1
Q
What are the fat soluble vitamins?
A
Vitamins A,D,E,K
2
Q
What are the water-soluble vitamins?
A
Vitamin C, Thiamin (B1), Riboflavin (B2), Niacin (B3), Pyridoxine (B6), Vitamin B12, Folic acid, Pantothenic Acid, Biotin
3
Q
What is tetrodotoxin from?
A
Puffer fish (live, skin, etc.)
4
Q
What is Vitamin A - Retinol (Alcohol)?
A
Occurs in nature as fatty acid ester
5
Q
What is Vitamin A - Retinol (All-trans form)?
A
Most active biologically
6
Q
What is Vitamin A - Retinol (13-cis isomer)?
A
Neo-vitamin A; 75% of biological activity of all-trans form
7
Q
What are the important sources of Vitamin A (Retinol)?
A
Fish liver oils, mammalian liver, egg yolk, milk and milk products
8
Q
What are the biological functions of Vitamin A (Retinol)?
A
Normal vision, reproductive functions, maintenance of growth and general health
9
Q
What are Provitamin A: Carotenoid pigments?
A
Predominant in plans: leafy green vegetables and yellow-red vegetables
Requires an unsubstituted beta-ionone ring
10
Q
Where is Provitamin A converted to retinol?
A
Intestinal mucosa
11
Q
When is Vitamin A stable in heat?
A
In the absence of oxygen
12
Q
Vitamin A is highly susceptible to oxygen because:
A
light sensitive, susceptible to conditions favoring lipid oxidation, sensitive to copper
13
Q
Vitamin A is unstable in:
A
Mineral acids (sulfuric acid, hydrochloric acid and nitric acid)
14
Q
Vitamin A is stable in:
A
Alkali
15
Q
Vitamin D2 (Ergocalciferol) is present in:
A
yeasts, plants, supplements
16
Q
Vitamin D3 (Cholecalciferol) is present in:
A
fish liver oils, eggs, milk, butter, cheese
17
Q
Vitamin D Fortification is present in:
A
Margarine and milk
18
Q
Provitamin D is converted to vitamin D by:
A
Irradiation with UV light
19
Q
Vitamin D: Biological role is…
A
biologically active form: 1,25-Dihydroxy Vitamin D (liver & kidney); stimulate absorption of calcium
20
Q
What is the Vitamin D deficiency disease?
A
Rickets
21
Q
What is vitamin D stable to?
A
pasteurization, boiling, sterilization, and frozen storage
22
Q
What are Vitamin E alpha-Tocopherol?
A
Most abundant, greatest biological activity
23
Q
Biological functions of Vitamin E (Tocopherols):
A
Biological activity related to antioxidant activity (protect cell membranes against free radicals)
24
Q
What is the stability of Vitamin E?
A
substantial losses in processing and storage
25
Vitamin C: Major sources?
Fruits, green vegetables, tomatoes, potatoes, berries, milk, liver
26
What are the Vitamin C activity?
L-ascorbic acid and L-dehydroascorbic acid
27
Vitamin C: Biological functions
Influences oxidation -- reduction reactions in tissues; role in collagen formation
28
Vitamin C: deficiency disease?
Scurvy
29
Factors Affecting Vitamin C Stability: Oxidation
exposure to oxygen (least stable at alkaline and neutral pH), exposure to metals, prolonged heating, exposure to light
30
Factors Affecting Vitamin C Stability: Enzymes
Direct: ascorbic acid oxidase
Indirect: phenolase, cytochrome oxidase, peroxidase
31
Processing treatments to improve stability of vitamin C?
Blanching prior to drying/freezing, pasteurization, deaeration, addition of metal chelating compounds
32
Definition of mineral
essential mineral elements that are nutritionally important and are needed for proper body function and maintenance of health
33
Where can you find minerals?
Naturally present in food, food ingredients
34
What do minerals provide?
functional properties in processed foods
35
What are the sources of minerals?
uptake from soil or feeds; contamination during processing
36
Whats the nutritional requirement for calcium
cobalt
37
Whats the nutritional requirement for chlorine?
copper
38
Whats the nutritional requirement for magnesium?
fluroine
39
Whats the nutritional requirement for phosphorous?
iodine
40
Whats the nutritional requirement for potassium?
iron
41
Whats the nutritional requirement for sodium?
manganese
42
Whats the nutritional requirement for sulfur
selenium and zinc
43
Nutritional Functions: Electrolytes
calcium, chlorine, potassium, sodium
44
Nutritional Functions: Component of Bones
calcium, phosphorous, fluoride
45
Nutritional Functions: ATP and Energy Processing
Phosphorous and magnesium
46
Nutritional Functions: Component of enzymes
copper, iron, selenium, zinc
47
Nutritional Functions: Component of hemoglobin
iron
48
Nutritional Functions: Biosynthesis of vitamins
Cobalt (b12)
49
Nutritional Functions: Biosynthesis of thyroxine
Iodine
50
True or False? Ferrous salts are more readily available than ferric salts.
True
51
What vitamin enhances iron absorption?
Vitamin C
52
What reduces iron absorption?
Calcium, phosphate, bran (fibers & phytic acid)
53
How does calcium affect iron absorption?
High levels of calcium can interfere with the iron-transporting protein
54
How does phosphate affect iron absorption?
Phosphate can bind to iron, forming insoluble complexes
55
What is Biosynthesis of vitamins (Cobalt) used in?
Energy drinks; tingling, weakness, numbness
56
What is Iodine?
thyroxine is a hormone; it is partially composed of iodine
57
What does a deficiency in iodine lead to?
Decrease production of thyroxine
57
Predominant Form in Foods: Soluble salts -- Ionized form
sodium and potassium cations; chloride and sulfate anions
58
Predominant Form in Foods: Equilibrium between ionic, dissolved nonionic, and colloidal species
Ions form colloids if at higher concentrations than are soluble; example: Ca in milk
59
Predominant Form in Foods: Chelates
coordinate covalent bonds between a ligand and metal cation; ex: iron bound to heme, Mg in chlorophyll
60
Factors Affecting Retention of Minerals
Losses of minerals
61
What are the two losses of minerals?
Physical removal and formation of chelates can decrease availability of minerals
62
Examples of physical removal:
leaching, trimming of plant tissues, milling of cereals
63
Examples of formation of chelates
mineral absorption (Fe, Zn, Ca) decreased by fiber
64
What are lipids?
non-polar, water soluble, contain C, H, and a little O; commonly called fats and oils
65
What is the most common group of lipids significant in food?
acylglycerol group
66
What does a lipid consist of?
mono, di, and triglycerides; consist of glycerol backbone (3 carbon polyhydric alcohol) and one or more fatty acid attached to the glycerol with ester linkages
67
Chemical structures: Fatty Acids
contain an acid group at one end, contain an even number of carbons, range from 2-20 carbons
68
Chemical structures: Saturated fatty acids
have no double bonds (contain all the hydrogen they can hold)
69
Chemical structures: Unsaturated fatty acids
contain one or more double bonds -- the more double bonds the lower the melting point
70
Types of double bonds
Trans and cis
71
What is a trans double bond?
hydrogen atoms attached on opposite sides of the double bond
72
What is a cis double bond?
hydrogen atoms attached on the same side of the double bond
73
Acylglycerols Melting Point: Chain length
as chain length (# of carbons) increases, melting point increases
74
Acylglycerols Melting Point:
Number of double bonds/degree of saturation
as number of double bonds increases, melting point decreases
75
Acylglycerols Melting Point:
Types of double bonds
Cis: have lower melting points than trans became cis-configurations puts a "kink" in the chain (Van der Waals)
76
Acylglycerols Crystallization
exhibits polymorphism (alpha, beta, beta prime, and intermediate); number of fatty acids attached to the glycerol backbone; configuration of triglycerides
77
Chocolate: Tempering Fat
special tempering procedure needs to be followed to produce desired polymorphs;
1. molten chocolate 50-60 C for 1 hr;
2. cool to 25-27 C to initiate crystallization
3. Heat to 29-31 C
4. Mold and final cooling to 5-10 C
78
Lipid Chemical Reactions
Hydrogenation
Interesterification
Oxidative Rancidity
Hydrolytic Rancidity
Smoke Point
Polymerization
Acrylamide
79
Hydrogenation:
Oil under heat in the presence of hydrogen
gas using a nickel/platinum catalyst
(Eliminates double bond; Makes the material more solid (increases melting
point); Used to make margarines, vegetable shortenings,
and peanut butter homogenous; Partially hydrogenated oil can form some trans (health issue))
80
Interesterification
Treatment of a fat with sodium methoxide or
another agent (lipase) to split fatty acids from
glycerol and then to reorganize them on
glycerol to form different fat molecules with
less tendency to form coarse crystals. (Raises the melting temperature of the fat; Produces shortening with a higher melting point
while avoiding the trans fatty acids)
81
Interesterification: Randomized
done using melted fat so there is a complete fat change
82
Interesterification: directed
Only the lipid molecules that are in the fluid state are altered by sodium methoxide when the fat is kept below its melting point
83
Oxidative rancidity
chemical free radical reaction, involving uptake of oxygen and production of off-flavors (and odors)
84
Oxidative Rancidity occurs in three stages:
Initiation, propagation, termination
85
Oxidative Rancidity: Initiation
formation of free radicals
86
Oxidative Rancidity: Propagation
formation of hydroperoxy radicals and hydroperoxide
87
Oxidative Rancidity: Termination
radicals can "run into each other," react and terminate the cycle, but usually not until several times (~500) through the sequence
88
Oxidative Rancidity Prevention
use of antioxidants, keep in low temp/low light, removal of O2 from the package
89
Hydrolytic Rancidity
Involves hydrolysis of lipid (triglycerides), usually via enzyme heat
90
Smoke point
The temperature at which fats or oils begin to emit smoke (~374 degrees F) or higher
91
What is the temperature at which fat degrades -- lipolysis to glycerol and free fatty acids occurs
~374 degrees F
92
______ can lead to dehydration of the glycerol molecule and the formation of acrolein.
Continued heating
93
Shortenings or other monoglycerides:
have only one fatty acid to be removed before free glycerol is left
94
Chemical Reactions: Polymerization
Formation of dimers and trimers of fatty acids containing at least one double bonds -- form due to intense heat
95
Polymerization: Formation of larger lipid molecules results in:
increasing viscosity, foaming, and darkening of frying oils
96
Chemical Reactions: Formation of Acrylamide
Carcinogen formed in starchy fried foods and baked products
97
Lipids Functional Roles:
color, flavor, texture, tenderness, emulsification, cooking medium
98
Functional Roles: Color
can contribute to yellow color
99
Functional Roles: Flavor
Richness (mouth feel), short chain fatty acids, aldehydes, ketones, other unique flavors and odors
100
Functional Roles: Texture
flakiness, aeration
101
Functional Roles: Tenderness
Due to interference with the development of proteins; related to shortening power: the ability of fat to cover protein in batters to prevent contact with water
102
Shortening power is increase by
The presence of double bonds in fatty acids, fluidity of the lipid
103
Functional Role: Emulsification
Phospholipids act as emulsifiers --> hydrophilic and hydrophobic ends from micelles
104
Functional Role: Cooking medium
Very effective, dehydrates foods as well, best lipids,
105
What are the best lipids for frying?
peanut, cottonseed, soybean (olive oil is NOT a good medium for frying)
106
Production: Extraction (Cold Pressing)
mechanical meals of extracting oil from vegetable materials (best oils are cold pressed but it's not very efficient)
107
Production: Extraction (Hot Pressing)
used for seeds; done at 70 degrees C with steam
108
Production: Refining
Removal of gums, lipoproteins, lecithins, ketones & aldehydes, free fatty acids
109
Production: Winterizing
Chilling of oils to remove high MP triaclyglycerols that make oils solid at refrigerated temperatures; used often by salad dressing companies
110
Production: Fractionation
oils are separated under controlled temp to remove fatty acids that crystallize at higher melting points; these high melting point saturated fats are then added to other oils
111
Melting point:
Saturation
112
Soft stearin -->
Shortening
113
Super stearin/Stearin -->
Replace hydrogenated vegetable oils and fat in margarine
114
Super olein -->
liquid oils
115
Production: Crystallization
tempering to produce beta crystals -- done at controlled temp with agitation
116
Substitutions: Consider
Amount of fat in product, melting point, color, flavors, shortening power
117
Substitutions: Protein-based
Made of milk proteins and egg white proteins and water
118
Substitutions: Starch-based
corn starch, pectin, gums & non-fat dry milk, oats, rice, microcrystaline cellulose, other gums
119
Starch-based: Stellar
made from cornstarch; used in cheese spreads and frostings
120
Starch-based: Oatrim
enzymatically modified (hydrolyzed) oat flour containing 5% beta-glucan soluble fiber
121
Substitutions: Sucrose polyesters
sucrose with attached fatty acids -- the resulting molecule is not digestible
122
Substitutions: Structured lipids
interestification of medium chain fatty acids to get molecules not stored in adipose; smaller carbon until fatty acid replacements that are not utilized effectively by the body (5 cal/g)
123
What is the DRI of protein?
0.8 grams of protein per kilogram of body weight (or 0.36 g/lb)
124
How many grams of protein per day for an average sedentary man?
55 grams
125
What is Quorn?
a meat substitute product originating in the UK and sold primarily in Europe; contains mycoprotein; mixed with egg albumen/potato protein
126
Composition of protein
Carbon: 50-55%
Hydrogen: 6-7%
Oxygen: 20-23%
Nitrogen: 12-19%
Sulfur: 0-3%
127
What is nitrogen used for in protein?
Estimate protein content in foods
128
Protein Classification: Gross Structural Organization
Globular: spherical, enzymes
Fibrous: Rod-shaped, structural proteins
129
Protein Classification: Complexity of protein
Simple proteins: contain only amino acids, not modified
Conjugated proteins: contain non-protein constituents, modified with non-protein constituents by enzymes
130
Protein Classification: What are the Conjugated Proteins?
Phosphoproteins, lipoproteins, glycoproteins, metalloproteins
131
What are phosphoproteins?
a major regulatory mechanism in cell
132
What do lipoproteins do?
transport hydrophobic lipid molecules
133
Where are glycoproteins?
immune, digestive and reproductive system
134
Classification: Sarcoplasmic protein:
soluble in neutral, salt-free water
135
Classification: Myofibrillar protein
soluble in neutral salt solutions
136
Classification of Side Chains (R): Hydrophobic
aliphatic, aromatic, limited solubility in water
137
Classification of Side Chains (R): Hydrophillic
charged, uncharged, highly soluble in water
138
Classification of Side Chains (R): Amphiphilic
hydrophilic and hydrophobic properties
139
How many different amino acids of side chains (R)?
20 different amino acids
140
Emulsification membranes: Myofibrillar proteins:
hydrophobic portion --> fat
hydrophillic portion --> water
141
True or false? Start with lean meat plus salt.
True
142
____ / _____ under vacuum can increase capacity and stability
Chopping/mixing
143
Isoelectric point
pH at which the amino acid is electrically neutral
144
Primary structure
simply the sequence of amino acids from the amino-end to the carboxyl-end
145
Secondary structure
localized regions of primary structure that fold into specific structures - alpha-helix, beta-sheet, turns, etc.
146
Tertiary structure
Packing of secondary structures into a larger fold. The overall fold of a single polypeptide chain
147
Quaternary structure
association of two or more individual polypeptides into a multi-subunit protein molecule
148
An ____ is a protein that is able to catalyze chemical reactions due to its specific power of activation
enzyme
149
Enzymes:
allow chemical changes to occur under mild conditions (37C, neutral pH), affect velocity, high specificity and selectivity, easily controllable by adjustment of pH, temperature, and enzyme concentration, are of natural origin and non-toxic
150
Enzyme _____ activation energy for reactions
lowers
151
Native state:
result of attractive and repulsive interactions (driven by side chain group); thermodynamically most stable
152
Change in native protein structure -->
change in function and activity of protein
153
Effect of processing on protein structrues
protein hydrolysis, protein denaturation, heat shear pH salts
154
Protein Hydrolysis (Protein Degradation)
by the addition of acid or proteolytic enzymes, cleaves peptide bonds, alters primary structure
155
When Protein Denaturation occurs:
change in 3-D structure (2-4 structure) of protein, peptide bonds not broken, folded to unfolded structure, changes in functional properties
156
Denaturation: change in functional properties
loss of enzyme activity, change in solubility, increased digestibility, improved foaming and emulsifying properties
157
Function after the denaturation
control denaturation during processing to optimize functional properties
158
Denaturing Agen: Heat: Destabilized _____
at high temperature: hydrogen bonding, electrostatic and van der Waals interactions
159
Denaturing agent: Heat: Stabilized _____
at high temperature: hydrophobic interactions
160
Denaturing agent: Heat: Net effect -- destabilization of proteins
proteins with hydrophobic amino acids tend to be more thermal stable than hydrophillic
161
Factors influence sensitivity to heat
characteristics of protein, length of heat treatment, temperature
162
Denaturing agent: Shear (shaking, kneading, whipping)
incorporation of air bubbles, absorption of protein molecules at air-liquid interface; conformational change in proteins depends on flexibility of proteins
163
Denaturing agent: pH
more stable against denaturation at their isoelectric point than any other pH
164
Salts: Low concentrations (<0.2 ionic strength)
hydrophilic proteins (surface); ions interact with proteins via nonspecific electrostatic interactions, stabilizes protein structure, and solubility increases
165
Salt: High concentrations ( > 1M)
dehydration of protein; salt ions compete with protein for water, decrease amount of water available to protein
166
Effects of processing on Protein Structure
1. Heat: hydrophobic interaction
2. Shear: flexibility of proteins
3. pH: Mild pH change -- reversible
4. Salt: Low concentration/high concentration
167
Definition: Functionality
those physical and chemical properties which affect the behavior of proteins in food systems during processing, storage, preparations, and consumption
168
Functionality of naturally occurring proteins -- Important
increasing emphasis placed on isolating proteins from plant and animal sources and using them as food ingredients
169
Chemical properties influencing functionality
size and shape, amino acid composition, net charge and charge distribution, hydrophobocity/hydrophilicity ratio, 2-4 primary structures, molecular flexibility/rigidity
170
Protein functionality challenges
model systems, complexity of foods, protein hydration, gelation, interfacial properties, binding
171
Protein hydration
interactions with water govern the folding, structure, and stability and activity of proteins
172
Factors affecting protein hydration: pH effects
1. At pI of protein: less hydration; enhanced protein-protein interactions decrease interaction with water
2. pI: increased water binding and solubility; increase net charge; electrostatic repulsion and hydration of charged residues
173
Factors affecting protein hydration: Salt effects
1. Low concentrations (<0.2 M): increase water binding capacity and solubility
2. High concentrations (> 1.0 M): dehydration of protein: salt ions complete with protein for water
174
Factors affecting protein hydration: Temperature
increase in temperature, denatured proteins, aggregated proteins
175
Decreased water binding capacity when:
increase in temperature and aggregated proteins
176
Increased water binding capacity when:
denatured proteins
177
Gelation
polymers cross-linked via covalent or non-covalent bonds to form a 3D network that is able to entrap water and other low MW substances
178
Transformation from sol to gel facilitated by:
heat, enzymes, acid, divalent cations
179
Stages of gelation (thermally irreversible gel):
1. Unfolding of protein (irreversible)
2. Maintain of protein network with cooling
180
Thermally irreversible
forms with heating, maintains structure upon cooling, gels from muscle protein and egg protein
181
Thermally reversible
forms with cooling (H-bonds), melts when reheated, gelatin
182
What bonds are involved with Gelation?
hydrophobic interactions, hydrogen bonds, electrostatic interactions, and disulfide bonds
183
What are the requirements for Gelation bonds?
ability to bind water; attraction between protein molecules
184
Gelation: Environmental Factors
pH, divalent cations, limited proteolysis, transglutaminase
185
Environmental factors: pH
pH 7-8: optimum pH for gel formation; pH extremes: weak gels form; strong electrostatic repulsion
186
Environmental factors: Divalent cations
Form crosslinks between negatively charged groups; tofu
187
Environmental factors: Limited Proteolysis
cleavage of part of protein - open protein structure so gel can form; cheeseE
188
Environmental factors: Transglutaminase
Enzymatic cross-linking of proteins at room temperature; forms crosslinks between glutamine and lysine
189
Interfacial properties
Important foams or emulsions; proteins (amphiphilic), and proteins need to form a cohesive film to prevent the 2 phases from coalescing
190
What are amphiphilic proteins?
Migrate to air-water interface or oil-water interface
191
Emulsions
mixtures of at least 2 immiscible liquids, one of which is dispersed in the other in the form of fine droplets
192
Dispersed phase:
droplets
193
Continuous phase
surrounding liquid
194
Factors influencing emulsification
solubility and pH
195
How does solubility affect emulsification?
100% solubility not required; 25-80% is good emulsification; solubility requirement: protein dependent
196
How does pH affect emulsification?
At pI, most proteins are poor emulsifiers (low solubility); pH <> pI: more effective emulsifiers
197
Foams
liquid or solid continuous phase surrounds a dispersed gaseous phase; formed by whipping or shaking a protein solution
198
Foaming property of a protein depends on ______
ability of protein to form a thin film at the interface
199
Factors affecting foam formation:
pH, lipids, partial heat denaturation,
200
How does pH affect foam formation?
foams are more stable at pI; lack repulsive interactions; promotes protein-protein interactions; promotes interactions between proteins and interface
201
How do lipids affect foam formation?
impair the foaming properties; readily absorb at air-water interface and inhibit absorption of proteins during foam formation; lipid films unable to stabilize air bubbles
202
How does partial heat denaturation affect foam formation?
improves foaming properties; increased molecular flexibility
203
Proteins can bind lipid/flavor compounds to:
impact sensory properties
204
Interactions -- non-covalent
van der Waals', hydrogen bonding, electrostatic interactions
205
Lipid-binding/Flavor-binding: Reactions -- irreversible
can contribute to aroma, taste and texture of protein food
206
Gluten free
1. gluten: glue in the bakery
2. allergy to gluten
3. gluten free: higher sugar and fat contents
4. gluten free food: vitamins and minerals
207
Proteins in milk
Two main fractions: casein and whey
208
Casein
make up 80% of cow's milk; alpha, beta, kappa, and gamma caseins
209
Whey
make up 20% of milk proteins; fairly soluble; do not precipitate out at pH 4.6
210
Caseins are primarily ____ expect for kappa which has a polar end
hydrophobic
211
Whey are _____ and form coat on bottom of pan when milk is heated
heat sensitive
212
Whey contributes to the cooked flavor of milk due to the formation of ______
hydrogen sulfide
213
Differences between Whey and Casein
Digestion rate (whey: fast, casein: slow) and protein profiles (whey: leucine; casein: protein preservation/breakdown)
214
NUFS 101A
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