Science Buddies: "Ask an Expert"

I am doing a science fair project on homemade yogurt and I was wondering how to measure the quality of homemade yogurt made with low fat and high fat. I originally thought that whichever yogurt was most solid (water content, viscosity, consistency, etc.) would be the best. However, I am not sure how to measure it. Also, any other suggestions would be nice.

Hi,

That's an interesting project because it relates to people's direct experience with food. My question is what do you mean by 'quality'? You could ask your friends to taste several samples of yogurt without telling them the difference and ask them to rate the flavor, consistency, appearance, etc on a scale of 1 to 5--1 being "hate it" and 5 being "love it". Also in the survey, you could ask them to briefly say why they rated it that way.

To get accurate results, you have to have a large enough group of people and I think they have to be people who do eat yogurt because people who don't probably won't like any yogurt. The other problem is sweetness. I don't know anyone who eats plain yogurt by itself. It's always sweetened and often flavored with fruit or vanilla. You could add a teaspoon of vanilla extract and a measured amount of powdered sugar to your yogurt to make it more palatable.

You said 'homemade' yogurt. Are you planning to make some with full-fat milk and some with low-fat milk? What about different bacterial starter cultures? I suspect that the type of bacteria affects the consistency and flavor of the yogurt. Be very careful to keep everything as clean and sterile as possible so you don't grow any bad bacteria by mistake: https://www.sciencebuddies.org/science- ... #materials

Here's some more information on yogurt projects that might give you some additional ideas: https://www.sciencebuddies.org/science- ... =&s=yogurt

Let me know what you decide. This is a fascinating study and should make a nice project.

Best wishes,

Scibee

Hi,

I think SciB has given you some good things to think about, since 'quality' is a very imprecise question. One thing I wanted to add is that since straining yogurt is very common right now (this is how greek yogurt is made, by straining regular yogurt) one thing you could try is to make your yogurt with full fat and low fat milk and then strain it at the end of the process. Then you could measure how much liquid you retrieve from your yogurt. You could combine this quantitative measure with the more qualitative taste tests. There may be other quantitative measures you could incorporate as well, such as final yield of the yogurt made, etc.

Hope this helps!