CHAPTER 13: LEAVENING AGENTS Flashcards
1
Q
Are baking powders all alike?
A
No. In fact, they have some interesting and important differences that are often overlooked.
2
Q
Three main leavening gases in baked goods.
A
Carbon dioxide, steam, air.
3
Q
Sometimes, bakers and pastry chefs categorize leavening by what?
A
The method used to incorporate (forming or adding) leavening gases to batters or doughs.
4
Q
Three categories of leavening.
A
Physical, biological, and chemical leavening.
5
Q
Does leavening often start before baked goods are placed in the oven?
A
Yes
6
Q
Are leavened baked goods light and porous?
A
Yes, they are higher in volume and more tender than if unleavened.
7
Q
Are leavened baked goods easier to digest?
A
Yes
8
Q
Three forms of matter.
A
Liquid, solid, gas.
9
Q
When temperature changes, can matter change from one form to another?
A
Yes, sold ice to liquid, liquid to gas.
10
Q
What happens to molecules as temperature increases?
A
They spread out and start moving faster.
11
Q
Were the very first breads leavened or unleavened? How were they made?
A
Unleavened, more like flat tortillas made by moistening and baking ground nuts, cereal grains, or seeds.
12
Q
First civilization to leaven bread. What did they use?
A
Egyptians as early as 2,300 BC, they used breadmash, which contained wild yeast from the air, to lighten doughs.
13
Q
For many centuries after the Egyptians started leavening bread, was yeast was the only leavening agent?
A
Yes
14
Q
When were chemical leavening agents introduced?
A
Late 1700s
15
Q
First popular chemical leavening agent.
A
Pearl ash, a crude form of potassium carbonate, an alkali.
16
Q
Pearl ash was removed from what?
A
The ashes of wood.
17
Q
What came after pearl ash?
A
Baking soda, which was used with sour milk or a cultured dairy product.
18
Q
What is the acid by-product of wine making?
A
Cream of tartar
19
Q
Almost a hundred years after baking soda, what became commercially available next?
A
Cream of tartar, it was used in the first commercial baking powder.
20
Q
How is baking powder made?
A
Mixing cream of tartar and baking soda with cornstarch.
21
Q
Baking soda is also called what?
A
Sodium bicarbonate
22
Q
Where was the first baking powder produced?
A
In San Fransisco, near the winemaking region of CA.
23
Q
Were baking powders refined throughout the 1800 and 1900s?
A
Yes, with newer, more versatile acids replacing cream of tartar.
24
Q
Are there several types of baking powder available today?
A
Yes
25
Baker's yeast was first purified and sold when?
1800s...no longer was the baker at the mercy of the flavor and gassing properties of wild yeast starters.
26
Few changes were made until the 1940s, when ____ ___ _____ was developed.
active dry yeast
27
Does active dry yeast perform like fresh yeast?
No, it did not and wasn't widely used by professional bakers.
28
When was instant yeast developed?
Late 1970s
29
What was so great about instant yeast?
It combined the convenience of dry yeast with the performance of fresh.
30
What expansion is the basis for leavening?
Molecules moving faster and spreading apart as temperatures increase.
31
What happens at a cellular level when gases expand from heat in the oven?
The force from these expanding gases pushes on wet, flexible cell walls, causing them to stretch. As long as structure builders stretch without excessive breaking, volume increases.
32
What happens to gases when baked goods are removed from the oven?
Gases evaporate or contract back to their original volume. Products with strong structure retain their shape.
33
Name to baked goods with weak structures that will shrink in size or collapse once gases evaporate or contract back to their original form.
Souffles and under-baked cakes.
34
Timing is important. For best volume, when must gas expansion occur? Use yeast-raised doughs as an example.
While baked goods structure is still stretchy and flexible, yet intact. In the case of yeast-raised baked goods, these ideal conditions occur during bulk fermentation, proofing, and the early stages of baking.
35
What happens to gases in bread doughs made with rye and other flours that do not contain sufficient gluten?
They won't rise properly because gases from fermentation escape from the dough soon after they are formed.
36
Do all liquids and gases expand when heated?
Yes
37
Besides air, steam, and carbon dioxide, name another liquid and gas that can be important in certain baked goods.
Alcohol and ammonia.
38
What is steam?
Water vapor, or the gaseous form of water.
39
When does steam form?
When water, milk, eggs, syrups, or any other moisture-containing ingredient is heated.
40
Is steam a very effective leavening agent? Why?
Yes, because it expands to occupy over 1,600 times more space than water. Imagine the power of this huge increase in volume.
41
Do all baked goods rely on steam for at least some of their leavening? Why?
Yes, because all baked good contain water or another liquid. In fact, many baked goods rely on steam for leavening more than one might imagine.
42
Do sponge cakes rely on steam for leavening? Why?
Yes, they rely on it as much as air. That is because SC batters are high in eggs, which are high in water.
43
Certain baked goods, such as choux pastry and popovers, are leavened almost exclusively by what?
Steam
44
Steam leavened baked goods are usually cooked in what?
Very hot ovens.
45
Besides leavening, what other uses does steam have for baked goods?
It's injected into ovens during the early stages of bread baking. This keeps crusts from forming too early, allowing bread to rise to its fullest potential without constraints of a hardened crust. Steam also affects the quality of bread crust.
46
How does steam affect the quality of bread crust?
Because crust formation is delayed, the crust remains thin, and there is enough time and moisture from the steam to fully gelatinize starches. Gelatinized starches are needed to form a crisp, glossy crust.
47
If volume is low in baked good, it could be that leavening was not properly timed with structure formation. What questions should you ask yourself to problem solve?
Is the oven working properly, and is it set to the correct temperature?
Is the product properly formulated, and were ingredients measured accurately?
Is the baking powder too fast- or slow-acting?
Was unbaked batter left out too long before it was baked?
48
Why is a low oven temp bad for leavening? Why items is this bad for?
It slows the formation and expansion of gases. This is especially bad for steam-leavened baked goods such as choux pastry, puff pastry, and certain sponge cakes.
49
High amounts of sugar and fats slow what? How does this affect leavening?
The coagulation process of proteins and gelatinization of starches, causing gas to be released before structures are set.
50
What happens if unbaked batter is left out too long before it is baked?
Small bubbles tend to migrate to large bubbles in thin batters, and large bubbles tend to rise to the surface and escape.
51
Can temps that are too high affect steam leavened goods? How?
Yes, a hard crust may form too quickly not allowing the baked goods to reach their maximum height.
52
Why is choux paste hollow when baked?
Raw egg proteins start twisted and coiled. As steam expands, egg proteins uncoil and stretch, and the paste puffs. Steam continues to expand, putting pressure on the stretched egg proteins. Eventually most of the egg protein structure breaks from the pressure, creating a characteristic cavity in the baked choux paste.
53
Why does the outside of baked choux paste resist breakage?
Gelatinized starch and coagulated egg proteins in these walls harden and set, defining the shell's final volume and shape.
54
What happens if choux pastry shells aren't thoroughly baked?
If side walls are even slightly moist, they will be weak. When the shells are removed from the oven and steam evaporates and condenses back to water, egg proteins in still-wet walls recoil. When this happens, shells shrink and collapse.
55
How should you check to see if a choux shell is sufficiently baked?
Do no rely on color alone. Remove a single shell to see if the inside is dry. If it is, the whole batch is ready to come out.
56
An undermixed batter creates what on the volume and crumb structure of baked goods?
Poor volume and coarse texture.
57
Properly mixed batter creates what on the volume and crumb structure of baked goods?
High volume and fine texture.
58
Overmixed batter creates what on the volume and crumb structure of baked goods?
Poor volume and dense texture.
59
Why is it easier to understand the importance of air to angel food cake and sponge cake but harder when comparing other baked goods such as cookies and biscuits?
Both angel and sponge cakes contain egg whites that are whipped and noticeably change in volume; the others don't.
60
Without air, would baked goods leaven?
No
61
How is air added to batters and doughs?
Through physical means: whipping, creaming, sifting, folding, kneading, and even stirring.
62
Is it near impossible to mix ingredients without adding some air?
Yes
63
What else do the physical mixing processes do besides add air? Example?
These physical processes also serve to break larger air cells into smaller ones, for a finer, more uniform crumb. Yeast-raised dough that has undergone bulk fermentation is punch down to redistribute gas bubbles into many smaller ones.
64
Like water, air is present in what?
All baked goods.
65
Unlike water, air is already a _____.
gas
66
While it expands a little when heated, air is already a gas and does not expand nearly as much as _______.
water
67
Air's role is subtler than water but no less important. Why?
When air is added to batters and doughs, it is added as small air bubbles or air cells during the mixing stage. These air or gas cells present in raw batter or dough can be thought of as seed cells. During baking, steam and carbon dioxide gas move to these seed cells, enlarging them. No matter how much water vaporizes into steam, no matter how much carbon dioxide is produced, no new air cells form during baking. Instead, steam and carbon dioxide fill and enlarge the seed cells that are already present in the batter or dough. Without seed cells, there would be no place for the gases to go except out. Without seed cells, there would be no leavening.
68
Why is it important to understand what it mens to whip, cream, knead, fold, and sift ingredients?
Batters and doughs will not aerate properly, and crumb appearance and volume will suffer.
69
If gases that expand during baking move to the few air cells formed during mixing, what happens to the size of air cells if enough aren't created?
The fewer the air cells, the larger those few will grow. Large air cells in baked goods mean a coarse crumb.
70
What happens if too many air cells are introduced into baking?
Egg and gluten proteins in the cell walls become overstretched, and cell walls are thin and weak. During baking, these thin cell walls stretch and further collapse. Again, the baked good will have poor volume.
71
The only one of three main leavening gases that is not present in all batters and doughs.
Carbon dioxide (while present in air, it is present in trace amounts only).
72
Carbon dioxide forms from what?
Yeast fermentation or chemical leaveners.
73
What is a biological source of carbon dioxide?
Yeast fermentation
74
What are chemical sources of carbon dioxide?
Baking soda and baking powder.
75
Is the role of carbon dioxide in leavening sometimes overstated? Explain.
Yes, many cakes are leavened more by steam and air than by carbon dioxide.
76
Are yeast cells very small single-celled organisms?
Yes
77
How many yeast cells are in one pound of compressed yeast?
15 trillion
78
Fermentation is a process in which yeast cells break down _____ for energy. Yeast uses the energy for what?
sugar; survival and reproduction
79
How do yeast cells reproduce?
Sugar energy is used for budding. This is where enlarged cells will break off from each other. They even leave scars from previous buddings.
80
Although yeast breads had been produced for thousands of years, it wasn't until when that who proved living yeast was necessary for fermentation?
mid-1800s, Louis Pasteur
81
Yeast can be thought of as what?
Tiny enzyme machines, breaking sugars into smaller and simpler molecules with every step.
82
What does yeast lack? How does this affect starch?
It lacks amylase and cannot break starch down into sugar. That is why amylase is an important additive in bread baking, especially in lean doughs.
83
What is a lean dough?
Those consisting of little more than flour, water, sat, and yeast.
84
Most common means of adding amylase into lean doughs?
Dry malt
85
Before it was understood that there are many steps in the breakdown of sugars to carbon dioxide, it was thought that an enzyme called what was responsible?
Zymase
86
The many steps of sugars being broken into carbon dioxide is called what?
Glycolysis, and separate enzymes control each step.
87
The term zymase is still sometimes used to refer to what?
The many enzymes in yeast that take part in the breakdown of sugars.
88
Overall process of yeast fermentation.
sugar ---(yeast)----> CO2 + alcohol + energy + flavor molecules
89
Does fermentation produce as much alcohol as it does carbon dioxide?
Yes
90
Most bakers would say that most important end product of fermentation is what?
Carbon dioxide, but alcohol adds significantly to oven spring, making it an important leavening gas..
91
Besides carbon dioxide and alcohol, what else is produced during fermentation? Why are they overlooked?
Small amounts of flavor molecules, including many acids. The molecules are sometimes overlooked because there are too many to name, and each is generated in such small amounts. Yet, they are the distinct aroma of freshly baked yeast bread. Often long, slow fermentation is best for developing the most desirable flavor.
92
Is the rate of yeast fermentation affected by several factors?
Yes
93
When is fast fermentation desirable?
When there are time constraints.
94
Slower fermentation is more desirable for what?
Flavor and gluten strength.
95
How does temperature of dough affect yes fermentation? Use different temperature stages.
Yeast in dormant at 32º-34ºF (0-1ºC) and begins to be quite active starting around 50ºF (10ºC). As dough temp rises above this, yeast fermentation increases. By about 120ºF (50ºC), fermentation slows, because yeast cells begin to die. Fermentation essentially stops at 140ºF (60ºC), when most yes cells are dead. Optimum fermentation is stated at 78º-82ºF (25º-28ºC).
96
Are most yeast cells really dead at 140ºF?
No, this is an estimate. Actual temp depends on the dough formula and on the strain of yeast in question.
97
How does salt affect yeast fermentation?
Salt retards, or inhibits, yeast fermentation. While the typical amount of salt is 1.8-2.5 percent (baker's %), bakers can vary the amount of salt in preferment, making up the difference in the final mix.
98
Preferment includes what?
Yeast and a portion of the other ingredients from the formula.
99
For a short fermentation, the preferment is made with a ____ amount of salt or none at all; for a longer one, it contains _____.
low, more
100
How does the amount of sugar affect yeast fermentation?
Small quantities--up to 5% (baker's %)--of sugar increase yeast activity. Large amounts--especially those above 10%--slow fermentation. For this reason, a common method for preparing rich, sweet doughs is to use a sponge or other preferment. Because large amounts of sugar are not added to the sponge, yeast can ferment without inhibition.
101
How does the type of sugar used affect yeast fermentation?
Sucrose, glucose, and fructose are all fermented rapidly; maltose is fermented slowly; lactose is not fermented at all.
102
Why is a mix of both fast- and slow-fermenting sugars important with lean yeast doughs?
It provides for continuous gassing through the final proof.
103
How does the pH of dough affect yeast fermentation?
The optimum pH for yeast fermentation is an acidic 4 to 6. Above and below that pH, yeast fermentation slows. As yeast ferments, it produces acids that lower pH to this ideal range.
104
How does the presence of antimicrobial agents affect yeast fermentation?
Certain AM agents slow or stop yeast fermentation. For example, when calcium proprionate is added to commercial doughs to prevent mold growth in breads, it must be added properly so that it does not prevent yeast fermentation. Most spices, including cinnamon,, have strong antimicrobial activity and can slow yeast fermentation.
105
Best way to apply cinnamon to yeast raised doughs?
Sprinkle it onto the dough later with sugar. Then roll it out and shape.
106
How does the amount of yeast affect yeast fermentation?
For the most part, the more yeast, the faster the fermentation. However, a large amount of yeast can add an undesirable yeasty flavor. A large amount of yeast can also exhaust dough, especially a lean dough, of sugars needed for fermentation during final proof and oven spring. That is why it's best to use a small amount of yeast during a long fermentation time.
107
How does the type of yeast affect yeast fermentation?
Some yeast products sold to bakers contain fast fermenting yeast, good for no-time doughs. This is particularly true of instant yeast. Quick-Fermenting yeasts are not as desirable, however, when a long fermentation time is used, since there might not be enough yeast activity to survive final proof.
108
Do some yeast strains grow well in rich doughs? What are they called?
Yes, doughs high in sugar are great environments for osmophilic yeast.
109
Where does the name osmophilic come from?
The fact that sugar increases the osmotic pressure in dough by tying up water.
110
When regular (nonosmophilic) yeast is used in sweet, rich doughs, it can take an hour or more for the yeast to adapt to the high-sugar environment. Explain.
Until it adapts, the yeast will not produce much carbon dioxide or alcohol. Even then, it can take two to three times the amount of yeast to get the same gas production as in a lean dough.
111
Bread flavor comes from what three main sources?
Flavor of the ingredients themselves, especially flour; Maillard browning that occurs during baking; flavor generated during yeast fermentation.
112
What is a poolish?
Liquid preferment batter.
113
What is a sponge?
Stiff preferment dough.
114
Preferments usually ferment for how long?
Several hours or overnight.
115
What is a pate fermentee? Is it better than a sponge or poolish?
Taking a portion of dough from a prior batch and adding it to a new one. This typically gives a slightly stronger flavor, more acidic flavor than a sponge or poolish, because it has already been through a full fermentation.
116
Bagels are typically retarded for how long?
Overnight or up to 18 hours.
117
How do you retard a dough? Does it produce a different flavor than yeast fermentation?
Divided and formed dough is held and refrigerated at 35-42ºF (2-5ºC). At this temp, lactic acid bacteria (present in flour and yeast) are still active, even as yeast are greatly slowed. As they ferment, these bacteria produce flavors that are different in character from this from yeast fermentation.
118
Bread can be made from a traditional, naturally fermented sourdough starter, called ______ in French.
Levain
119
How is a sourdough starter made?
Mixing flour and water and allowing wild yeast--and lactobacilli bacteria--from the flour and air to ferment the mix. Sometimes rye flour, onion, potato or another source of food for the microorganism is added to the flour and water.
120
How long does a sourdough starter need to be cared for and fed?
A few days to a week. A portion of it is made into a sponge and allowed to ferment, then used to leaven a batch of bread.
121
What don't all sourdoughs taste the same?
Because different microorganisms and ways of handling a starter affect flavor. San Fransisco sourdough is noticeably sour, French sourdough (pain au levain) is usually milder.
122
Does fresh starter need to be made for each new day's production?
No, instead, a small amount of starter is mixed with fresh flour and water and saved for the next days bread. Or, a piece of raw dough from one day's production is added to the next days sponge. In fact, some bakeshops pride themselves on the number of years they have continued to bake from their original starter.
123
What is saccharomyces cerevisiae?
A species of yeast. It is perhaps the most useful yeast, having been instrumental to winemaking, baking, and brewing since ancient times. It is believed to have been originally isolated from the skin of grapes (one can see the yeast as a component of the thin white film on the skins of some dark-color fruits such as plums; it exists among the waxes of the cuticle). It is one of the most intensively studied eukaryotic model organisms in molecular and cell biology, much like Escherichia coli as the model bacterium. It is the microorganism behind the most common type of fermentation.
124
Three main forms of yeast available today.
Compressed, active dry, instant.
125
Does each yeast work best with a specific temperature range?
Yes
126
A more consistent source of yeast is to use what?
Pure yeast cultures.
127
How is compressed yeast sold?
As moist cakes or blocks that are about 30% yeast, the rest moisture.
128
How long does impressed yeast last?
Up to two weeks when stored and wrapped in plastic and refrigerated, and three to four months when frozen.
129
Does fresh compressed yeast vary in color? What are they?
Yes, it generally has a light grayish tan color, crumbles easily, and has a pleasant yeast aroma.
130
When do you know compressed yeast has gone bad?
When its darkened extensively and turned gummy, or has an off aroma. This could indicate bacterial contamination.
131
The most common way to use compressed yeast. Water temp?
First, dissolve it in twice its weight of warm (100ºF, 38ºC) water.
132
Can compressed yeast be crumbled directly into dough?
Yes, but it's not recommended since it risks uneven distribution of yeast throughout the dough.
133
How is active dry yeast sold?
Dry granules sold in vacuum-packed jars or pouches.
134
Why does active dry yeast have an extended shelf life?
Low moisture and vacuum seal.
135
How long does active dry yeast last once opened?
Several months at room temperature, longer if frozen or refrigerated.
136
Active dry yeast is dried in what? How much moisture is left?
A spray drier to less than 10% moisture.
137
What is spray drying do to yeast cells?
It's a slightly harsh treatment, and the outside layer consists of dead yeast cells.
138
How much of active dry yeast is dead yeast cells?
Every pound contains about 1/4 pound dead yeast cells.
139
Why is active dry yeast not popular with professional bakers?
Dead yeast cells release a substance called glutathione that is detrimental to gluten development.
140
What kind of doughs does active dry yeast tend to produce?
Slack, sticky doughs and dense loaves.
141
When can a tendency of active dry yeast to slacken dough be used to an advantage?
When it is used in pizza or tortilla production, where extensible dough is desirable.
142
How should active dry yeast be prepared for baking? Water temp?
Dissolved in four times its weight in very warm (105-115ºF, 41-46ºC) water.
143
How much active dry yeast should you use compared to fresh compressed?
Half as much active dry as you would fresh compressed.
144
Why is instant yeast "instant?"
It can--and should be--added directly to dough without first hydrating in water.
145
How is instant yeast sold?
Dried and vacuum packed.
146
How is the drying process for instant yeast different from active dry?
The drying process--a fluidized bed--that produces instant yeast is much gentler than the one used for active dry yeast, so while there are still some dead and damaged yeast present, there is not the same high level.
147
What is bad about instant yeast being more vigorous than either compressed or active dry?
It is easy to overproof doughs leavened with it.
148
When is it best to use instant yeast?
When fermentation time is short--as in conventional or no-time doughs--since it will easily overproof a dough.
149
How much much instant yeast should be used in place of compressed fresh yeast?
1/4 or 1/2 the amount.
150
Initial dough temperatures for adding instant yeast?
70ºF (21ºC) and 95ºF (35ºC)
151
How long will instant yeast last?
If unopened, will last up to one year at room temp without loss in activity. If it is opened, refrigerate for several months, or freeze.
152
The chemical production of gases occurs when chemical learners break down in the presence of what?
Moisture or heat.
153
What is bench tolerance?
A measure of how well batters or doughs withstand--or tolerate--a delay before baking without risking a large loss in leavening gases.
154
Do heavy doughs typically have a higher bench tolerance than thin batters?
Yes
155
The most common chemical leavener.
Baking soda combined with one or more acids. The acids are either added separately or added together to create baking powder.
156
Baking ammonia is another chemical leavened popular where?
Europe, at least more so than North America.
157
Baking ammonia is another name for what?
Ammonium bicarbonate
158
When ammonium bicarbonate is exposed to heat in the presence of moisture, it quickly decomposes to what?
Ammonia, carbon dioxide, and water. All three sources of leavening in baked goods.
159
Many European _____ ______ are leavened with baking ammonia.
packaged cookies
160
The best application of baking ammonia is in what?
Small dry cookies and crackers or choux paste.
161
When properly used in small dry cookies and crackers or choux past, baking ammonia leaves no what?
Chemical residue
162
Why should you be careful with baking ammonia?
Do not breathe the powder, which has a very strong ammonia smell.
163
Why is baking ammonia more suitable for small dry goods and not large or moist products?
- Reacts rapidly in the presence of water and heat.
- Increases uniformity and spread in cookies.
- Increases browning
- Produces a crisp, porous crumb.
- Adds an ammonia-like, off flavor to still-moist baked goods.
164
Why is baking ammonia good for bench tolerance?
Because, unlike baking soda and certain baking powders, it is not very reactive at room temperature.
165
At what temp does baking ammonia start to break down?
104ºF, 38ºC so it is considered relatively fast acting.
166
Baking ammonia should only be used in what? Why?
Small products that bake to a low moisture content (less than 3% moisture), so the ammonia gas can fully bake out. Otherwise, baked goods will have an ammonia off flavor.
167
Name 4 products baking ammonia should never be used in.
Muffins, biscuits, cakes, or soft and moist cookies.
168
Baking soda is another name for what?
Sodium bicarbonate or bicarbonate of soda.
169
Like baking ammonia, baking soda decomposes to what?
Carbon dioxide and other gases in the presence of moisture and heat.
170
Is baking soda by itself a practical leavening agent? Why?
No because very high amounts are needed to produce sufficient leavening gas.
171
What happens to color if high amounts of baking soda are used? What about flavor?
High amounts produce yellow and green discoloration and a strong chemical off flavor in baked goods.
172
When baking soda is used for leavening is it used with one or more acids?
Yes
173
Do acids react with baking soda in the presence of moisture?
Yes, so baking soda breaks down more quickly and easily to carbon dioxide and water.
174
With acid, is more baking soda needed to produce carbon dioxide?
No, less is needed. So there is less discoloration and fewer chemical off flavors.
175
Can any acid be used with baking soda?
Yes
176
Does each acid react differently with baking soda?
Yes, and each produces a different salt residue.
177
The overal reaction of baking soda and acid.
baking soda + acid --(moisture)--> carbon dioxide + water + salt residue
178
What contributes to the off flavor of baking soda when too much is used?
Unreacted baking soda and the remaining salt residue.
179
What are the disadvantages of using ingredients (such as yogurt, buttermilk, sour cream, vinegar, most syrups, brown sugar, unsweetened chocolate and natural cocoa) in baked goods?
One, they vary in acid content. Buttermilk, sour cream and yogurt increase in acidity as they age. Two, these ingredients tend to react with baking soda almost immediately, especially in thin batter. This will give the batter poor bench tolerance.
180
How do you make your own baking powder? Will this recipe react quickly? Is it bench tolerant?
Combine cornstarch, baking soda, and cream of tartar in the following proportions: 1 part cornstarch: 1 part baking soda: 2 parts cream of tartar. These ratios are by volume, not weight. Baking soda and cream of tartar react almost completely within two minutes of mixing, so this baking powder is not bench tolerant.
181
When using a single acting baking powder, when should you bake doughs?
Immediately.
182
Are there several different types of baking powders? What do they all contain.
Yes, all contain baking soda, one or more acids--in the form of acid salts--and dried starch or another filler.
183
When do acid salts release acid?
Once they dissolve in water.
184
Name an acid salt.
Cream of tartar.
185
Cream of tartar is also called what?
Potassium acid tartrate.
186
When cream of tartar dissolves in a batter or dough, what is released?
Tartaric acid, which reacts with baking soda to create carbon dioxide.
187
Often, for simplicity, acid salts are simply called _______.
acids
188
Do all baking powder release the same minimum amount of carbon dioxide? What is it?
Yes, by federal law, 12%, by weight of baking powder. This means that most baking powders are more or less interchangeable--as long as they're still fresh.
189
Is it still useful to categorize baking powders as single or double acting?
No, since essentially all baking powders sold today are double acting.
190
What is a good way to categorize baking powders?
By their reaction rates. Another is by the type of acid each contains. The two are related.
191
What are single-acting baking powders?
They contain an acid that dissolves quickly in room temperature water. No heat is required for the acid to dissolve. As soon as it dissolves, it is available to react with baking soda.
192
Do single-acting baking powders have a good bench tolerance?
No, poor bench tolerance because they react so quickly.
193
What are single -acting baking powders great for?
Lightening batters and doughs.
194
What are double-acting baking powders?
Contain two or more acids: one that dissolves and reacts with baking soda at room temperature; another that requires heat to dissolve and react.
195
In some cases, dose double acting baking powder only contains one acid? What's different about it than single-acting?
Yes, but the acid is treated so that some of it dissolves at room temperature and the rest of it requires heat to dissolve.
196
Why are single-acting baking powders no longer sold?
They release carbon dioxide too quickly, producing batters with poor bench tolerance.
197
When was single-acting baking powder first developed?
1800s
198
Why was the quick release of carbon dioxide thought to be desirable when created?
It more closely simulated gas production by yeast--which mostly takes place before baking.
199
Are chemically leavened baked goods different from yeast raised baked goods? How?
Yes, very different. Their batters do not contain sufficient gluten to hold much gas before baking. Chemically leavened baked goods need gases timed to release when structure building proteins coagulate and starched gelatinize.
200
What is DRR?
Dough reaction rate.
201
Why is DRR used?
Measure the amount of carbon dioxide released from baking powder when it is used under controlled conditions.
202
How is DRR tested?
Biscuit mix is placed in an airtight mixing bowl. The bowl is attached to a device that measures the amount of gas released as water is added and as the mixture is stirred at a specific temperature for a specified length of time.
203
Often, the DRR--the % of carbon dioxide that is given off--is defined after how much mixing?
2-3 minutes of mixing and again after 8 or 16 minutes of bench time.
204
Do all baking powders release the same amount of carbon dioxide at room temperature, when heated, and at the same rate?
No, they all differ; it all happens at different rates too. They differ in their DRR.
205
A common fast-acting baking powder releases how much of its total carbon dioxide during mixing?
60-70% during mixing, 30-40% during baking.
206
How much carbon dioxide does a slow-acting baking powder release during mixing?
30-40% during mixing and 60-70% during baking.
207
Name 4 acid salts.
Cream of tartar, MCP (mono calcium phosphate), SAS (sodium aluminum sulfate), SAPP (sodium acid pyrophosphate).
208
Major features of cream of tartar.
Fast-acting--releases over 70% of carbon dioxide during mixing, which is too quick for general use; very clean flavor, little aftertaste; fast action lowers pH, to give a whiter crumb than most; expensive.
209
Major features of MCP (mono calcium phosphate).
Fat-acting--releases almost 60% of carbon dioxide during mixing; often coated so it dissolves and reacts more slowly; relatively clean taste; a very common acid salt in household and commercial baking powders, when combined with slower-acting SAS or SAPP.
210
Major features of SAS (sodium aluminum sulfate).
Slow-acting--requires heat to release acid, but releases it all during early stages of baking, by about 120ºF (50ºC); bitter aftertaste when used alone; combined with fast acting MCP for the most common household baking powder.
211
Major features of SAPP (sodium acid pyrophosphate).
Many kinds available, all slow-acting--releasing only 25-45% of their carbon dioxide within 16 minutes of bench time; most have noticeable unpleasant chemical aftertaste; combined with fast-acting MCP for the most common commercial baking powder.
212
Why might cake doughnuts require a different baking powder than cakes?
Cake doughnuts and cakes both do best with slow-acting baking powders, where more carbon dioxide is released after heat is applied. However, cake doughnuts require faster release of carbon dioxide since they fry up in minutes. If release is too slow, crust sets up before leavening occurs. Once leavening takes place, the force of expanding gases cracks the doughnut's surface or produces pinholes on it. If this happens, the doughnut absorbs fat in cracks and pinholes, becoming soggy and greasy.
213
For best volume and symmetry in cakes, generation of carbon dioxide must be timed with what?
Protein coagulation and starch gelatinization.
214
If you have a liquid shortening cake, why is it important that carbon dioxide is timed properly with egg and starch gelatinization?
Liquid shortening cakes are high in fat and sugar that delay coagulation of egg proteins and gelatinization of starches. If CO2 is to be timed with these processes, then baking powder must be slow acting.
215
Why do most bakers and pastry chefs use mixes instead of commercial baking powders for doughnuts?
Because most commercial baking powders are designed for cakes more than doughnuts. Doughnut mixes already contain the proper type and amount of baking powder.
216
The list of acids used in baking powders reads like alphabet soup.
MCP, SAS, SAPP, SALP, and more. All differ in reaction rates, flavor, and price.
217
Baking powders for professionals are most apt to contain what?
A mixture of SAPP and MCP, but they also contain SAS and MCP.
218
Eagle double acting is a combo of what?
SAPP/MCP
219
Clabber Girl is a combo of what?
SAS/MCP
220
Functions of chemical leaveners.
Leaven, tenderize, adjust pH, provide a finer crumb, add flavor.
221
Name that function: Occurs when gases form from the breakdown of the leavening agents and when these gases expand during the baking process.
Leavening
222
Name that function: As with all leavening, as gases form and expand, cell walls in baked goods stretch and thin out. This makes them easier to bite through; that is, it makes them more...
Tender
223
True or Flase: Many batter and doughs have a neutral pH if no baking powder, baking soda, or other chemical leavener is added.
True
224
Cream of tartar tends to ______ pH, while baking ammonia and baking soda--both ______--tend to ______pH.
decrease, alkalis, increase
225
Fast-acting baking powders, which release acidic CO2 quickly, ______ pH of batters and doughs, while slow-acting baking powders do not, and can even ______ pH.
decrease, increase
226
Changes in pH affect many things, including what?
Color, flavor, crumb texture, and gluten strength.
227
A small amount of baking soda in chocolate brownies or gingerbread provide what?
A darker, richer-looking product. The higher pH also smoothes out the flavor of gingerbread and chocolate, so that it is mellower and less sharp (unless a very high amount of baking soda is added; high levels or baking soda give baked goods a sharp, chemical taste.)
228
A small amount of baking soda or baking ammonia does what to cookies? What does this accomplish?
Raises pH, weakening gluten. The result is more spread, tenderness, and a coarser, more open crumb that dries and crisps more quickly. Higher pH also increases rate of browning.
229
A small amount of baking soda in baking powder biscuits does what?
Decreases pH and weakens gluten. The result is more tenderness. Unlike with baking soda, the lower pH from cream of tartar also provides a whiter crumb, often one that is fine and tight.
230
Six physical processes that incorporate small air cells (seeds cells) to batters and doughs.
Stirring, creaming, whipping, folding, sifting, kneading.
231
Do chemical leaveners contribute to the size of seed cells?
Yes
232
Why should you be careful when weighing chemical learners?
While a small amount can be beneficial, too much leaves a bitter chemical aftertaste and discolors goods.
233
Why is cornstarch added to baking powder?
Two main functions: Absorbs moisture, so that baking soda and acid salt do not react in the box. Also serves to standardize baking powders, so that an ounce of one brand provides the same leavening potential as an ounce of another.
234
Small amounts of baking powder and baking soda have a distinct salty-sour flavor that is characteristic of certain baked goods such as what?
Baking powder biscuits, scones, and Irish soda bread.
235
How should chemical leaveners be stored?
Tightly covered containers at room temperature.
236
Shelf life of baking powder.
6 months to 1 year. Uncovered or un-properly stored will reduce it significantly since chemical learners can easily absorb moisture, which leads to loss of potency. They also pick up off odors if left uncovered.
