1
Q
What counts as potential energy?
A
Gravitational, Elastic, Chemical Energy
2
Q
Types of Food energy?
A
Chemical energy, heat transfer, mechanical energy
3
Q
What counts as heat transfer energy?
A
Radiation, conduction, convection
4
Q
Types of Heat energy?
A
Specific heat, boiling point, temperature and motion, temperature calculation equation
5
Q
What are the two common forms of energy?
A
Kinetic energy and potential energy
6
Q
What is kinetic energy?
A
Energy due to motion (ex: waves hitting the shore)
7
Q
What is Potential energy?
A
Energy stored within an object that can be transformed into another form of energy (ex: calories)
8
Q
What is Gravitational Potential Energy?
A
Potential energy due to an object’s position
9
Q
What is Elastic Potential Energy?
A
Potential energy due to compression or expansion of an elastic object
10
Q
What is Chemical Potential Energy?
A
Potential energy stored within the chemical bonds of an object
11
Q
What are forms of energy common to foods?
A
Chemical energy and heat energy
12
Q
What is chemical energy?
A
Used or released in chemical reactions that take place in foods
13
Q
What is Heat energy?
A
In food that represents all the internal energy of motions of atoms and molecules in food
14
Q
When heat energy moves into foods we call it _______.
A
Heat transfer
15
Q
What is specific heat?
A
The amount of heat needed to raise the temperature of 1g of a food component by 1 degree celsius
16
Q
What is sensible heat?
A
Heat that can be measured by a thermometer and felt by us (ex: celsius, fahrenheit, kelvin)
17
Q
What is latent heat?
A
Energy required to change a substance to a higher energy state
18
Q
In the body, what is heat measured in?
A
Calories and Joules
19
Q
What is a calorie?
A
Amount of heat necessary to raise 1 g H2O by 1 degree C
20
Q
What is a kilocalorie?
A
Amount of heat necessary to raise 1 kg of H2O by 1 degree C
21
Q
1 calorie = _________
A
4.18 joules
22
Q
1 joule = ________
A
0.239 calories
23
Q
When we count calories, we are counting: ________.
A
kcals
24
Q
What is boiling point?
A
The temperature at which vapor pressure just exceeds atmospheric pressure
25
What is the boiling point at sea level?
100 degrees C or 212 degrees F
26
True or False? Cooking times will increase as elevation increases.
True
27
_________, vacuum processing can alter the vapor pressure.
Pressure cookers
28
Molecules in food are in _______.
Constant motion
29
What does the rate of motion depend upon?
Temperature and the state of matter
30
True or False? The hotter the food, the slower the movement.
False
31
True or False? The colder the food, the slower the movement.
True
32
Calculations: Fahrenheit
Tf = 9/5 Tc + 32 ̊
33
Calculations: Celsius
Tc = 5/9 (Tf - 32 ̊)
34
Calculations: Kelvin
TK = Tc + 273
35
How is heat transferred in food?
By a hot source
36
What sources help transfer heat to/into a food?
Radiation, conduction, convection, mixed conduction/convection
37
What is mechanical energy?
Energy entering food by means of physical movement (beating, high speed mixing)
38
How does Radiation energy transfer work?
Direct transfer of heat energy from its source to the surface of the food in the form of waves or rays
39
How does Microwaves energy transfer work?
Electro magnetic waves cause polar molecules (water) to oscillate and generate heat energy
40
How does Conduction transfer energy?
Direct molecule to molecule transfer of energy in a linear fashion
41
Conduction medium of a Pan:
Set over heat source
42
Conduction medium of Air:
Conventional ovens
43
Conduction medium of Water:
Boiling
44
Conduction medium of Fat:
Deep-frying
45
Is Convention Energy Transfer forced or natural?
Natural
46
What is Natural Convection Energy Transfer?
As liquids or gases are heated, the portion closest to the heat source becomes less dense, expands, and rises. As it rises, it displaces cooler, more dense material
which is forced down.
47
What is Forced Convection Energy Transfer?
Movement of the material over heat source occurs by mechanical means
48
What is Mass Transfer?
Refers to the movement of substances in or out of foods
49
True of False? Mass Transfer is governed by the similarities in the concentration (relative pressures/Aw) of the
compound inside and outside of the food.
False
50
Solids are ________
crystalline or amorphous
51
True or False? Solids have very little movement of molecules.
True
52
Amorphous solids are _______
"glass-like", no definite order, and contain very high concentration of molecules
53
Liquids
exhibit flow behavior and molecules are bound to each other for very short periods of time
54
Liquids bound by ______
Van der Waal's forces or by hydrogen bonding
55
As temperature increases:
volume increases and density decreases
56
Van de Waal's forces
Distance-dependent interactions between atoms or molecules
57
As liquids heat _______
Molecules within move faster trying to escape
58
As liquid temperature increases:
Density decreases and vapor pressure increases
59
Surface tension of a liquid....
Resists the escape of molecules until vapor pressure > surface tension
60
Gases have ______
spaces between molecules with constant and rapid movement of molecules
61
True or False? Water vapor (steam), CO2 and O2 are all important gases in food.
True
62
What is desiccant?
A hydroscopic substance used to induce or sustain a state of dryness
63
Name an oxygen absorber
iron
64
Dispersion classification based on ________
particle size
65
Size of True Solutions
less than 1.0 nanometer
66
What is the most stable and homogenous dispersion?
True Solutions
67
Discontinuous phase
Solute = dispersed particles
68
Continuous phase
Solvent = liquid in which particles are dispersed
69
As temperature increases, the amount of solute ______
Increases
70
Unsaturated solutions
Can dissolve more
71
Saturated solutions
Maximum solute is dissolved
72
Supersaturated solutions
Contains more solute than theoretically possible
73
Dispersed particles are macro-molecules ranging from:
0.001-1.0 micrometer in diameter
74
Emulsion
One liquid dispersed in another liquid
75
Sol
Solid dispersed in a liquid
76
Gel
Liquid dispersed in a solid
77
Foam
Gas dispersed in a liquid
78
Suspensoid
Gas dispersed in a solid
79
Oil in water = _______
Milk
80
Water in oil = ________
Butter
81
What do emulsifiers do?
Coat the surface of the droplets and reduces the surface tension
82
Example of emulsifiers
Phospholipids in egg yolks
83
Stability of the emulsion depends on:
Viscosity of the continuous phase, concentration, and size of droplets
84
What is sols?
Solid material distributed throughout a liquid
85
What is the consistency of sols?
Thick to very thick consistency
86
What is gels?
Phase inversion from sol where liquid is now trapped in solid and the consistency is solid and does not flow
87
What are foams?
Gas dispersed within a liquid
88
What is needed for a good foam?
Low surface tension and liquids with low vapor pressure
89
How big are Coarse Suspension dispersed particles
larger than one micrometer
90
Are Coarse Suspension Dispersions stable?
No, its unstable and settle to the bottom or float
91
Monosaccharide
Carbohydrate containing only one saccharide unit
92
What are two common monosaccharides?
Pentoses and Hexoses
93
Example of Pentoses
Ribose
94
Example of Hexoses
Glucose and Fructose
95
Carbonyl Group
Aldehyde or Ketone
96
Sucrose is ______ sweetness scale
100
97
Glucose is _____ sweetness scale
70
98
Fructose is _____ sweetness scale
150
99
Glucose is a ________ sugar
Reducing
100
Hygroscopicity
Taking up moisture from air
101
Nucleation sites can be
Seed crystals, air bubbles, or dust mites
102
Hydrolysis
Process of breaking of glucosidic/glycosidic linkages in disaccharides
103
Inversion
Hydrolysis reaction for sucrose
104
Inversion of sucrose --->
Glucose + fructose
105
Series of reactions
1. Hydrolysis
2. Dehydration of sugar molecules
3. Degradation of sugar rings
4. Condensation to form polymers
106
Caramelization occurs at
Very high temperature (<170 degrees C)
107
Caramelized products have a lower _____ and organic acids are formed
pH
108
Maillard Reaction is also called
Non-enzymatic browning
109
Maillard reaction involved...
The reaction of the active sight site of sugars with an amine group on an amino acid/protein
110
Sucrose is a _______
Non-reducing sugar
111
Color intensity increase with _______
increasing temperature
112
Carbon content pigment increases at _______
higher temperature
113
Sulfur dioxide reacts with carbonyl groups to
prevent further reactions
114
Sulfur dioxide reacts with thiamin and proteins to
reduce nutritional value
115
Functions of nitrites in curing:
1. Color
2. Microbial inhibition
3. Antioxidant
4. Flavor
116
What are do Crystalline Candies have?
Large areas of organized sugar crystals which contribute to candy structure
117
When Viscosity increases: _______
Diffusion decreases
118
As sugar solutions become supersaturated:
The presence of nucleation sites can readily initiate crystallization
119
In the presence of acid, sucrose will...
Become hydrolyzed to fructose and glucose
120
In the presence of proteins and fats...
They coat the crystal surfaces and make it difficult for molecules to attach
121
For crystal, when temperature is too high:
solution is not supersaturated enough, fewer nucleation sites, less viscous/diffusion is rapid, large crystals
122
For crystals, when solution is too low:
viscosity is too high, crystallization is inhibited; sticky and dry candy
123
For crystals, when temperature is just right:
Numerous nucleation sites formed but small crystals from increased viscosity and decreased diffusion rates
124
What sweetener best for soft beverages?
Aspartame
125
Sorbitol
Sugar alcohol slowly absorbed by the body
126
What makes up Aspartame
Aspartic acid and phenylalanine
127
Polysaccharides
Carbohydrates with 10 or more sugar units
128
Homo-Polysaccharides
one monosaccharide, one or more glycosidic linkages
129
Examples of homo-polysaccharides
Starch, cellulose, glycogen
130
Hetero-polysaccharides
Polymers with more than one type of monosaccharide unit, one or more glycosidic linkage
131
Examples of hetero-polysaccharides
Gums, dietary fiber, pectic substances, hemicelluloses
132
After death of meat:
glycogen breaks up into lactic acid; decreased acidity from pH 7-pH 5.6
133
Major form of energy storage in higher plants such as:
Seeds, tubers, roots, stems, fruit
134
What chemical used to ripen fruits?
Ethylene
135
What catalyst is needed to synthesize ethylene?
Aluminum oxide or Sulfuric acids
136
What are the two polymers of glucose?
Amylose and amylopectin
137
Amylose?
Linear molecule, alpha 1-4 linkages, flexible structure
138
Amylopectin
Highly branched molecule, larger than amylose, alpha 1-4 linkages, alpha 1-6 linkages, cluster structure
139
What is mw of Amylopectin?
mw 10^8-10^9
140
What is the mw of Amylose?
mw 10^6
141
How much amylose is in Waxy Starch?
0-8% amylose
142
How much amylose is in Normal starch?
cereal: 20-30% amylose
root: 15-20% amylose
143
How much amylose is in High-Amylose starch?
> 40& amylose
144
Properties of waxy starch
Forms clear paste, does not form gel
145
Properties of normal starch
cereal starches: form strong gel
Root starches: do not form gel
146
Properties of High-amylose starch:
Forms strong gel
147
What percent of amylose is needed to form gel?
> 20% amylose
148
What is Native starch type?
found in original form; good freeze-thaw characteristics
149
Physical treatments of Native starch type?
Pregelatinization; spherical aggregates
150
Chemical means of Native starch type?
Thin-boiling starch, cross-linking, starch phosphates
151
What is Modified starch type?
Modified by chemical or physical means
152
Physical treatments of Modified starch type?
1. Pregelatinization: precooked and dried; no need for heat
2. Cold water swelling
3. Spherical aggregates: spray-dried
153
Example of Native Starch
Waxy Maize Starch: 100% amylopectin
154
What is micro-encapsulation
A process in which tiny particles or droplets are surrounded by a coating to give small capsules, of many useful properties
155
What is essential oil?
A concentrated hydrophobic liquid containing volatile (easily evaporated at normal temp.) chemical compounds from plants
156
What is supercritical fluid extraction?
The process of separating one component (the extractant) from another (the matrix)
157
What is most used in supercritical fluid extraction?
Carbon dioxide; sometimes modified by co-solvents such as ethanol or methanol
158
Chemical means of starch modification
Thin-boiling starch, cross-linking, and starch phosphates
159
What is thin-boiling starch modification?
treated with HCl or nitric acids to get acid hydrolysis
160
What is cross-linking starch modification?
Increase cross-linking, retain viscosity/thickening agent, limited retrogradation, increased resistance to acid, heat, shear force, applications (acidic/canned foods)
161
What is starch phosphate starch modification?
Esterification with phosphates (sodium tripolyphosphate); molecules repulse each other because they are charged, results in increased stability and translucence and reduced syneresis
162
Starch Functional Properties
1. Gelatinization -- pasting -- implosion
2. Gelation
3. Retrogradation -- syneresis
4. Dextrinization
163
How do homo-polysaccharides differ from hetero-polysaccharides?
Homo: Composed of same type (one type)
Hetero: Composed of more than one type
164
Example of homo-polysaccharide:
starch, glycogen, cellulose
165
Example of hetero-polysaccharidea:
Hyaluronic acid, pectins, peptidoglycan
166
What is PSE meat, and how is it formed?
During 24 hours after death of an animal occurs: process of breaking up of the glycogen to the lactic acid; decreasing acidity of the muscles from pH 7 to ph 5.6
167
Can you explain what a non-destructive test?
method used to assess the quality, safety, and nutritional content of food products without causing any damage to the food itself
168
Example of non-destructive test:
Near-infrared spectroscopy (NIRS), X-ray Computed Tomography (CT)
169
If a starch contains 12% amylose, can it form a gel?
No, amylose content must be > 20%
170
What are the applications of starch with high amylose and amylopectin?
Amylose: Pudding
Amylopectin: Anything you don't want to make gel with
171
Which type of modified starch is suitable for instant pudding?
Pregelatinization starch
172
If you aim to enhance flavor retention in plant-based bacon, what type of starch would you choose?
Spherical aggregates
173
What type of starch is suitable for acidic food?
cross-linked starch
174
Which starch can increase the water-holding capacity in food?
Phosphate starch
175
What is the physical process of Gelatinization?
Process that results in thickening as starch granules heated in water
176
True or False? During Gelatinization, when viscosity increases, translucency increases.
True
177
What is Pasting?
The change that occur to starch after gelatinization has taken place and heating continues
178
What happens during Pasting?
Amylose is lost from granules and Crystalline structure is lost
179
What is the Starch Granules Structure?
radial arrangements of starch molecules; crystalline regions: double helices, strong interchain H-bonding between hydroxyl groups, requires energy to dissociate
180
What is the amorphous starch granules structure?
Random associations and weak interchain interactions
181
What factors affect gelatinization and pasting?
Temperature, Starch Type, Added Ingredients
182
Effect of added ingredients on gelatinization/pasting: Sugar
Sugar - competes with water with the starch granule and cross-links with the starch molecules; delays gelatinization and level of sugar increases
183
Effect of added ingredients on gelatinization/pasting: Acid
Acid - especially below pH 4 alone with heat results in hydrolytic reactions that break starch into shorter molecules; results in thinner paste; rapid heating accelerate acid hydrolysis
184
Effect of added ingredients on gelatinization/pasting: Fats
Fats - reduce gelatinization and max viscosity temperatures; coat surfaces of starch granules
185
Effect of added ingredients on gelatinization/pasting: Egg yolk
Heat sufficiently to coagulate the yolk proteins (alpha-amylase)
186
The process of gelation:
Starch gel is formed; hot starch exist as sols; while hot amylose moves freely and quickly; when cooled, amylose moves slowly and stable H-bonding is formed
187
What is the difference between gelatinization and gelation?
Gelatinization is the process of becoming a paste through heating; gelation is the process of paste to gel
188
Three factors need for Gelation
1. Types and concentration of starches
2. Extent of heating
3. Agitation
189
What is retrogradation?
The gradual process of recrystallization of crystalline regions of starch gels
190
What does retrogradation result in?
Gritty texture of gel and syneresis
191
What is Syneresis?
Free water trapped within the starch gel structure by H-bonds
192
What is dextrinization?
Results from starch being heated in dry form so that the starch is broken down to shorter molecules
193
Example of dextrinization:
Flour is browned in a pan by itself or with fat or as a coating on foods to be cooked
194
What are examples of Food Applications?
- Starch sugars
- Thickeners/stabilizers
- Formation of gels
- Disposable food containers
195
Caramelization vs. Dextrinization
Caramelization: break down for sugar at high temp
Dextrinization: break down of starch at lower temp
196
What is Fiber?
A combination of materials in foods that cannot readily be digested
197
The two types of fiber?
Soluble and insoluble fiber
198
What is soluble fiber?
digested to a limited extent
199
Example of soluble fiber
gums, pectic substances, beta-glucans
200
What is insoluble fiber?
pass through the body undigested
201
Examples of insoluble fiber
cellulose, hemicellulose, and lignin
202
What are the five plant pigments?
Chlorophyll, carotenoids, flavonoids, enzymatic browning, and myoglobin
203
What are the two different Flavonoids?
Anthocyanin and Anthoxanthin
204
What are the two Chlorophyll Degradative Reactions?
Acid and Alkaline
205
What happens in a Chlorophyll Acid Degradative Reaction?
Acid displaces magnesium from chlorophyll (results in olive green color)
206
What are the two Chlorophyll Degradative Reactions?
Acid and Alkaline
207
Examples of Chlorophyll Acid Degradative Reactions
Acid fermentation of pickles and olives, canned green vegetables (natural organic acids)
208
What happens in an Chlorophyll Alkaline Degradative Reaction?
Alkaline prevents displacement of Mg++; significant softening of tissue
209
What do carotenoids do?
Reactions affecting color
210
Are Carotenoids heat and acid stable under normal cooking conditions?
Yes
211
What does high heat cause in Carotenoids?
Can cause conversion of the trans and cis double bonds; results in lighter, less intense color
212
What does oxidation do to Carotenoids?
Responsible for some loss in color in fruit and vegetables containing carotenoids particularly in dried fruits
213
How can oxidation reactions in Carotenoids be minimized?
By blanching prior to drying; dissolve the carotenoids into lipids
214
What is a Flavonoid?
Related group of pigments consisting of 2 phenyl rings joined by 5 or 6 membered ring
215
What is an Anthocyanin?
Oxygen in the center ring is charged (+); highly colored and water soluble (red to purple to blue)
216
What is an Anthoxanthin?
Oxygen in the center ring is uncharged; colorless or white (acid) or cream (neutral), color may change to yellow (basic)
217
What three reactions affect color in Anthocyanins?
Oxidation, contact with metallic ions, and enzymes
218
How does oxidation affect color of Anthocyanins?
Can readily undergo oxidation in the presence of oxygen and/or heat -- color vibrancy decreases
219
How does contact with metallic ions affect color of Anthocyanins?
Iron, copper, aluminum, tin can complex, with the pigments and form weird off-colors
220
How can Enzymes affect color of Anthocyanins?
Anthocyanese can destroy color or cause oxidative reactions; mild heat treatment sufficient to inactivate most of these enzymes
221
What are Anthoxanthins responsible for?
Subtle in color but also sensitive to changes in pH. Responsible for taste (astringency)
222
What are Anthoxanthins more prone to?
Complexing with metal ions; complex aluminum is yellow and with iron is dark
223
What is Enzymatic Browning?
A chemical process which occurs in fruits and vegetable by the enzyme polyphenol oxidase, which results in brown pigments
224
How can enzymatic browning be prevented?
Cold temperature storage, addition of acid to cut surfaces, sulfur dioxide, elimination of oxygen, addition of ascorbic/citric acid
225
What are two Heme Pigments?
Hemoglobin and Myoglobin
226
What is hemoglobin?
MW: 68,000; present in blood
227
What is Myoglobin?
MW: 17000; present in muscle tissue, accepts and stores oxygen in muscle; necessary to bind oxygen tightly; contributes to color of fresh and processed meats
228
What color is oxymyoglobin?
Cherry red (fresh meat)
229
What color is myoglobin?
Purple-red (interior of muscle)
230
What color is metamyoglobin?
Brownish-red (less acceptable meat)
231
What are the color layers in whole muscle?
Outer layer: RED w/ oxygen
Middle layer: BROWN (oxidized)
Inner layer: PURPLE (no oxygen)
232
When you use nitrites as a catalyst what do you get?
Nitric oxide myoglobin (red)
233
When you heat nitric oxide myoglobin, what do you get?
Nitrosyl Hemochrome intense pink-red
NUFS 101A
flashcards
Decks in class (2)
# Cards
