Abstract
One of the most important factors in the preparation of diabetic diets, as well as in the study of the relationships between diet and sugar metabolism, is the carbohydrate content of the injested foodstuffs. The most extensive data on this subject is found in Bulletin No. 28 of the U. S. Department of Agriculture. Unfortunately the carbohydrates in the majority of cases have been determined by difference and hence do not differentiate between the free and hydrolyzable sugar content. Furthermore, since the carbohydrate content of fruits and vegetables varies between wide limits, it is often necessary to analyze the diet used, rather than depend upon figures gathered at random. Of the various procedures for the analysis of the carbohydrate content of foodstuffs the method of Dutcher and Thomas for reducing sugars in plants seemed to adapt itself most readily to the rapid analysis of food materials.
1. Dutcher and Thomas 1 method for analyzing the free sugar content of plant material has been adopted to the analysis of the free carbohydrates in general foods and fruits.
2. Lloyd's reagent may be substituted for mecururic nitrate as a clarifying agent and the Benedict-Osterburg or Lewis-Benedict methods are applicable in the presence of alcohol.
3. A four-hour extraction period with 75 per cent alcohol is sufficient to extract completely 2,000 mgs. of glucose, fmctose, galactose, xylose, and arabinose.
4. Maltose, lactose, raffinose and sucrose are extracted by 75 per cent ailcohol.
5. Sucrose is not appreciably hydrolyzed by a four-hour extractioln with 75 per cenlt alcohol, nor as pointed out by Dutcher and Thomas, is it hydrolyzed by 15'boiling with picric acid and Na2 CO3.
6. The analysis of a few common food materials for free and hydrolyzable carbohydrates is presented.
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