Does yeast turn color as it ages?

The correct response is that yeast can darken as it ages. This change in color is primarily due to various biochemical processes occurring within the yeast cells over time. When yeast is exposed to certain environmental factors, such as oxygen and light, oxidative stress can lead to the formation of melanoidins and other pigments that contribute to darker hues.

In addition to color changes, aging yeast might also see changes in cell viability and metabolic activity. However, the primary focus of the question is on color, which can indeed shift towards darker tones. This characteristic is relevant to brewers and bakers alike because the age and condition of yeast can impact fermentation performance and ultimately influence the final product's flavor profile and aroma.

Other options do not accurately reflect the typical behavior of yeast. While some types of yeast might maintain their color, the potential for darkening is a noted phenomenon in yeast cells over prolonged periods. Thus, acknowledging that yeast can darken with age encapsulates a significant aspect of yeast biology and its implications for brewing practices.