Question

Your friend has added high concentration of sugar while baking the cookies, what will be its effect on the yeast action?

• A. Increase the yeast activity
• B. Retard the yeast activity
• C. Over fermentation
• D. Kills the yeast

Hint:

When making sweet breads (like Brioche), bakers often use special "Osmotolerant Yeast" which is designed to withstand high sugar levels.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Yeast feeds on sugar to produce carbon dioxide (fermentation). However, like most living organisms, yeast is sensitive to high concentrations of solutes like salt and sugar.

Step 2: Detailed Explanation:
When sugar concentration is very high, it creates a high osmotic pressure environment.
This osmotic pressure draws water out of the yeast cells (a process called plasmolysis), which makes the yeast cells dormant or sluggish.
While a small amount of sugar (up to 5%) boosts yeast, a high amount (above 10-12%) acts as a preservative and retards (slows down) the yeast action significantly.
It typically doesn't "kill" the yeast immediately, but it stops them from producing gas effectively.

Step 3: Final Answer:
High sugar concentration will retard the yeast activity.