AOCUEACY I]Sr COMMEECIAL GEADING OF OPENED EGGS. H 



RELATION BETWEEN THE NUMBER OF BACTERIA AND THE PHYSICAL 

 CONDITION OF THE EGG CONTENTS. 



CONDITION OF YOLK. 



The physical condition of an egg indicates to a large extent its 

 state of preservation. The white of a strictly fresh egg is stiff and 

 the yolk stands up lirnily, as can be seen very clearly from Plate I.^ 

 As the egg ages, the white becomes thinner, the yolk flatter, and 

 the vitelline membrane weaker. When a stale egg is opened, the 

 vitelline membrane frequently is ruptured and the contents of 

 the yolk flows into and through the white, as illustrated in Plate 

 III.^ This type of egg is commonly called a "weak egg" or a "soft 

 egg," and occurs most frequently in summer weather. Fertile eggs 

 showing advanced hatch spots almost invariably contain weak yolks. 



Eggs produced in the spring of the year generally have a firm 

 consistency; that is, both white and yolk have the viscosity of the 

 fresh egg. Occasionally it happens that a portion of the contents of 

 the yolk has seeped through the vitelline membrane into the white 

 in sufficient amount to give it a yellowish tinge. (See Plate II.) 

 Although this condition prevails before the egg is opened, it is rarely 

 detected by candling. 



Because of their physical condition neither "soft eggs" nor eggs 

 with incipient seeping yolks can be separated satisfactorily into white 

 and yolk. These eggs appear to have whole yolks before the candle. 

 If, on breaking, their odor is normal and the white not green, they 

 may be considered suitable for baking and cooking. Wh,en the seep- 

 age of the yolk is so advanced that it extends entirely through the 

 white, the egg should be discarded. Such an egg has the appearance 

 of a mixed rot before the candle.^ 



Further deterioration in the shell of a "weak egg" or "soft egg" 

 results in the final rupture of the vitelhne membrane and a partial 

 mixing of white and yolk. This egg, which is one type of a mixed 

 rot, is illustrated in Plate IV. The physical mixing of the white and 

 yolk progresses untd. the egg becomes what is kno\vTi as an addled 

 egg or a white rot. Frequently, eggs containing blood rings or adher- 

 ent yolks pass through the different stages of deterioration until 

 they become addled eggs. 



It was found that the percentage of eggs with bacteria increased 

 with the physical breaking down of the yolk, as shown by Table V, 

 The percentage of eggs containing bacteria was as follows: 10.6 for 

 eggs with whole yolks, 22.7' for soft eggs, and 43.5 for eggs with 

 partially addled contents or with yolks adherent to the shell. 

 The results of the examination of eggs with partially or entirely 



1 Reprint from U. S. Pept. Agr. Bui. 51, pi. I, and U. S. Dept. Agr. Bui. 224, pi. XVII. 



2 Reprint from U. S. Dept. Agx. Bui. 224, pi. XTV. 



3 U. S. Dept. Agr. Bui. 224, pi. XVI. 



