1916] DAIEY FARMING DAIRYING. 277 



flavor is a member or a strain of the Bacterium lactis acidi group. Metallic 

 flavor may develop in cream of eitlier good or poor flavor, and the indications 

 are that enzyms may be a factor in its production. 



It was found that high acid content is essential for the development of the 

 flavor. It is possible that electrolytic action plays an important part in its 

 production when the source is directly from metal. The flavor was most liliely 

 to appear during the hottest season. It may be that this was noticeable because 

 the degree of acidity of the product Is likely to be greater when the temperature 

 is high. 



A high fat content seemed necessary for the development of the flavor except 

 in the case of buttermilk. Whenever the flavor was found in whole milk it was 

 always near the surface, in the cream, and it was never observed in skim milk 

 or cottage cheese. For some reason it was often found in buttermilk, but with 

 this exception never in a dairy product low in fat content. 



It is deemed difficult to explain why metallic flavor develops to a greater 

 degree in buttermilk than in any other dairy product. It was thought that 

 there might be a relation between the acids of the milk fat and the metallic 

 flavor. Samples of butyric, caproic, caprylic, palmitic, stearic, and oleic acids 

 were obtained, also propionic acid, which is lower in the fatty acid series, and 

 succinic acid, which is a dibasic organic acid and may be found in dairy prod- 

 ucts. No sign of metallic flavor, however, could be detected in any of these 

 acids. 



The flavor appeared spasmodically. Often it could not be detected in bdtter 

 for several weeks, and sometimes for many months, after which it suddenly 

 appeared for perhaps a few days or possibly for several weeks. During all 

 this time the same utensils were being used on the farms and in the creamery 

 laboratories. Low temperatures often seemed to make the flavor more ap- 

 parent. 



Note on the neutralization of cream in butter manufacture, and the effect 

 on the butter produced, A. A. Ramsay (Dept. Agr. N. S. Wales, Sci. Bui. 16 

 {1915), pp. 10). — A method of treating cream before manufacturing it into 

 butter, known as " neutralizing and pasteurizing," is described. The term 

 neutralizing, in conjunction with pasteurizing in the method of treating creams 

 for the manufacture of butter, is used to indicate the reducing of the acidity, 

 probably the excessive acidity, of the cream, not to the neutral point but to 

 faint or slight acidity, say, to 0.2 per cent of acid expressed as lactic acid. 



Sodium bicarbonate or, as an alternative, washing soda (crystallized sodium 

 carbonate) is generally used on account of its cheapness and because the 

 supply is plentiful. The result of the neutralization or partial neutralization 

 is the formation of the sodium salt of the organic acids and the liberation of 

 carbon dioxid. The carbon dioxid so formed is impeded in its passage through 

 the cold mass of cream on account of the viscosity of the latter. This viscosity 

 is lessened when the cream is heated to 170° F., as in pasteurizing, and the 

 gas then escapes into the air. As it rises through the mass of cream it is 

 claimed that it carries with it mechanically the volatile substances which 

 give the cream an unpleasant smell or taste, as, for example, " food taint," and 

 the heating to 170° assists in the removal of the gas and in the destruction of 

 the micro-organisms present. The result is a product from which unpleasant 

 odors and taints have been removed, and one which, if not absolutely sterile, 

 is very nearly so. Into this mixture the pure culture of lactic bacilli, or 

 " starter," is added, thus making an abundant growth of the lartic bacilli and 

 producing good, clean lactic acid. The carbonates which may be used for the 



