482 F.XPKHTMKNT STATION RECORD. 



ill oilier (•■•iscs the <;iusc of niiicidit.v was not known. " Sinfo in flio doooiuposi- 

 tion of fat all llic diflcn'nt ^Jyccrids aiv usually altackod in the sanio way, 

 and since less llian Hi per (.-cnt of the fatty acids of Iniltcr have any taste at 

 ail. it seems iui|trol»able that tbo rise of acidity of o.lT. wliicli is the hi>;hest 

 increase noticed in the 12 good samples, could cause a rancid taste." As there 

 were so few fat-siilitting bacteria "the question arises whether there is aijy 

 other pt)ssible way of decomposing fat without the iirodnction of free acids, or 

 ivlielher the off flavor is mostly due to cleava^'e jiroducts of other substances 

 in butter, especially of i)roteln which certainly could j^ive rise to strouf^ly tast- 

 ing and smelling compounds." 



Pure cultures of many of the organisms found wi're incubated in a cold 

 storage I'oom at a temperature of 4 to 5° C. A lai'ge number of them were 

 found to bo capable not only of remaining alive, but also of growth and develop- 

 ment at a comparatively low temperature, when jirovided with a suitable nutri- 

 ent pabulum and protected fi'ouj inhibitive substances. 



A bililiography of the literatuiv on the subject is appended. 



Keeping qualities of butter. II, The influence of salt. Ill, The decom- 

 position of proteins, <). Ji.viiN, ('. \V. I>i:own, and L. M. Smith {Midi if/an Sta. 

 Ti eh. liiil. 2, J)]), o-'i'h figs. 6). — A continuation of the work noted above. 



The specific problems studied were the influence of salt upon microbial life 

 and the changes wrought upon the proteins by micro-organisms. For this work 

 there was obtained from a single churning four 30-lb. tubs, 2 with salt and 2 

 without salt, from each of o different creameries. One of the salted and one 

 of the luisalted samples from each lot were placed in the laboratory storage 

 at +4 to -+-10° C, and the other two in a Lansing cold storage, which main- 

 tained a tempei'ature of — 4 to — 6°. Samples of both the unsalted and salted 

 butter were also taken from the churn from which the first bacteriological and 

 chemical analyses were made. The butter was scoi-ed at three different times, 

 the relative scores showing that there was no hope of keeping unsalted Imtter 

 for a longer time than salted butter. 



The methods for making the chemical determinations are given in detail. 

 In all samples the percentages of salt and moisture decreased, and after about 

 ,S months of storage there was considerable difference between the fresh and 

 the old samples. The average loss of moisture was in the 3 salted warm sam- 

 ples 3.67 per cent, in tlie unsalted warm samples 1.60 per cent, in the salted 

 cold samples 2.73 per cent, and in the unsalted cold samples 0.99 per cent. The 

 brine concentration was nearly constant, proving that the loss of moisture was 

 due almost entirely to leakage, hence it is concluded that in comparing water- 

 soluble compounds with butter more accurate results are obtained by recording 

 them not in percentages of butter but in percentages of the moisture. This 

 method of interpretation was used in the discussion of the soluble nitrogen, 

 which allowed however for soluble substances only. 



All samples without salt stored at +6° showed a very high increase in acid- 

 ity, but notwithstanding this, the comparative scores of the salted samples 

 at +6° are higher than those of the unsalted at — 6°, Inasmuch as 2 out of 

 6 samples stored at —0° remained for 8 months without an increase in acidity 

 and as they deteriorated in scores from 93 and 90 to 82 and 79, respectively, 

 an increase of acidity is not necessarily coincident with the spoiling of butter. 

 The soluble acids obtained from the washing of the butters constituted about 

 one-tenth of the total acidity and ran almost parallel with it. 



There was very little loss of lactose during storage, and apparently little or 

 no relation between the water-soluble acids and the amount of lactose lost. 

 So much lactose, esjjecially in the unsalted warm samples which had an abun- 

 dant growth of molds, was not expected. "There is, of course, .i possibility 



