Determination of alginate in dairy products.
Abstract Comprehensive study was made of the precipitability of several hydrocolloids and other related compounds by divalent cations and, specifically, of the optimum conditions for recovering alginate from milk and dairy products by precipitation as calcium, strontium, and manganese salts. In aqueous dispersion, these cations selectively precipitated alginate, pectinic acids, and pectic acid. Alginate was recovered from milk, chocolate milk, ice cream, cheese spreads, cream cheese spreads, and other products by predigesting the mixture with papain, clarifying the digest with Celite 535 and charcoal, filtering and converting any pectin, pectinic acid, and pectic acid to galacturonic acid by pectinmethylesterase (pectinesterase) and polygalacturonase. Then, calcium chloride was added to the filtrate. The calcium alginate precipitate was washed free of sugars, dispersed by sodium hexametaphosphate, and the amount of alginate in the dispersion determined by the phenol-sulfuric acid test. Recoveries obtained were 96-101% for water dispersions, 92-96% for milk, 90-95% for ice cream, and 85-95% for cheese products.
PROCEDURE FOR THE SEPARATION, DETECTION, AND IDENTIFICATION OF THE MORE COMMON VEGETABLE GUMS IN DAIRY PRODUCTS, WITH SPECIAL REFERENCE TO ALGINATES
A procedure is presented for detecting the more common vegetable gums in dairy products. Alginates are separated, in the presence of other gums, by precipitation as algenic acid and redissolving fr...
The syntbesis of heparin by slices of mouse mast cell tumor.
The incorporation of radioactive sulfate into heparin in z&o has been demonstrated unequivocally (3) and there is suggestive evidence for the reaction in rat liver slices (4). The identification of the radioactive product as heparin was not rigorously established in the experiments in vitro, however, and no experiments have been reported on the incorporation of glucose into heparin either in uivo or in vitro. The availability of mouse mast cell tumors (5) and the development of a method for the isolation of heparin in small quantities in a suitable state of purity (6) have now permitted an investigation of this problem. A thorough study of the mechanism of biosynthesis of heparin offers several interesting prospects. One is the revelation of the process of formation of the sulfamide bond, a structure almost unique among biological compounds. Another is that by a combined study of the paths of synthesis in mammalian mast cells and degradation by bacterial enzymes (7-9) the structure of heparin may be determined. Finally, if, as now seems possible, heparin does function in the metabolism of lipoproteins, it is at least conceivable that defects in the metabolism of heparin may be responsible for certain of the abnormalities in lipide metabolism. The data in this paper demonstrate that heparin is synthesized by slices of mouse mast cell tumor. Sulfate is incorporated into both the amide and ester positions and glucose is converted into the hexose moieties of the carbohydrate chain. These studies provide a firm basis for further investigations of the mechanism of biosynthesis of heparin in soluble systems.