UNIT 4

Question 1

heat of fusion or solidification

Answer 1

• at freezing point, 1 grams of water requires 80 CALORIES of energy to be withdrawn

Question 2

heat of vaporation

Answer 2

• at boiling point, 1 grams of water requires 540 CALORIES of energy to change to steam

Question 3

water activity

Answer 3

• the ratio of the vapor pressure of a food sample (p) to the vapor pressure of pure water at the same temperature
• amount of free water in a food

Question 4

solution

Answer 4

• when solute molecules completely dissolve in a solvent without precipitating out

Question 5

saturated solution

Answer 5

• solution that has the maximum amount of solute that can be dissolved in the solvent

Question 6

dispersion

Answer 6

• formed when substances called colloids are too large to dissolve in a solvent
• instead, they remain in the solvent as an unstable dispersion
• classified as suspensions or emulsions

Question 7

suspension

dispersion

Answer 7

• large colloidal molecules remain suspended in the media and are visibly distinct, such as when starch is suspended in cold water

Question 8

emulsion

Answer 8

• colloidal particles disperse completely within the medium (the second phase)
• milk, mayonnaise, gravies are examples

Question 9

hydrolisis

Answer 9

• chemical reaction where a water molecule is used to split a compound into simpler molecules

Question 10

carbohydrates

Answer 10

• one of four major classes of nutrients

- energy: 4 calories per gram

Question 11

glycogen

Answer 11

• primary carbohydrate in animal tissue

Question 12

cryoprotectant

sucrose

Answer 12

• a molecule that protects biological tissue against structural damage (due to ice formation) during freezing and thawing

Question 13

starch gelatinization

Answer 13

• the loss of molecular organization within starch granules characterized by irreversible swelling and loss of birefringence

Question 14

starch gelation

Answer 14

• process whereby amylose molecules leach out of the starch granules and form intermolecular hydrogen bonds
• result is a three-dimensional network of amylose molecules with entrapped water and starch granules
• responsible for the texture of many sauces and puddings

Question 15

syneresis

Answer 15

• “weeping” of a starch gel due to rapid heating or cooling

Question 16

resistant starch (RS)

Answer 16

• starch that cannot be enzymatically digested by humans

Question 17

dietary fiber

Answer 17

• carbohydrates and lignin that are intrinsic to a plant’s structure but that are indigestile by human digestive enzymes

Question 18

functional fiber

Answer 18

• indigestible carbohydrates that have been isolated, extracted, or manufactured and that have been clinically proven to have a physiological benefit

Question 19

cellulose

Answer 19

• a homo-polysaccharide of glucose that is indigestible by human enzymes
• predominant component of plant cell walls
• no caloric contribution

Question 20

temporarily hard water

water hardness

Answer 20

• contains bicarbonate salts

- precipitates after boiling

Question 21

permanently hard water

Answer 21

• contains calcium and magnesium sulfates

- does not precipitate