Question

a home brewer sets up a container with grain, water, and yeast. she opens the container twice per day to check the progress and gently stir the mixture. assuming she had all of the essential ingredients in the proper amounts, why cant she make beer? the container should never have been closed. the buildup of co₂ is detrimental to fermentation. opening the container so frequently supplies the yeast with oxygen for cellular respiration; they never switch to fermentation. stirring just makes it worse! the grain must have been very poor quality and lacked enough sugar and starch to support fermentation. opening the container so frequently introduces oxygen, which kills the yeast before they can ferment the grain. stirring just makes it worse! i dont know yet

Explanation:

Beer production relies on yeast fermentation, which is an anaerobic process. When the container is opened frequently, oxygen is supplied. Yeast will first undergo aerobic respiration (using the supplied oxygen) instead of switching to fermentation (anaerobic). Stirring can further increase oxygen exposure.

Answer:

Opening the container so frequently supplies the yeast with oxygen for cellular respiration; they never switch to fermentation. Stirring just makes it worse!