sept. ii. 1916 Progressive Oxidation of Cold-Storage Butter .935 



means of the specially devised apparatus, and the quantities of carbon 

 dioxid and oxygen determined. 



A perusal of Table I discloses the fact that very little alteration occurred 

 in the composition of the air inclosed in this sample of sweet-cream butter 

 made from cream having an acidity of 0.1 1 per cent when it was kept for 

 about 6 months at a temperature of o° F. During this interval practically 

 no diminution of the original oxygen content took place, and the only 

 apparent change to be noted is a probable decrease in the small quantity 

 of carbon dioxid which was known to be present in the butter at the time 

 it was made. An appreciable and progressive change did occur, however, 

 when the butter was kept for nearly two months at a temperature of 32 

 F. In this case it will be noted that the original oxygen content de- 

 creased, while there was a corresponding increase in the initial quantity 

 of carbon dioxid. 



Every effort was made to keep the tubes containing this sample, as 

 well as those containing the other differently prepared samples, under 

 comparable conditions. In this connection it may be mentioned that, 

 since it is necessary to surround the tubes with warm water (45 C.) to 

 melt the butter sufficiently to cause it to flow through the apparatus 

 used and that this procedure if carried out immediately upon the removal 

 of the tubes from storage might result in cracking them, the plan was 

 adopted of allowing them to warm up slightly at room temperature for 

 one hour, except in two cases, in which the tubes were intentionally per- 

 mitted to remain a longer period at room temperature for the purpose of 

 obtaining additional information. It was found that a tube of this 

 butter, when allowed to remain for 5 hours at room temperature after a 

 storage period of no days at a temperature of o° F., contained less 

 oxygen than a corresponding tube of the same sample kept for the same 

 length of time at a temperature of o° F., and for 1 day at a temperature 

 of 32 ° F. In measuring the effect of raising the storage temperature to 

 32 ° F. on a sample which had been stored at o° F. for 81 days, it is of 

 interest to note that after holding for 1 day at the higher temperature 

 there is a measurable decrease in the quantity of oxygen known to be 

 present in the sample after the 81 days at the lower temperature, and 

 this effect on the same sample is much more pronounced after holding at 

 the higher temperature for an additional 12 days, or a total of 13 days. 



It may be concluded, therefore, that sweet-cream butter prepared as 

 this sample was and containing a considerable number of bacteria will 

 show but little alteration in the composition of the air inclosed in it 

 when it is kept for six months at a temperature of o° F. A perceptible 

 change, however, occurs when the butter is kept at a temperature of 32 

 F., and a very noticeable one when it is kept at room temperature. The 

 sample of butter used scored 92 when made and 91 at the end of three 

 months. After a period of six months in storage at a temperature of o° 

 F. the score was given at 90, there being no trace of any undesirable flavor. 



