Egg Quality and Freshness PDF

Genital tract of hen  Vitelline membrane 40-50%White Chalazae White & Shell 10%White Shell membranes Pigment...

Genital tract of hen  Vitelline membrane 40-50%White Chalazae White & Shell 10%White Shell membranes Pigment Cuticle 1-Cuticle. 3- Shell 2- The membranes. shell. 4 Air cell.  Thin albumin 5- The white (albumin). 6- yolk 7- Vitelline membrane. 8- Chalazae.  Flabby and flattened Increase in pH (pH of yolk of fresh egg is 6). Change in the fluorescence Stretched and weakened Cease anchoring yolk to thick white Increase in size as water evaporates from liquid content of the egg and air replaces it Water gradually passes to yolk Thick white thin white Attachment of thick white to Sh.Mem becomes weak  Old egg Fresh egg Notice the white and yolk of both eggs  Penicillium Alternaria Mold Aspergillus Growth Mucor Rhizopus Claosporium  large air cell Running air cell Ringed air cell faulty Rough shell Weak shell Shelless egg Misshapen shells Cracks Leakers Sided yolk Stuck yolk  spread patchy Discolored Darker or greenish Blood spots Bloody egg Meat spot Incubated egg Thin blood vessels Blood ring Infertile egg Fertile egg 11 days old chicken embryo Mould growth Rot Tainted  Judgment of eggs A.Unfit for human consumption: 1. Bloody spots 2. Incubated egg 3. Rot 4. Stuck and spread yolk 5. Mould growth 6. Discolored white and yolk 7. Meat spots 8. Tainted eggs B.Suitable for immediate use (as cooking eggs) 1.Large air cell 2.Dirty shell 3.Small blood spots 4.Sided or patchy yolk Definitions: is the properties of any given food that have an influence on the acceptance or rejection of this food by the consumer. is a general term which refers to several standards which define both internal and external quality of the egg. cleanliness Albumin or texture white Yolk shape ▪Covers a small area ▪Covers moderate area. ▪Covers a large area ▪White is thick and firm ▪white is reasonably firm ▪ White is thin and stands and stands high. and stands fairly high. low ▪Yolk is high and ▪yolk is high and round. ▪Yolk is wide and flat round ▪Clean unbroken shells ▪Unbroken shells but may Clean unbroken shells be slightly stained A- Before eggs are laid 1. Breed Egg shell color , Egg size , Blood spots Nutritional value of the egg ,Shell quality 2. Ration Albumen and yolk quality ,Yolk color Undesirable flavour ,Blood spots( ↓ vit k&A) 3. Disease → shape , size , thin albumin , yolk mottling 4. Age 5. Environmental B- After eggs are laid 1. Frequent Collection of egg. 2. Separation of clean eggs from dirty or other ones with any defect. 3. Immediate refrigeration of collected eggs at 10-13c and 70%- 80% relative humidity. 1-Brine test 2-Shaking test 3-Examination of egg under ultra violet-rays  1- brine test: could be used for examination on a small scale. - 56 gm of sodium chloride are dissolved in 567 ml of water. - Fresh egg ::: settlr down. - Bad egg ::::: float in various position.  2- shaking test: attachment of the white to the shell membranes as well as the fixing of the yolk by the chalazae. - Fresh egg ::: no sound. - Not fresh egg :: sound.  3-Examination of egg under ultra violet-rays  the basis depend on the presence of porphyrin in the cuticle on the shell of fresh eggs. 4- Egg candling Candling lamp of a 60- watt electric bulb of clear glass ❑Candling is used for examination of large commercial scale ❑It is preferable to be done in dark room The broad end of the egg is held against the opening of candling lamp and twisted along its longitudinal axis Most of egg faults can be detected by candling  Lysozyme enzyme Ovotransferrin Avidin-Biotin complex Microorganisms transmitted through raw or semi-raw eggs S. typhimurium E.coli S.aureus Avian T.B