EXPERIMENT STATION BULLETINS. 421 



CONCLUSIONS. 



It was not intended in these investigations to reach final conclusions but 

 only to define the different problems that are furnished by the cold storage 

 of butter, in order to examine some of these later. 



From our preliminary results we may outline the cold storage problems 

 as follow: 



CREAMERY PROBLEMS. 



The creamery problems indicated in the cold storage of butter are the 

 improving of the quality of cream, the advisability of pasteurization, the 

 use of ripened or sweet cream, and the salting and packing. Most of these 

 problems have been taken up by one or more of the experiment stations, 

 but since these results depend so much upon the conditions of churning, and 

 still more upon the care taken in the whole process, the results of one series 

 of experiments do not allow of final conclusions. 



From our own work we cannot add very much to the creamery problems, 

 for our samples were made without relation to each other and differ in so 

 many points that no conclusions can be drawn in regard to a single point. 

 We simply make the statement that butter can be kept for 9-12 months in 

 cold storage and still be ui?ed as table butter, but that most of our samples 

 lost very much in value. This loss must have been due to dairy or creamery 

 conditions. 



SCIENTIFIC PROBLEMS. 



The chief problem is to cUscover what compounds cause an off flavor and 

 how they are produced in butter. When this is known, we can consider how 

 to avoid the off flavor. 



The extensively described experiments show that only a few of the cold 

 storage samples have an increased acidity, while most of them did not change 

 in acidity at all, or only very slightly; whereas, all samples kept above the 

 freezing point, and all samples of other authors kept at ordinary temperature 

 showed a very pronounced increase of free acids. 



Since in the decomposition of fat, all the different glycerides are usually 

 attacked in the same way, and since less than 10% of the fatty acids of butter 

 have any taste at all, it seems improbable that the rise of acidity of .3°, 

 which is the highest increase noticed in the 12 good samples, could cause a 

 rancid taste. 



We found only very few fat-splitting bacteria in fresh butter and none in old 

 butter. The question arises whether there is any other possible way of de- 

 composing fat without the production of free acids, or whether the oflf flavor 

 is mostly due to cleaveage products of other substances in butter, especially of 

 protein'which certainly could give rise to strongly tasting and smelling com- 

 pounds. It may be recalled that the decrease of hquefying bacteria did not keep 

 step with fhe decrease of lactic acid bacteria, and that after six months of 

 decrease, we found a distinct increase. If the decomposition of proteids 

 is the cause of the spoiling of cold storage butter the amount of proteids should 

 be decreased as much as possible, and the addition of starter to the churned 

 butter would be the worst thing to improve its quality. 



When the products of decomposition in butter are found, the next step 



