=Other abnormal flavors.= Among the numerous abnormal flavors that have been noted in butter is one of quite frequent appearance, the so called "fishy" flavor. It is now believed by many that this flavor is due to the presence of small amounts of iron or copper salts that have been introduced into the milk from utensils from which the protective coating of tin has been worn. If the milk or cream stored in such utensils develops any marked degree of acidity, the acid will dissolve a small amount of the iron or copper. The fishy flavor has not been found in sweet-cream butter as would be expected from the above explanation. In fresh butter a metallic taste is sometimes present. It is believed by some that on storage this flavor changes to the fishy flavor. All utensils used for the storage of milk and cream should be kept in good condition so as to prevent the acid milk or cream from coming in contact with iron or copper. [Illustration: Fig. 33.--Moldy Butter. The mold grows on the paper in which the butter is wrapped rather than on the butter. The print on the left was wrapped in the same paper as the print on the right except that the parchment cover had been steamed for a few moments.] =Moldy butter.= A defect that causes a great amount of loss is the development of mold on the surface of the butter, either in tubs or in prints. This trouble is easily prevented. Butter is not well suited to the growth of mold, but the paper used for lining the tubs, or wrapping the prints is an excellent medium for mold growth. The wood of the tub also furnishes ample food for this type of life, especially where the wood contains any sap. One other essential condition for mold growth is a supply of oxygen. The mold spores are widely disseminated, and are always to be found on the butter tubs and on the paper. The number is not likely to be sufficient to cause trouble unless the tubs and paper have been kept under such conditions, as to allow growth to take place on them before use. During damp, hot weather, the amount of moisture absorbed by these materials is often sufficient to allow molds to grow on them. This trouble can be prevented by the storage of tubs and paper in a clean dry place, or by a disinfecting treatment which will destroy the mold spores. The most successful method of treatment of tubs is to apply paraffin to the inner surface, which can be easily done by the use of some one of the various machines now on the market. The thin layer of paraffin excludes the moisture from the wood, and also prevents the mold from obtaining a supply of oxygen for its growth. The tubs may be steamed, treated with hot water, or filled with a dilute solution of formaldehyde, and allowed to stand overnight. Soaking in brine as is usually done in the creameries is of some effect, but will not completely kill mold spores. [Illustration: Fig. 34.--Moldy Butter.