Yeast fermentation at different pH levels
Demonstrate how environmental pH levels can affect the growth rate of yeast. Students can explore pH scales and how this relates to the process of fermentation, which is the process in which microorganisms (like yeast) break down sugars into energy sources for its own use. Changes in pH can ultimately affect the growth ability of yeast. Baker’s yeast thrives in a pH range of 4 to 6, and growth can be inhibited in pH levels outside this range.
Yeast growth at varying temperatures
Demonstrate the effect of temperature on yeast growth. Students may have a prior belief that temperature effects are linear, ex: a culture at 10℃ will grow at half the rate compared to a culture at 20℃, and a third the rate at 30℃. This experiment would show the non-linear effect of temperature on growth (and relate it to how refrigerators halt spoilage for so long). Students and the teacher can pick temperatures to test beforehand.