Thesis - Open Access
Master of Science (MS)
Dairy scientists have known for a number of years that diacetyl is one of the principle flavor components of butter, buttermilk, and cheese cultures. Of the tests which have been introduced to determine diacetyl, one of the first was the heavy metal gravimetric method. This procedure involved distillation of the diacetyl from the mother substance. The most common derivative formed was nickel dimethylglyoximate. Principle disadvantage of this method were that large amounts of sample were required for steam distillation when the products were low in diacetyl. It was also a time consuming procedure because the steam distillation could take as long as 1 hr followed by a 24 hr period for the dimethylgiyoxime derivation to precipitate. It has been known for a number of years that the speed and accuracy of colorimetric determinations were far superior to the gravimetric method. All attempts to perfect a reliable colorimetric test had failed until Prill and Hammer (21) introduced their method in 1938. Other procedures have been introduced since that time, however none has been used as extensively. Some of the tests introduced were direct methods of estimation. These methods usually deleted the steam distillation and color was developed from the original sample. It was necessary to filter the sample to obtain a color complex relatively free from impurities. It has been common knowledge that a direct analysis would shorten the time that war inherent in the steam distillation methods. Anantharamaiah et al. (1) used the modified Voges-Proskauer reaction to estimate diacetyl quantitatively. They attained some degree of success with this direct method. It was the purpose of the research reported herein to ascertain if the modified Voges-Proskauer method introduced by them was capable of yielding reproducible result, or if certain modifications are necessary.
Library of Congress Subject Headings
Includes bibliographical references (pages 42-44)
Number of Pages
South Dakota State University
Finkenbiner, Dwain, "A Modified Voges-Proskauer Method of Determining Diacetyl in Dairy Cultures" (1965). Theses and Dissertations. 1257.