonic, as well as french fries from Sonic. We wanted to see how fast they would decay in stomach acid and after the process of digestion.


  1. Obtain fries or potatoes from different fast food locations
  2. Measure out 50 mL of stomach acid solution
  3. Spit into cup in order for the salivary amylase to help with digestion
  4. Divide equally between 3 solutions
  5. Break one of the fries up (to simulate chewing)
  6. Put tater tot, whole fry, and chewed up fry in different beakers of stomach acid solution
  7. Measure pH
  8. Churn
  9. Repeat steps 7 and 8 over the next 3 days
  10. Record data
  11. Collect as many videos and pictures as possible


Dependent- pH, the physical appearance

Independent- Amount of time elapsed, churning speed

Uncontrolled- Temperature of experiment

Experimental Constants

Churning at a speed of 4 every 24 hours

Amount of spit and stomach acid distributed

Amount of time we kept the potato products in the solution


McDonalds Fry

Materials Needed


pH tester on iPad

Fries from different locations

Stomach acid


Churning magnets

pH of fries over time

What types of statistical analysis will you use or how will you analyze your data once obtained:

We will place the pH data in a chart (above) while documenting through pictures the physical appearance of the potatoes after intervals of 24 hours

sonic french fry after 96 hours of digestion

what should you get out of this expirament?

If you look through our quantitative data in the charts and graphs, as well as the qualitative data, you can see that these fast food items have not digested properly. The pH fluctuates, which would be normal pertaining to digestion. However, through the pictures and videos, you can see that the food items still kept their shape. It wasn't able to be documented, but our group as well as many outsiders all agreed that it still smelled like, even after 92 hours, normal french fries and tater tots. All of the grease, oils, and fats all contribute to the disturbing preservation of the potato products. All of this data should raise awareness and suspicion about the cons of fast food. We can only hope that you make the healthy decision pertaining to what you choose to digest!

Rachel Vincenzo, Brittany Ellinger, Elizabeth fisher, Kristin Hodges

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