A new colorimetric method of analysis for acrolein has the advantages over previous methods of a spectrally purer color with e maximum in the absorption curve, a colorless blank, and greater specificity. The method is based on the color produced by the condensation of acrolein with tryptophane Induced by concentrated hydrochloric acid, and is capable of detecting quantitatively as little as 15 micrograms of acrolein. The method is suitable for quantitative work only in the absence of other aldehydes, unless their concentration is relatively much less than that of the acrolein.
Quantitative cultural data on bacterial contamination in a distillery are difficult to obtain because ordinary methods will not distinguish between yeast and bacteria. Direct counts are unreliable because of the large number of grain particles which are difficult to distinguish from bacteria. This investigation was begun, therefore, in order to find a reliable cultural method for counting bacteria in distillery mashes. A procedure which seemed worthy of investigation was the "tube count" method which has been used for many years by the Bureau of Dairy Industry of the United States Department of Agriculture in counting lactate-fermenting bacteria in Swiss cheese. Dr. W. C. Frazier of the University of Wisconsin suggested that the method had possibilities in routine work, and under his direction it was used extensively in research work on brick cheese (Garey et al., 1941). METHODS Of several special culture media tried, the following medium was found to give satisfactory results:
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.