Eggs - PowerPoint PPT Presentation

Loading...

PPT – Eggs PowerPoint presentation | free to view - id: 1d13ae-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Eggs

Description:

mainly glucose, may cause brown discoloration in dried eggs and hard cooked eggs ... addition of citric acid. addition of salt. Processed Eggs. Egg substitutes ... – PowerPoint PPT presentation

Number of Views:140
Avg rating:3.0/5.0
Slides: 35
Provided by: peggy75
Category:
Tags: citric | eggs

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Eggs


1
Chapter 7
  • Eggs

2
Composition of eggs
3
Composition of Eggs -egg white (albumen)
  • Water (88)
  • CHO (1)
  • mainly glucose, may cause brown discoloration in
    dried eggs and hard cooked eggs (Millard
    reaction)
  • Fat (trace)

4
Composition of Eggs -egg white (albumen)
  • Proteins (11), most are glycoproteins
  • Three primary proteins
  • ovalbumin (54) Structure of Baked Products
  • ovotransferrin (12), Binds metal, Discoloration
  • ovomucoid (11) Protease Inhibitor
  • ovomucin (1.5) A Fibrous Protein,
    contributes to the thickness of the white (4 x
    more abundant than in yolk), contributes to
    the stability of egg white foam

5
Composition of Eggs -egg white (albumen)
  • Proteins (contn)
  • globulins (8) including lysozyme, are important
    for foaming
  • lysozyme ability to hydrolyze a polysaccharide
    in the cell wall of some bacteria to prevent
    bacterial spoilage
  • others ovoinhibitor, ovoflavoprotein,
    ovomicroglobulin, avidin (binds biotin, but is
    heat sensitive)

6
Composition of Eggs -egg yolk
  • Proteins (16.4)
  • plasma (78) livetin LDL (protein content
    10)
  • granular fraction phosvitin (16, carrier of
    Fe), lipovitellins (70) LDL (12)
  • Water (48)

7
Composition of Eggs -egg yolk
  • Lipids (32 to 34)
  • triglycerol (66)
  • phospholipid (28) including lecithin
  • (has remarkable emulsifying ability)
  • cholesterol (3, or 250 mg)
  • The color of yolk depends on the presence of
    carotenoids.
  • xanthophylls not carotene
  • (Lutein and zeaxanthin)

8

9
Egg Quality
  • Commercial grading of eggs according to the USDA
    standards
  • External quality shell characteristics, shape,
    soundness, cleanliness, color
  • Interior quality size of the air cell, firmness
    of the white, the yolk (distinct or flattened
    during aging)
  • Evaluated by candling

10
Egg quality during storage
  • The size of the air cell increases
  • water evaporates from the egg through shell
  • The egg white becomes thinner
  • ovomucin undergoes degradation
  • pH of white increases (from 8 to 9)
  • due to the loss of CO2 through the pores

11
Egg quality during storage
  • The yolk enlarges and the membrane weakens
  • (water moves from white to yolk, viscosity
    decreases, yolk becomes flatter and spreads
    farther)
  • Deterioration of odor flavor
  • Increased storage temperature accelerates loss
    of
  • quality

12
Functionality of Eggs
  • Coagulation
  • Emulsification
  • Foaming

13
Functionality of EggsCoagulation or Gelation
14
Protein Coagulation
  • Denaturation Relaxation of the tertiary
    structure to the secondary structure, accompanied
    by decreasing solubility of a protein
  • Precipitation of protein as molecules aggregate
    (often as a result of energy input, such as
    heating or beating)
  • Process that results in a loss of solubility or a
    change from a fluid state to a solid state.
    (Gelation is also used to describe the process.

15
Functionality of Eggs -coagulation
  • egg white begins to thicken at 62oC, yolk at
    65oC. 72oC Firm
  • The gel firmness depends on time temperature of
    heating
  • Gel hardness dependents on the pH and the
    concentration of protein
  • increased pH or protein will increase gel
    hardness
  • diluted protein will increase coagulation
    temperature ?

16
Functionality of Eggs -coagulation
  • Sugar decreases the rate of heat denaturation
    increases the coagulation temperature
  • Salts promote coagulation

17
Functionality of Eggs
18
Functionality of Eggs -emulsification
  • Formation of emulsion
  • mechanical agitation makes it insoluble and
    stiff or stable
  • emulsifying agent (Lecithin)
  • Egg Yolk is an oil-in-water emulsion

19
Functionality of EggsFoaming
20
Functionality of Eggs - foaming
  • A colloidal suspension bubbles surrounded by egg
    albumen (protein)
  • globulins have greater foaming ability
  • ovomucin stabilizes the foam

21
Functionality of Eggs - factors affecting foaming
  • Method, time and temperature of beating
  • as beating time increases, volume and stability
    of the foam 1st increases then decreases
  • maximum stability is reached before maximum
    volume
  • room temperature vs refrigerator temperature

22
Functionality of Eggs - factors affecting foaming
  • Characteristics of the egg white
  • thin white vs thick white
  • stored eggs vs fresh eggs
  • pH
  • acids or acid salts increases foam stability but
    delays foam formation

23
Functionality of Eggs - factors affecting foaming
  • Water
  • water increases the foam volume but decreases its
    stability
  • fat
  • oil reduces foam volume
  • sodium chloride
  • reduces the foam stability, increases whipping
    time

24
Functionality of Eggs - factors affecting foaming
  • Sucrose
  • delays foam formation (so beat then add)
  • produces a more stable foam
  • egg yolk
  • decreases the foam volume
  • additives
  • surfactants and stabilizers may reduce whipping
    time, increase foam volume

25
Functionality of Eggs
26
Functionality of Eggs - factors affecting foaming
  • Method, time and temperature of beating
  • characteristics of the egg white
  • pH
  • water and fat
  • sodium chloride
  • sucrose
  • egg yolk
  • additives

27
Functionality of Eggs
28
Processed Eggs
  • Frozen eggs
  • egg whites perform well after freezing thawing
  • add 10 (w/w) of sugar or salt to yolks before
    freezing to control the gelation of frozen yolk
  • To prevent syneresis in frozen cooked egg
    products
  • addition of gums
  • addition of citric acid
  • addition of salt

29
Processed Eggs
  • Egg substitutes
  • use of egg white together with a yolk-like
    mixture containing no cholesterol
  • fortify with fat-soluble nutrients
  • addition of carotenoid for giving the yolk color
  • addition of carboxymethyl-cellulose (CMC) reduces
    weeping
  • aroma and flavor are not as good as fresh eggs

30
Processed Eggs
  • Dried eggs (spray drying)
  • products whole-egg solids, yolk solids,
    fortified whole-egg solids and whites
  • growth of microorganisms is inhibited
  • coagulation is not affected
  • foaming potential is reduced
  • add whipping agents (surface active)

31
Processed Eggs
  • All liquid eggs should be pasteurized (61C for
    3.5 min) to kill salmonella and other potential
    pathogens.
  • Ultrapaseurized liquid whole eggs
  • retain functional properties of fresh shell eggs
  • are aseptically packaged

32
Functionality of Eggs Summary
  • coloring agent (carotenoids in yolk)
  • emulsifier
  • mayonnaise, hollandaise sauce, cream puff
  • thickening agent (coagulation)
  • baked (gel) or stirred (sol) custards,
  • foaming
  • meringues, foam cakes (angel, sponge, and
    chiffon)

33
(No Transcript)
34
Proverbs 1215
  • The Way of a Fool
  • Seems right to Him
  • BUT a Wise Man
  • Listens to Advice
About PowerShow.com