The egg is a biological construction intended by nature for reproduction. It provides complete protection and serves as an of import beginning of nutrients/food for the developing biddy. The egg is besides one of the most alimentary nutrients for worlds every bit good.
STRUCTURE OF AN EGG
Very first line that inhibits the entry of any microorganism that acts as defense mechanism line is the SHELL, which may be white or brown in colour and is chiefly composed of Ca carbonate ( CaCO3 ) . It has about 8,000-10,000 bantam pores which allow the developing embryo to take a breath.
Second defense mechanism line is the SHELL MEMBRANES, which are two in figure ; one sticks to the shell and other is environing the white albumins. It is composed of protein fibres.
GERMINAL DISC appears on the surface of the yolk and is the site where the fertilisation of egg occurs.
ALBUMEN is besides known as egg white, consisting of two beds ; thick albumins and thin albumins. It is composed of high quality proteins, H2O and some minerals. Thick albumins steadfastly surrounds the yolk.
CHALAZA is the distorted, milky ; cord like construction on the opposite side of the yolk that keeps the yolk in the centre.
VITELLINE MEMBRANE is the yolk membrane environing the egg yolk.
Major beginning of fat and cholesterin ( minerals and vitamins ) is the EGG YOLK. Its colour ranges from light xanthous to deep orange depending on the provender that is given to a biddy.
AIR CELL is formed towards the broader terminal of the egg after the egg is laid. It is for respiration of the developing biddy.
COMPOSITION OF AN EGG
Some standard dimensions of an mean egg are as follow ;
Surface country ( cm2 )
Long perimeter ( centimeter )
Short perimeter ( centimeter )
Long axis ( centimeter )
Short axis ( centimeter )
Volume ( cm3 )
Weight ( gram )
Whole egg consists of 9-11 % eggshell, 28-29 % yolk and 60-63 % albumins. Following tabular array shows the chemical composing for whole egg ;
VALUE/ 100 g
VALUE/ 100 g
VALUE/ 100 g
VALUE / 100 g
VALUE / 100 g
Fatty acids, entire saturated
Fatty acids, entire monounsaturated
Fatty acids, entire polyunsaturated
Now the approximative composing of whole egg, eggshell, albumins and yolk is given below ;
EGG COMPONENT ( % of sum )
( 100 % )
( 9-11 % )
( 28-29 % )
( 60-63 % )
0.4- 0.9 %
BIOACTIVE COMPONENTS OF AN EGG
Bioactive constituents of an egg are divided into two parts ;
Bioactive constituents in egg white
Bioactive constituents in egg yolk
BIOACTIVE COMPONENTS IN EGG WHITE
Egg white is the common name for the clear liquid in the egg ( besides known as albumins ) . It is formed from the beds of secernments of anterior portion of Fallopian tube. Its primary map is to protect the yolk and supply nutrition to the developing embryo. It is rich in proteins.
Major proteins, which act as bioactive constituents in egg white, include ; Ovalbumin, ovotransferrin, ovomucin, muramidase, ovoinhibitor, ovomacroglobulin ( ovostatin ) , cystatin, and avidin
It is a major protein in albumins upto 54 % of egg white. It is a glycoprotein, composed of 385 aminic acids with a molecular mass of 45 KDa. Ovalbumin may function as a beginning of amino acids for the turning embryo. It biologically acts as anticancer, antihypersensitive, antimicrobic and antioxidant agent.
This glycoprotein is besides known as conalbumin. It makes upto 13 % of protein content in egg albumins. OTf is composed of 686-residue individual polypeptide concatenation of aminic acids. Its molecular mass is 78-80 KDa. Ovotransferrin exhibits antimicrobic belongings, depending on its ability to sequester ferrous ions ( Fe3+ ) , of import for bacterial growing. OTf is responsible for reassigning ferrous ions from biddy ( Fallopian tube ) to turning embryo.
It is sulphated glycoprotein of egg white. It is composed of 2087 amino acids with a molecular mass of 230, 900 Da. It is besides present in chalaza and vitelline membrane. It accounts about 2-4 % of egg white proteins. In thick egg white ( thick albumins ) , ovomucin is 2-4 times more than in thin egg white ( thin albumins ) . It acts as gelling agent of egg albumins. Cutting of egg white during storage occurs because ovomucin complex degrades.
It is besides known as N – acetylmuramideglycanohydrolases. Lysozyme is a polypeptide of 129 amino acids, holding a molecular mass of 14.3 KDa. It is 3.5 % of the entire egg white proteins. It acts as defense mechanism mechanism until the embryo starts bring forthing its ain Igs.
ovoinhibitor is a serine protease inhibitor with a molecular mass of 48 KDa. It inhibits a broad spectrum of proteases.
Ovomacroglobulin is a 640 KDa glycoprotein. It has a wide spectrum activity against peptidases and strong anticollagenase activity in egg albumins.
Cystatin has a molecular mass of 12.7 KDa and is composed of 115 aminic acids. It possesses antibacterial activity, therefore prevents growing of streptococci, Salmonella typhimurium.
It is a tetrameric glycoprotein composed of 128 aminic acids with a molecular weight of 15-15.8 KDa. It constitutes of 0.05 % of the entire egg white proteins.
BIOACTIVE COMPONENTS IN EGG YOLK
Egg yolk is a portion of egg that feeds the turning embryo. Water transportation from albumins to yolk takes topographic point during egg storage. Yolk makes upto 36 % of the weight of whole egg. Yolk consists of several proteins, fatty acids.
Protein composing of egg yolk is as follows ;
Name OF PROTEIN
( % )
Low denseness lipoproteins
( LDL )
Plasma and granules
High denseness lipoprotein
( HDL )
Egg yolk vitamin B2 binding protein
The LDL of egg yolk is subdivided into VLDL ( really low denseness proteins ) , because of its high lipid content ( 85-89 % ) and low specific gravitation ( 0.89 ) . LDLs are spherical atoms ( 17-60 nanometer in diameter with a mean of about 35 nanometers ) holding a lipid nucleus in a liquid province ( triglycerides and cholesterin esters ) surrounded by a monofilm of phospholipid and protein ( in this circumstance called apoprotein )
High denseness lipoproteins are composed of 75-80 % proteins and 20-25 % lipoids ( phospholipids, triglyceride and cholesterin ) . Lipovitelline ( HDL ) is a ball-shaped protein, subdivided into ?-lipovitelline and ?-lipovitelline.
Phosvitin is a glycoprotein holding a higher P content, ( about 10 % ) and is one of the most extremely phosphorylated natural ( i.e. , nonsynthetic ) proteins. Phosphorus is present as phosphorous acid edge to seryl residues ; approximately 96 % of seryl residues are phosphorylated. The phosphoserines
are arranged in a remarkable manner, organizing blocks that can transport up to 15 back-to-back residues ( Byrne et al. 1984 ; Fig. 1 ) . This confers to the protein a really big and cardinal hydrophilic country surrounded by two little hydrophobic countries at the N- ( 9 residues ) and C- ( 3 residues ) terminus parts.
ribofl avin – adhering protein in yolk comprises ofglycoprotein and riboflavin. Ribofl avin – binding protein ( RBP ) is present in both egg yolk and egg white ; nevertheless, the egg yolk RBP differs from the egg white RBP by a omission of 11 – 13 amino acids at the C end point due to limited proteolytic cleavage during oocyte consumption.
Livetins are major constituents of H2O – soluble egg yolk protein. There are three types: i?Yiˆ – livetin ( MW 80 kDa ) , i?Yiˆ – livetin ( MW 40 – 42 kDa ) , and i?Yiˆ – livetin ( MW 180 kDa ) . Livetins can besides be transferred from blood serum and are identifi erectile dysfunction as serum albumin189
In general, the lipid content entire egg yolk weight is about 30 % ; therefore the 20 g of yolk in the mean egg contains about 6 g of lipoids. Impersonal lipoid ( 65 % ) , the phospholipids ( 30 % ) , and cholesterin ( 4 % ) are the major constituents of egg yolk lipoids. The function of impersonal lipoid in the hatching procedure is chiefly as an energy – providing beginning, while the phospholipids and cholesterin are of import ingredients advancing the formation of bodily cell constructions and the cell membrane of cranial nervus cells ( phospholipid bilayer ) of the biddy.
The IgG protein is by and large found in biddy blood serum is known to roll up in egg yolk to supply an acquired unsusceptibility to offspring. An antibody in egg yolk has been identifi erectile dysfunction as IgY.
Hens, s egg is full of all indispensable foods that are needed by the developing embryo and homo every bit good ( for usage in commercial, industrial, cosmetics, medical specialties etc… )