Does yeast produce the same amount of gas from every type of sugar? Yeast breaks down sugars through fermentation (a process that releases carbon dioxide). Not all sugars have the same structure, and yeast is picky about which ones it can use.
You dissolve different carbohydrates in water and adjust the pH to 6.5. After adding yeast you warm the mixture to 37.5 degrees Celsius. An upside-down water-filled cylinder collects the CO2 so you can measure its volume.
Sugars like sucrose and glucose produce lots of gas. Others like galactose and lactose produce almost none. The results show that yeast prefers sugars with structures similar to sucrose.
Hypothesis
The hypothesis is that different carbohydrates will produce different amounts of C02 when yeast ferments them.
Yeast breaks down sugars and releases carbon dioxide, but not all sugars work equally well. You dissolve different carbohydrates in water, adjust the pH to 6.5, add yeast, and warm the mixture to 37.5 degrees Celsius. Sucrose and glucose produce lots of gas. Others like galactose and lactose produce almost none. The results show that yeast is picky about which sugars it can use.
Not all sugars have the same structure, and yeast is picky about which ones it can use for energy. You dissolve different carbohydrates in water, adjust the pH to 6.5, add yeast, and warm the mixture to 37.5 degrees Celsius. Glucose and sucrose — sugars with structures that yeast cells can easily break down — produce lots of gas. Others like galactose and lactose produce almost none.
Not all sugars have the same structure, so yeast breaks them down for energy at different rates. You dissolve different carbohydrates in water, adjust the pH to 6.5, add yeast, and warm the mixture to 37.5 degrees Celsius. An upside-down water-filled cylinder collects the carbon dioxide so you can measure its volume. Sugars like sucrose and glucose produce lots of gas. Others like galactose and lactose produce almost none.
Table sugar — sucrose — is one of the carbohydrates you dissolve in water for this experiment. After adjusting the pH to 6.5 and adding yeast, you warm the mixture to 37.5 degrees Celsius. An upside-down water-filled cylinder collects the CO2 so you can measure its volume. Sucrose and glucose produce lots of gas. Others like galactose and lactose produce almost none.
Method & Materials
You will dissolve different carbohydrates in water, adjust the pH to 6.5, add yeast, and heat the solution to 37.5°C. You will then measure the C02 produced and compare the results.
You will need table sugar, different carbohydrates, water, yeast, a pH meter, and a volumetric cylinder.
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The results showed that yeast is capable of fermenting different carbohydrates, but that it demonstrated substrate structure specificity to ferment carbohydrates that have structures similar to D-sucrose. The pH changed continuously during the fermentation reaction, and yeast was able to ferment at a wide range of temperatures and pH levels.
Why do this project?
This science project is interesting because it shows how different carbohydrates can affect the amount of C02 produced when yeast ferments them. It also shows how yeast can ferment different carbohydrates and how the pH changes during the fermentation reaction.
Also Consider
Experiment variations to consider include testing different temperatures and pH levels, or testing different types of carbohydrates.
Full project details
Additional information and source material for this project are available below.
