CHAPTER 7: GLUTEN Flashcards
Is gluten one one the three main structure builders in baked goods?
Yes, egg proteins and starch are the other two.
What is the most difficult structure builder to control? Why? What about in yeast doughs?
Gluten, because small changes in a formula or mixing method have large effects on gluten development.
Why is gluten important especially important in yeast baked doughs?
They rely heavily on gluten for unbaked dough structure. Without gluten, yeast-leavened dough is not good at retaining gases produced during the fermentation process. The dough does not expound well, if at all, and the expansion does not hold throughout the baking process. Cell wall tear, and the final crumb is dense.
Flour consists mainly of a solid what?
Solid matrix of proteins embedded with starch granules.
What proteins are unique to the wheat endosperm?
Gliadin and glutenin.
What happens to gliadin and gluten when water is added to flour?
They absorb water and swell.
Does mixing promote the absorption of water? How?
Yes, by exposing new surfaces of flour to particles of water.
Besides water absorption, how else does mixing help (3 things)?
It incorporates oxygen, which oxidizes and strengthens gluten; wears down particles, until they are small and no longer spherical; distributes particles evenly throughout the dough, so that ultimately a strong, continuos gluten network form.
Does gluten become stronger as it is mixed?
Yes
Gluten–and dough–is considered fully developed when it is what?
Strong, cohesive and elastic.
Glutenin is thought to provide what?
The strength and cohesiveness of the gluten network, as well as its springiness or elasticity.
Gliadin is thought to contribute what?
Stretchiness and extensibility.
Why should dough be mixed evenly in all direction when gluten is involved?
Because gluten strands align in the directions they are mixed.
How must dough be kneaded by hand? What if it’s laminated dough?
Dough must be turned 90º with every knead. Likewise, when laminated doughs are folded or sheet, the dough is rotated with each fold or run through the sheeter. Otherwise, gluten strands align in one direction. This becomes especially evident when dough is not allowed to relax before being shaped and baked.
How can you tell if dough hasn’t been kneaded properly before being shaped and baked?
The dough will tend to shrink in whatever direction that the gluten strands are oriented.
The backbone of the gluten network consists largely of what? What does it look like? What about gliadin?
The largest glutenin molecules, or subunits, aligned and tightly linked to on another. These tightly linked glutenin subunits associate more loosely, along with gliadin, into larger gluten aggregates.
Portions of ________ are thought to loop, making gluten stretchy and flexible.
glutenin
Gluten is further made flexible by the presence of compact, coiled _______ molecules interspersed throughout.
gliadin
At the next level of gluten structure, gluten aggregates interact to form a tangled network of larger gluten particles that loosely interact with what?
Starch granules, fats, sugars, and gums.
Altogether, does it seems like gluten structures are held together by some very strong and many more weak bonds that break and reform easily? Explain.
Many bonds break, in particular, during mixing, only to reform around the surfaces of expanding air bubbles during proofing and the early stages of baking. It is this combination of strong and weak forces breaking and reforming that contributes to the unique nature of gluten.
Fully developed dough has what type of appearance?
Dry, silky appearance. It stretches into a smooth, thin film without tearing or breaking, yet still retains some ability to spring back.
Bakers use what test to see if dough is fully developed?
Windowpane test.
How do you make a windowpane?
Pull off a piece of dough about 1 inch or so in diameter. Roll it between your hands to shape into a ball, then gently pull the dough between your hands. Rotate the dough as you do this so that you are pulling it in all direction, forming a paper thin sheet of dough. Fully developed dough should form a thin film without tearing.
Although changes to gluten network cannot be seen, what happens, how are they reflected by what is seen?
Batters and doughs become smoother, stronger, and less lumpy as they are mixed and kneaded, and they are better able to stretch and trap solid particles, liquids, and gases as they expand.
When batters and doughs are baked, what happens to most of the moisture?
It’s either absorbed by gelatinized starch granules or evaporates.
With the loss of moisture and in the presence of heat, what happens to gluten? Is it unique to gluten?
Gluten coagulates into a firm and rigid yet porous structure that holds up its shape. While not unique to gluten (egg proteins, when heated, also coagulate into a firm,rigid structure), this is nonetheless and important feature of gluten.
Can doughs have too much gluten? What is it called when dough is too tight and bouncy?
Yes, it’s usually called “bucky.”
What is the problem with “bucky” dough?
Bread tends to be tough and chewy, have a low volume because they cannot stretch, and develop soft and thin crusts.
What happens of parties have too little gluten?
Pie crusts crumble easily, cakes collapse and baking powder biscuits slump.
Gluten’s makeup and structure are responsible for its unique nature, which scientists describe as what?
Viscoelastic
What is viscoelasticity?
The ability of a material to stretch and easily change shape–like a thick of viscous liquid–without breaking or tearing, and to partly bounce back to its original shape–like a rubber band.
Viscoelastic products can be thought of as what?
Part liquid, part solid.
What requires the most gluten of all baked goods?
Yeast-raised breads.
Gluten is so important to bread making that when bakers speak of flour, they are generally referring to what?
The amount of quality gluten that form from flour.
Is corn syrup viscoelastic? Why?
No, it does not have elasticity or rubberiness; it cannot bounce back to original shape once it flows. Also not strong enough to hold gas bubbles.
Is shortening viscoelastic? Why?
No, it cannot stretch or flow like liquid. While it’s soft enough to change shape and hard enough to hold, it cannot stretch and hold expanding gases.
Is peanut brittle viscoelastic? Why?
No, it is too firm and rigid. While it holds its shape quite nicely, PB will not stretch or change shape easily. If gases were able to expand at all in PB, the brittle would crack and shatter from buildup of pressure.
Is bread dough made from high-quality flour best at holding gases produced during fermentation and oven spring?
Yes
Of common breads, which usually require the most gluten if high volume is desired?
Hearth breads - those that are baked directly on sheet pans or baking stones.
What happens to hearth breads without sufficient gluten or pans to hold them in shape?
They collapse on themselves.
With less gluten, does a dough break and tear more readily?
Yes, it’s why you have larger air pockets in rustic, artisan breads.
Should flour quality be judges by its intended use?
Yes
Are high-gluten flours often described as high quality? How is this wrong?
Yes, but all baked products don’t necessarily need high amounts of gluten.
Describe high quality pastry flour.
Typically low in gluten, has a very fine granulation, is relatively low in pentosans and other gums, and has few damaged starch granules.
Is “high-quality” flour particularly high in nutritional value? Why?
No, because it is white flour and contains no bran or germ particles. Which means it’s not a good source of dietary fiber and low in lysine (no complete proteins).
Do wheat germ proteins form gluten?
No
Why is it difficult to compare the gluten requirements of various pastries?
They are complex mixtures of tenderizers and tougheners, moisteners and driers.
Is it safe to say that products containing significants amounts of other structure builders require less gluten?
Yes
Why do liquid shortening cakes require very little gluten?
They rely on a soft structure of gelatinized starch.
Why do sponge cakes not require much gluten?
Their high egg content.
Three main ways gluten is developed during baking.
Mixing and kneading, chemical dough development, over time during bulk fermentation and final proof.
Mixing and kneading is sometimes called what?
Mechanical dough method.
What is chemical dough development?
Use of ascorbic acid and other maturing agents that strengthen.
Besides the main three, are the other ways of controlling gluten development? List ingredients and methods.
- type of flour
- amount of water
- water hardness
- water pH
- mixing and kneading
- batter and dough temperature
- fermentation
- maturing agents and dough conditioners
- reducing agents
- enzymes
- tenderizers and softeners
- salt
- other structure builders
- milk
- fiber, bran, fruit pieces, spices, and the like
*Most items tend to have their greatest effect on baked goods that rely heavily on gluten, and not eggs and starch, for structure.
Of the last list, what items apply exclusively to yeast-raised doughs?
Heat-treated milk and dough conditioners. The others apply to all baked goods.
What items off the list will only affect high-ratio liquid shortening cakes and other baked goods made from cake flour?
Fats, sugars, and water pH - they have a larger affect on structure builders like eggs and starch in liquid shortening cake.
Is the type of flour important in gluten control?
Yes
Why is the type of grain important?
Because wheat flour is the only common grain with the potential for forming a good amount of high-quality gluten.
Does rye have the same amount of protein?
Yes, but very little of it is gluten forming.
Do oat, soy, corn or buckwheat form gluten?
No
Do different varieties of wheat vary in the amount of quality gluten that forms from them?
Yes
Thousands of different wheat varieties are classified as what two things?
Soft wheats or hard wheats.
What wheat is typically low in protein, and the protein quality is typically poor (from the standpoint of gluten development)? Explain.
Soft wheat has a lower amount of glutenin for the amount of gliadin, and the glutenin subunits tend to be smaller in size. Soft wheat forms gluten that is weak and tears easily.
Why are hard wheats good for gluten development?
They are high in protein, contain a higher percentage of glutenin for the amount of gliadin, and the glutenin subunits tend to be large in size. Strong wheat flours form gluten that is strong, cohesive, and elastic.
Is the amount of protein dependent on environmental conditions?
Yes, such as climate, solid quality, and the amount of fertilizer applied.
Why does whole wheat flour not produce the same gluten as white flour?
Bran and germ interfere with gluten development, and that protein from these components does not form gluten.
Glutenin and gliadin are found exclusively in what part of the wheat?
Endosperm
What is an alveograph?
Machine that blows air into dough made from flour, water, and salt, forming an expanding bubbles. This mimics the fermentation process. Three values are measured: dough strength, dough tenacity, and extensibility.
What is dough tenacity?
A measure of the pressure reached as the bubble inflates
Is the amount of water important for gluten development?
Yes
How much do glutenin and gliadin swell when contact with water is made?
Two times their weight in water.
Should you worry about adding water to biscuits and pie doughs?
Yes, low water is what keeps them tender.
What does adding excess water do to cake batters? Form more gluten?
Cake batters are more fluid and have plenty of water already; adding more won’t create more gluten development. Instead, adding more water dilutes out proteins, weakening gluten.
Does oil interfere with gluten development?
Yes, it’s a tenderizer.
Is water always added in as an ingredient in its own right?
No, other items such as eggs, milk etc contain water.
Does water hardness affect gluten?
Yes
What is water hardness?
The measure of the amount of mineral, like calcium and magnesium, in water.
Does hard water have high or low minerals?
High, and soft water has low.
How do you know (by sight) if water is hard or soft?
If you ever see hard white mineral deposits, called scale, on equipment surfaces, you know the water is hard.
Do minerals strengthen gluten? What does this do to yeast breads?
Yes, which causes them to become too strong and elastic; they do not stretch when gas expands or they quickly bounce back.
What happens to doughs prepared from soft water?
They are often too soft, slack, and sticky. Ideally, water for bread baking isn’t too hard or soft.
What effect does gluten have on hole size if it’s weak and tears easily?
It creates appealing large, irregular holes.
How do bakers achieve these large, irregular holes?
Using low protein flour and a lot of water, sometimes or 70 percent bakers percentage, compared with 50-60 percent for irregular lean dough.
What kind of dough is created with excess water?
A well-hydrated dough that is a cross between batter and dough.
Is well-hydrated dough messy to work with?
Yes, but it can produce fine artisan breads.
Not only is the grain coarsened by additional water but a longer bake time is needed to what?
Dry out the bread, resulting in a thicker, crisper crust.
Why are soft waters hard and others soft? Think ground water vs surface water.
Water becomes hard as it picks up minerals from contact with the earth. Ground water, which percolates through soil on its way to water wells, is usually harder than surface water from lakes and reservoirs.
Since the earth varies in composition from one location to the next, does water hardness also vary?
Yes
How do you compensate for water that is too hard or soft?
They have dough conditioners designed for this.
How do dough conditioners for soft water work?
They contain calcium salts, such as calcium sulfate, to increase the mineral content.
How do dough conditioners for hard water work?
They contains acids that prevent minerals from interacting with gluten.
