Making Yogurt at Preston High School

Making yogurt involves a lot of chemistry!

What better way is there to start a fun-filled year of exploring chemistry than with an exciting…and delicious… experiment? For its first official meeting of the 2013-2014 academic school year, the ChemClub at New York’s Preston High Schooldid just that. With the help of its dedicated club advisor, Mrs. Wicks-Dharmay, who also teaches chemistry at Preston High School, the ChemClub commenced a year of exciting experiments with an experiment to make yogurt.

Yes, yogurt! Who would’ve thought yogurt could be made in a high school chemistry laboratory?  Mrs. Wicks-Dharmay gathered all of the materials (see below) for our yogurt experiment,  including a gallon of milk and commercial yogurt.  The yogurt contains bacteria that ferment the lactose in milk producing lactic acid, which turns the milk into yogurt. She also provided  cups and spoons so  the entire Chem Club would be able to taste the outcome of the experiment.

With the entire Chem Club gathered to make yogurt, each member took a turn stirring the milk as we heated it. With all this stirring, our arms started to cramp after a while, but eventually the milk started thickening and turning into yogurt. The milk was left to sit for a day as it finished fermenting into yogurt and was then stored in the fridge.

Chem Club members came to the lab after school the next day to pick up their cups of yogurt and were pleasantly surprised by the results. The yogurt was delicious and it was even better knowing we made it ourselves. This experiment showed us how the bacteria in yogurt produce lactic acid for the fermentation process making yogurt from milk. This yogurt-making experiment is the first of many more fun and exciting experiments that Preston High School’s Chem Club will be performing this year. Stay tuned as this club journeys through the world of chemistry and a myriad of education enhancing experiments.

The yogurt recipe we used cannot be found on the internet, as it was the recipe from our ChemClub advisor’s own mother-in-law. Mrs. Wicks-Dharmay mother-in-law lived an all-natural life as a vegetarian and lived to be 101. Her yogurt recipe and making was something she took pride in. It was this memorable recipe we used in ChemClub to perform our experiment.

The recipe is as follows:

We used our Advisor’s family recipe.
  • 1 gallon of whole milk
  • 2 cups of sugar (more or less depending on taste)
  • 2 tbsp of vanilla
  • 1 small container of plain yogurt

  1. Put the milk, sugar, and vanilla in a pot and let it boil.
  2. Boil for about 10 minutes, while stirring constantly to avoid clots.
  3. Remove from heat, and continue stirring the mixture until it cools to your body temperature (you may test the temperature by placing a small dot on your skin, until it is no longer hot)
  4. After the mixture has cooled, add 3-4 tbsp plain yogurt and stir well to incorporate.
  5. Let the mixture sit overnight without moving, so it may thicken.
  6. Separate into smaller yogurt cups and store in refrigerator.

If your ChemClub tries making yogurt, be sure to send pictures to the, or leave a Reply to this post.