ANNUAL REPORT, 1947-48 29 



Permanency of Synthetic Ascorbic Acid Added to Milk. (Arthur D. Holmes and 

 Carleton P. Jones.) In a study of the stability of ascorbic acid in mares' milk, 

 Holmes and Jones found the rate of disappearance of ascorbic acid from mares' 

 milk was only about one-seventh that reported by Hand for cows' milk. Mares' 

 milk contains several times as much ascorbic acid as is found in cows' milk. Ac- 

 cordingly a study was made of the rate of loss of reduced ascorbic acid from cows' 

 milk to which a sufficient amount of synthetic ascorbic acid had been added so 

 that the ascorbic acid content of the milk approximated that of mares' milk. 



Two series of 20 samples each were prepared by adding 75 mg. or 150 mg. of 

 ascorbic acid to a liter of raw cow's milk. The samples were stored in 500-cc. 

 flasks in the dark at 10°C. As aliquots were removed day by day for analysis, 

 the volume of milk decreased and the volume of air in the flasks increased cor- 

 respondingly. For the series of samples of milk to which 75 mg. of ascorbic acid 

 per 1. was added, the loss was 11 percent per day for the first 3 days and 5 percent 

 per day for the remaining 7 days, or 7 percent per day for the entire period. 

 For the series of samples of milk to which 150 mg. of ascorbic acid per 1. was 

 added, the loss was 6 percent per day for the first 4 days and 1 percent per day 

 for the remaining 6 days, or an average of 3 percent per day for the 10 days of 

 storage. 



A Study of the Changes in Vitamin Content Coincident with Different Stages 

 and Rates of Maturity of Vegetables Used for Home Consumption. (Arthur D. 

 Holmes.) The investigations conducted on this project during the past fiscal 

 year were confined to two vegetables, tomatoes and squashes, that were grown 

 on the University farm under controlled experimental conditions. Assays were 

 made of typical specimens to determine the extent that cultural conditions or 

 varieties affected the nutritive value of the vegetables under investigation. 



Variation in Composition of Winter Squashes. (Arthur D. Holmes, C. Tyson 

 Smith, and William H. Lachman.) Assays of the edible portion of five varieties 

 of squash commonly used in this area as a winter vegetable showed considerable 

 \'ariation. Blue Hubbard was not as rich in carotene, phosphorus, and potassium 

 as Butternut and Golden Cushaw, which are relatively new varieties that are 

 gaining popularity. The Buttercup squash, which is frequenth^ referred "to as 

 "a dry squash," contained less water and more reducing sugars than any of the 

 other varieties. The Butternut was very rich in carotene, phosphorus, and 

 potassium. Des Moines contained the smallest amount of carotene and ascorbic 

 acid but the largest amount of calcium and magnesium of any of the varieties. 

 Golden Cushaw was rich in carotene and contained the most protein, phosphorus, 

 and potassium of any of the varieties included in this study. The results of the 

 assays show considerable variation in the composition of the different varieties 

 of winter squashes and of the different squashes within the varieties even though 

 all were grown under uniform soil, fertilizer, and climatic conditions. 



Effect of Different Mulches upon the Nutritive Value of Tomatoes. (Arthur D. 

 Holmes, C. Tyson Smith, Charles Rogers and William H. Lachman.) An ex- 

 periment of 6 years' duration was made to determine the possible effect of mulch- 

 ing upon the composition of tomatoes. A standardized Rutgers-Stokes strain 

 of tomatoes was used. Plots with comparable soil were selected for three mulch 

 treatments and a check, with two replicates of each. Four-inch layers of three 

 types of mulch — horse manure with shavings, rye straw, and Servall (shredded 

 sugar cane stalks) — were spread on the experimental plots as soon as the tomato 

 plants were set out. During the past year, the sixth of the experiment, 12 samples 



