FOOD CHEM PART 1

Question 1

what are the six elements that make up almost all living things

Answer 1

carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur

Question 2

how are molecules/compounds formed

Answer 2

when elements combine

Question 3

what are the six groups of molecules/compounds

Answer 3

protein, lipid, vitamins, minerals, water, carbs

Question 4

what is the most important nutrient

Answer 4

water

Question 5

why is water essential for life

Answer 5

needed for digesting, absorbing, transporting, metabolizing, and excreting nuutrients

Question 6

how much of the human body is water

Answer 6

60-70%

Question 7

what foods have the most water

Answer 7

fruits/veggies (70-95%), milk (90%), (meats 70%)

Question 8

describe the chemical structure of water

Answer 8

one oxygen atom covalently bound to two hydrogen atoms; O -2 charge and H+1 charge so neutral overall charge, but the charges aren’t uniformly disturbed

Question 9

describe hydrogen bonds

Answer 9

noncovalent bonds that form between the slightly positive H of one molecules and slightly negative O of another molecules

Question 10

how many H-bonds can one water molecule form

Answer 10

up to 4

Question 11

what would happen to water without H-bonds

Answer 11

would be gas at room temp

Question 12

when does water form H-bonds?

Answer 12

with other polar components in foods (sugars, proteins, etc)

Question 13

what are the unique properties of water that H-bonding gives rise to

Answer 13

high specific heat + high latent heat

Question 14

whats high specific heat

Answer 14

amount of heat required to raise the temp of 1g of substance 1C and water’s is 4.186 joule/gram which is higher than any other common substance

Question 15

describe high latent heat

Answer 15

amount of energy released or absorbed for a substance to undergo a phase change

Question 16

what happens when you increase temp of water

Answer 16

increases kinetic energy

Question 17

whats the relationships between elevation and boiling point

Answer 17

increasing elevation decreases boiling point

Question 18

how does cooking change at higher elevatiions

Answer 18

lower pressure, takes longer to cook

Question 19

whats boiling point

Answer 19

temp at which vapor pressure of liquid = external pressure surrounding the liquid

Question 20

describe BP dropping

Answer 20

drops 1F for every 500 ft inc

Question 21

what do pressure cookers do

Answer 21

reduce cooking time buy increasing pressure and allowing liquid water to reach higher temps

Question 22

describe dispersions + name the three types

Answer 22

mixtures containing particles (solid, liquid, gas) dispelled in a continuous phase; true solutions, colloids, suspensions

Question 23

what are true solutions

Answer 23

smallest particles size; solutes completely dissolve and will not precipitate (like carbonated water or alcohol)

Question 24

what are colloids

Answer 24

particles too large to truly dissolve (emulsions, gels, foams)

Question 25

what are suspensions

Answer 25

biggest particle size; very unstable, particles will eventually settle out (like oil and vinegar dressing)

Question 26

what are ionizations

Answer 26

solutes ionize into electrically charged ions, so like NaCl -> Na + Cl

Question 27

what are pH changes

Answer 27

water can participates in ace-base rxns

Question 28

whats hydrolysis

Answer 28

water breaks chemical bond

Question 29

whats CO2 release

Answer 29

baking powder needs water to release CO2

Question 30

differentiate between bound and free water

Answer 30

bound water incorporated into chemical structure of other food components, not readily removed or available

Question 31

what are the functions of water in food

Answer 31

heat transfer medium (because of water's high specific heat), solvent, medium for chemical rxns

Question 32

what are carbs

Answer 32

sugars, starches and fibers of food; contribute to sweetness, color, texture and fermentatin

Question 33

what is the primary source of carbs

Answer 33

plants

Question 34

how are carbs synthesized

Answer 34

through photosynthesis

Question 35

what are carbs made up of + how are they classified

Answer 35

CHO, mono, di, sligo (3-10), poly saccharides (more than 10)

Question 36

what are the two categories of polysacchardes

Answer 36

digestible + undigestible

Question 37

what are some digestible carbs

Answer 37

starch (plants) - amylose and amylopectin glycogen (animals)

Question 38

what are some undigestible carbs

Answer 38

fiber (cellulose, pectin, gums)

Question 39

what are the four categories of monosaccharides

Answer 39

pentoses (5 C), hexoses (6C), fructose, galactose

Question 40

what are the types of pnetose

Answer 40

ribose + arabinose

Question 41

what are the types of hexose

Answer 41

glucose

Question 42

what are the types of fructose

Answer 42

free form in fruits and honey; sweetest

Question 43

whats galactose

Answer 43

rarely in free form; part of lactose

Question 44

what are the three types of disaccharides +DESCRIBE

Answer 44

sucore (glucose + fructose - table sugar), lactose (glucose + galactose - milk sugar), maltose (glucose + glucose - malt sugar)

Question 45

what are the most common oligosaccharides

Answer 45

raffinose and stachyose (found in beans, not well digested)

Question 46

what are fructo-oligosacchardies

Answer 46

short chains of fructose founf in fruits and veggies; prebiotic

Question 47

what are olgosaccharides

Answer 47

used as bulking agents and fat replacers in commercial foods