474 BUTTER 



Unsalted butter is much more prone to become moldy than 

 salted butter, the salt exerting a considerable retarding, if not in- 

 hibiting, effect on mold growth. In fact, it is frequently very 

 difficult to prevent unsalted butter from showing moldiness, in 

 spite of the' observance of otherwise successful and effective 

 precautions. 



There are numerous classes and species of molds that are capa- 

 ble of developing mold spots on butter, such as Penicilium, Tri- 

 chosporium, Streptothrix, Cladosporium oidium. Griepenberg 1 

 who examined storage butter, found that most of the molds in 

 butter belonged to the genera Penicilium and Trichosporium and 

 that of these, Penicilium cruslaceum and Trichosporium collae 

 were the most common species. Penicilium glaucum and oidium 

 lactis are also known to be very common molds of butter. 

 Most of these organisms thrive on the caseous matter of the 

 butter and some are also capable of splitting the butterfat. 



According to Thorn and Shaw, 2 mold in butter usually takes 

 three forms : 



"1. Orange-yellow (red) areas with a submerged growth of 

 mycelium, which are produced by Oidium lactis. Cannot develop 

 in butter containing 2.5% of salt. 



2. Smudged or dirty-green areas, either entirely submerged 

 or with some surface growth. These are produced by species 

 Alternaria and Cladosporium. Cannot develop in butter con- 

 taining 2.5% salt. 



3. Green surface colonies, which are produced by Penicilium, 

 or more rarely, Aspergillus, either upon the butter, causing de- 

 composition, or upon the container or wrapping, injuring the 

 appearance of the sample in the market." 



The natural channels through which butter becomes contam- 

 inated are infection of milk and cream on the farm, and con- 

 tamination of cream or butter in the factory, from the air in ill- 

 ventilated plants, from unclean vats, pipes, churns and packing 

 equipment, from impure starters and impure washwater, and 

 from mold-infected material used for packing, such as parchment 

 wrappers and liners, and butter tubs and boxes. 



1 Griepenberg 1 , Fleischmann, Lehrbuch der Milchwirtschaft, p. 324, 1915. 



2 Thorn and Shaw. Moldiness in Butter. Jour. Agr. Research. Vol. Ill, 

 No. 4, 1915. 



