Agricultural and Biological Chemistry 



A New Fluorometric Determination of Thiamine. 



The reaction between cyanogen bromide and thiamine is the basis for 

 a new, simple, and rapid fluorometric determination of this vitamin. The 

 method has a relatively high degree of sensitivity and specificity, and results 

 compare favorably with the microbiological assay. 



A. E. Teeri, D. Josselyn 



Starch Hydrolysis in Winter Squash. 



A highly active phosphorylase in the fiber of the fruit of Blue Hubbard 

 squash has been obtained in a solution free from other enzymes affecting 

 starch. This enzyme forms and breaks down the straight chain type of starch 

 molecule (amylosel. 



A branching enzyme, which forms the amylopectin type of starch, has 

 been separated from the phosphorylase. It has not been possible to free this 

 enzyme entirely from the small amount of amylose which is also present. 



T. G. Phillips 



Factors Influencing the Vitamin C Value for Strawberries and Tomatoes. 



Studies upon certain components of strawberries and tomatoes indicate 

 it is inadvisable to place too much reliance upon published values for the 

 vitamin C ( ascorbic acid ) content of these foods. Some sugars and naturally 

 occuring organic acids interfere with the method commonly used for de- 

 termining this vitamin ( reaction of ascorbic acid with 2,6-dichlorophenol- 

 indophenol I . It is probable that to date, no true ascorbic acid values are 

 found in literature for fruits and vegetables containing considerable sugar 

 or dicarboxylic acids. Fresh strawberries contain large amounts of both of 

 these groups of compounds. Their apparent vitamin C value, as determined 

 by the dye reaction method, can be affected by variations in content of these 

 components. When these berries are preserved by freezing, either with or 

 without addition of sugar, changes in composition of the constituents other 

 than ascorbic acid occur during the freezing and holding periods, again re- 

 sulting in changes of apparent vitamin C content as determined by the afore- 

 mentioned method. 



Also, no true values are available for foods containing an enzyme system 

 capable of destroying ascorbic acid. The existence of such an enzyme system 

 has been known for some time, but its actual occurrence has not been shown 

 in very many common foods. Because of some side studies in connection with 

 this project, we are reasonably sure such an enzyme can exist in certain 

 tomatoes — a food commonly relied upon for furnishing nutritional needs 

 for ascorbic acid. 



It seems apparent that much work must yet be done to rectify ascorbic 

 acid values for foods in which either the enzyme system is present, or sugars 

 and organic acids make up a considerable portion of the total composition, 

 before the nutritive value of these foods can actually be stated. 



H. P. Shimer, S. R. Shimer 



