INTRO TO FOOD SCIENCE: EXAM 2 FULL
QUESTIONS AND ANSWERS
What are the functions of the egg whites in the angel food cake recipe?
-Dissolve and disperse other ingredients
-provided protein for foam structure
-small amount of sugar for Maillard reaction
-liquid for steam leavening - Correct Answers -Dissolve and disperse other ingredients,
provide protein for foam structure, small amount of sugar for Maillard reaction, liquid for
steam leavening
How does cream of tartar stabilize the foam structure? - Correct Answers -as an acid,
lowers the pH and brings the egg white proteins nearer the isoelectric point so they can
cross-link with each other and stabilize the foam
How does cream of tartar affect the color of angel food cake? - Correct Answers -the
interior is whiter because the acid turns the anthoxanthins whiter
What are the functions of the sugar?
-stabilizes foam
-crystallizes to provide structure
-contributes to Maillard browning reaction
-sweetness - Correct Answers -stabilizes foam, contributes to maillard browning
reaction, sweetness
What are the functions of the cake flour?
-provides reducing sugars and protein for the Maillard reaction
-minimizes loss of volume before the batter is baked
-Provides structure during baking - Correct Answers -provides reducing sugars and
protein for the Maillard reaction, provides structure during baking
What are the functions of the cream of tartar?
-provides acid to stabilize the egg white foam
-causes the final product to be whiter
,-raises the pH of the cake, making it more yellow
-The acid in cream of tartar denatures the egg whites - Correct Answers -provides acid
to stabilize the egg white foam, causes the final product to be whiter
What are the functions of removing any traces of fat from the pan in step 1?
-to prevent the cake from sliding out of the pan after baking
-to prevent the fat from impairing the foam
-so the foam can "climb up" the sides of the pan while baking
-to tenderize the side crusts - Correct Answers -to prevent the cake from sliding out of
the pan after baking
What are the functions of adding the salt and cream of tartar when the egg whites are
foamy in step 3?
-So the cream of tartar is added early enough that it can stabilize the foam
-so the salt can denature the proteins
-so they can dissolve completely
-so the salt can stabilize the foam - Correct Answers -so the cream of tartar is added
early enough that it can stabilize the foam, so they can dissolve completely
Why is the sugar added in step 4 (at the soft peak stage)?
-adding the sugar earlier would prevent the egg proteins from absorbing enough water
to form a stable foam
-adding later might allow the foam to become too stiff and dry
-sugar causes the egg whites to denature, forming a more stable foam
-adding it earlier would interfere with the foam formation, greatly slowing or even
preventing the foam from reaching the stiff peak stage - Correct Answers -adding later
might allow the foam to become too stiff and dry, adding it earlier would interfere with
the foam formation, greatly slowing or even preventing the foam from reaching the stiff
peak stage
What is the function of inverting the pan after removing it from the oven in step 9?
-so the cake cools faster
-the residual heat from the oven causes the cake to expand more while inverted
-to take the cake out of the pan
-to prevent cake from collapsing - Correct Answers -to prevent the cake from collapsing
When preparing an angel food cake, the assigned reading suggests using bowls made
from which of the following materials?
-copper
-stainless steel
-plastic
,-glass - Correct Answers -stainless steel, glass
Egg yolks prevent the formation of egg white foams. What substance(s) in egg yolks
is/are responsible for this?
-livetin
-lysozyme
-lipovitellin
-ovomucin - Correct Answers -livetin, lipovitellin
How does microwave heating differ from heating in a conventional oven?
-microwave heating produces relatively more Maillard browning
-heating in a microwave results in evaporative cooling on the surface
-microwave heating produces a crisp crust
-microwave heating heats from inside the food - Correct Answers -heating in a
microwave results in evaporative cooling on the surface, microwave heating heats from
inside the food
How does beating past the stiff-peack stage affect an egg white foam?
-the foam will become stiff and dry
-the foam will become more shiny
-the foam will drain more when allowed to stand
-the foam will continue to increase in volume - Correct Answers -the foam will become
stiff and dry, the foam will drain more when allowed to stand
Why would a foam made from reconstituted dried egg whites require more time to reach
the stiff peak stage?
-because of the heat treatment used to dry the egg whites
-because dried egg whites contain small amounts of egg yolk
-because corn starch is included in dried egg white powders to keep them dry
-because the proteins were previously denatured during pasteurization - Correct
Answers -because of the heat treatment used to dry the egg whites, because the
proteins were previously denatured during pasteurization
What are the functions of the bananas and apples in the enzymatic browning lab?
-the apples and bananas provide the enzyme for the browning reaction
-the apples and bananas provide sugars that participate in the enzymatic browning
reaction
-the apples and bananas provide quinones that are oxidized by the polyphenoloxidase
-the apples and bananas provide the substrates for the browning reaction - Correct
Answers --the apples and bananas provide the enzyme for the browning reaction
-the apples and bananas provide the substrates for the browning reaction
, What are the functions of the lemon juice in the enzymatic browning lab?
-the lemon juice inactivates the enzymes
-the lemon juice contains citric acid which lowers the pH
-the lemon juice contains polyphenoloxidase that catalyzes the browning reaction
-the lemon juice contains citirc acid which acts as a chelator of copper
-the lemon juice contains ascorbic acid which serves as a reducing agent - Correct
Answers --the lemon juice contains citric acid which lowers the pH
-the lemon juice contains citric acid which acts as a chelator of copper
-the lemon juice contains ascorbic acid which serves as a reducing agent
What are the functions of the sugar in the enzymatic browning lab?
-the sugar is an antioxidant
-the sugar denatures the enzyme
-the sugar syrup serves as an oxygen barrier
-the sugar inactivates the enzyme - Correct Answers --the sugar syrup serves as an
oxygen barrier
What are the functions of blanching the fruit for 30 seconds?
-blanching for 30 seconds inactivates the substrate (polyphenols).
-blanching for 30 seconds will inactivate the enzymes on the surface of the fruit
-blanching for 30 seconds is used to remove the skins of the apples
-blanching for 30 seconds will convert quinones back to polyphenols - Correct Answers
--blanching for 30 seconds will inactivate the enzymes on the surface of the fruit
What are the functions of blanching the fruit for 3 minutes?
-blanching for 3 minutes reduces the quinones back to polyphenols, preventing
browning
-blanching for 3 minutes stimulates the activity of the enzyme, increasing the amount of
browning
-blanching for 3 minutes denatures the enzyme throughout the piece of fruit
-blanching for 3 minutes inactivates the substrate - Correct Answers --blanching for 3
minutes denatures the enzyme throughout the piece of fruit
Which of the following could be slow or reduce the extent of enzymatic browning?
-holding in an oxygen-rich environment
-white wine
-freezing
-warming the fruit to slighting above room temperature
-a solution of sodium chloride
-a solution of cream of tar-tar - Correct Answers --white wine
QUESTIONS AND ANSWERS
What are the functions of the egg whites in the angel food cake recipe?
-Dissolve and disperse other ingredients
-provided protein for foam structure
-small amount of sugar for Maillard reaction
-liquid for steam leavening - Correct Answers -Dissolve and disperse other ingredients,
provide protein for foam structure, small amount of sugar for Maillard reaction, liquid for
steam leavening
How does cream of tartar stabilize the foam structure? - Correct Answers -as an acid,
lowers the pH and brings the egg white proteins nearer the isoelectric point so they can
cross-link with each other and stabilize the foam
How does cream of tartar affect the color of angel food cake? - Correct Answers -the
interior is whiter because the acid turns the anthoxanthins whiter
What are the functions of the sugar?
-stabilizes foam
-crystallizes to provide structure
-contributes to Maillard browning reaction
-sweetness - Correct Answers -stabilizes foam, contributes to maillard browning
reaction, sweetness
What are the functions of the cake flour?
-provides reducing sugars and protein for the Maillard reaction
-minimizes loss of volume before the batter is baked
-Provides structure during baking - Correct Answers -provides reducing sugars and
protein for the Maillard reaction, provides structure during baking
What are the functions of the cream of tartar?
-provides acid to stabilize the egg white foam
-causes the final product to be whiter
,-raises the pH of the cake, making it more yellow
-The acid in cream of tartar denatures the egg whites - Correct Answers -provides acid
to stabilize the egg white foam, causes the final product to be whiter
What are the functions of removing any traces of fat from the pan in step 1?
-to prevent the cake from sliding out of the pan after baking
-to prevent the fat from impairing the foam
-so the foam can "climb up" the sides of the pan while baking
-to tenderize the side crusts - Correct Answers -to prevent the cake from sliding out of
the pan after baking
What are the functions of adding the salt and cream of tartar when the egg whites are
foamy in step 3?
-So the cream of tartar is added early enough that it can stabilize the foam
-so the salt can denature the proteins
-so they can dissolve completely
-so the salt can stabilize the foam - Correct Answers -so the cream of tartar is added
early enough that it can stabilize the foam, so they can dissolve completely
Why is the sugar added in step 4 (at the soft peak stage)?
-adding the sugar earlier would prevent the egg proteins from absorbing enough water
to form a stable foam
-adding later might allow the foam to become too stiff and dry
-sugar causes the egg whites to denature, forming a more stable foam
-adding it earlier would interfere with the foam formation, greatly slowing or even
preventing the foam from reaching the stiff peak stage - Correct Answers -adding later
might allow the foam to become too stiff and dry, adding it earlier would interfere with
the foam formation, greatly slowing or even preventing the foam from reaching the stiff
peak stage
What is the function of inverting the pan after removing it from the oven in step 9?
-so the cake cools faster
-the residual heat from the oven causes the cake to expand more while inverted
-to take the cake out of the pan
-to prevent cake from collapsing - Correct Answers -to prevent the cake from collapsing
When preparing an angel food cake, the assigned reading suggests using bowls made
from which of the following materials?
-copper
-stainless steel
-plastic
,-glass - Correct Answers -stainless steel, glass
Egg yolks prevent the formation of egg white foams. What substance(s) in egg yolks
is/are responsible for this?
-livetin
-lysozyme
-lipovitellin
-ovomucin - Correct Answers -livetin, lipovitellin
How does microwave heating differ from heating in a conventional oven?
-microwave heating produces relatively more Maillard browning
-heating in a microwave results in evaporative cooling on the surface
-microwave heating produces a crisp crust
-microwave heating heats from inside the food - Correct Answers -heating in a
microwave results in evaporative cooling on the surface, microwave heating heats from
inside the food
How does beating past the stiff-peack stage affect an egg white foam?
-the foam will become stiff and dry
-the foam will become more shiny
-the foam will drain more when allowed to stand
-the foam will continue to increase in volume - Correct Answers -the foam will become
stiff and dry, the foam will drain more when allowed to stand
Why would a foam made from reconstituted dried egg whites require more time to reach
the stiff peak stage?
-because of the heat treatment used to dry the egg whites
-because dried egg whites contain small amounts of egg yolk
-because corn starch is included in dried egg white powders to keep them dry
-because the proteins were previously denatured during pasteurization - Correct
Answers -because of the heat treatment used to dry the egg whites, because the
proteins were previously denatured during pasteurization
What are the functions of the bananas and apples in the enzymatic browning lab?
-the apples and bananas provide the enzyme for the browning reaction
-the apples and bananas provide sugars that participate in the enzymatic browning
reaction
-the apples and bananas provide quinones that are oxidized by the polyphenoloxidase
-the apples and bananas provide the substrates for the browning reaction - Correct
Answers --the apples and bananas provide the enzyme for the browning reaction
-the apples and bananas provide the substrates for the browning reaction
, What are the functions of the lemon juice in the enzymatic browning lab?
-the lemon juice inactivates the enzymes
-the lemon juice contains citric acid which lowers the pH
-the lemon juice contains polyphenoloxidase that catalyzes the browning reaction
-the lemon juice contains citirc acid which acts as a chelator of copper
-the lemon juice contains ascorbic acid which serves as a reducing agent - Correct
Answers --the lemon juice contains citric acid which lowers the pH
-the lemon juice contains citric acid which acts as a chelator of copper
-the lemon juice contains ascorbic acid which serves as a reducing agent
What are the functions of the sugar in the enzymatic browning lab?
-the sugar is an antioxidant
-the sugar denatures the enzyme
-the sugar syrup serves as an oxygen barrier
-the sugar inactivates the enzyme - Correct Answers --the sugar syrup serves as an
oxygen barrier
What are the functions of blanching the fruit for 30 seconds?
-blanching for 30 seconds inactivates the substrate (polyphenols).
-blanching for 30 seconds will inactivate the enzymes on the surface of the fruit
-blanching for 30 seconds is used to remove the skins of the apples
-blanching for 30 seconds will convert quinones back to polyphenols - Correct Answers
--blanching for 30 seconds will inactivate the enzymes on the surface of the fruit
What are the functions of blanching the fruit for 3 minutes?
-blanching for 3 minutes reduces the quinones back to polyphenols, preventing
browning
-blanching for 3 minutes stimulates the activity of the enzyme, increasing the amount of
browning
-blanching for 3 minutes denatures the enzyme throughout the piece of fruit
-blanching for 3 minutes inactivates the substrate - Correct Answers --blanching for 3
minutes denatures the enzyme throughout the piece of fruit
Which of the following could be slow or reduce the extent of enzymatic browning?
-holding in an oxygen-rich environment
-white wine
-freezing
-warming the fruit to slighting above room temperature
-a solution of sodium chloride
-a solution of cream of tar-tar - Correct Answers --white wine
