Changes in the Diacetyl and the Acetylmethylcarbinol Contents during the Manufacture of Butter

Abstract

Summary Marked changes in diacetyl content, both decreases and increases, were noted during the neutralization and pasteurization of sour cream. The changes in the acetylmethylcarbinol content were relatively small. Progressive increases in diacetyl were found after mixing regular butter culture with pasteurized cream (either sweet or sour), after holding the mixture at a low temperature over night, and after the mixture had been partly churned. The acetylmethylcarbinol content increased somewhat during the holding period. The results when aerated or modified aerated butter culture was added to sweet cream were similar to those when regular culture was employed, except that no increases in diacetyl were noted immediately after mixing, and the subsequent increases, while quite significant in actual amounts, were small on a percentage basis because of the relatively large amounts of diacetyl already supplied by these cultures. It was not possible to note a close relationship between the diacetyl contents of the butter cultures added to the cream and those of the resulting butter. Aerated or modified aerated cultures, as compared with equal percentages of regular cultures, yielded butter having higher diacetyl contents, but these values were really much lower than they would have been if a proportionality existed between the diacetyl contents of the cultures and the butter. On the average, 8.8 per cent of the diacetyl and 4.5 per cent of the acetylmethylcarbinol plus diacetyl in the churning mixture were retained in the butter.