ANNUAL REPORT, 1943-44 25 



into inorganic, organic, resistant esters, phytin, phospholipid and phosphoprotein 

 phosphorus. The results indicate that the bulk of the phosphorus is in the in- 

 organic form; that the organic fraction may be composed of widely varying 

 amounts of resistant esters, and phosphoproteins and phospholipids; and that 

 phytin was absent in all cases. Therefore, there are no unavailable forms of 

 phosphorus in these vegetables. 



The Chemical Investigations of Hemicelluloses. (Emmett Bennett.) The 

 numerical values of the soluble sugars, pectic compounds, and hemicelluloses are 

 usually not given as such but are included in the nitrogen-free extract value. 

 Data obtained from 14 common vegetables indicate that the percentage content 

 of soluble sugars may range from 4 to 51 percent of the dry matter or about 12 to 

 66 percent of the nitrogen-free extract. Pectic materials and hemicelluloses col- 

 lectively may constitute from 5 to 19 percent of the dry matter or from 11 to 52 

 percent of the nitrogen-free extract. These data indicate that the amount of 

 soluble sugars, pectic compounds, and hemicelluloses varies with the species, 

 and that the numerical value of the nitrogen-free extract gives little information 

 regarding the relative amounts of these fractions. 



Hemicelluloses from corn cobs and rye straw have been isolated and purified 

 for work designed to indicate the chemical nature of these substances. 



Factors Affecting the Riboflavin Content of Milk. (Arthur D. Holmes.) Al- 

 though it is generally accepted that milk is one of the rich natural sources of 

 riboflavin, and many investigators have reported studies on the subject, there 

 are still many phases about which knowledge is incomplete or lacking. These 

 studies were made for the purpose of filling some of these gaps. The milk used 

 was produced by the college herd of Ayrshire, Guernsey, Holstein, Jersey, and 

 Shorthorn cows. The large number involved would eliminate any influence of 

 individual characteristics of the cows. Since farm herds in this locality are made 

 up of more than one breed of cows, and since the management and feeding of 

 the cows were similar to those of modern, local dairy farms, the results should 

 be applicable to commercially produced milk, in this region at least. 



The Effect of Pasteurization on Riboflavin Content. (Arthur D. Holmes.) 

 Winter milk (December and January) was assayed before and after pasteuriza- 

 tion. The raw milk contained an average of 1.46 mg. of riboflavin per liter; after 

 pasteurization, the milk contained 1.43 mg. per liter. Accordingly, the con- 

 sumer can be assured that, from a practical dietetic standpoint, he will obtain 

 essentially as much riboflavin from milk recently pasteurized (under the con- 

 ditions of this study) as he would obtain from the same milk just before pasteur- 

 ization. 



The Uniformity of the Riboflavin Conte?tt of Milk Produced under Standardized 

 Conditions. (Arthur D. Holmes and Julia O. Holmes.) The riboflavin content 

 of milk, as reported in the literature, is extremely variable, with extremes of 

 0.53 and 7.8 mg. per liter. At intervals during the four months, December to 

 March, inclusive, 80 samples of milk were taken and assayed for riboflavin. The 

 average amount of riboflavin per liter of milk was 1.45 mg. for December, 1.50 

 mg. for January, 1.49 mg. for February, and 1.46 mg. for March. These results 

 seem to justify the conclusion that it is possible to standardize the feeding and 

 management conditions for a dairy herd sufficiently so that milk of relatively 

 uniform riboflavin content may be produced for considerable periods of time. 

 This would be true particularly for dairy herds that are stall fed continuously 

 year after year. Such a source of milk would be especially helpful to the physician 

 who desired for his patients milk with a dependable, uniform riboflavin content. 



