Egg Products and Technology-2022.pdf
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It provides basic knowledge regarding the formation of an egg, structure of egg, nutritional importance of eggs as well as egg processing technology and egg products.
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Egg Products and Technology-2022.pdf
- 1. 23/10/2022 1 Introduction to Egg, Egg Products and ProcessingTechnology Muhammad Arslan B.Sc. (Hons.) & M.Sc. (Hons.) Poultry Science (UAF) arslan2062@gmail.com Contents Egg formation Egg structure Egg composition and food value Egg Quality Egg Processing Muhammad Arslan
- 2. 23/10/2022 2 Egg Formation Process in Chicken Muhammad Arslan B.Sc. (Hons.) & M.Sc. (Hons.) Poultry Science (UAF) arslan2062@gmail.com Chicken Egg • Semi-solid nutritional mass enclosed in hard calcareous shell produced by female of bird • Chicken egg contain 8000-10000 pores in shell • Hen requires 2-2.5 gram Ca for normal egg shell formation Muhammad Arslan
- 3. 23/10/2022 3 Egg Formation Ovary = yolk formation Oviduct = Albumin, shell membrane and shell • Mature hen have 3600-4200 ova • Egg formation requires 23-26 hours Muhammad Arslan • Yolk matured in 10 day • Ovulation take place 15-75 minutes after oviposition • The earlobe color of hen can be an indication of eggshell color with some exceptions Muhammad Arslan
- 4. 23/10/2022 4 Hormones during Egg Formation FSH = Activate ovary and oviduct LH = Release ova from ovary (Ovulation) Progesterone = release LH from pituitary Arginine Vasotocin = Uterine contraction (oviposition) Testosterone= comb growth, albumin formation Estrogen= plumage growth, mating and nesting behavior, oviduct development, nutrient supply to ovary and oviduct Muhammad Arslan ReproductiveTract • Reproductive tract = ovary + oviduct • In Chicken, only left side remains functional • Right ovary and oviduct regressed during embryonic growth • Mullerian Inhibiting Substance (MIS) is responsible for regression • Right one is functional in Hawk while both sides functional in Brown Kiwi Muhammad Arslan
- 5. 23/10/2022 5 Ovary • Smooth before laying and later looks granular • Looks like cluster of grapes before laying • Left ovary present near proximity to left kidney • During incubation, approximately 20,000 ova present in hen • Mature hen have 3600-4200 ova • Ovary size is 40-50 g in laying hen and 3-5 grams in broody hen Muhammad Arslan
- 6. 23/10/2022 6 Oviduct (Fallopian tubes) Part of Oviduct Time (hours) 1 Infundibulam 15 minutess 2 Magnum 3 3 Isthmus 1.15 4 Uterus 20-21 5 Vagina Few minutes
- 7. 23/10/2022 7 Medullary Bone Formation • Soft and spongy bones inside long bones • Calcium store for layer • High estrogen level in blood initiate its formation • Only present in females of chicken • Highly important during night for egg formation in absence of feed Muhammad Arslan Role of Light • Photoreceptors are present in hypothalamus • Photoreceptors perceive light and hypothalamus release GnRH • GnRH act on pituitary to release FSH • Specific light duration and intensity is required • 16-17 hours light with 0.75 fc intensity Muhammad Arslan
- 8. 23/10/2022 8 Initiation of Egg Formation • 11 days before first egg, anterior pituitary release FSH • FSH activate ovary and oviduct • Active ovary produced estrogen, progesterone and testosterone • Hormonal + Nervous system is responsible for first ovulation • Second ovulation regulated by first oviposition Muhammad Arslan Estrogen • Enlargement and redding of comb and wattles • Medullary bone formation initiates • Stimulate yolk formation in liver • Widening of pubic bones • Enable oviduct to secrete its secretions Muhammad Arslan
- 9. 23/10/2022 9 Release of Ova into the Oviduct •When ova get matured, progesterone hormone is released by ovary •Progesterone stimulates hypothalamus to release LH from anterior pituitary •LH cause rupture of follicle from stigma (suture line) and ovulation takes place Muhammad Arslan Infundibulum (Funnel) • Approx. 9 cm funnel-like structure • Capture ova from ovary • Sperms from males are temporarily stored here for fertilization • Fertilization takes place if sperms are present • Ova remains 15 minute here • Only becomes active just after ovulation Muhammad Arslan
- 10. 23/10/2022 10 Egg Fertilization • Cock mate 10-30 times a day with hen • Semen ejaculation is 1 ml for first mating and then reduced to 0.5 ml or less • 100 million to 5 billion sperms are ejaculated per mating • Sperms are stored in utero-vaginal junction • Fertile eggs can be produced for 4 weeks after removal of males Muhammad Arslan • Movement of sperm from this junction to infundibulum - 30 minutes in absence of ovulation - 5-10 minutes after an ovulation • 50 sperms penetrate outer layer of ovum (less than 30 leads to poor fertility) • Few sperms move to germinal disk • 1 sperm unite with female pronucleus to form zygote Muhammad Arslan
- 11. 23/10/2022 11 Magnum • Largest part of oviduct (33 cm long) • Major portion of albumin secreted here • Chalazae also secreted here • All 4 layers of albumin produced and completed except outer thin white • Developing remains here for 2-3 hours • Only one type of albumin secreted in magnum but addition of water and rotation of egg make layers Muhammad Arslan Isthmus •Small length of 10 cm •Less developed than magnum •Ova remains here for 75 minutes •Inner and outer shell membranes secreted here •Outer membrane is about 3 times thicker than inner •Eggs from young birds have thicker shell membranes Muhammad Arslan
- 12. 23/10/2022 12 Uterus (Shell gland) • 10-12 cm long in laying birds • Egg remains here for 20-21 hours • Fourth layer of albumin (outer thin layer) is completed here by addition of water and salts • Plumping Muhammad Arslan • Approximately 15 ml fluid is added by plumping process • Egg shell, its pigment and cuticle is added here • 2-2.5 g calcium is used for shell formation from which 53% taken from feed and 47 % from bones Muhammad Arslan
- 13. 23/10/2022 13 Vagina • Last part of oviduct and12 cm long • Egg remain for few minutes here • No egg formation occurs here • Only expel the eggs outside the body • Sperm store glands are present at junction of shell gland & vagina • It can store sperms for 10-14 days Muhammad Arslan
- 14. 23/10/2022 14 Oviposition • Egg laying process is called oviposition •Arginine Vasotocin from anterior pituitary control shell gland contraction during oviposition • Broader end comes first in the environment Muhammad Arslan • Initially egg has smaller end outward • Just before oviposition hen rotates egg in horizontal position and broader end comes first from body • Rotation takes about 2 minutes Muhammad Arslan
- 15. 23/10/2022 15 Air Cell Formation • Air cell (0.7 inches) formed between inner and outer shell membrane at broader end • Egg inside hen has no air cell • When egg is laid its contents are contracted due to temperature difference Muhammad Arslan • As the egg contents contracted, air cell is formed • Broader end comes first so normally it formed at broader end • As egg get older, moisture contents evaporated from eggs, air cell size increased Muhammad Arslan
- 16. 23/10/2022 16 Egg after Laying •Freshly egg has temperature of about 104 •Egg takes 4-8 hours to attain room temperature •Air cell formed after egg laying Muhammad Arslan
- 17. 23/10/2022 17 Egg Structure MuhammadArslan M.Sc. (Hons.) Poultry Science arslan2062@gmail.com Muhammad Arslan Protoporphyrin IX (PpIX) is the main pigment resulting in the brown coloration of eggshell
- 18. 23/10/2022 18 Egg Structure Structure of Egg • Cuticle • Shell • Shell Membranes • Albumen • Chalazae • Vitelline membrane • Yolk Muhammad Arslan
- 19. 23/10/2022 19 Cuticle • Most external layer of egg • Protect the egg from moisture and microbial invasion Muhammad Arslan Eggshell • 10-12 % of egg weight • 7000-17000 funnel shaped pores • Normal eggshells can withstand 3 to 4 kg (6 to 9 lb) per square centimeter before breaking. Muhammad Arslan
- 20. 23/10/2022 20 FoodValue and Chemical Composition of Chicken Egg Muhammad Arslan B.Sc. (Hons.) & M.Sc. (Hons.) Poultry Science (UAF) arslan2062@gmail.com Introduction • Egg is an excellent food and well-balanced source of nutrients for all ages • Provide good nutrition with comparatively low calorie contents • High quality proteins with highest biological value • Egg devoid fibers and its components are highly digestible • Egg can contribute to overall health across the life span • Eating two eggs per day covers 10% to 30% of the vitamin requirements for humans The perfect balance and diversity in its nutrients along with its high digestibility and its affordable price has put the egg in the spotlight as a basic food for humans Muhammad Arslan
- 21. 23/10/2022 21 Chemical Composition of Egg Muhammad Arslan Muhammad Arslan
- 22. 23/10/2022 22 EggYolk Composition Egg White Proteins
- 23. 23/10/2022 23 Lipid Composition of Egg Amino Acid Composition Muhammad Arslan
- 24. 23/10/2022 24 Eggshell Composition Biological Activities of Egg Proteins (Lee and Paik, 2018)
- 25. 23/10/2022 25 (Réhault-Godbert et al., 2019)
- 26. 23/10/2022 26
- 27. 23/10/2022 27 Egg proteins are distributed equally between egg white and egg yolk, while lipids, vitamins and minerals are essentially concentrated in egg yolk Egg White Yolk (Réhault-Godbert et al., 2019) Muhammad Arslan Egg antimicrobials in edible parts are essentially concentrated in egg white and the vitelline membrane
- 28. 23/10/2022 28 Egg is an encapsulated source of macro and micronutrients that meet all requirements to support embryonic development until hatching Muhammad Arslan
- 29. 23/10/2022 29 Egg-ceptions • Natural source of vitamin D (Second to cod liver oil) • Highly digestible and least-cost animal protein sources • Multivitamin Source Muhammad Arslan Health Benefits of Egg • Rich nutrient source • Muscle development (Proteins and amino acids) • Eggs are second only to fish liver oils as a natural source of vitamin D • Good for vision (Vitamin A, Lutein, Zeaxanthin) • Good for cell functions, brain health and neurotransmission (Choline) • Source of cholesterol (essential component of cell membranes and a precursor for hormones, vitamin D, and bile acids) Muhammad Arslan
- 30. 23/10/2022 30 • Good for maintaining stronger bones (Vitamin D, Ca, P) • Boost Immune system (Vitamin B12, E, Se, Zn) Muhammad Arslan Egg Cooking and Nutrition Muhammad Arslan
- 31. 23/10/2022 31 Effect of Cooking on Egg Nutrients (Réhault-Godbert et al., 2019) Digestibility Evenepoel P, Geypens B, Luypaerts A, Hiele M, Ghoos Y, Rutgeerts P. Digestibility of cooked and raw egg protein in humans as assessed by stable isotope techniques. J Nutr. 1998 Oct;128(10):1716-22. doi: 10.1093/jn/128.10.1716. PMID: 9772141. Muhammad Arslan
- 33. 23/10/2022 33 Shell Membranes • Two membranes surround the albumin • The outer shell membrane is thicker and is attached to the shell • Highly fibrous and permeable to moisture and gasses such as oxygen and CO 2, but can prevent most microbial invasions • Air cell formed at broader end Muhammad Arslan Fresh eggs will sink in water while older eggs will float
- 34. 23/10/2022 34 Micrometer Inner shell membrane 0.1-3 Outer shell membrane 1-7 Muhammad Arslan
- 35. 23/10/2022 35 Albumen • 58 to 60% of the egg's weight • Four layers - Inner thick layer (Chalaziferous layer) 3 % - Outer thick layer 57% - Inner thin layer 17 % - Outer thin layer 23 % • Large amount of ovomucin is present in inner thick and almost absent in outer thin • The percentage of thin albumen increases as hens age and as eggs age • Chalazae hold the yolk in the center Muhammad Arslan Yolk • Constitutes 30 to 32% of the egg's weight • Surrounded by vitelline membrane • Concentric rings of white and yellow yolk material due to alternating deposition during day and night • Fat-soluble pigments, normally xanthophyll, are transferred rapidly from the digestive tract to the blood stream and then to the yolk Muhammad Arslan
- 36. 23/10/2022 36 • The deep yellow yolk is formed in the daytime, and the light yellow yolk is formed at night Muhammad Arslan
- 37. 23/10/2022 37 Infertile (Blastodisc/Germinal disk) Fertile (Blastoderm) Shape Irregular Round (bullseye/doughnut) Size Smaller (3.5-4 mm) Larger (4-5 mm) Muhammad Arslan
- 39. 23/10/2022 39 Egg Quality Evaluation and Grading Muhammad Arslan Muhammad Arslan B.Sc. (Hons.) & M.Sc. (Hons.) Poultry Science (UAF) arslan2062@gmail.com
- 40. 23/10/2022 40 Muhammad Arslan Purposes of Egg Quality Evaluation • To evaluate the status of farm • To benchmark the quality of eggs against the offering of competitors Muhammad Arslan
- 41. 23/10/2022 41 Egg Structure Egg Size 1. Egg shape (Oval, become slightly elongated over the cycle) 2. Egg weight (Genetic, age, nutrition) • With an extra 1g of protein consumed per day translating into an average increase of 1.4g in egg weight • Egg weight is used in many countries to grade and sell the eggs Muhammad Arslan
- 42. 23/10/2022 42 Egg Shell Quality • Appearance and cleanliness (color uniformity, clean, smooth etc.) • Shell thickness (0.33-0.37) • Eggshell breaking strength (above 3.5 kgf/ 34 N) Muhammad Arslan Egg Freshness • Albumin Quality • Yolk Muhammad Arslan
- 43. 23/10/2022 43 Albumin Quality • Albumen contains a large amount of carbon dioxide • Its pH ranges from 5.6 to 7.5 with time and gas exchanges with the outside environment • When the carbon dioxide dissipates, the pH of the albumen rises to about 9.5 • This rise in pH will affect the structure of ovomucin • It make the albumen lose its viscosity • Haugh unit (HU) is the common method for determining albumin quality Muhammad Arslan Haugh Unit HU= 100log(h-1.7w0.37+7.6) h=albumin height (mm) W= egg weight (grams) The Haugh unit value ranges from 0 - 130 and can be ranked as below: • AA : 72 or more • A : 71 - 60 • B : 59 - 31 • C : 30 or less Muhammad Arslan
- 44. 23/10/2022 44 Yolk • Color (Yolk fan, digital color fan) • Shape Muhammad Arslan
- 45. 23/10/2022 45 Yolk Index YI= Yolk height /yolk diameter
- 46. 23/10/2022 46 Egg Grading Grading • Grading is the sorting of products according to quality, size, weight, and other factors that determine the relative value of the product • Egg grading is the grouping of eggs into lots having similar characteristics as to quality and weight • U.S. standards for quality of individual eggs have been developed
- 47. 23/10/2022 47 Advantages of Grading • Sorted eggs bring more money to the investor than unsorted • Reduces wastage • Eliminates the need for personal inspection of the eggs by sellers, buyers, and other interested people • Development of improved quality at producer level through "buying on grade" programs • Market price reporting in terms understood by all interested parties • A basis for settling disputes involving quality • A basis for paying damage claims • A basis for developing advertising • A uniform basis for establishing brand names • Establishment of buying guides for consumers Muhammad Arslan Quality Factors • Quality may be defined as the inherent properties of a product that determine its degree of excellence • Those conditions and characteristics that consumers want, and are willing to pay for, are, in a broad sense, factors of quality • Quality factors are classified as External and Internal
- 48. 23/10/2022 48 Shell Color Eggs sell better when sorted and packed according to color than when sold as "mixed colors
- 49. 23/10/2022 49 Muhammad Arslan Exterior Quality Factors Muhammad Arslan
- 50. 23/10/2022 50 Shell Shape andTexture • The normal egg has an oval shape with one end larger than the other, and it tapers toward the smaller end • The ends of an egg are commonly called the large end (air cell end) and the small end • Strength and appearance of many eggs to develop the "ideal" egg shape • The shape of an egg can be considerably different from the ideal, but may still be considered practically normal Muhammad Arslan • Eggs that are unusual in shape may have ridges, rough areas, or thin spots • Abnormal shells may result from improper nutrition, disease, or the physical condition of the hen • Sometimes a shell is cracked while the egg is still in the body of the hen. These eggs, which are commonly referred to as "body checks," are repaired by an additional deposit of shell over the cracked area, generally resulting in a ridged area. • Shells with thin areas and some other types of defects are usually weaker than normal shells, and the danger of breakage en route to the consumer lowers the utility value of the egg. Eggs of abnormal shape also lack consumer appeal. Muhammad Arslan
- 51. 23/10/2022 51
- 52. 23/10/2022 52 Interior Egg Quality • Even under the most favorable conditions, egg quality is relatively unstable as the interior quality of the egg deteriorates • Sometimes quality changes render eggs useless for food before they reach consumers • However, when eggs are properly cared for, the quality decline can be minimized Muhammad Arslan
- 54. 23/10/2022 54 Air Cell • Temperature of freshly laid egg is about 105 ⁰F • As the egg cools, the liquids contract more than the shell • The inner shell membrane separates from the outer to form an air space • Evaporation of water from the egg increase air cell size • The air cell is the easiest quality factor to evaluate, as it can be judged objectively by a simple measuring device “Air cell gauge” Muhammad Arslan Muhammad Arslan
- 58. 23/10/2022 58
- 59. 23/10/2022 59 Muhammad Arslan No Grade Eggs Muhammad Arslan
- 61. 23/10/2022 61 Muhammad Arslan The interior quality of broken-out eggs for each of the designated grades as specified in the U.S. standards with respect to white and yolk quality Muhammad Arslan
- 63. 23/10/2022 63 Egg Processing and Products Muhammad Arslan M.Sc. (Hons.) Poultry Science arslan2062@gmail.com Muhammad Arslan Introduction • Shell eggs are transported to egg processing plant • “Egg products” refers to eggs that are removed from their shells for processing • Egg products processing includes breaking eggs, filtering, mixing, stabilizing, blending, pasteurizing, cooling, freezing or drying, and packaging • Egg products include whole eggs, whites, yolks, and various processed and pasteurized blends, with or without non-egg ingredients • Egg products may be available in liquid, frozen, and dried forms Muhammad Arslan
- 64. 23/10/2022 64 Egg Processing in Pakistan • Al Waha is a pioneer in processing egg products • Barkat Frisian Pasteurized Egg Company (Pvt) Ltd is a Pakistani – Dutch Joint Venture Company Muhammad Arslan Egg Processing • Receiving shell eggs was • Washing/sanitizing/candling eggs • Breaking eggs • Handling liquid egg product: – filtering – blending – mixing • Cooling • Pasteurization • Freezing or drying • Packaging • Storage • Shipping Muhammad Arslan
- 67. 23/10/2022 67 Muhammad Arslan Receiving of Shell Eggs • In-line system vs off-line system • Production starts with loading of eggs • Vacuum cups transfer the eggs from the flats to the egg washer conveyor (Off- line) • Off-line operations usually have separate coolers for incoming eggs for overnight cooling Muhammad Arslan
- 68. 23/10/2022 68
- 69. 23/10/2022 69 Cleaning and Sanitization • Primary objectives are to remove surface contaminants, to enhance appearance and appeal of the egg to the consumer, and to assure a safe high quality product • Shell eggs, when presented for breaking, must be clean • Washing is followed by sanitizing and then by immediate drying • Modern egg washers use pressure sprays, rotating brushes, and an egg-spinning device • Increases contact between the egg and the brush and minimizes damage to the eggs Muhammad Arslan • Sodium hypochlorite (NaCIO) is the most commonly used sanitizer • Shell eggs ineligible for breaking during the candling operation • After washing and sanitizing, eggs are air dried with the use of electrical fans, and oiled to help reduce weight loss and preserve interior egg quality • Shell eggs continue on the conveyor to the breaking room Muhammad Arslan
- 70. 23/10/2022 70 WashWater • Wash water temperature must be at least 90°F (32.2°C) to provide appropriate cleaning • Further, wash water should be at least 20°F (11°C) warmer than egg temperature to help prevent microbial penetration • In practice, a range of 100 to 114 °F (37.8 to 46.1°C) is commonly used • The initial pH of alkaline detergent wash water should be approximately 11 • During the washing cycle, water pH should range between 10 and 11 • Salmonella are able to grow at temperatures of 100 to 108°F (38 to 42°C) when wash water pH is 9.5 or less Muhammad Arslan Muhammad Arslan
- 71. 23/10/2022 71 Egg Candling • Eggs are mechanically rotated several times over a bright light to examine the internal quality of the egg • Critical step in the processing of the shell eggs • Defective eggs are identified and removed • Inedibles are eggs with broken shells and membranes (leakers), dirty, or eggs with blood spots • Plant employees sort, classify, and segregate the eggs to ensure that only eggs eligible for breaking enter the breaking room Defective Eggs Sent for breaking Destroyed, if inedible Rewashed Shell Eggs Packing • From the grading area, eggs are conveyed to the packaging machine, where they are individually weighed and separated into one of six weight • Containers are commonly stamped with date-of-packing and sell-by-date codes to facilitate inventory control • In the United States, shell eggs were commonly refrigerated at 55 to 66°F (12.6 to 15.6°C) during pre- and post-processing and in retail storage and displays • In most parts of the world, eggs are not refrigerated
- 72. 23/10/2022 72 Specific Flock Management Systems Free-range Barn Vegetarian-diet eggs Organic shell eggs Designer eggs (modification/fortification) Modifications Cholesterol reduction Elevating vitamin E level Changes in fatty acid profile Fortifications Nutraceuticals supplementation Omega-3 fatty acids Muhammad Arslan Muhammad Arslan
- 74. 23/10/2022 74 Further Processed Egg Products • These are out-of-the-shell egg ingredients which are combined with other ingredients to create finished food products for retail and foodservice users • Further processed egg products are classified into four groups: i. Refrigerated liquid egg products ii. Frozen egg products iii. Dried egg products iv. Non food by-products Muhammad Arslan Breaking Eggs • This process transforms shell eggs into liquid products: whole egg, egg whites and egg yolks • After the egg is broken, the breaking machine can separate the yolk from the white • Further-processed liquid eggs are then manufactured into chilled, frozen, or dried products
- 75. 23/10/2022 75 Muhammad Arslan Handling of Liquid Eggs • After breaking, the liquid egg flows into collection vats (balance tanks) by gravity • A perforated plate contained within the vat serves as a filter to remove eggshells • The liquid egg is pumped through a filter and then is pumped to the cooling system • After cooling, the liquid egg is pumped to a storage silo for further processing Muhammad Arslan
- 76. 23/10/2022 76 • Pasteurization, stabilization, or drying operations shall start as soon as practicable after breaking to prevent deterioration of product • Preferably within 72 hours from time of breaking for egg • Liquid products can be used as is, or can be incorporated as an ingredient into other finished food products Muhammad Arslan
- 77. 23/10/2022 77 Pasteurization • Liquid egg products are pasteurized to eliminate Salmonella • Pasteurization involves rapidly heating the product and holding the product at a minimum required temperature for a specific time • Rapid cooling of liquid eggs during pre- and post-pasteurization further improves product quality, safety, and shelf life Muhammad Arslan Pasteurized liquid egg product may be handled as i. Packed in containers (plastic buckets, bag-in-box, packages, milk containers, etc.) to be marketed ii. Further processed (add ingredients post pasteurization, freeze or dry) iii. Shipped in tankers to another egg products plant or distributor Muhammad Arslan
- 78. 23/10/2022 78 Why Pre and Post Pasteurization Refrigeration is Required? • Many spoilage bacteria and spores remain viable after pasteurization • Without refrigeration, these organisms will multiply rapidly, to about 10 million cells per gram, at which time the egg product starts to deteriorate • Refrigeration slows down this process and increases the shelf life of the product • Furthermore, microorganisms release enzymes into the media in which they live Some of these enzymes are heat-resistant, thus they will survive pasteurization • Rapid breaking + pasteurization + pre/post refrigeration = reduce enzyme activity Muhammad Arslan USDA Regulations for Pasteurization • All egg products be free of Salmonella, which is accomplished through the use of pasteurization • The USDA requires that all pre-pasteurized liquid egg products be refrigerated to holding temperatures between 40 and 70 ⁰ F (4.4 and 21.1°C) • The specified temperatures must be achieved within 2 hours from the time the eggs are broken Muhammad Arslan
- 79. 23/10/2022 79 Temperature, time, and pH all affect the successful pasteurization of liquid eggs Higher pH requires lower pasteurization temperature with the alkaline pH of 9.0 being the most effective for destroying Salmonella Muhammad Arslan
- 80. 23/10/2022 80 Muhammad Arslan Storage and Distribution of Liquid Egg Products • Chilled liquid egg products are extremely perishable and should be rapidly cooled immediately after pasteurization to 40°F (4.4°C) or below, and kept cold at 34 to 40°F (1.1 to 4.4°C) during storage • Shelf-life at 34 to 40°F (1.1 to l.4°C) is about 5 to 12 days, depending on the product's quality
- 81. 23/10/2022 81 Freezing • Frozen egg products include separated whites and yolks, whole eggs, blends of whole eggs and yolks, and whole eggs with added ingredients • They are produced from pasteurized liquid egg products by using a blast freezer at temperatures of –10°F to – 40°F • Frozen egg products have a long shelf life when kept at less than 10°F • Freezing whole liquid eggs or yolks to below 21°F (-6°C) creates gelation problems and when these eggs are thawed, they do not have the same characteristics as shell eggs or fresh egg products Muhammad Arslan Gelation • Gelation is an irreversible increase in the apparent viscosity • The thawed yolks do not return to their original smooth texture, but become lumpy, gummy, and do not mix well with other ingredients • Gelation is formed when water molecules freeze around the egg's lipoproteins • Gelation of liquid whole egg is less severe than that of yolk, as egg albumen is only slightly affected • To prevent gelation, salt or sugars are added to the yolk at a 10% level • Mechanical action, such as passage through a homogenizer, also prevents gelation
- 83. 23/10/2022 83 Packaging and Storage of Frozen Products • The frozen products are stored in a cold room with ambient temperature of 0 to –l0 °F (-17.8 to -23.3°C) • To prevent gelation, salted yolks are frozen and stored at 0 °F (-17.8°C) • One of the major drawbacks of frozen egg products is the lengthy thaw time which reduces the flexibility of work scheduling, especially in emergencies or when additional eggs are needed Muhammad Arslan Drying (Dehydration of Eggs) • Industry has developed a variety of dried egg products, including dried egg white, dried plain whole egg and yolk, and specialty dried egg products • Egg products fall under two basic categories when considering their drying characteristics i. egg white products ii. whole egg and yolk products • Before the liquid egg products go through the drying process, industry uses processing techniques to achieve the desired finished product Muhammad Arslan
- 84. 23/10/2022 84 • Industry uses chemical additives to improve and keep the functional properties (whipping, coagulation, emulsification, flavor, nutrition, and color) of the final dried egg products • Examples of chemical additives include carbohydrates, whipping aids, emulsifiers, and anti-caking agents (colloidal silicon dioxide) • The dried egg product must be handled aseptically during packaging Muhammad Arslan Drying Systems 1. Spray Drying 2. Pan Drying Muhammad Arslan
- 85. 23/10/2022 85 Spray Drying • The liquid egg is atomized by pressure nozzles which operate at 500 to 6,000 psi • The centrifugal atomizer consists of a rotating or spinning disc or rod, which rotates at 3,500 to 50,000 rpm • The atomized droplets meet a hot air cyclone at 250 to 450°F (121 to 232°C), which is created and driven by a fan blowing it in the opposite direction • The moisture level in spray dehydrated products is approximately 5% Types of Spry Dryers Vertical (Most widely used) Horizontal Muhammad Arslan
- 86. 23/10/2022 86 Desugarization of Liquid Egg Products Prior to Drying • Millard Reaction (reducing sugar + proteins) • As a result, the color of the products can be darkened from yellow to brown and the products shelf life can be significantly reduced • Therefore, the glucose in the eggs must be removed before drying • The glucose fermentation process is widely used today by most commercial operations Desugarization Methods Bacterial fermentation Yeast fermentation Glucose oxidase-catalase enzyme fermentation Muhammad Arslan Freeze-Drying Eggs (lyophilization) • Water is removed from food by direct sublimation • If the frozen food is placed under a high vacuum and heated, the moisture in the product will be transformed into vapor without first being liquefied • Freeze-dried eggs are superior to air-dried eggs but are also much more expensive (up to four times) to produce Muhammad Arslan
- 87. 23/10/2022 87 Packaging of Dried Egg Products • Fiber drums with polyethylene liners for packaging dried egg products • Thick paper bags with liners for 25 or 50 lb (11.4 or 22.8 kg) of product are also used in other countries • Liners are required to protect the egg products from absorbing moisture through the packaging walls • Freeze-dried eggs are more hygroscopic, and therefore require packaging with improved moisture barriers Muhammad Arslan Storage of Dried Egg Products • Dry glucose-free egg whites are very stable under most storage conditions with years of shelf life • Yolk-containing products are less stable and have about 8 months shelf life in dry storage at room temperature • Store successfully for more than a year in refrigeration Muhammad Arslan