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Eggs

Eggs. Chapter 11. Foods containing eggs. Chicken eggs Standard Fertile Free-range Organic. Non-chicken eggs Duck Goose Ostrich Quail Turkey. Eggs types. Value-added eggs. Health of Consumer Special Attributes Nutrient Content of Feed Conditions Under Which Hens Raised

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Eggs

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  1. Eggs Chapter 11

  2. Foods containing eggs

  3. Chicken eggs Standard Fertile Free-range Organic Non-chicken eggs Duck Goose Ostrich Quail Turkey Eggs types

  4. Value-added eggs • Health of Consumer • Special Attributes Nutrient Content of Feed Conditions Under Which Hens Raised • Lower-Cholesterol Eggs • Omega-3 Fatty Acids • Vitamin E Levels • Animal Friendly Practices

  5. Eggs parts • Yolk Germinal Disc Vitelline Membrane • Albumen Egg White Chalaza pl. Chalazae • Shell Membranes Inner Outer • Air Cell Between 2 Shell Membranes • Shell Cuticle or Bloom

  6. Eggs Components • Chalaza pl. Chalazae Ropy Twisted Strands Of Albumen Anchor Yolk to Center of Thick Egg White • Vitelline Membrane Membrane Surrounding Egg Yolk Attached to Chalazae • Cuticle or Bloom Waxy Coating on Eggshell Protects Against • Bacterial Contamination & Moisture Loss

  7. EGGS

  8. Egg parts • Shell: 9-12% of total egg weight. Made of calcium carbonate and magnesium carbonate deposited on protein network. • Egg whites or albumen: about 60% of total egg weight. Contains over 40 proteins. • Yolk:30-33% of total egg weight. The only egg part containing fat and cholesterol.

  9. Chemical (proximate) composition of egg components

  10. Eggs micronutrients • Vitamins Fat-Soluble A D E K B2 B12 Folate Biotin Pantothenic Acid • Minerals Selenium Iodine Zinc Iron Copper Iron Not Bioavailable Iron & Sulfur React in Overcooked Eggs ―> Strong Off-Odor

  11. Egg safety • Remember -egg may cause illness known as salmonellosis. This may result from contamination on the outside of the shell as well as infection inside the egg itself. • Any egg that is cracked when purchased or that cracked during preparation should be discarded. • Eggs should not be stored at room temperature for more than two hours. • Hard cooked eggs should be kept cool until serving

  12. Egg safety • Separating the yolk from albumen after the shell is broken in half by passing it back and forth between the halves should be avoided. • Eggs should be thoroughly cooked for those at risk for infections: the elderly, infants, young children or the ill.

  13. Uses of eggs in food preparation • Binding and coating • Leavening • Emulsifying agent • Interfering agent • Clarifying agent

  14. Changes in the egg quality • Occurs as soon as egg is laid • Are affected by the conditions the egg is held. • First change - loss of weight • Formation of the air cell on blunt side of egg - due to contraction of egg content. • Egg becomes more alkaline due to loss of carbon dioxide. • pH of albumen rises from 7.6 to 8.9-9.4 • pH of yolk rises from 5.9-6.1 to 6.8

  15. Eggs storage • Size of An Egg’s Air Cell Provides Another Indication of Its Age

  16. Grading of eggs involves • assessment of interior and exterior quality • condition of albumen and yolk • size of air cell • soundness of egg shell • weight • cleanness of egg

  17. Eggs grading Haugh Units • Freshness of An Egg Detected By Cracking It Open Onto A Flat Surface & Looking At Height of Thick Albumen • Fresh Egg Whites Sit Up Tall & Firm • Older Ones - Spread Out

  18. Egg Sizes by weight

  19. Egg Candling

  20. Proteins • Ovalbumin - 54%; globular protein that readily denatures. • Ovotransferrin (Conalbumin) - 12%; it forms complexes with iron. The most heat sensitive if not bound to metal ion. • Ovomucoid - 11%; resistant to heat denaturation; trypsin inhibitor. • Lysozyme - 3.4%; enzyme that hydrolyses polysaccharides present in the cell wall of certain bacteria. • Avidin - 0.5%; it forms complex with biotin. Vitamin antagonist. Biotin deficiency is produced after consumption of 24 raw eggs per day. • Vitellin and lipovitellins - proteins found in yolk -excellent emulsifying agents.

  21. Egg proteins cont.

  22. Coagulation of egg proteins • Albumen: coagulation starts at 62 C, mass fully coagulates at 65 C. At 70 C coagulum is firm. • Yolk: coagulation starts at 65 C; mass fully coagulates at 70 C. • Beaten eggs coagulate at slightly higher temperature ~ 69 C.

  23. Thickening/coagulation of egg mixture depends on: • Rate of heating - egg proteins tend to curdle when heated too quickly. • Heating time and heating past coagulation - causes albumen protein to lose water, shrink and toughen, while egg yolk becomesmore crumbly due to fat content. • Addition of sugar -elevates the coagulation temperature and produces more tender coagulum. • Addition of salt - lowers the coagulation temperature • Addition of acid - lowers the coagulation temperature - too much acid will curdle the proteins. • Addition of starch - the coagulation temperature of egg proteins and gelatinization temperature of starch are different. Best results are obtained by adding uncooked egg to gelatinized starch. • Addition of water - elevates the coagulation temperature.

  24. Microwaving Eggs Cook Extremely Rapidly Special Caution Taken to Avoid Overcooking Manufacturer’s Instructions Should Be Followed for Microwave Egg Cooking Whole Eggs w/ Intact Shells Never Microwaved!! Steam Expanding Within Shell Can Cause Eggs to Burst Same Principle Applies to Whole Eggs Out of the Shell Puncture Egg Yolks w/ Toothpick or Tip of a Knife Prior to Microwaving Eggs preparation

  25. Custards Ingredients Milk &/or Cream Sweeteners Sugar Honey Flavorings Vanilla Nutmeg Etc. Eggs or Egg Yolks Sweet or Savory Preparation Stirred or Baked Sweet Custards Puddings or As Fillings SavoryCustards Nonsweet Quiches Stirred Custard Soft Custard or Custard Sauce Ingredients Stirred While Heated Baked Custard Poured Into Ungreased Custard Cups Placed In The Oven Eggs preparation

  26. Restaurants Food Service Institutions Other Food Manufacturers Must Be Especially Careful About Storing Eggs Because Large Quantities are Purchased Storage Eggs Used w/i 1 Mo Stored Up to 6 Mos. Eggs Treated w/ A Light Coat of Oil or Plastic Stored In High Humidity At Low Refrigerator Temperatures Very Close to Egg’s Freezing Point 29°-32°F –1.5°-0°C Eggs storage

  27. Preservation of eggs • REFRIGERATION: • Storage under modified atmosphere (humidity, carbon dioxide) • Dipping in mineral oil • Thermostabilization - dipping for a short time in hot liquid.

  28. Eggs preservation Freezing • Cannot Freeze Whole Egg It Will Crack Under the Expanding Liquids • Food Manufacturers Break the Eggs Open At the Processing Plants Where Contents Are Frozen Whole Whites & Yolk Mixed Separated As Whites or Yolks

  29. Preservation of eggs • FREEZING cont. : • Albumen can be frozen without addition of any protectants. • Yolk -without addition of protectant will form irreversible gel. Therefore glycerin, salt or sugar are added to prevent gelation • Cooked eggs can be frozen by any method.

  30. Preservation of eggs by drying • Egg can be dried by spray drying. Free flowing of powder is achieved by addition of silicoaluminum or silicone dioxide. • Glucose present in egg affect lower solubility, affect the flavor and color (Maillard reaction) • Glucose is removed by oxidation to glucuronic acid in the presence of glucose oxidase. • Hydrogen peroxide formed in this reaction is removed by catalase.

  31. Dried Drying Eggs Is a Simple Process Whole Eggs or Separated Yolks Are Spray-Dried Create a Fine Powder Which Is Mixed w/ Anti-Caking Substances to Prevent Clumping Egg Whites Granule, Flake, or Milled Textures Stored Up to 1 Year In Refrigerator Kept In Tightly Closed Containers to Prevent Clumping That Can Result from Moisture Accumulation Preservation of eggs by drying

  32. Food foams • Foam is a gas (air) dispersed in liquid. • Foam is stabilized by surface acting agent referred to as foaming agent (example protein that forms a film coat arround air bubble. Hydrophobic groups are directed towards air, while hydrophilic towards water. • Egg foams (meringues, angel cakes, sponge cakes, souffles, fluffy omelets) • Milk foams

  33. Egg foams Factors Affecting Foaming • Beating Technique Start Slow Gradually Increasing Speed • Testing for Doneness Observe Peak Formation • Avoid Overwhipping Prevent Collapse & Separation of Foam • Temperature Bowl Beaters Eggs Room Temperature

  34. EGGSFUNCTIONS

  35. Quality of egg foam is affected by: • Sugar • Acids • Salt • Fat • Temperature • Equipment used

  36. Egg foams Factors Affecting Foaming • Bowl Deep Bowl Rounded Bottom Sloping Sides Avoid Plastic Bowls • Separation of Eggs Egg Yolk Contains Fat Interferes w/ Foam Egg Separators • Careful Separation of Egg White from Yolk Imperative • Do Not Pass Egg Back & Forth Between Two Shell Halves

  37. Egg substitutes • Better’n Egg • Egg Beaters • Scramblers • Second Nature • Simply Eggs

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