96 



The atmosphere plays only a direct part in the rancidity of 

 butter when sunlight or an elevated temperature co-operate at 

 the same time. The butter becomes oxidised and this leads to 

 a disagreeable taste and odour but the butter does not become 

 rancid. 



Butter only becomes rancid through the action of certain 

 micro-organisms. As it is necessary for the organisms to have 

 air for their development, the process sets in at the surface of 

 the butter when in contact with air, and afterwards affects 

 the remainder. 



Jensen considers the presence of Cladosporiiim butyri the 

 principal factor which causes rancidity. This is a mould which 

 gives rise to the highest degree of rancidity, and especially so 

 when in co-operation with a few other organisms e. g. Oidium 

 lactis. Cladosporium butyri splits butterfat, thereby producing 

 volatile fatty acids and certain esters which latter are the chief 

 characteristics in rancidity. 



Jensen further points out the danger of infection of butter 

 through impure water and through germs in the atmosphere. 

 He recommends a few means which may prevent rancidity. 



As to the preserving of butter and margarine the researches 

 of Fischer and GruenERT i) are of importance. They made 

 a special study of the preservative influence of some substances 

 (benzoic acid, hydrin, salicylic acid, boric acid) — in comparison 

 to salt — on butter and margarine and recorded the chemical 

 changes peculiar to rancidity. Though their researches are very 

 important we cannot agree with their inference that rancidity 

 cannot be prevented by the addition of preservatives other than 

 salt. In fact we have come to the very opposite conclusion. 



Though Jensen had defined the cause of the rancidity of 

 genuine butter, that of vegetable margarine was until recently 

 unsolved. Consequently no one had succeeded in preventing 

 large quantities of margarine from going bad in summertime. 



As to the constancy of cocoa nut oil and palm kernel oil in 

 relation to the various influences which may play a part in 



1) FrscHER, K. und Gruenert O. Ueber den Einfluss einiger Konservierungs- 

 mittel auf Haltbarkeit und Zusammensetzung von Butter und Margarine. Zeitschr. 

 f. d. Unters, d. Nähr. u. Genussmittel Bd. XXII, 191 1, S. 553. 



