proteins

Question 1

9 essential AA

Answer 1

Essential:

1. Histidine
2. Isoleucine
3. Leucine
4. Lysine
5. Methionine
6. Phenylalanine
7. Threonine
8. Tryptophan
9. valine

Question 2

conditionally indispensable

Answer 2

CONDITIONALLY INDISPENSABLE:

1. Arginine
2. Cysteine
3. Glutamine
4. Glycine
5. Proline
6. tyrosine

Question 3

5 nonessential

Answer 3

1. Alanine
   
   2. Asparagine
   3. Aspartic acid
   4. Glutamic acid
   5. serine

Question 4

protein responsible for milk allergy

Answer 4

B-lactoglobulin (10% of the proteins present in cow’s milk)

- present as a dimer (2 identical subunits)

Question 5

protein denaturation ex: egg whites + what happens with coagulation

Answer 5

1. SOLIDIFACTION/OPAQUENESS upon heating is due to THERMALLY INDUCED denaturation of egg-whites proteins (cant return to the original state)
   
   2. PRODUCTION OF A FOAM when egg white is whipped (meringue) is due to encapsulation of air bubbles by SURFACE-DENATURED PROTEIN MOLECULES (can return to the original state/not permanent)
   • COAGULATIONl permanent denaturation results when liquid or semi-liquid proteins from solid or semisoft clots
   1. It change physical characteritics
   2. Alters the ability to bind with water
   3. Interferes with biological interactions of enzymes

Question 6

5 causes protein denaturation

Answer 6

1. TEMPERATURE CHANGES
   
   • Heat speeds up denaturation
   • Colder temp. May cause curdling
   2. MECHANICAL ACTIONS
      - Beating, rolling and kneading disrupt protein structures
      - Gluten strenghtens during kneading
   3. SOUND WAVES AND IRRADIATION
      - Prolonged exposure at high levels is needed
   4. CHANGES IN PH
      - Exposure to acids or alkalis can cause structure to unfold
      - Sour cream, buttermilk and yogurt are the result of acids denaturing milk proteins
   5. EXPOSURE TO MINERAL SALTS OR METALS
      - Sodium and potassium salts and various metals denature proteins

Question 7

examples of ionized functional groups

Answer 7

Many of the side chains on AA contains hydrogen-bonding or ionized functional groups:

1. Hydroxyl (OH)
2. Sulfhydryl (SH)
3. Amide (O=C-NH2)
4. Carbocyl (COOH, ionized to COO- at pH=4)
5. Amino (NH2, ionized to NH3+ at pH=10) * * THERE ARE POLAR AND HYDROPHILIC

Question 8

4 thigns food scientists analyze to determine how effectively a protein will work in a food product

Answer 8

• Degree of water absorption
  
  • Solubility
  • Viscosity
  • Stability in acids and alkalis

Question 9

7 functional properties of proteins

Answer 9

1. Thickening agents
   
   2. Gelling agents
   3. Curd forming
   4. Emulsifying agents
   5. Meat analog formation
   6. Viscoelasticity
   7. Agents for production of color and/or flavor

Question 10

role of amylase, glucose isomerase, papain, glucose oxidase, rennet

Answer 10

1. AMYLASES, GLUCOSE ISOMERASE:production of high-fructose sweeteners
   
   2. PAPAIN (protein present in the papaya plant): meat tenderization
   3. GLUCOSE OXIDASE: removal of headspace oxygen from foods (to prevent oxidation of food components)
   4. RENNET: curd formation in cheese manufacture

Question 11

nutritional contribution of proteins

Answer 11

1. Support growth and repair (provide nitrogen and AA)
   
   2. Fight disease
   3. Maintain fluid and mineral balance
   4. Maintain pH balance (buffers that control acid and base)
   5. Control bodily functions (part of hormones)
   6. Provide energy

Question 12

coenzymes work by..

Answer 12

• Acting as a transfer agent in accepting an atom or molecular group that is broken off and transferring it to another compund
  
  • Vit. And minerals including B vit, calcium, magnesium, zinc

Question 13

putrefaction

Answer 13

• PROTEOLYTIC ENZYMES (proteases and peptidases) degrade proteins to AA, which then undergo DEAMINATION (loss of the amino group as ammonia gas) and DECARBOXYLATION (loss of the carboxyl groups as CO2 gas) by the action of deaminase and decarboxylase enzymes.
  
  • Producets of these reactions have bad odors/flavors

Question 14

rancidity of lipids

Answer 14

• Lipolysis rancidity: refers to off-flavors produced by lypolysis of triglycerides that contain short-chain fatty acyl groups. Only hsort-chain FA like BUTYRIC ACID are associated with off-flavors
  
  • LIPOXYGENASE= enzymes that catalyze lipid oxidation, resulting in rancidity

Question 15

factors that affect enzyme acitivity

Answer 15

1. Water availability
   
   2. Concentration of the solution
   3. Temperature
   4. Acids and bases
   5. Electrolytes
   6. Enzyme inhibitor

Question 16

positive and negative effects of enzymes in food supply

Answer 16

POSITIVE:

- Food easier to eat
- Preserve food
- Improve flavor, quality or apperance
- Plays a role in fermentation

NEGATIVE

- Break down structure of F and V
- Unpleasant flavor and odor changes
- Undesirable changes in texture and color

Question 17

3 roles of enzyme in food industry

Answer 17

• Converting one food product into another like milk to cheese
  
  • Extracting food components from food systems such as the separation of juice from insoluble residues
  • Playing a key role in developing ingredients

Question 18

products of carbohydrase when it reacts with starches and sugars

Answer 18

• Make corn syrup and high-fructose corn syrup
  
  • Ferment wine and beers
  • Stabilize chocolate syrup
  • Clarify fruit juices

Question 19

protease and lipase in food production

Answer 19

LIPASES:
1. Extract unwanted egg yolk from egg white to improve the whipping properties of egg white
2. Improve flavor and texture of various products including cheese, ice cream, margarine, butter and baked goods
PROTEASES
1. Tenderize meat by breaking long protein fibers, as in solutions for MARINATED meat
2. Reduce the size of proteins extracted from malt and grains during beer and ale production
3. Increase pliability
4. Reduce mixing time
5. Change food into a different product, such as milk into cheese