Technical Challenges (9)

Question 1

what are reasons for low predictability of structural contributions of individual food components?

Answer 1

1. integration of proteins w/ polysaccharides
2. proteins and polysaccharides change functionality during formulation and processing
3. functionality depends on kinetic factors and processing conditions

Question 2

describe protein-sweetener interactions

Answer 2

• proceeds through maillard rxn or strecker degradation
• requires proper rxn conditions for pH, Aw, temp
• rxns can be controlled by acid, Aw, sulfites

Question 3

how do sweeteners influence gelatinization point of starch?

Answer 3

they raise temp where gelatinization occurs

Question 4

describe the interactions of sweeteners w/ fats and oils

Answer 4

they don’t chemically react w/ fats and oils. Instead, they interact physically to impact rheological characteristics via:

1. particle size distribution
2. moisture released from amorphous sugars

Question 5

how does the particle size of a sweetener affect the amount of fat needed?

Answer 5

decrease sweetener particle size = increase in surface area = increase need for more fat to maintain the same rheological characteristics

Question 6

what are the two mechanisms/interactions in which surfactant-biopolymer interactions occur through?

Answer 6

1. electrostatic

2. hydrophobic interactions

Question 7

the binding of surfactants to biopolymers has an influence on what?

Answer 7

bulk physicochemical properties of biopolymer solutions (eg. appearance, rheology, phase behaviour)

Question 8

describe the critical aggregation concentration

Answer 8

the conc at which the interaction between the surfactant and the biopolymer first occurs

Question 9

describe what happens as surfactant concentration increases from the critical aggregation concentration

Answer 9

surfactant conc increases until polymer is saturated w/ surfactant

Then micelles start to form

Question 10

describe interactions b/w emulsifiers and polysaccharides. What are the effects of this?

Answer 10

• surfactants form inclusion complexes w/ starch by inserting their hydrocarbon tails into helical coils formed by amylose or linear regions of amylopectin
• this increases loaf volume, reduced crumb firmness and delays staling (slower retrogradation of starch)

Question 11

describe direct interactions between emulsifiers and proteins

Answer 11

binding of surfactants to proteins which causes changes in conformation, stability or interactions of protein molecules

Question 12

describe indirect interactions b/w emulsifiers and proteins

Answer 12

surfactants can compete or displace proteins

Question 13

describe interactions b/w emulsions and lipids

Answer 13

transitions from one crystal form to another during storage of fat based pdts can cause undesired effects (fat crystallization)

Question 14

what are 2 main contributors to phospholipid-protein binding?

Answer 14

1. electrostatic interactions

2. hydrophobic interactions

Question 15

how does soy lecithin affect soy proteins?

Answer 15

• lecithin has strong affinity to soy proteins

- emulsifying property of the complex increases by ethanol heat treatment

Question 16

how does sonicating proteins with egg yolk phosphatidylcholine affect emulsifying properties of proteins?

Answer 16

enhances the emulsifying properties

Question 17

how do phospholipids affect protein functionality?

Answer 17

improves functionality by forming a conjugate w/ low emulsifying globular proteins

Question 18

what is LPC?

how does it affect interfacial absorptivity of ovalbumin?

Answer 18

lysophosphatidylcholine

promotes interfacial absorptivity of ovalbumin

Question 19

which is better at producing emulsion droplets?

a) proteins
b) polysaccharides

Answer 19

proteins are better when used at low conc

Question 20

which is better at producing emlsions that are stable to a wider range of environmental conditions?

a) proteins
b) polysaccharides

Answer 20

polysaccharides are better

Question 21

describe how protein polysaccharide complexes are held together.

when are they formed?

Answer 21

by physical or covalent interactions

formed before or after homogenization

Question 22

how does the addition of lipids affect starch properties?

Answer 22

• reduces swelling and gelatinization
• prevents leaching of amylose from starch when heated
• slows retrogradation
• increases resistance of starch to amylase (forms resistant starches)

Question 23

what type of protein-starch complexes are most effective stabilizers and emulsifiers?

Answer 23

neutral complexes

Question 24

what happens when you add starch to a protein gel?

Answer 24

• increases stiffness of resulting gel
• increases temp of peak viscosity of amylopectin starch
• overall influence on rheological properties of dough pdts