Technical Challenges (2)

Question 1

what are examples of other functions of sugars, besides nutritional value?

Answer 1

• sweeteners
• humectants
• plasticizers
• color and flavor producers through browning rxns
• texturizing agents (crystallization)
• flavor binding
• food preservatives

Question 2

what are 2 types of alternative sweeteners to reduce need for sucrose in food pdts?

describe each. examples?

Answer 2

1. bulk sweeteners:
   - caloric alternatives; more intense sweeteners than sucrose
   - eg. crstalline fructose, high fructose corn syrup, mannitol
2. intense sweeteners:
   - contributes no/few calories to food
   - not approved in any country

Question 3

describe mannitol

Answer 3

• high laxation potential
• low solubility
• high melting point

Question 4

describe maltitol

Answer 4

• disaccharide with half the calories

- 90% sucrose sweetness

Question 5

describe xylitol

Answer 5

• non-cariogenic properties

- cooling effect (hence it’s popularity in oral care, chewing gum and mint pdts)

Question 6

describe tagatose

Answer 6

• monosaccharide made from whey

- 92% sweetness of sucrose

Question 7

what are 4 major determinants for choosing a sweetener

Answer 7

1. quality of flavor (bitter or undesirable aftertastes)
2. cost
3. consumer perception of safety
4. stability in food system

Question 8

describe aspartame

Answer 8

• 180x sweeter than sucrose
• limited heat stability
• hydrolyzes at acidic pH to yield methanol and dipeptide
• participates in non-enzymatic browning

Question 9

describe neotame

Answer 9

• 30-60x swweter than aspartame
• 6,000-10,000 sweeter than sugar
• doesn’t participate in maillard browning rxns
• approved for use as a sweetener and flavor enhancer in foods (except meat and poultry)

Question 10

describe sucralose

Answer 10

• 600x sweeter than sucrose

- heat stable

Question 11

describe saccharin

Answer 11

• 300x sweeter than sucrose
• bitter after taste
• heat stable
• not legal in canada

Question 12

describe acesulfame K

Answer 12

• used in Aspartame blends
• heat stable
• bitter aftertaste

Question 13

describe stevioside

Answer 13

• 300x sweeter than sucrose
• extract of stevia leaves
• not permitted everywhere

Question 14

how do sugars function as humectants?

Answer 14

• through hydrophilic nature of CHOs
• promotes moisture retention
• increases water mobility

Question 15

define plasticizer or softeners

Answer 15

additives that increase the softness or fluidity of the foods to which they are added

Question 16

why are hygroscopic sugars used in baked goods, plastic candies and chewy foods?

Answer 16

they help to retain moisture and inhibit crystallization

Question 17

why are sugars added in intermediate moisture foods (Aw of 0.5-0.9)?

Answer 17

to prevent their toughening and hardening

Question 18

what happens when enough h2o is removed from a sugar solution?

Answer 18

crystallization occurs as in a fondant or fudge

Question 19

crystallization can’t occur until what?

Answer 19

the phase is supersaturated or undercooled = nucleation and growth

Question 20

as sugar crystallizes, amount of plasticizer ___ (incr/decr)

Answer 20

decreases

Question 21

what is the function of osmotically active materials in ice cream?

Answer 21

they act as cyroprotectants to control ice crystals in frozen food systems

Question 22

what does the boiling point elevation curve describe?

Answer 22

how the boiling point temp increases as the amount of dissolved solids increases

Question 23

sweetener solubility is governed by what?

Answer 23

molecular interaction b/w sweetener and h2o

Question 24

what does the equation by Pancoast and Junk describe?

Answer 24

relationship between sucrose, temp and sucrose solubility

Question 25

what needs to be considered in sweetener mixtures?

Answer 25

each sweetener influences the solubility concentration of the others

Question 26

when does glass transition occur?

Answer 26

(Tg) when the glassy state converts to the rubbery state

Question 27

what equation can be used to predict Tg?

Answer 27

Gordon-Taylor equation Tg = (w1Tg1 + kw2Tg2)/ (w1+kw2)

Question 28

describe the state diagrams of fondant vs hard candy

Answer 28

fondant: increase temp until sucrose is soluble, then cool quickly to crystallization temp (approx 40C) hard candy: reach peak temp and then cool quickly to glass transition temp (approx20C)

Question 29

what are the effects of staying in the glassy state?

Answer 29

minimized crystallization and damage due to crystal growth example, drying of pasta is improved by controlling glass transition

Question 30

higher sucrose in synergy with other polysaccharides reduces what? why?

Answer 30

growth of ice crystals b/c sugar renders the cryoprotectant more effective

Question 31

describe how sugars act as color and flavor producers

Answer 31

through non-enzymatic browning (maillard reaction)

Question 32

describe how sugars act as flavor binding agents

Answer 32

sugars can bind to water, alcohols, esters and ketones

Question 33

with starches, what are the 2 levels that needs to be considered

Answer 33

1. molecular level: amylose and amylopectin ratio | 2. morphology of the granule (mechanical properties of starch)

Question 34

what are main functional properties of starch?

Answer 34

- thickening agent - gelling agent - edible films - textural modifier

Question 35

what two features are responsible for the behaviour of starch in foods?

Answer 35

1. ease with which the polymer forms inclusion complexes | 2. ability of the molecules to form crystalline bodies with strong molecular interactions

Question 36

describe the process of starch gelatinization

Answer 36

- H bond rupture within the starch granule - H2O penetration into the loosened disorganized structure - heat addition enables H2O to enter and enlarge granules (swelling) which increases viscosity of solution - cooling: gel forms (uless only amylopectin molecules are present)

Question 37

compare starches with high amylose vs high amylopectin

Answer 37

starches w/ high amylose content makes a stronger and firmer gel b/c more amylose can move out of the granule and into the water a starch with only amylopectin molecules cannot form a gel

Question 38

what is retrogression?

Answer 38

- problem that starch is prone to | - causes starch to form granular and compact textures in the final pdt

Question 39

compare retrogradation to crystallization

Answer 39

retrogradation occurs more often that crystallization

Question 40

what is crystallization?

Answer 40

when starch molecules become irreversibly insoluble in water due to the formation of very powerful intermolecular bonds

Question 41

can the retrogradatioon of amylopectin and amylose be reversed? if yes, how?

Answer 41

amylopectin retrogradation can be reversed by heating strong retrogradation of amylose can't be reversed

Question 42

The cross-bonding of starches effects what physical properties?

Answer 42

- swelling of the granules | - increases stability against breakdown in viscosity in acid foods and at high temp

Question 43

how does substitution of ester or ether groups for OH groups affect retrogradation?

Answer 43

it decreases retrogradation by decreasing association of the OH groups

Question 44

acid modified starches allow for what?

Answer 44

preparation of hot starch solutions of low viscosity which gel upon cooling

Question 45

tapioca starches create what kind of products?

Answer 45

creamy products

Question 46

describe resistant starches

Answer 46

- undigested - serves as dietary fiber - has health promoting effects

Question 47

what are the 4 types of resistant starches?

Answer 47

type 1 RS: physically unavailable starch. Amylolytic enzymes have no access to starch accumulated in plant cells since the GI tract lacks enzymes capable of degrading plant cell walls type 2RS: raw starch of some plant species type 3 RS: retrograded starch occurring in the form of H2O insoluble semi-crystalline structures type 4 RS: chemically or physically modified

Question 48

how does the presence of sugars affect the properties of starches?

Answer 48

1. sugars compete with starch for water, retarding the swelling of the granule which reduces viscosity and gel strength 2. sugars minimizes retrogradation of starch

Question 49

how do fats affect the properties of starches?

Answer 49

they have little effect on viscosity of starch suspension but an increase in fat content causes temp of max viscosity to decrease

Question 50

when fat content increases, how does this affect the temp of max viscosity of starches?

Answer 50

incr fat content = decr max viscosity

Question 51

how do monoglycerides with emulsifiers affect the properties of starches?

Answer 51

1. increase the temp which granules swell | 2. prevents gel formation