My topic is bacteria. I discovered a lot about the pH of yogurt, sour cream, cheese and milk. I chose this topic because I find the growth of bacteria interesting.
The question I tried to answer was, why is the pH of some dairy products higher and others lower? I thought of that question when poeple from Becton Dickinson came and told us about bacteria. Some people think that the pH is the same in all dairy products, but they are wrong as my results will prove.
I have learned a lot about bacteria from my reference books. Bacteria is one of the most common life forms. Some bacteria can kill you. Bacteria is both animal and plant. There is a lot we know about bacteria but there is a lot more to be learned.
What I did to answer my question was to first take the pH of milk, cheese, sour cream, and yogurt. Next, I tried to think why is the pH higher or lower. Finally, I came to my conclusion. It is because the yogurt and sour cream were pasteurized better than the milk and cheese. Pasteurized means to take all of the bacteria out of the product (by heat) and make it ready and safe for us to eat. The pH levels ranged from 3.5 to 6.3.
After studying the pH in milk, cheese, yogurt, and sour cream I learned a lot. The cheese and milk have higher pH of 6.3. The yogurt and the sour cream were so low that I had to use a special kind of pH paper. Their's was 3.5.
If I had more time I would research the growth of my milk, cheese, yogurt, and sour cream on a streak plate. (A streak plate has sheep blood at the bottom of a glass container.) A future scientist might want to go to a higher level with my research by mixing two of my dairy products and seeing if the pH goes higher or lower. There is a lot of research yet to do.
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