Final DOHT

Question 1

Original piece of meat and one that is 1/2 the thickness, so how much do you cut the cooking time?

Answer 1

You would cook it for 1/4 of the original cooking time.

Question 2

All foods transmit heat to core by _____.

Answer 2

conduction

Question 3

Describe how electromagnetic waves are formed.

Answer 3

Hydrogen atoms fuse together to make helium. Energy is shot out from this and we get photons to form. As these photons go through space, electric/magnetic forces cause this to be repelled or come closer due to attraction.

Question 4

What are the visible wavelengths we can see?

Answer 4

400-700 nm.

Question 5

What kind of waves deliver more energy?

Answer 5

Higher frequency waves which have shorter wavelengths.

Question 6

What is being absorbed and what is being reflected when we see color?

Answer 6

All other colors are absorbed and the one that you are seeing is being reflected.

Question 7

What are the factors that influence energy transfer and flavor development when grilling something?

Answer 7

Oxygen availability, convective currents, reflective properties of the grill, temperature of the coals, location of the food on the grill, color/reflective properties of the item being grilled.

Question 8

What controls the electromagnetic energy being emitted by the coals in grilling?

Answer 8

The draft (less dense, hot air rises) (cold air containing oxygen enters the grill fueling the fire)

Question 9

Only way heat can get to the center of a food is through _____.

Answer 9

conduction

Question 10

How does microwaving cook food?

Answer 10

From the outside in (vibrating the water molecules in the food).

Question 11

The more viscous something is, the _____ it is.

Answer 11

thicker

Question 12

What is a boil?

Answer 12

Large bubbles breaking at the surface (when vapor pressure is equal to atmospheric pressure).

Question 13

What does freezing do to foods?

Answer 13

Slows down the biochemical breakdown and alters textures.

Question 14

Why can freezing fruit have positives?

Answer 14

When making a smoothie or a fruit sauce, this gives off better flavor and a more immediate fruit taste.

Question 15

The more alcohol in a substance, the more ______ it has.

Answer 15

volatility (nail polish remover ex)

Question 16

Adding substances to water will do what to the boiling temperature?

Answer 16

It will take longer to boil and at a hotter temperature.

Question 17

Difference between evaporation and boiling?

Answer 17

Evaporation - Enough energy that some molecules gain and then evaporate. Boiling - Quicker, happens throughout the entire liquid and only at the boiling temperature.

Question 18

How does adding solutes effect the boiling point molecularly?

Answer 18

Adding solutes will effect pressure, this creates an intermolecular force between water and whatever is in there. So now more energy needs to be put in to break these bonds, causing the temperature to rise. Once the bonds are finally broken, then they can overcome atmospheric pressure. The more solutes, the more energy required. (Vapor pressure decreases with solutes.)

Question 19

How do vapor ovens work?

Answer 19

Control of relative humidity and therefore controlling the rate of evaporative cooling. Heat transfer is more efficient this way.

Question 20

Describe squeezing ketchup out of a bottle and what is occurring.

Answer 20

As it rubs against the jar, gains enough heat energy through friction to begin shear thinning and flowing out of the bottle (heat from hands also contributes to this).

Question 21

How do things solidify?

Answer 21

They lose heat energy to the surrounding environment so particles will slow down and eventually solidify.

Question 22

What does thickening do to the molecules in a substance?

Answer 22

It makes it harder for these molecules to flow past each other (slowing down, less enthalpy and less entropy and more solid).

Question 23

What happens to water in gels/foams?

Answer 23

Water doesn’t change it just becomes trapped in the web/network of proteins which stops the movement of water.

Question 24

What do you consider when choosing a gelling agent?

Answer 24

Hydration/dispersion, thermoreversible or not, bulkier molecules tend to inhibit flavor release whereas smaller molecules don’t.

Question 25

How are polymers built?

Answer 25

Dehydration synthesis

Question 26

Why does syneresis occur?

Answer 26

Because it is not stable, “weeping” of liquid from a gel.

Question 27

How does the rate of cooling effect the outcome of something?

Answer 27

The slower the process is of cooling, the more crystalline and uniform the final product will be (ionic are more likely to form crystals).

Question 28

What are the four physical measurements used for gases?

Answer 28

(PV=nRT) Pressure, Volume, Number of particles, Constant Gas Law and Temperature in K (they all depend on each other and correlate).

Question 29

Boyle’s Law?

Answer 29

The volume of a gas at constant temperature is inversely proportional to the pressure (P1 x V1 = P2 x V2).

Question 30

Do gases dissolve better at a higher temperature or a lower temperature?

Answer 30

Lower temperature

Question 31

Why does popcorn come out the way it does?

Answer 31

There is still moisture inside of the kernel that expands once pressure is applied in an oven for instance.

Question 32

How does surface affect reflection?

Answer 32

On a smooth surface, colors are reflected the way they go in. On a bumpy surface, comes in, broken apart and then goes out and you view whatever made it out.

Question 33

As you remove water, the translucency of an object should increase or decrease?

Answer 33

Decrease.