Date of Award
Master of Science
J.T. Miles, Melvin R. Johnston
The development of off flavors plays a very important part in the acceptance of dairy products by the consumer. The term "flavor" denotes a blend of complex chemical compounds. These chemical compounds are sometimes volatile under various processing procedures and on storage of product after it has been removed from its native state. It is the job of the research worker dealing with the flavor compounds to elucidate their exact chemical nature and to quantitatively express their approximate concentrations in various products. Also, the exact influence of processing techniques on the release of the volatile compounds must be determined so that steps can be taken to alter the release of the volatiles from the products as they are processed or stored.
Flavor research on volatile compounds has been hampered in the past by the inadequacy of available analytical procedures, instrumentation is opening the way to investigations which will unlock the causes of certain flavor developments and provide a sound basis Now modern for control.
Modern methods of processing sometimes contribute to a large extent to the development of undesirable flavor components. Perhaps in no industry is this more pronounced than in the processing of milk and milk products. Of great importance is the cooked flavor of milk which results when milk is heated to high temperatures. Some research workers believe that the cooked flavor occurs chiefly in the beta-lactoglobulin fraction of the serum proteins. Upon the denaturation by heat this protein fraction is believed to be altered by the changing of cystine to cysteine which releases a free sulfhydryl group which is thought to be the chief constituent of the cooked flavor.
Research by Gould (20) and by Jackson (33) has shown, however, that the amino acids themselves can be denatured with the release of sulfhydryls. Four constituents in milk containing sulfur in their molecular structure are the amino acids, cystine, cysteine, methionine, and Vitamin B1 (thiamine). Specific experiments dealing with the volatility of sulfur from these com- pounds in milk has not been found in the literature, Therefore, the present work was undertaken to study the volatility of sulfur from these compounds at the "critical' or threshold temperature and slightly above this temperature. The influence of various processing temperatures of milk in a dairy plant operation on the destruction of Vitamin B| has also been investigated in this study.
Gibbs, Andrew Wesley, "A study of origins of volatile sulfhydryls in milk. " Master's Thesis, University of Tennessee, 1964.