Citric acid combinations with

In addition to the common iron control agents listed in table 6-8, service companies provide other iron control systems. Citric acid combined with acetic anhydride has been a common system in the past. Special iron control add mixtures (blends of acetic, formic, and citric acids) are commercially available. 

The valency of the metal ion changes in every step so that a single atom of heavy metal (Me) may produce many free radicals. Metal chelating compounds, such as citric, tartaric or phosphoric acids, ascorbic acid, phytin or phosphatidic acids, combine with metals to form non-reactive compounds so that the oxidation reactions are inhibited and natural food antioxidants are saved. 

The tetraanionic [H2O Al3(/r-OH)(/r-OR)3]" [R = C(CH2C02)2C02] moiety has been achieved by the combination of (H20)9 Al(N03)3 with citric acid [101], with the synthesis establishing the existence of polynuclear complexes of a type previously postulated [102, 103], Al NMR spectroscopic studies have established that the tris(aluminium) cluster (Section 3.2.5) is not fluxional in D2O but instead retains three distinct metal environments over a wide pH range (3.0-9.0) with acid hydrolysis occurring below pH 3.0 and the resultant spectrum revealing the presence of [(H2O), (RO)Al3] and/or [(H20) (ROH) A13] " and also [(HjOlg Al] "" [101]. 

Antioxidants added before rendering improve the fat stability. Sims and Hilfman (42) studied the stabilization of lard and edible beef fats during pressure steam rendering. Antioxidants tested included butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate and citric acid combinations, and a mixmre of BHA and BHT. Best results for a given stabihzer level were obtained with the individual phenolics BHA and BHT. Poorer results were obtained with the mixtures in propylene glycol. 

Sodium bicarbonate, sold as baking soda, can be dissolved in water directly and taken as an antacid. It can also be purchased as Alka-Seltzer, a combination of sodium bicarbonate, citric acid, and aspirin. The citric acid reacts with some of the bicarbonate ions to produce gaseous CO2, the familiar fizz ... 

Supplement (combined with Volume IV) III, 2nd 1929 195-449 Hydroxy-carboxylic acids Carbonic acid, 3. GlycoUic acid, 228. Lactic acid, 261. Tartaric acid, 481. Citric acid, 556. Urea, 42. Cyanamide, 74. Thiocyemic acid, 140. 

Evaporated milk is a Hquid product obtained by the partial removal of water only from milk. It has a minimum milk-fat content of 7.5 mol % and a minimum milk-solids content of 25.0 mol %. Evaporated skimmed milk is a Hquid product obtained by the partial removal of water only from skimmed milk. It has a minimum milk-solids content of 20.0 mol %. Sweetened condensed milk is a product obtained by the partial removal of water only from milk with the addition of sugars. It has a minimum milk-fat content of 8.0 mol % and a minimum milk-solids content of 28.0 mol %. Skimmed sweetened condensed milk is a product obtained by the partial removal of water only from skimmed milk with the addition of sugars. It has a minimum milk-solids content of 24.0 mol %. AH may contain food additives (qv) as stabilizers, in maximum amounts, including sodium, potassium, and calcium salts of hydrochloric acid at 2000 mg/kg singly citric acid, carbonic acid, orthophosphoric acid, and polyphosphoric acid at 3000 mg/kg in combination, expressed as anhydrous substances and in the evaporated milk carrageenin may be added at 150 mg/kg. 

Ascorbic acid also forms soluble chelate complexes with iron (142—145). It seems ascorbic acid has no effect on high iron levels found in people with iron overload (146). It is well known, in fact, that ascorbic acid in the presence of iron can exhibit either prooxidant or antioxidant effects, depending on the concentration used (147). The combination of citric acid and ascorbic acid may enhance the iron load in aging populations. Iron overload may be the most important common etiologic factor in the development of heart disease, cancer, diabetes, osteoporosis, arthritis, and possibly other disorders. The synergistic combination of citric acid and ascorbic acid needs further study, particularly because the iron overload produced may be correctable (147). 

Aqueous solutions of citric acid make excellent buffer systems when partially neutralized because citric acid is a weak acid and has three carboxyl groups, hence three p-K s. At 20°C pifj = 3.14, pi 2 4.77, and = 6.39 (2). The buffer range for citrate solutions is pH 2.5 to 6.5. Buffer systems can be made using a solution of citric acid and sodium citrate or by neutralizing a solution of citric acid with a base such as sodium hydroxide. In Table 4 stock solutions of 0.1 Af (0.33 N) citric acid are combined with 0.1 Af (0.33 N) sodium citrate to make a typical buffer solution. 

Citric acid is utilized in a large variety of food and industrial appHcations because of its unique combination of properties. It is used as an acid to adjust pH, a buffer to control or maintain pH, a chelator to form stable complexes with multivalent metal ions, and a dispersing agent to stabilize emulsions and other multiphase systems (see Dispersants). In addition, it has a pleasant, clean, tart taste making it useful in food and beverage products. 

Citric acid and its salts are used in dry beverage mixes, convenience teas, and cocktail mixes for pH control and flavor, and are used in wine coolers at 0.10—0.55%, combining well with fmity and light flavors. 

Seafood. Citric acid is used in combination with other preservatives/antioxidants to lower the pH to retard microbial growth, which can lead to spoilage, formation of off-flavors, and colors on fish and other seafood products. 

A suspension of lithium methoxide (prepared from 1.00 g (31.2 mmol) of methanol in 50 mL of THF and 17.7 mL (27.2 mmol) of 1.54 M butyllithium in hexane) is transferred via a cannula into a — 78 C sol ution of 5.86 g (27.1 mmol) of 2-[(/ )-(/T)-1-chloro-2-butenyl]-4,4,5,5-tctramethyl-l,3,2-dioxaborolane in 100 mL of THF. The solution is warmed, becoming homogeneous at 0 JC, and stirred for 1 h. Solvents arc removed in vacuo and the residue dissolved in 150 mL of petroleum ether (bp 40 -60 °C). This solution is washed with a citric acid/boric acid/phosphate buffer (pH 3) until the aqueous phase shows a pH of 4. The aqueous phase is extracted with 50 mL of petroleum ether (bp 40 - 60 rC). The combined organic extracts are dried over MgS04 and concentrated in vacuo to give a slightly tan oil yield 5.34 g (90%) ca. 90% ee. 

Sodium bisulfite is often combined with an acid such as citric acid to make it produce gas faster. It is also used to sterilize winemaking... 

The pH indicator shows the acid or basic properties of sample molecnles. Commonly used for acid indicating are solutions of bromocresol green (20 mg dissolved in 10 ml of ethanol combined with 1 ml of 0.1-molar aqueous NaOH) or bromophenol blue (20 mg dissolved in 10 ml of ethanol, pH-adjusted with 0.1-molar NaOH or 0.2% aqneous citric acid). In the presence of acids, 2,6-dichloroindophenol (40 mg dissolved in 100 ml of ethanol) changes the color from blue to red. The fluorescent dye acridine orange (20 mg dissolved in 100 ml of ethanol) changes pH-dependently the color of its flnorescence from yellow-green to yellow. 

A cranberry syrup was combined with sucrose, pectin, citric acid, and TWP to obtain a protein-fortified confection (Faryabi et ah, 2008). 

The aqueous citric acid layers were combined, adjusted to pH 9-10 with ammonia, and extracted three times each with 1 liter of chloroform. The aqueous layer was neutralized, and a portion was evaporated to dryness and found to have no antimicrobial activity. 

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