YEAST 1 Flashcards
what are yeast breads leavened with
CO2 produced from yeast—
Saccharomyces cerevisiae
what temp does yeast bread need to be brought to when making
room temp
what do sodium or calcium phosphate slow the growth of in yeast breads
molds and bacteria that cause rope
– bread is internally mushy/stringy
to the point it can be pulled into
ropes
whats the sponge method of making bread
yeast is combined with water and
~1/3 flour and allowed to ferment (30-60 min)
*Creates a foamy, bubbly,
mixture (resembles sponge)
whats the batter method of making bread
Ingredients combined then beaten to develop gluten
*Used for making hot dog and hamburger buns
whats the rapid mix method of making bread
*For use in bread-making machines
*Ingredients poured into machine that mixes and kneads
the dough, allows it to rise, and bakes all in the same pan
when is kneading finished
when dough springs
back when pressed or when
translucent “gluten window”
appears when stretched
whats proofing
letting the dough rise via fermentation to adequately aerate dough
*Yeast breads often proofed twice
when does second proofing occur and whats the purpose
After dough has ~doubled in size, it is punched down and briefly kneaded:
(1) Even out temp,
(2) Break large air bubbles into smaller ones,
(3) Redistribute sugar, yeast, and gluten
- bread doubles in size again which takes about half the time as the first proof
what does second proofing produce
a bread with greater volume
and finer texture
what does yeast produce CO2 from during fermentation
glucose
what happens to pH of bread during fermentation
goes down
what does the produced CO2 do
react with water to create carbonic acid
what other acids does yeast produce
lactic and acetic acids
describe the activity of a-amylase
starch to dextrins
describe the activity of b-amylase
dextrins to maltose
describe how yeast is very sensitive to temp
Temps too low will ferment too slow
*Temps too high will kill the yeast
if humidity too low, yeast will crack
what are proof boxes
special containers
that maintain temp/humidity
what will overfemerntation cause
ause overextension of gluten and cell
structure collapse -> low volume
*Can develop sour flavor from acid production
what happens if yeast uses up sugar
, Maillard reaction will be reduced
(affecting color and flavor)
why is the dark heavy-weight steel the pan of choice to shape after bread is proofed
Promotes golden brown color and
perfect crust
what increases browning
brushing with milk or egg wash
why are breads scored
Allows even rising without tearing
crust (lets out excess steam)
how does oven temp change during baking
oven temp is high (400°F) for the first 10-15 min
and then lowered (350°F) for the remainder
what does changing oven temp do
Contributes to oven spring: the quick expansion of
dough during initial baking
what happens if oven temp not hot enough
Proteins will not coagulate
*Yeast will continue to ferment causing dough to spill
over
what happens to yeast and enzymes during baking
*Yeast are killed
*Enzymes inactivated
*Starch gelatinizes
*Caramelization
*Starch broken down into dextrins (dextrinization)
*Maillard reaction (substrates from added milk, sugar, egg)
what happens to alcohol and proteins during baking
*Alcohol from fermentation is vaporized
*Proteins coagulate
what happens to starch during baking
*Starch gelatinizes
*Caramelization
*Starch broken down into dextrins (dextrinization)
*Maillard reaction (substrates from added milk, sugar, egg)
