Chapter 4 - Leavening Agents and Gelling Agents

Question 1

What is leavening?

Answer 1

Leavening is the production or incorporation of gases in a baked product to increase volume and produce shape and texture. These gases must be retained in the product until the structure is set enough (by the coagulation of gluten and egg proteins and gelatinization of starches) to hold its shape.

Question 2

What are the 3 main gases that leaven baked goods?

Answer 2

1. Carbon dioxide
2. Steam
3. Air
   Steam and air are present in all baked goods

Question 3

What is fermentation?

Answer 3

Fermentation is the process by which yeast acts on sugars and changes them into carbon dioxide gas and alcohol. This release of gas produces the leavening action in yeast products. The alcohol evaporates completely during and immediately after baking.

Question 4

How does yeast accomplish fermentation?

Answer 4

Yeast is a microscopic plant that accomplishes fermentation by producing enzymes, some of which change complex sugars (sucrose and maltose) into simple sugars. Other enzymes change the simple sugars into carbon dioxide gas and alcohol.

Question 5

At what temperature is yeast Inactive? (storage temp)

Answer 5

34F / 1C

Question 6

At what temperature does yeast have slow action?

Answer 6

60-70F / 15-20C

Question 7

At what temperature does yeast have best growth? (fermentation and proofing temperatures for bread doughs)

Answer 7

70-90F / 20-32C

Question 8

At what temperature does the yeast reaction slow?

Answer 8

Above 100F / 38C

Question 9

At what temperature is yeast killed?

Answer 9

140F / 60C

Question 10

Does yeast contribute flavor to bread doughs?

Answer 10

Yes, flavor molecules are produced by the yeast during fermentation. For this reason, breads produced by long fermentations usually have more flavor than short-fermentation products.

Question 11

Commercial yeast is available in _____ forms

Answer 11

3

1. Fresh yeast/Compressed yeast
2. Active dry yeast
3. Instant dry yeast/Rapid rise/Quick rise yeast

Question 12

Which type of dry yeast must be mixed with water before use?

Answer 12

Active dry yeast must be rehydrated in 4x its weight in warm water before use. About 25% yeast cells in active dry yeast are dead, and this can have a negative effect on dough quality.

Question 13

What kind of yeast can you use in doughs with a high sugar content?

Answer 13

Osmotolerant yeast.

Question 14

Convert fresh yeast to regular active dry yeast.

Answer 14

Fresh x 0.5 = Active dry

Question 15

Convert fresh yeast to instant dry yeast.

Answer 15

Fresh x 0.35 = Instant dry

Question 16

Convert instant dry to fresh yeast

Answer 16

Instant dry x 3 = Fresh

Question 17

Convert instant dry to active dry

Answer 17

Instant dry x 1.4 = Active dry