FLOUR 2 Flashcards
how is bleached flour whitened
artificial agents whiten via oxidation
- Bleaching agents evaporate, no residues left behind
- Oxidation also number of disulfide bonds which
protein strength and elasticity
what color is unbleached flour
yellowish color bc of carotenoids
what are some common agents of oxidation in bleached flour
- Common agents:
- Nitrogen tetroxide gas
- Chlorine gas— cake flour always bleached with this * Benzoyl peroxide — most common bleaching agent
what does oxidation do to disulfides bonds
increases the amount, which also increases strength and elasticity
how is aged flour made by storage
stored for several months until flour becomes naturally bleached by oxygen in air
why is aged flour expensive
due to required storage space and labor
[Baking powder = baking soda + acid]
how is phosphates flour leavened
with baking soda rather than baking powder because acid — monocalcium phosphate is added
whats self-rising flour a combination of
all-purpose flour + leavening agent (baking powder)
Starch can be broken down by enzymes (amylases) into dextrins, maltose, and glucose. what does this do to the final product?
Adds sweetness, darkens crust (Maillard reaction), and improves fermentation — making product light in texture.
what is the rising ability of the bread related to
protein content
what flour has the highest gluten content
wheat, because of glutenin and gliadin, so preferred for baking
how are protein and gluten related
directly
what happens when water is mixed with flour
glutenin and gliadin combine to form elastic network of gluten
what does gliadin provide
fluidity and stickiness
what does glutenin provide
elasticity
what do glutenin and gliadin allow gluten to withstand
pressure of produced gases
what proceeds carbon dioxide
yeast and leavening agents
what does kneading entrap and stretch
air bubbles and stretches the gluten
what do steam and expanding gases cause during baking
gluten to expand further
heat eventually causes starch gelatinization and protein
coagulation — what does this set?
the structure
what are the two major steps in gluten formation
hydration and kneading
whats the overall formula for gluten formation
hydration + kneading + glutenin + gliadan
what does kneading do to the dough
changes it from sticky to smooth/stretchy; evenly distributes yeast; increases gluten development
what are the two types of cereal grain allergies
baker’s asthma (from inhalation of flour particles)
Cereal allergies (from eating the cereal grain)
what happens to gliadins in enzyme in individuals with celiac disease
gliadins are partially broken down by an enzyme in the small intestine
what does the enhanced recognition of gliadins by immune cells in celiacs disease cause
damages surface of intestinal wall
what do leavening agents cause
flour mixtures to rise through incorporation of gases
During baking, heat further expands the gases. what are the three types?
Physical: air and steam
2. Biological: yeast and bacteria (via CO2)
3.Chemical: baking powder and baking soda (via CO2)
which contribute the most
biological and chemical
how is air incorporated during mixing
during creaming of fat
and sugar, sifting dry ingredients, or whipping egg whites
what are air and steam (physical) primary learning agents for
piecrusts and pastries
what does yeast produce through fermentation
CO2
what do yeast and glucose yield
ethanol and CO2
what are the three forms of bakers yeast
dry (active)yeast, fresh / compressed yeast, instant / quick-rising / fast-acting yeast
how is dry / active yeast stored
can store at RT
* Ideal rehydration/activation temp is 115°F
* Temp must be carefully controlled: too low will ruin texture of dough, too high will kill the yeast
whats the most available type
dry / active yeast
how is fresh yeast stored
Semi-solid cake (~70% moisture)
* Short shelf-life (refrigeration required)
what are the drawbacks of fast rising yeast
Reproduces faster, bread rises twice as fast
* Drawbacks: less time for flavor development, very temp sensitive
