Sodium acids

Table 6 Hsts the leavening acids and the corresponding rates of reaction. The leavening acids most frequently used iaclude potassium acid tartrate, sodium aluminum sulfate, 5-gluconolactone, and ortho- and pyrophosphates. The phosphates iaclude calcium phosphate [7758-23-8] CaHPO, sodium aluminum phosphate, and sodium acid pyrophosphate (66).

There are occasions where the mud pH must be lowered such as after drilling fresh cement or overtreatment by one of the alkaline materials discussed. Organic acids that have been used for this purpose include acetic acid [64-19-7], citric acid [77-92-9], and oxaHc acid [144-62-7]. These materials are used infrequently. Inorganic additives used to lower pH levels include sodium bicarbonate [144-55-8] and sodium acid pyrophosphate [7758-16-9] (SAPP). Of the two, sodium bicarbonate is used the most by far. 

Sodium Pyrophosphates. Known pyrophosphate compounds in the Na20—H2O—P20 system are given in Table 10. Commercially important sodium pyrophosphates include tetrasodium pyrophosphate (TSPP), Na4P20y, and disodium pyrophosphate, Na2H2P20y, commonly referred to as sodium acid pyrophosphate (SAPP). These are prepared industrially by thermal dehydration of disodium and monosodium orthophosphate, respectively. Tetrasodium pyrophosphate exists in five crystalline modifications, only one of which is stable at room temperature. 

Fig. 8. Solubihties of sodium acid pyrophosphate and tetrasodium pyrophosphate.

A number of acidic phosphates which vary in their rate of reaction are available for use in a wide variety of bakery appHcations. These acids, which include monocalcium phosphate, sodium aluminum phosphate, and sodium acid pyrophosphate, release carbon dioxide at a controlled rate to give a certain fraction prior to baking the remaining fraction is released at a specific time during baking. Controlled releasing of carbon dioxide at the time it is needed can also be achieved by a mixture of different types of leavening acids. 

Ch nical Designations - Synonyms Sodium acid sulfite Sodium metebisulfite Sodium pyrosulfite Chemical Formula NaHS04-Na2S205. 

Chemical Designations - Synonyms Sodium phosphate is generic term and includes the following (1) monosodium phosphate (MSP sodium phospWe, monobasic), (2) disodium phosphate (DSP sodium phosphate dibasic), (3) trisodium phosphate (TSP sodium phosphate, tribasic), (4) sodium acid pyrophosphate (ASPP SAPP disodium pyrophosphate (TSPP), (6) sodium metaphosphate (insoluble sodium metaphosphate), (7) sodium trimetaphosphate, and (9) sodium tripolyphosphate (STPP TPP) Chemical Formula (1) NaHjPO (2) Na HPO (3) NajPO (4) Na H P O, (5) Na P O, (6) (NaPOj) (7) (NaP03)3 (8) (NaP03) NaO (9) Na,P30,o. 

Sodium, acid sulfite or sodium hydrogen sulfite (NaHS03) has a MW of 104 and a sp. gr. of 1.48. It is a white, corrosive crystalline powder that is very soluble in hot or cold water. It is approved in the United States under 21CFR 173.310, GRAS. It is typically available as a 40% w/w... 

The correlation of phosphate precipitation with decrease of conductivity (Wilson Kent, 1968), increase in pH (Kent Wilson, 1969) and hardness (Wilson et al, 1972) is shown in Figure 6.16. These results demonstrate the relationship between the development of physical properties and the underlying chemical changes, but there are no sharp changes at the gel point. Evidence from infrared spectroscopy (Wilson Mesley, 1968) and electron probe microanalysis (Kent, Fletcher Wilson, 1970 Wilson et al, 1972) indicates that the main reaction product is an amorphous aluminophosphate. Also formed in the matrix were fluorite (CaF ) and sodium acid phosphates. 

Chemical leavening takes place when carbon dioxide is produced chemically rather than biochemically. Typically, this involves treating sodium bicarbonate with an acid such as sodium acid... 

E450 disodium dihydrogen diphosphate (sodium acid pyrophosphate)... 

Monocalcium phosphate monohydrate reacts almost as quickly as cream of tartar (potassium acid tartrate). Anhydrous monocalcium phosphate has four-fifths of the reactivity. At ambient temperatures dicalcium phosphate dihydrate, sodium aluminium phosphate and some grades of sodium acid pyrophosphate are essentially unreactive. 

The reaction rate of sodium acid pyrophosphate can be controlled by adding calcium ions. While this process happens anyway in the presence of skim milk solids, manufacturers deliberately add calcium ions to sodium acid pyrophosphate to give grades with slower dissolution. 

Sodium acetylide, 1 179, 22 765 Sodium acid pyrophosphate (SAPP),... 

Buffers contain mixtures of weak acids and their salts (i.e., the conjugate bases of acids), or mixtures of weak bases and their conjugate acids. Typical buffer systems used in pharmaceutical dosage forms include mixtures of boric acid and sodium borate, acetic acid and sodium acetate, and sodium acid phosphate and disodium phosphate. The reason for the buffering action of a weak acid, HA (e.g., acetic acid) and its ionized salt, A" (e.g., sodium acetate) is that A" ions from the salt combine with the added hydrogen ions, removing them from solution as undissociated weak acid. 

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