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Edible Eggs Abeer Abdel-naser Awad Abdel-All
<ul><li>Items of lecture:  </li></ul><ul><li>Changes occur after laying. </li></ul><ul><li>Egg quality (external and inter...
A-changes occur after laying <ul><li>A- chemical changes: (aging) </li></ul><ul><li>The rate of deterioration is closely r...
<ul><li>The  pH  of the white may rise from about  7.6  in a freshly laid egg to high as  9.0 to 9.7  within few days (due...
Why the white become thinner? <ul><li>The  rise in pH  allows the  electrostatic complex  between lyzozyme and ovomucin to...
<ul><li>The  thinner white   cannot  withstand the  yolk centered  in the egg. In addition the  white became yellow. </li>...
<ul><li>The  yolk  becomes  enlarged  and  flattened . </li></ul><ul><li>The  chalazae  become  detached  allowing the  yo...
<ul><li>Air cell   enlarged due to the water evaporates from liquid contents through the shell pores and the air replaces ...
<ul><li>B-Microbial changes: </li></ul><ul><li>Rot and mold: </li></ul><ul><li>These develop in some eggs by the presence ...
<ul><li>These organisms mainly enter the egg after laying from dirty and moist shell. Washing increase the case due to rem...
<ul><li>Rotten eggs: </li></ul><ul><li>These eggs normally contain a mixed infection of  Gram-negative  and a few  Gram-po...
<ul><li>Bacteria causing abnormal flavors (taint): </li></ul><ul><li>Proteus vulgaris-------------- foul odor. </li></ul><...
Organisms produce pigments Type of rot Organism   Black  rot Proteus sp. Black  rot Aeromonas liquefaciens Red  rot Serrat...
<ul><li>Mold spoilage: </li></ul><ul><li>Less important than bacteria, only under humid conditions the shell could be clot...
<ul><li>On candling these show up as dark or colored patches or rings. </li></ul><ul><li>Further growth results in the com...
B- Egg quality <ul><li>Egg quality standards are based on: </li></ul><ul><li>Shell cleanliness. </li></ul><ul><li>Shell so...
What is Egg Quality? <ul><li>Exterior egg quality  – shell quality based on shell cleanliness, shell soundness, shell text...
Judging Egg Quality <ul><li>External quality: </li></ul><ul><li>Shell stability faults </li></ul><ul><li>Cleanliness </li>...
Controlling Egg Size <ul><li>In many markets, producing eggs that are above the size of large eggs holds </li></ul><ul><li...
Controlling Egg Size <ul><li>Factors that influence egg size: </li></ul><ul><li>Protein Intake, esp. Methionine and Lysine...
Internal egg quality  (Broken-out Egg Quality) <ul><li>Shape and Uniformity of Albumen </li></ul><ul><li>Amount of Thick A...
Egg grading - exterior <ul><li>Grade A  – Clean, unbroken, practically normal shape. Ridges and rough spots that do not ma...
 
 
 
 
 
 
 
 
 
 
 
Egg grading - interior Grade B Grade A Grade AA Quality factor Over 3∕16 inch depth 3∕16 inch or less depth 1∕8 inch or le...
A Grade AA  egg will stand tall. The yolk is firm and the area covered by the white is small. There is a large proportion ...
AA Quality High AA Average AA Low AA
A Quality High A Average A Low A
B Quality High B Average B Low B
Practice Grade AA
Practice Grade AA
Practice Grade AA
Practice Grade Inedible
Practice Grade Inedible
Practice Grade Inedible
Practice Grade A
Practice Grade A
Practice Grade B
Practice Grade B
Important functional and aesthetic properties of egg <ul><li>1- act as a  leavening  agent in  baked  goods (texture of br...
<ul><li>5- yolk contains  lecithin  (a natural  emulsifier ) which helps keeping fat and other ingredients in a uniform su...
Egg handling for quality preservation <ul><li>by frequent gathering. </li></ul><ul><li>by careful handling & proper coolin...
C- Egg freshness <ul><li>The ideal conditions that keeping eggs so long fresh and of good quality are: </li></ul><ul><li>-...
Testing egg for freshness <ul><li>Egg shell: </li></ul><ul><li>On small scale: </li></ul><ul><li>Brine solution:  10% NaCL...
<ul><li>c) Ultra-violet rays:  using  Quartz lamp  fresh egg give  pink  color due to reaction between UV rays and  ooporp...
<ul><li>On large scale: </li></ul><ul><li>Only one method to detect freshness without breaking eggs  “candling “. </li></u...
Individual candling
“ candling an egg”
Measuring Air Cell Depth
Mass candling
<ul><li>B) Broken out appearance: Egg contents </li></ul><ul><li>Fresh egg: </li></ul><ul><li>Normal odor, yolk stand up w...
<ul><li>Old egg: </li></ul><ul><li>Abnormal odor may be present. </li></ul><ul><li>Thick albumen is not apparent. </li></u...
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Egg Quality1

Egg Quality1

  1. 1. Edible Eggs Abeer Abdel-naser Awad Abdel-All
  2. 2. <ul><li>Items of lecture: </li></ul><ul><li>Changes occur after laying. </li></ul><ul><li>Egg quality (external and internal quality). </li></ul><ul><li>Egg freshness. </li></ul>
  3. 3. A-changes occur after laying <ul><li>A- chemical changes: (aging) </li></ul><ul><li>The rate of deterioration is closely related to the loss of CO 2 through the shell and increase alkalinity of egg contents. </li></ul><ul><li>The higher the temperature the higher the loss of CO 2. </li></ul>
  4. 4. <ul><li>The pH of the white may rise from about 7.6 in a freshly laid egg to high as 9.0 to 9.7 within few days (due to loss of CO 2 ). </li></ul><ul><li>The white become thinner , so spread more when the egg is broken out. </li></ul>
  5. 5. Why the white become thinner? <ul><li>The rise in pH allows the electrostatic complex between lyzozyme and ovomucin to break. </li></ul><ul><li>Breaking of disulphide bonds in ovomucin has been suggested as a factor in the thinning of egg white. </li></ul>
  6. 6. <ul><li>The thinner white cannot withstand the yolk centered in the egg. In addition the white became yellow. </li></ul><ul><li>The vitelline membrane which confines the yolk stretches due to water passage from the white to the yolk. </li></ul>
  7. 7. <ul><li>The yolk becomes enlarged and flattened . </li></ul><ul><li>The chalazae become detached allowing the yolk to move freely within the egg . </li></ul><ul><li>The free yolk may rest against the shell leading to sided or stuck yolk or may be ruptured leading to spreading yolk </li></ul>
  8. 8. <ul><li>Air cell enlarged due to the water evaporates from liquid contents through the shell pores and the air replaces the water lost. </li></ul><ul><li>The egg becomes extremely suitable for invasion by microorganisms. </li></ul>
  9. 9. <ul><li>B-Microbial changes: </li></ul><ul><li>Rot and mold: </li></ul><ul><li>These develop in some eggs by the presence of microorganisms like bacteria, mold and yeast within the egg. </li></ul>
  10. 10. <ul><li>These organisms mainly enter the egg after laying from dirty and moist shell. Washing increase the case due to removal of the bloom and help the microorganisms to invade the egg contents through the pores. </li></ul>
  11. 11. <ul><li>Rotten eggs: </li></ul><ul><li>These eggs normally contain a mixed infection of Gram-negative and a few Gram-positive organisms also. </li></ul><ul><li>Alcaligenes, Achrimobacter, Pseudomonase, Serratia, Cloaca, Hafnia, Citrobacter, Proteus and Aeromonase. </li></ul>
  12. 12. <ul><li>Bacteria causing abnormal flavors (taint): </li></ul><ul><li>Proteus vulgaris-------------- foul odor. </li></ul><ul><li>Pseudomonase-------------- ammoniacal odor. </li></ul><ul><li>Bacillus subtilis------------- H 2 S production. </li></ul><ul><li>Eggs may pick up flavors from strange odors in the storage area. </li></ul>
  13. 13. Organisms produce pigments Type of rot Organism Black rot Proteus sp. Black rot Aeromonas liquefaciens Red rot Serratia marcescens Green rot Pseudomonase maltophilia Fluorescent green changed to pink Pseudomonase fluorescens Fluorescent green rot Pseudomonase putida Fluorescent blue rot Pseudomonase aeruginosa Yellow rot Flavobacterium Colorless Alcaligens
  14. 14. <ul><li>Mold spoilage: </li></ul><ul><li>Less important than bacteria, only under humid conditions the shell could be clothed with mycelium “Whiskers”. </li></ul><ul><li>Hyphae penetrate the pores and grow on the shell membranes associated with gelling of the albumen around patches of mycelia. </li></ul>
  15. 15. <ul><li>On candling these show up as dark or colored patches or rings. </li></ul><ul><li>Further growth results in the complete gelling of the albumen and the break down of yolk membrane. </li></ul><ul><li>Cladosporium and Sporotrichum the most common types. </li></ul>
  16. 16. B- Egg quality <ul><li>Egg quality standards are based on: </li></ul><ul><li>Shell cleanliness. </li></ul><ul><li>Shell soundness. External </li></ul><ul><li>Shell texture. </li></ul><ul><li>Shell shape. </li></ul><ul><li>Relative viscosity of albumen. </li></ul><ul><li>Freedom from foreign matter in albumen. Internal </li></ul><ul><li>Shape and firmness of yolk. </li></ul><ul><li>Freedom from yolk defects. </li></ul>
  17. 17. What is Egg Quality? <ul><li>Exterior egg quality – shell quality based on shell cleanliness, shell soundness, shell texture, shell shape . </li></ul><ul><li>Interior egg quality – based on relative viscosity of the albumen, freedom from foreign matter in the albumen, shape and firmness of the yolk, and freedom from yolk defects. </li></ul>
  18. 18. Judging Egg Quality <ul><li>External quality: </li></ul><ul><li>Shell stability faults </li></ul><ul><li>Cleanliness </li></ul><ul><li>Appearance faults </li></ul><ul><li>Grades- A, B, Loss </li></ul>
  19. 19. Controlling Egg Size <ul><li>In many markets, producing eggs that are above the size of large eggs holds </li></ul><ul><li>no economic benefit. Larger eggs tend to have weaker shells </li></ul><ul><li>and are more likely to be broken in transit due to current packaging </li></ul><ul><li>materials and shapes. </li></ul>
  20. 20. Controlling Egg Size <ul><li>Factors that influence egg size: </li></ul><ul><li>Protein Intake, esp. Methionine and Lysine </li></ul><ul><li>Breed </li></ul><ul><li>Caloric intake </li></ul><ul><li>Linoleic acid levels in the feed </li></ul><ul><li>Body weight at the onset of production. </li></ul>
  21. 21. Internal egg quality (Broken-out Egg Quality) <ul><li>Shape and Uniformity of Albumen </li></ul><ul><li>Amount of Thick Albumen </li></ul><ul><li>Shape and Height of Yolk </li></ul><ul><li>Presence of Meat or Blood Spots </li></ul><ul><ul><li>Less than 1/8 inch diameter = Grade B </li></ul></ul><ul><ul><li>More than 1/8 inch diameter = Inedible </li></ul></ul>
  22. 22. Egg grading - exterior <ul><li>Grade A – Clean, unbroken, practically normal shape. Ridges and rough spots that do not materially detract from the appearance of the egg are ok. </li></ul><ul><li>Grade B – Unbroken, clean to moderately stained (1/32 of surface if localized, or 1/16 of surface if scattered). Maybe somewhat unusual to misshapen, or show pronounced ridges or thin spots. </li></ul><ul><li>Dirty – Unbroken . Adhering dirt or foreign material, prominent stains, or moderately stained if in excess of B grade. </li></ul>
  23. 34. Egg grading - interior Grade B Grade A Grade AA Quality factor Over 3∕16 inch depth 3∕16 inch or less depth 1∕8 inch or less depth Air cell Weak and watery. Small (< 1/8 inch diameter) blood and meat spots may be present Clear and reasonably firm Clear and firm White Outline plainly visible, enlarged and flattened. May have clearly visible germ development but no blood. Outline fairly well defined Outline slightly defined Yolk
  24. 35. A Grade AA egg will stand tall. The yolk is firm and the area covered by the white is small. There is a large proportion of thick white to thin white. Grade A egg covers a relatively small area. The yolk is round and upstanding. The thick white is large in proportion to the thin white and stands fairly well around the yolk A Grade B egg spreads out more. The egg yolk is flattened and there is about as much (or more) thin white as thick white
  25. 36. AA Quality High AA Average AA Low AA
  26. 37. A Quality High A Average A Low A
  27. 38. B Quality High B Average B Low B
  28. 39. Practice Grade AA
  29. 40. Practice Grade AA
  30. 41. Practice Grade AA
  31. 42. Practice Grade Inedible
  32. 43. Practice Grade Inedible
  33. 44. Practice Grade Inedible
  34. 45. Practice Grade A
  35. 46. Practice Grade A
  36. 47. Practice Grade B
  37. 48. Practice Grade B
  38. 49. Important functional and aesthetic properties of egg <ul><li>1- act as a leavening agent in baked goods (texture of breads and cakes). </li></ul><ul><li>2- act as binding agent to hold other ingredients together. </li></ul><ul><li>3- act as a thickening agent (custards, puddings, etc.). </li></ul><ul><li>4- albumen act as a smoothing agent to give icings a desirable texture. </li></ul>
  39. 50. <ul><li>5- yolk contains lecithin (a natural emulsifier ) which helps keeping fat and other ingredients in a uniform suspension. </li></ul><ul><li>6- eggs are used as a clarifying agent which are used to remove extraneous materials from beverages, coffee, etc. </li></ul><ul><li>7- eggs are used as a coating for cakes, rolls, cookies, etc. </li></ul><ul><li>8- yolks add color and richness to foods. </li></ul><ul><li>9- eggs tend to take up flavors and odors of surroundings. </li></ul>
  40. 51. Egg handling for quality preservation <ul><li>by frequent gathering. </li></ul><ul><li>by careful handling & proper cooling. </li></ul><ul><li>by holding under controlled humidity. </li></ul><ul><li>by proper packaging. </li></ul><ul><li>by frequent marketing. </li></ul><ul><li>by moving eggs rapidly through marketing channels. </li></ul><ul><li>by proper care of eggs at home. </li></ul>
  41. 52. C- Egg freshness <ul><li>The ideal conditions that keeping eggs so long fresh and of good quality are: </li></ul><ul><li>-Temperature that don’t go above 4 o C. </li></ul><ul><li>-Relative humidity 70-80%. </li></ul><ul><li>-Proper handling. </li></ul>
  42. 53. Testing egg for freshness <ul><li>Egg shell: </li></ul><ul><li>On small scale: </li></ul><ul><li>Brine solution: 10% NaCL solution but actually it is used to determine shell thickness. </li></ul><ul><li>Shaking test: fresh egg emit no sound, while old egg will emit sound due to thin albumen and loose chalazae and free yolk. </li></ul>
  43. 54. <ul><li>c) Ultra-violet rays: using Quartz lamp fresh egg give pink color due to reaction between UV rays and ooporpherin pigment in the bloom, while old egg give violet color due to reflection of UV on surface of an egg. </li></ul><ul><li>N.B.: </li></ul><ul><li>Disadvantages : it depends on the presence of bloom which may be lost due to: aging after 14 days or, washing, or brushing, or bad handling. This test is restricted to white shell eggs only. </li></ul>
  44. 55. <ul><li>On large scale: </li></ul><ul><li>Only one method to detect freshness without breaking eggs “candling “. </li></ul><ul><li>Tow types of candling either individual candling or mass candling. </li></ul><ul><li>In individual candling the egg is hold and the broad end upper most to measure the air cell using the egg caliber as increase its volume exceeding 3mm. means old egg. </li></ul><ul><li>In mass candling rows of egg is tested. </li></ul>
  45. 56. Individual candling
  46. 57. “ candling an egg”
  47. 58. Measuring Air Cell Depth
  48. 59. Mass candling
  49. 60. <ul><li>B) Broken out appearance: Egg contents </li></ul><ul><li>Fresh egg: </li></ul><ul><li>Normal odor, yolk stand up well centrally by the albumen, yolk color is even yellow, no mottling or foreign bodies. </li></ul><ul><li>Both chalazae are distinct and firmly attached to yolk. </li></ul><ul><li>Albumen is clear with no taint or color, both thick and thin are distinct, no blood, no bodies. </li></ul><ul><li>Germinal disc is just visible </li></ul>
  50. 61. <ul><li>Old egg: </li></ul><ul><li>Abnormal odor may be present. </li></ul><ul><li>Thick albumen is not apparent. </li></ul><ul><li>Chalazae become detached and very weak. </li></ul><ul><li>Yolk is displaced, flattened and severely patched or mottled. </li></ul><ul><li>Blood or meat spots may present. </li></ul>

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