Master Brewer Certification Yeast Biology & Fermentation Science

Question 1

What is the scientific name of the yeast species most commonly used in ale brewing?

Accepted Answer

Saccharomyces cerevisiae

Answer

Saccharomyces cerevisiae is the top-fermenting yeast responsible for producing ales at warmer temperatures.

Question 2

During which phase of the yeast growth curve does the most vigorous fermentation activity occur?

Accepted Answer

Log (exponential) phase

Answer

The log phase is when yeast cells multiply rapidly and sugar consumption and CO2 production are at their peak.

Question 3

What is the primary byproduct of yeast fermentation alongside ethanol?

Accepted Answer

Carbon dioxide

Answer

Yeast converts sugars into ethanol and carbon dioxide through glycolysis and alcoholic fermentation.

Question 4

What is the typical optimal fermentation temperature range for lager yeast (Saccharomyces pastorianus)?

Accepted Answer

50–55°F (10–13°C)

Answer

Lager yeasts are cold-tolerant bottom-fermenters that work best in the 50–55°F range, producing clean flavor profiles.

Question 5

What is the brewing term for the act of adding yeast to cooled wort to begin fermentation?

Accepted Answer

Pitching

Answer

Pitching refers specifically to the introduction of yeast into wort to initiate the fermentation process.

Master Brewer Certification Practice Test