Calcium sources

The abihty of algiaates to form edible gels by reaction with calcium salts is an important property. Calcium sources are usually calcium carbonate, sulfate, chloride, phosphate, or tartrate (20). The rate of gel formation as well as the quaUty and texture of the resultant gel can be controlled by the solubihty and availabiUty of the calcium source. 

Calcium sources, such as gypsum and lime, promote cation exchange from sodium clay to a less-sweUing calcium clay. Calcium concentrations ate normally low (<1000 mg/L) and osmotic swelling is only reduced if other salts are present. Calcium chloride has been used infrequently for this purpose but systems are available that allow high calcium chloride levels to be carried in the mud system (98). 

Two bacterial Shewanella species, S. putrefaciens and S. oneidensis, previously selected on the basis of their ability to degrade azo dyes, were also tested in saline medium at different salt concentrations of up to 10% to evaluate their potential to decolorize four structurally different azo dyes Reactive Black 5, Direct Red 81, Acid Red 88, and Disperse Orange 3. Full decolorization was reached at salt concentrations up to 6% the decolorization velocity was inversely related to salt concentration. The rate of decolorization was increased by yeast extract and a calcium source, while was decreased by glucose and by a nitrogen source [54]. 

Megagraft 1000, the calcium phosphate bioceramic, is synthesized by chemical reaction between calcium and phosphate ion sources (6-9). This synthesis is done by taking the mixture of a calcium and a phosphate source and heating it to a temperature below the starting melting point for an extended period of time. The calcium source can be from calcium phosphates, calcium hydroxide, calcium halides,... 

To determine how the degree of exchange between an extrinsic isotope and the intrinsic calcium in the food or meal is affected by the method of incorporating the isotope, the calcium source itself or foods fed with it. 

Calcium absorption data are needed from animal and human subjects having similar nutritional and physiological characteristics and which have consumed identical calcium sources. 

An attempt was made to collate data on human and rat apparent calcium absorption values for several calcium sources. Absorption values were so variable within species and calcium sources that a correlation could not be justified. Much of this variability may be due to methodological differences between the design of the rat and the human experiments. Most of the animal experiments were conducted using rapidly growing rats which were fed modest amounts of calcium but which have high calcium requirements. 

The calcium source for the crystallization is the aragonite form of calcium carbonate which is wet ballmilled with closed-loop hydrocyclone classification to ninety-five percent minus two hundred mesh. The thirty weight percent aragonite slurry is fed to the crystallizer by pH control. A very pure carbon dioxide stream evolves from the crystallizer. 

Calcium chloride has several industrial applications. The major applications of this compound are in deicing of roads, dust control, imparting stability to roads and buildings, and to improve traction in tractor tires. It is mixed with ice to make freezing mixtures. Hexahydrate mixed with crushed ice can lower the temperature of the cooling bath to below -50°C. It also is used as a desiccant for dehydrating gases and liquids. It is added to cement in various proportions to manufacture different types of concrete. Other uses are in adhesives, to lower gel temperatures, and as a calcium source in liquid feed supplements for dairy cattle. Also, the compound is used to control particle size development and reduce coalescence in plastics. 

Andon, M. B. (1995). Concentrated bioavailable calcium source U.S. Patent No. 5,468,506. The Procter and Gamble Company. 

Brink, E. J., van den Heuvel, E. G. H. M., and Muijs, T. (2003). Comparison of six different calcium sources and meal type on true fractional calcium absorption in postmenopausal women. Curr. Top. Nutraceut Res. 1,161-168. 

Corneau, L., Lavigne, C., and Zee, J. A. (1996). Effect of calcium and zinc concentrations and calcium source on in vitro calcium and zinc solubility in a fiber-fortified enteral formula. Nutr. Res. 16,1659-1669. 

Deehr, M. S., Dallal, G. E., Smith, K. T., Taulbee, J. D., and Dawson-Hughes, B. (1990). Effects of different calcium sources on iron absorption in postmenopausal women. Am.. Clin. Nutr. 51, 95-99. 

Heaney, R. P., Recker, R. R., and Weaver, C. M. (1990a). Absorbability of calcium sources The limited role of solubility. Calcif. Tissue Int. 46,300-304. 

Henry, M. H., and Pesti, G. M. (2002). An investigation of calcium citrate malate as a calcium source for young broiler chicks. Poult. Sci. 81,1149-1155. 

The objective of this work was to identify calcium sources and their relative contributions in rural central Illinois as a step toward understanding the role of airborne alkaline... 

Blair, R., English, P.R. and Michie, W. (1965) Effect of calcium source on calcium retention in the young chick. British Poultry Science 6,355-356. 

Figure 3.5 Doppler effect with calcium source, indicated by 4. The calcium line in the spectrum at top is redshifted in the bottom spectrum because the source is moving away from Mr. Plex. For stars moving tens of thousands of miles per second away from us, the redshift can be quite pronounced.

Larsen T, Thilsted SH, Kongsback K, et al. Whole small fish as a rich calcium source. Br J Nutr 83 191-196, 2000. 

One of the most commonly used calcium sources in the reclamation of brine-contaminated soil-water environments is gypsum (CaS04-2H20). In highly calcare-... 

Blum, J. D., Klaue, A., Nezat, C. A. et al. (2002). Mycorrhizal weathering of apatite as an important calcium source in base-poor forest ecosystems. Nature, 417, 729-31. 

A more direct approach to study EM weathering is the use of tracer elements as used by Blum et al. (2002). They examined calcium uptake by different tree species in the Hubbert Brook Experimental Forest in northeastern USA. They used the fact that the different calcium sources (atmospheric deposition, calcium silicate weathering and apatite weathering) have different Ca/Sr ratios. In the ecosystem, strontium is believed to behave in a similar fashion as calcium (Aberg et al., 1990). Atmospheric deposition, calcium silicate minerals and soil water have similar Ca/Sr ratios (120-300), but apatite has a much higher Ca/Sr ratio (2200-2920). 

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