60 BULLETIN" 846, U. S. DEPARTMENT OF AGRICULTURE. 



INTERPRETATION OF RESULTS OF INVESTIGATION. 



A series of plots (figs. 1, 2, 3, 4, and 5) was made, with the purpose 

 of finally grouping into a single expression the information obtained. 



AMMONIA NITROGEN. 



On cross-section paper the amounts of ammonia nitrogen, expressed 

 as milligrams per 100 grams of sample on the wet basis, were plotted 

 as ordinates against the percentages of ether extract as abscissas. The 

 percentages of ether extract as abscissas were chosen not because the 

 ether extract is destroyed by bacterial or enzymatic action in direct 

 proportion as the ammonia increases, but because the normal amount 

 of ammonia was found to be greater in yolk than in whole egg, even 

 when prepared from the freshest eggs obtainable. It is also a known 

 fact that practically all of the ammonia nitrogen occurs in the yolk 

 and that there is no appreciable increase of ammonia nitrogen in the 

 whites of storage eggs or in decaying liquid whites. Therefore any 

 increase in ammonia nitrogen in whole egg is due to decomposition 

 of the yolk, of which the white acts practically as a diluent. Because 

 the ether extract is the best available measure of the amount of yolk 

 present, it was used as the abscissa. Moreover, there is a very great 

 tendency at present to make yolky mixtures, which theoretically 

 may be judged as to quality, as far as ammonia is concerned, if a 

 curve can be drawn, one end of which is determined by the results 

 found for white and the other end for yolk, and which will pass at an 

 intermediate point through the results for whole egg. 



The increased amounts of yolky mixture now made are largely 

 due to the demand at present for much more yolk than white. If 

 no preventive steps were taken, white would become a drug on the 

 market. Consequently, in making contracts, especially in the pro- 

 ducing section, many breakers demand that the bakers shall take 

 equivalent amounts of yolk and white. x^.s this would provide the 

 bakers with more white than they need if they based orders on their 

 requirements for yolk, they overcome the difficulty by ordering what 

 white they need and then arranging that the equivalent amount of 

 yolk shall be mixed with enough whole egg to give them an amount of 

 yolky mixture equal to the necessary amount of yolk. They can not 

 entirely substitute yolky mixture for yolk, but they can do so to a 

 very large extent, if they are careful not to have so much whole egg 

 in the mixture that their baking recipes are upset. Obviously, in 

 filling one contract, the amount of yolk in the yolky mixtures may be 

 high, while in another it may be low, with the possibility of all de- 

 grees of intermediate mixtures. The amount of whole egg in the 

 mixture has been observed to increase as the season advances. To 

 judge such mixtures fairly it has been proposed that the ammonia 



