3i8 



Summary of Agricultural Experiments. 



[JULY, 



appears year after year, although many of them use the most approved 

 machinery and methods, and are managed by competent butter makers. 



Fishy flavour may develop in butter within a week or ten days after 

 making, or it may not appear until the butter has been several months 

 in storage. In the warm summer months butter is frequently fishy 

 when it reaches the commission merchant. The condition may occur in 

 one shipment only or in a few tubs in a shipment, but it is not 

 uncommon for the trouble to persist in a creamery for days or even 

 weeks. Where this happens it is almost always during or following 

 warm weather, and it is generally believed that fishy flavour is most 

 common in hot, rainy seasons. 



The most serious loss is caused in the case of butter held in cold 

 Storage, and although low temperatures retard the development of fishy 

 flavour they do not prevent it. It was found that at 32 0 F. there is little 

 retarding influence, but at io° F. its appearance is perceptibly delayed. 

 At io° below zero the retardation is very marked, but even at this 

 extremely low temperature butter may become fishy. 



In the course of his experiments Mr. L. A. Rogers has been unable 

 to confirm the results of Mr. O'Callaghan's investigations, as inocula- 

 tions with O'idium lactis did not produce any flavour resembling 

 fishiness. Many lots of fishy butter have been made in which this 

 fungus was known not to occur, either in the butter or in the cream 

 from which the butter was made. Mr. Rogers concludes that though 

 O'idium lactis may be the cause of what is known as " fishy flavour "in 

 Australian butter, and may even occasionally cause the flavour in 

 American butter, it is certainly not the common cause in that country. 



Experiment showed that fishy flavour in butter is not actually caused 

 by anything of a basic or of an acid nature, but the results suggested an 

 aldehyde which could be produced in a great variety of decompositions 

 and by many kinds of bacteria. The results obtained also seemed to 

 exclude the possibility of any direct connection between the food of the 

 cows and the presence of fishy flavour in the butter, while it was not 

 found possible to produce fishiness in butter when made under winter 

 conditions. Bacteriological examinations made it evident that there 

 were no unusual varieties of bacteria connected with the production of 

 the bad flavour; but an analysis of all the inoculated butter which 

 developed fishy flavour showed that this flavour always occurred in 

 butter made with an active iactic-acid organism or in wriich a high 

 degree of acidity had been developed with ordinary lactic-acid bacteria. 



In all the experimental butter made in the last three years there has 

 been no trace of fishy flavour in that made from pasteurised sweet 

 cream churned without the addition of a starter; and, on the other 

 hand, fishy flavour was produced with reasonable certainty by over- 

 working the butter made from sour cream. 



In conclusion, Mr. Rogers expresses the opinion that fishy flavour is 

 caused by a slow, spontaneous chemical change to which acid is 

 essential, and which is favoured by the presence of small amounts of 

 oxygen. The flavour, he states, may be prevented with certainty by 

 making butter from pasteurised sweet cream; and butter made from 

 such cream with a starter, but without ripening, seldom if ever becomes 

 fishy. 



In Denmark the trouble is less prevalent than formerly, and this has 



