COMPOSITION AND PROPERTIES OF BUTTER 549 



The lactose content of butter decreases slightly in storage, 

 partly because of the probable conversion of small portions of 

 the lactose, through bacterial, or through chemical action, into 

 lactic acid, glycolic acid and other acids, and partly due to loss 

 of water or brine by leakage. 



The lactose is one of the unstable and readily fermentable 

 constituents of butter, it rapidly yields to bacterial action, split- 

 ting up into simpler compounds, of which lactic acid is a very 

 prominent one, but not necessarily the only one. 



Under certain conditions lactose also readily yields to 

 chemical decomposition detrimental to the market value of the 

 butter. Being itself a powerful reducing agent, it invites and 

 accelerates oxidation in butter, especially in a weakly alkaline 

 condition. In butter made from over-neutralized cream, the 

 lactose may give rise to most disastrous butter defects, such as 

 bleached and tallowy butter, as demonstrated by Hunziker and 

 Hosman. 1 



In butter with a decided acid reaction, on the other hand, 

 lactose appears to have no deteriorating action, on the contrary, 

 it tends to exert a slight, but distinct preservative influence. It 

 is for this reason that some butter manufacturers purposely add 

 lactose to their butter. 



The Acid. Fresh butter contains from about .1 to .35 per 

 cent acid, presumably largely, but generally not exclusively, 

 lactic acid. In a similar manner, as in the case of curd and ash 

 of butter, the acid is derived from the cream o'f which it is a 

 natural constituent. Therefore, sweet cream butter contains less 

 acid than ripened-cream butter, and butter made from sour 

 cream that has been neutralized contains less acid than butter 

 from unneutralized sour cream. Butter made from pasteurized 

 cream contains less acid than butter made from raw cream. 

 This is especially the case with the flash process, or high tem- 

 perature pasteurization, as shown by Hunziker, Spitzer and 

 Mills 2 in Table 77. 



The decrease of the acidity of butter, due to pasteurization 

 of the cream is in all probability due to the presence, in the raw 



1 Hunziker & Hosman Tallowy Butter, Blue Valley Research Laboratory, 

 also Journal of Dairy Science, Vol. I, No. 4, 1917. 



2 Hunziker, Spitzer and Mills Pasteurization of Sour, Farm-Skimmed 

 Cream for Butter Making. Purdue Bulletin 203, 1917. 



