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FN 2232 > Lecture 10 > Flashcards

Lecture 10 Flashcards

1
Q

What is the trend in egg consumption in Canada?

A

Increase in 3.8%

-value of eggs also increased

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2
Q

How many egg farms were there ?

A

1143 registered farms

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3
Q

Which province produces the most eggs and the percentages?

A

Ontario 35.8%
Quebec 20.1%
Western Provinces & NWT 36.8%
Eastern provinces 7.3%

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4
Q

How large are chicken flocks normally?

A

average 22,479

-can be as low as a few 100 or as high as 400,000

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5
Q

What is the most popular breed of chicken?

A

White leghorn

-then Rhode Island reds

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6
Q

What are the 2 kinds of eggs on the market?

A

Table eggs: whole uncracked eggs

Processed eggs: cracked so are used and processed in other products

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7
Q

What does the national egg organization do?

A

Regulate egg farmers in all of Canada

Manage supply of eggs

Promotes eggs

Develops standards for egg farming

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8
Q

What is the difference between free run vs free range?

A

Run: able to run around in the barn

Ranges: Run around in barn and also have access to the outside weather permittting

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9
Q

What is the nutritive value of eggs?

A

13 essential vitamins and minerals

High quality protein (albumen)

  • PDCAAS= 1 (very high quality protein)
  • riboflavin
  • selenium

Fat (Talk)

  • Fe
  • Vit A
  • Choline
  • Lutein
  • Zeaxanthin
  • cholesterol
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10
Q

What is the composition of an egg in %?

A 
75% water
12% Protein
10% Fat
1% Carb
1% minerals

2/3 albumen
1/3 yolk

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11
Q

How much does an average egg weigh?

A

57g with shell

50g without shell

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12
Q

What does albumin contain?

A

1.2 the protein and other nutrient of the egg

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13
Q

What is the most common protein in eggs?

A

Albumen

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14
Q

What are the 3 major proteins in egg whites?

A

Ovalbumin

Ovomucin

Lysozyme

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15
Q

What is the pH of a fresh egg?

A

7-8.5

-loss of CO2 during storage decreases egg pH

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16
Q

What is ovalbumin?

A

Contributes to foaming

Denatured by heat

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17
Q

What is Ovomucin?

A

Viscous gel properties

Large molecule with fibre–like nature

Contributes to egg foam stability

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18
Q

What is lysozyme?

A

Antimicrobial enzyme that’s part of the innate immune system

Thermally stable up to 72C

pH range from 6-9

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19
Q

What is the composition of the protein?

A

Protein found in the. yolk

-Lipoproteins which have. emulsifying properties

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20
Q

What is the composition of lipids?

A
  • Trigluycerides
  • Phospholipids
  • Cholesterol (186mg)
  • taste mainly
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21
Q

what gives the yolk its colour?

A

Exanthophil (colour pigment)
-not changed to Vit A in the body

Deep yellow colour has Vit A already in it

Pale yolk has Vit A added to it

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22
Q

Who is recommended to limit their egg consumption?

A

People with:

  • high cholesterol
  • Diabetes
  • Cardio

limiting their cholesterol intake to 1-2egg/week

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23
Q

What are the main structures of the egg?

A 
Shell
Shell Membrane
Air cell
Thin albumen 
Thick albumen
Chalazae
Yolk 
Yolk membrane
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24
Q

What is special about the egg shell?

A

Shell is porous. to allow for gas exchange and can lose moisture

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25
Q

What is the air cell?

A

Bigger the air cell the less fresh the egg is

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26
Q

What are the characteristics of a fresh egg?

A

When broken it keeps rounded form due to viscosity of thick portion of white

Cloudy or milk white sure to dissolved CO2 shortly after laying

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27
Q

What are deterioration characteristics of an egg (aging)?

A 
Thinning whites
Flatter yolks
Weaker chalazae
Larger air cell
Greater alkalinity
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28
Q

How is the quality of an egg impacted?

A

Flavour and odour determined by feed and type of hen as well as storage

  • microorganisms
  • environment packaging
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29
Q

If properly refrigerated how long should eggs last?

A

3-5 weeks after purchase

30
Q

What is commercial cold storage?

A 
~0C, just above freezing point
85-90% Humidity
Circulation, free of objectionable odours
Controlled atmosphere of CO2 or O2
Maintained quality for 6 months
31
Q

What is candling?

A

Holding anew up to a strong light in a dark room to measure the interior quality of an egg

32
Q

In candling what qualities are we looking for?

A 
Quality of shell
Size of air cell
Position and mobility of yolk
Blood spots
Molds
Fertilized
33
Q

What is the grading system for eggs?

A

Canada A
Canada B
Canada C

34
Q

What is a grade A egg used for?

A

Grocery stores

When candling should see a firm albumen, indistinct yolk outline, rounded centred yolk and air cell <5mm

Shell should have less than 3 stain spots and uncracked

35
Q

What is a grade B egg used for?

A

Commercial baking

When candling should see yolk floats freely when twirled, germ development, oblong shape yolk, air cell <9mm

Shell should have stain spots less than 320mm, and uncracked

36
Q

What is a grade C egg used for?

A

Commercially process foods

When candling should see prominent yolk outline and blood sports less than 3mm

Shell should have stain sport less than 1/3 of the shells surface and cracked but not leaking

37
Q

What are the different sizes that eggs come in?

A 
Jumbo at least 70g
XL at least 63g
Large at least 56g
-most recipes standardized for this
Medium at least 49g
Small 42g
38
Q

Where can eggs get salmonella?

A

On the egg shell via:
-infection of chickens reproductive system (inside the intact shell as the egg is being formed)

-Contamination on exterior of shell (moves through the shell pores to the white and yolk)

39
Q

Why do we refrigerate eggs?

A

Helps to slow the aging process and prevent the rapid growth of bacteria
-should also rapid cool after egg has been laid

40
Q

What is the difference between Canadian and European eggs?

A

Canadian:

  • refrigerated
  • chickens not vaccines
  • pasteurization of eggs

European

  • Not refrigerated
  • chickens vaccinated
  • egg not pasteurized
41
Q

What are the 3 forms of killing off bacteria for eggs?

A
  1. Radio Frequency waves
  2. Hot water immersion, microwave, irradiation
  3. Under investigaiton
42
Q

What is Radio frequency ?

A 
Patented
Kills salmonella and ecoli 
Hot water and RF energy
Fast and low cost 
-egg is a little more mushy from this method when you cook it, egg is not fluffy and won't whip well
43
Q

What is Hot water immersion, microwave, irradiation ?

A

Longer and more expensive

Potential denaturation and coagulation

Decreased whipping ability

44
Q

What is under investigation?

A

HHP (high hydrostatic pressure)

High moisture and hot air
-helps to maintain characteristics of the egg so it does have better whipping ability

45
Q

Why are there there products removed from the shell?

A 
Convenient
Easy to handle and store
Pasteurized
Can have separate white, yolks or both in one
Free of salmonella
No shell contamination
Good for food service
46
Q

What happens when you freeze eggs?

A

Functional properties intact

When thawed you get viscous and gummy texture
-should mix with sugar, salt, syrup before freezing

47
Q

What happens when you have dried eggs?

A

Stay dried to have a doing shelf life
Required in dry mix products
Remove any glucose to retain Quality
Low moisture and cool conditions

48
Q

What do egg substitutes not have?

A

Do not contain yolk but have high concentration of whites
-add corn oil, nonfat dry milk, soy protein isolate and soy bean old for yolk like properties

-these products have low cholesterol, fat and salt

49
Q

Where do we see changes with heat coagulation of egg proteins?

A 
Thickening
Gel formation
Opacity
Insoluble 
Gradual 
Denature anda aggregate to form 3D gel network
50
Q

When denatured proteins interact what to they form?

A

Bonds and a network stabilized by cross linking (including disulphide bonds)

51
Q

At what temperatures to egg white, yolk and whole egg coagulate at?

A

White 60C
Yolk 65C
Whole 80C

52
Q

What happens when you heat an egg fast vs slowly?

A

Slowly reduces curdling

Fast with high heat results in immediate curdling

53
Q

What happens when you heal whites beyond coagulation point?

A

The protein shrinks and becomes tougher

54
Q

What happens to heat coagulation of egg proteins when you add sugar, salt and acid?

A

Sugar: increases heat stability of proteins, used in custards
-higher coagulation temp by increasing heat stability

Salt: Promote coagulation or gel formation

Acid: Coagulate at lower temp

  • Firmer
  • too much may cause curdling
  • minima hardness at pH6 but increases as pH decreases
55
Q

What are the steps to coagulation by mechanical beating and egg foams?

A

Dispersion of air in liquid

  1. proteins unfold and surround air cells as a viscoelastic film around the bubbles
  2. Protein absorbs at the hydrophobic surface of air bubble with more proteins unfolding on the air bubble surface as the whipping time increases
  3. S-S disulphide linkages forms
56
Q

What is globulin protein responsible for?

A

High formability of egg whites when beaten

57
Q

What is albumen protein responsible for?

A

Surrounding the air bubble to help stabilize the bubbles in the foam

58
Q

What can affect the bubble size and the foam?

A

Protein content

Whipping time

59
Q

What does protein unfolding increase with?

A

Moderate decrease in pH

60
Q

What are 4 stages of whipped egg whites?

A 
Foamy
-mostly liquid with some bubbles
Soft peaks
-White and hold shape but peaks will slump
Firm Peaks
-Peaks remain straight
Over beaten
-foam collapses, gets grainy watery and flat
61
Q

What happens to the fine particles when over beaten?

A

Fine particles become more climbed together and are drier

62
Q

When whipping eggs what can impact the quality?

A

Freshness
Temp
Type of beater
Bowl

63
Q

What are some factor to improve egg foams?

A
  1. Pasteurization and spray drying of egg whites (partial unfolding of egg protein)
  2. Thick whites produce a more stable foam and increase volume of cooked products
  3. Room temp whites will whip easily and quickly and to a larger volume (due to lower surface tension at air-water interface)
  4. Fine wire beater will create smaller air cells
  5. Small rounded bottom bowl with sloping sides if using a mixer
  6. Large, wide bowl for hand mixing to allow for rapid vigorous mixing
  7. Copper bowl has increased resistance to foam breakdown due to copper-conalbumin complex
64
Q

What are factors decrease egg foam quality?

A
  1. Egg yolk contamination- (fat interferes with foaming
  2. Over beating
    - over coagulated
    - loss of flexibility in the films and the braking of Manu air cell
    - Decreased foam volume and stability
    - Brittle and inelastic
    - Will not blend well with other ingredients
    - Liquid will separate from foam
65
Q

What effect does sugar have on egg foam quality?

A

Sugar: stabilizes foam, reduces over beating

  • texture fine, shiny/satiny appearance
  • Slows coagulation resulting in longer beating time, add after foam created
  • Adding too qwuicksl can result in loss of air from the foam
66
Q

What effect does acid have on egg foam quality?

A 
Moderate pH lowering ~5
Increased protein unfolding
Increased albumen hydrophobicity
Improved ovomucin foaming stability 
Cream of tartar
Add after foamy stage as they reduce coagulation
67
Q

What effect does salt have on egg foam quality?

A

decreases volume and stability and increases whipping time due to ions disrupting foam formation

Added after foamy stage

68
Q

What is the functional uses of eggs in food?

A 
Binding
Leavening
Thickener/gelling
Glaze
Clarify
Slows crystallization
Emulsifier
Colour 
Flavour
Nutritional Value
69
Q

Which emulsions do lecithin and cholesterol promote?

A

Lecithin: oil in water

Cholesterol: water in oil

70
Q

Why top eggs turn green?

A

Fe in yolk reacts with hydrogen sulphide in albumin to produce ferrous sulphide

  • holding too long
  • over cooking
  • more likely to occur in older egg cause pH is higher
71
Q

What prevents and egg from turning green?

A

Citric acid

FN 2232 (20 decks)

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