Sequestrants citric acid

Electrodeposition of Metals. Citric acid and its salts are used as sequestrants to control deposition rates in both electroplating and electroless plating of metals (153—171). The addition of citric acid to an electroless nickel plating bath results in a smooth, hard, nonporous metal finish. 

A common form of EDTA used as a preservative is calcium disodium EDTA (CaNa2EDTA). What metals will this form of the sequestrant scavenge effectively The dissolution of the solid will yield calcium ions, sodium ions, and the EDTA anion. Any metal more effectively complexed than calcium will be readily scavenged, including all ions listed in Table 9.1 except silver (Ag+) and magnesium (Mg2+). (In the absence of the calcium counterion, as in the case of the acid form of EDTA, chelation of calcium in the body can occur. In fact, EDTA administered orally is an FDA-approved treatment for calcium deposits in the bloodstream that lead to cardiovascular disease.) Citric acid (Fig. 9.3.3) is another sequestrant of metal ions in foodstuffs. 

Chelators. The type of positive synergistic effects described above are not to be confused with synergism as referred to when an antioxidant is added with an add chelator, such as citric acid. Acid chelators, or sequestrants, are referred... 

Chelating agents or sequestrants remove metallic ions, especially copper and iron, that are powerful prooxidants. Citric acid is widely used for this purpose. Amino acids and ethylene diamine tetraacetic acid (EDTA) are other examples of chelating agents. 

In order to avoid the autoxidation problem it has become a common practice in the edible oil industry to construct reaction vessels of stainless steel. Citric acid is often added as a metal sequestrant to effectively inactivate trace metal ions. 

Butylated hydroxyanisole is frequently used in combination with other antioxidants, particularly butylated hydroxytoluene and alkyl gallates, and with sequestrants or synergists such as citric acid. 

Since there are synergistic effects between antioxidants, commercial preparations usually contain mixtures of these antioxidants. As oxidative rancidity is strongly catalyzed by some heavy metal ions, in particular QT+, antioxidant mixtures often contain sequestrants (e.g., citric acid and ethylenediaminetetraacetic acid (EDTA)) in order to complex these ions. Reductants such as ascorbic acid, which decrease the local concentration of oxygen, are also able to decrease the formation of peroxy radicals. 

Citric acid Sequestrant Calcium citrate Nutrient/dietary suppl Isopropyl citrate Sequestrant... 

Sequestrants can bind Ca or Mg ions present in hard water, thus blocking the formation of insoluble soaps or other salts during washing and rising. They can also improve, to a lesser extent, product stability by preventing catalytic decomposition of coloring agents and perfumes in the presence of trace metal ions [97], Citric acid, EDTAand its salts, and polyphosphates are commonly used sequestrants [63]. 

Citric acid International Numbering System (INS) No 330 FW 192.13 Chem. name 2-hydroxy-1,2,3-propenetricarboxylic acid. Citric acid is a premier acid in the food industry. The functional uses of citric acid are acidulant, sequestrant, and antioxidant synagist. It is a flavor enhancer [46] and a leavening agent [43]. It may be produced from sources such as lemon or pineapple juice or... 

Phosphoric acid INS No 338, FW 98 other chemical name orthophosphoric acid. Phosphoric acid is an inorganic acid, the second most common acidifier (after citric acid—60%) used iu the food industry—around 25% with its salts. All other acidifiers together account for 15% [9]. Phosphoric acid can be used in foods as an acidulant, sequestrant, and antioxidant synergist. The quantity used varies in a broad range of 1-20 g/kg (up to 2g/L in beverages). No ADI has been established for phosphoric acid, however the maximum tolerable daily intake (MTDI) from all sources is limited to 70mg/kg dw. 

Commonly, the oil is bleached with 0.25-1% clay depending on the severity of the problem. The addition of citric acid or phosphoric acid to the oil to act as a sequestrant is helpful in stubborn cases and to achieve clay savings. Appropriate levels are 10-100 ppm added to the oil before bleaching. Nickel removal by bleaching is more efficient when moisture in the oil-clay mixture is maintained at about 0.1%. 

Synonyms Citric acid, isopropyl ester Monoisopropyl citrate Empirical C9H14O7 Properties M.w. 234.23 Toxicology LD50 (oral, dog) 2250 mg/kg Hazardous Decomp. Prods. Heated to decomp., emits acrid smoke and irritating fumes Uses Sequestrant, antioxidant, antioxidant synergist, preservative in foods plasticizer in food pkg. food antioxidant (Japan)... 

Ammonium lignosulfonate sequestrant, wine Calcium phytate set time regulator, concrete Citric acid... 

Red beet pigments are heat labile, especially in the presence of metals (e.g., Cu, Mn, Fe, Zn) and at temperatures above 121°C, betanin is rapidly destroyed. Copper is the most efficient catalyst for the breakdown. The color can be stabilized by sequestrants and/or antioxidants such as citric acid, sorbic acid, and ascorbic acid though ascorbic acid has also been shown to decrease the color stability of betanin in aqueous solutions. 

Sequestrants form complexes with metal ions, which accelerate oxidative degradation, and show synergistic effects with the a.m. antioxidants. - Phytic acid, calcium gluconate (- gluconic acid), - lactic acid and lactates, - tartaric acid and tartrates, - citric acid and citrates and - lecithin are such RR-based products. 

One series of Ni/Al binary hydroxide coprecipitates was prepared with an initial atomic ratio of 1 1 Ni/Al with nickel equilibrated with anionic agents acetic acid or- citric acid or EDTA in a molecular ratio 1 1 and mixed with the initially precipitated A1 hydroxide. In this system sequestration of the Ni in solution occurred until a pH of 10-12 was attained precluding a staged coprecipitation in an acid regime. A second series of Nl/Al binary hydroxide coprecipitates using a lower Initial atomic ratio of 0.5 for Nl/Al was prepared In the presence of a 1 1 molecular ratio of citric acid or oxalic acid. (Table 1.). In this case Ni loadings in the range of 4.0-4.3 wt.% were obtained at pH values of 10.0 and 7.5 respectively but no Improvement in the state of dispersion as Indicated by the BET areas of the precipitates calcined at 350° C was obtained. 

According to the food laws and regulations of the Food and Drug Administration (FDA), organic acids can be used as acidulants (e.g., citric, fumaric, malic, and sorbic acid), antimicrobial additives (e.g., propionic acid), and sequestrants (e.g., tartaric acid) (14). Most fatty acids of... 

Calcium forms stable insoluble salt with oxalic acid (see Section 10.2.3.2). In plant cells with higher concentrations of oxalic add, caldum oxalate can be actually present in the form of crystals. Some plants have been shown to bind metals in mixed complexes. For example, chromium can be bound in an oxalate-malate complex, and nickel and zinc can form a dtrate malate complex. Citric add has been proven to be a low molecular weight zinc ligand in human milk, and in casein micelles it binds calcium. It is also used as a food additive (acidulant, synergist to antioxidants and sequestrant), so great attention has been paid to the formation of its complexes with metal ions. The addition to cereal products leads to increased solubihty of naturally present iron, due to its release from phytic acid salts (phytates). 

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