THE BUTTER OVERRUN 1 75 



taining from 3 to 5 per cent salt, which is often preferred in the 

 Western markets. 



1. Amount of Salt that May be Dissolved in Butler. — The 

 amount of salt that may be dissolved in butter depends upon 

 the moisture content of the butter, as the fat has no power as a 

 salt solvent. Well-worked butter will contain brine of as much 

 as 16.78 per cent sodium chloride.' Suppose the butter con- 

 tains 15.5 per cent of moisture, then the amount of salt con- 

 tained in the solution in such butter is 2.6 per cent. Any 

 amount contained in excess of that will be left in the butter as 

 undissolved salt. If the proportion of undissolved salt becomes 

 too high, the butter appears gritty. It is possible that butter 

 containing only 2.5 per cent of salt may appear gritty. This 

 may be due either to a low water content of the butter or to 

 insufficient working. 



2. Unsalled Butter. — Unsalted butter is manufactured from 

 ripened cream, no salt being added to the butter. This is 

 often incorrectly called sweet butter, which term rightfully 

 belongs only to such butter as is made from unripened cream 

 and without the addition of salt. The moisture and casein 

 content of unsalted butter is practically the same as that of 

 salted butter while fresh, but as the butter becomes older the 

 salted butter has a tendency to lose more in moisture content 

 than the corresponding unsalted butter. The greater difference 

 between the composition of the two kinds of butter, however, 

 is the lack of salt in one and a corresponding increase in fat 

 which brings about a corresponding decrease in the overrun. 

 Unsalted butter is therefore of greater value per pound to the 

 manufacturer than salted butter. The corresponding value of 

 unsalted butter may be determined as follows: 



Let s represent per cent of salt contained in salted butter, 

 p, price per pound of salted butter, and y, price per pound of 

 unsalted butter. 



Then 



100 



y = p- 



100— s 



> Bulletin 80, by McKay and Larsen, Iowa Experiment Station, 1904. 



