Food Chem Test 1

Front 1

Alteration of texture

Back 1

loss of solubility
tougher or softer

Front 2

Alteration of flavor

Back 2

off flavors from lipid oxidation

Front 3

Alteration of nutritive value

Back 3

loss of vitamins over long term storage

Front 4

Alteration of color

Back 4

browning reactions
enzymatic or maillard

Front 5

Alteration of safety

Back 5

toxic substances formed or helpful substances formed

Front 6

Reactions leading to deterioration of food quality or safety

Back 6

Non-enzymatic browning
Enzymatic browning
Oxidation
Hydrolysis
Metal interactions
Lipid isomerization
Lipid cyclization
Lipid oxidation-polymerization
Protein denaturation
Protein cross linking

Front 7

Product factors governing stability of foods

Back 7

chemical properties of individual constituents
oxygen
pH
water activity
Glass transition
Wg

Front 8

Environmental factors governing stability of foods

Back 8

Temperature
time
Composition of atmosphere
chemical, physical, biological treatments
exposure to light
contamination
physical abuse

Front 9

how can food scientists help society

Back 9

good food supply
cost of food
health of food
food regulations
resolve controversies about food:
GMOs, hormones

Front 10

why is water important

Back 10

in every food product
solvent in processes
heat transfer medium
allows reactions to occur
influences sensory
affects storage

Front 11

water comparing to other compounds

Back 11

High
melting point
heat capacity
surface tension
heat of phase transitions

low density

normal viscosity

Front 12

water can hydrogen bond to ___ water molecules

Back 12

4

Front 13

how much are hydrogen bonds affected in thawing ice

Back 13

about 15% of H bonds disrupted

Front 14

How do large ions affect fluidity of water

Back 14

large ions interrupt the structure, making the water more fluid

Front 15

how do small ions affect fluidity of water

Back 15

small ions make the water come together, the water is less fluid

Front 16

hydrophobic interactions

Back 16

hydrocarbon groups with other hydrocarbons in order to get away from polar water
means less surface area is by the water

Front 17

water binding

Back 17

tendency of water to associate with hydrophilic substances

Front 18

bound water

Back 18

water not removed from food
not a solvent

Front 19

water-holding capacity

Back 19

ability of a matrix of molecules to trap large amounts of water

Front 20

hydrophobic interaction

Back 20

non-polar groups go together to avoid interaction with polar water

Front 21

water activity

Back 21

vapor pressure of solvent above sample
-----------------------------------------------------------
vapor pressure of pure water at same temperature

Front 22

when is vapor pressure a bad indicator of stability

Back 22

when present with solutes, look at ability of microbe to grow in food with the solute
temperature changes
prep by adsorption

Front 23

molecular mobility

Back 23

translational or rotational motion of molecules

Front 24

when is molecular mobility useful to predict stability

Back 24

proton transfer
radical recombination
acid-base reactions
enzyme-catalyzed
protein folding
polymer chain growth

Front 25

when is molecular mobility not useful for stability

Back 25

small molecules
growth of vegetative microbes

Front 26

use of molecular mobility in food

Back 26

starchy foods
boiled confections
protein based foods
dried, frozen, freeze-dried foods

Front 27

temperature of glass transition
Tg

Back 27

temperature at which a supersaturated solution converts to a glass

Front 28

glass

Back 28

substance that is an amorphous (noncrystalline) solid

Front 29

multilayered water

Back 29

finishes first-layer available sites
H bonds to neighboring water molecules
plasticizing action on solutes

Front 30

bulk phase water

Back 30

freezable
large increase on molecular mobility
decrease in viscosity
increase rates of reactions

Front 31

hysteresis

Back 31

adding water back to a sample that has already been dried
not superimposeable on an isotherm prepared by desorption

Front 32

2 types of dispersions

Back 32

change in particle size
change in arrangement of particles

Front 33

change in particle size

Back 33

dissolve/grow
ostwald ripening
coalescence-particles come together

Front 34

change in arrangement of particles

Back 34

aggregation/peptization
sedimentation
move farther or closer apart in a large group
sink or float

Front 35

causes of deaggregation of aggregated particles

Back 35

lowers osmotic pressure
lowers ionic strength
enhances solvent quality
changes temperature
changes pH
shear forces

Front 36

Polymer gels
covalent cross links

Back 36

can be flexible or stiff

Front 37

polymer gels
microcrystallites

Back 37

noncovalent
salt bridges

Front 38

particle gels

Back 38

when structures attract at random
cluster to cluster

Front 39

ostwald ripening

Back 39

growth of large particles in a dispersion at expense of small ones
leads to disappearance of small particles

Front 40

creaming

Back 40

dispersed particles move upward
opposite of sedimentation

Front 41

Bancroft's rule

Back 41

emulsion of water, oil, surfactant
continuous phase becomes one in which surfactant is most soluble

Front 42

emulsion formation

Back 42

intense agitation to disrupt droplets
emulsifier transported to new surface area

Front 43

partial coalescence

Back 43

parts of particles associate but never fully come together
triacylglycerol crystals

Front 44

3 main types of instability of foams

Back 44

ostwalt ripening
drainage of a liquid through foam layer
coalescence of bubbles due to instability of film between them

Front 45

emulsions

Back 45

dispersions of one liquid in another

Front 46

foam formation
supersaturation

Back 46

gas is dissolved in the liquid at high pressure. When the pressure is released, gas bubbles form.