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Help needed with a biology IA on yeast fermentation!

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Hello! So I have been brainstorming about what kind of experiment I could do for my biology IA for a couple of months now, and yesterday I had an eureka moment and figured out that I could do it about yeast. We brew a national Russian drink (kvass) at home and it hit me that we actually use yeast for that (I just never thought about it before). Since it's a biological process I could write an investigation about it, and the fact that yeast fermentation is something that my family deals with quite often and that it produces one of the most beloved drinks in my country, would make the investigation more personal and get me a better grade.

So now I know that I want to do it about yeast fermentation, but I am having a big problem figuring out what to actually investigate. A thing I thought about was perhaps finding the optimum sugar concentration for fermentation, but it seems to me that it is a topic that has been overdone and is a bit too simplistic. So I wonder: is there anything else about yeast/yeast fermentation that is worthy of investigation and that doesn't require some advanced lab technique to carry out? Are there any other factors that I could manipulate that will influence the rate of fermentation, or the quality of the fermented drink, or the ethanol content, or the activity of the yeast?

Some of the other factors (IVs) that I have thought about:

  • Effect of different vitamins (Vitamin E, vitamin B, etc etc) on yeast activity. It sounds like the most interesting one out of everything else, but I am unsure about how long time it will take me to see any results (I don't want this experiment to be too long)
  • Effect of pH on yeast activity
  • Effect of temperature
  • Effect of different types of sugars on yeast activity (glucose, fructose, sucrose?)
  • Effect of oxygen availability on the rate yeast fermentation (this seems like an interesting one, but not sure how I could manipulate the oxygen supply)
    • I found this on a website: "The presence of oxygen at normal atmospheric concentrations will inhibit any fermentation process. At very low concentrations, however, oxygen can actually increase the yield of ethanol. This is sometimes referred to as themicroaerobic effect. As the level of oxygen is increased beyond this point, byproducts such as glycerol and acetic acid (vinegar) are produced by the yeast in addition to ethanol, and the yield and purity of the ethanol are reduced. As I mentioned before, fermentation will stop altogether once oxygen concentrations become too high. This is sometimes referred to as the Pasteur effect." This seems like the other most interesting thing to investigate out of all the things I have mentioned above, and I don't think that I have seen that many IAs being done on this. But again, I have no idea how I can vary the level of oxygen, so if anybody has any idea I would be really happy :)
  • Effect of ethanol concentrations on yeast activity

So yeah, these are all the ideas that I have so far. Any other ideas, comments on my existing ideas, or pointers towards relevant research or interesting areas would be greatly, greatly appreciated. Sorry for the long post by the way!

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That sounds like an interesting IA, and it's good that you have a solid reason as to why you want to do your IA about this. You can write about your motives in your intro, which will count towards the personal engagement criterion (pp.155-156 of the bio guide). You seem to almost have your IA completely planned out, and you should have a talk with your teacher to see if he has any suggestions.

Concerning the Oxygen's effect, that would indeed be an interesting research (and I believe it's the most likely to yield results). The best way to control the oxygen is by placing the yeast in a closed container with a small vacuum pump. You can also get little attachments for your tap (Aspirators) that creates a void based on the venturi principle. The latter is less accurate but also probably cheaper (it's what our school uses, in any case). It would probably be a satisfying conclusion if you could find the limit you talk about (when the efficiency flips drastically).

Good luck.


My opinion on the other variables:


For the vitamins, I don't know about the effect they'll have on the yeast process. However, if you're able to do research to the extent you're more or less sure you'll get results, then try. Otherwise, do a trial run with estimated values to see if there is a significant enough result.

I personally don't advise the classic temperature, pH, and ethanol variables, especially considering the other interesting ideas you have.

I don't know how interesting the different sugars would be, considering the yeast process requires glucose, fructose might still have an effect since it's slightly similar to glucose in structure. I would doubt that sucrose would react given that it's a disaccharide (hence you'd probably need an enzyme). Then again, I'm saying this based on my knowledge without research, so I could be wrong.



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