Jan. 15, 1915 Moldiness in Butter 309 



If, as in butter, the fluid present is a strong brine, the temperature must be 

 actually carried considerably below the freezing point of water to elimi- 

 nate danger from the growth of micro-organisms. Temperatures a few 

 degrees above freezing accompanied, as they frequently are, by moist con- 

 ditions are favorable to molding in butter. Unsalted butter is more sub- 

 ject to deterioration from micro-organisms than salted butter. Success- 

 ful storage of such butter is therefore even more dependent upon scrupu- 

 lously clean dry refrigeration at low temperatures than is the case with 

 salted butter. Cellars and ice refrigeration rarely furnish conditions 

 which will prevent mold growth in unsalted or low-salted butter, although 

 such growth may be delayed or reduced. Butter properly made and 

 salted normally, as indicated above, will not show mold under reasonably 

 careful handUng. 



SUMMARY 



(1) Mold in butter usually takes three forms: 



a. Orange-yellow areas with a submerged growth of mycelium are 

 produced by Oidiuni lactis. 



h. Smudged or dirty-green areas either entirely submerged or with 

 some surface growth are produced by species of Alternaria and Clado- 

 sporium. 



c. Green surface colonies arc produced by species of Penicillium, or, 

 more rarely, Aspergillus, either upon the butter, causing decomposition, 

 or upon the container or wrappings, injuring the appearance of the sample 

 in the market. 



(2) Species of Oidium, Alternaria, and Cladosporium can not develop 

 in butter containing 2.5 per cent of salt. The occurrence of any of these 

 forms in a sample of butter indicates low salting. 



(3) Excess of curd favors mold growth. Well-washed butter is less 

 subject to mold. 



(4) lycaky butter — butter from which water of buttermilk exudes and 

 collects in the wrappings or in the container — ^furnishes the best condi- 

 tions for the beginning of mold growth. From these wet areas colonies 

 may spread to the butter itself. 



(5) Wet surfaces, wet wrappings, or high humidity are essential to 

 mold growth in butter. Mold will not grow upon the surface of a piece 

 of butter exposed to humidities of 70 per cent or lower. The water in the 

 butter is thus not sufficiently available to the mold to support the de- 

 velopment of a colony, unless evaporation is reduced by high humidities. 

 In closed packages, wet or damp cellars, or carelessly packed masses with 

 cracks or fissures in which moisture collects, mold may seriously injure 

 the appearance of butter packages or actually induce great changes in 

 the butter itself. 



(6) Salt up to 2.5 to 3 per cent in butter is sufficient to eliminate mold 

 or reduce it to negligible amount. This is equivalent to the use of a 12 

 to 1 5 per cent brine. 



