New YorK AGRICULTURAL EXPERIMENT STATION. ets 
6. Results of investigation of preceding conditions.—When the 
churning was managed so as to make the butter-granules of the 
size of rice-grains and these were carefully washed twice with 
water below 45° F., removing most of the buttermilk adhering to 
the outer surface of the granules, no mottles were obtained, how- 
ever conditions were varied in other respects. Mottles were 
always found when the buttermilk was not sufficiently re- 
moved. 
7. Relation of proteids to mottled butter.—The amount of proteid 
(casein lactate) in mottled butter is greater in the light portions 
than in the darker portions, and is the cause of the lighter color of 
the mottles.. | 
8. Relation of salt to mottles.—(1) Salt brine does not change 
in any way the color of butter-fat. (2) Salt brine, as it commonly 
occurs in butter, has the power of hardening and localizing the 
proteid particles, the action requiring several hours for comple- 
tion. (3) Butter, free from buttermilk adhering to the outer 
surface of the granules, does not produce mottles when salted, 
whether the salt is evenly or unevenly distributed. (4) Mottles 
do not occur in unsalted butter. (5) In mottled butter, the light 
portions usually contain less salt than the darker portions. 
9. Cause of mottled butter—Mottles in butter are due, prima- 
rily, to the presence and uneven distribution of buttermilk adher- 
ing to the outer surface of the small granules; and, secondarily, 
to the hardening and localizing effect of salt brine upon the pro- 
teid of the buttermilk thus retained in butter. The light por- 
tions of mottled butter owe their lighter color to the presence 
of localized proteid (usually casein lactate). The yellow or clear 
portions occur where the spaces between the butter-granules are 
filled with clear brine and are comparatively free from casein com- 
pounds. Several hours are required to complete the action of the 
brine upon the proteid of the butter. 
10. Prevention of mottles in butter.—Mottles in butter can be 
prevented by avoiding those conditions that retain buttermilk 
in the butter and observing those conditions that favor the 
removal of buttermilk from butter-granules before salting. The 
butter-granules should be about the size of rice-grains and should 
be washed twice with water at a temperature of 35° to 45° F, 
18 
