454 BUTTER STORAGE: 



the butter must be protected against agents and conditions 

 which cause it to deteriorate in quality. The chief of the con- 

 ditions injurious to the quality of butter in storage are air. 

 light, heat and moisture. 



Air, Light and Heat. Excessive exposure to air causes de- 

 terioration of butter through oxidation, or through bacterial 

 action, or both. This oxidation is greatly intensified in the 

 presence of light, or heat, or both, and bacterial action is 

 enhanced in the presence of heat. Exposure to air is minimized 

 by the use of packages of comparatively large size and by 

 packing in wrappers and containers that have previously been 

 made as near impervious to air as possible. Butter is best 

 stored in packages of the largest possible size consistent with 

 convenient handling. The larger the cubic content of the pack- 

 age, the smaller, relatively, is its surface and the smaller is, 

 therefore, the area of butter which is exposed to the air. For 

 this reason the firkin used in Europe, the 63 pound tub which 

 predominates in the central and eastern United States and the 

 56 to 68 pound cube used in the Pacific Coast states, furnish 

 more suitable forms of packages, than smaller packages such 

 as one, two, or five pound prints, slabs or rolls. The firkins, 

 tubs and cubes should be properly paraffined and lined with 

 heavy, brine-soaked parchment paper, so as to furnish as nearly 

 herrnetical a seal as possible. These same conditions, large 

 size and imperviousness of package to air, also protect the 

 butter against light. In full containers butter keeps better 

 than in containers only partly filled. This was experimentally 

 demonstrated by Gray and McKay, 1 who stored butter in cans 

 and in tubs completely filled and similar containers only partly 

 full. At 10 degrees F. to +10 degrees F. there was practically 

 no difference in the keeping quality of butter packed in full cans 

 and full tubs, but at 32 degrees F. there was a slight difference 

 in favor of the cans. 



Humidity of Storage Rooms. Aside from the oxidizing 

 effect of air, light and heat on the constituents of butter, the 

 deterioration of butter in storage results from the decomposition 

 or cleavage of the non-fatty constituents, especially the proteins 



1 Gray and McKay, Investigations in the Manufacture and Storage of 

 Putter, U. S. Dept. of Agriculture, B. A. I. Bulletin 84, 1906. 



