Acid Pyrophosphate and Soda (Barackman)

Time, Minutes

Water solution

Biscuit Doughs

Doughnut doughs

A

B

C

D

B

C

D

0

0

0

0

1/2

84.3

27.0

.....

.....

25.6

.....

.....

1

111.3

42.1

.....

.....

36.0

....

.....

2

120.4

58.1

14.2

43.9

40.5

4.5

36.0

3

122.9

64.9

18.0

46.9

42.9

6.0

36.9

4

124.2

69.9

21.8

48.1

44.7

6.7

38.0

5

124.9

73.8

25.6

48.2

46.0

7.5

38.5

6

125.6

77.5

28.4

49.1

47.5

8.2

39.3

7

125.9

81.0

30.3

48.7

48.1

9.0

40.1

8

126.5

84.3

33.2

51.1

50.5

9.0

41.5

9

127.2

86.6

35.1

51.5

51.9

9.7

41.2

10

127.6

88.8

37.0

51.8

52.0

10.5

41.5

15

129.4

98.2

43.6

54.6

56.7

12.7

43.0

A. Reaction in water.

B. Reaction in dough.

C. Dough volume.

D. Volume of CO2 lost.

Barackman's results for the rate of reaction of sodium acid pyrophosphate are given in Table 54.

From the results obtained Barackman concluded that a rapid-acting baking acid caused a larger loss of carbon dioxide from the dough during mixing, whereas a slow-acting acid has a smaller loss and consequently a greater quantity of available gas left in the dough for baking. "Of the gas generated during mixing only 20 to 30 per cent is retained by the doughs. This, plus the gas in the undecomposed soda, is available for leavening in the oven. No appreciable loss of gas occurs after mixing."

In the following tables the specific volume was obtained by dividing the volume of the biscuits or cake by their weight.

The Percentage of Carbon Dioxide Lost from Biscuit Doughs Compared with the Reduction in Specific Volume of Biscuits (Barackman)

Acid ingredients

CO2 avail-able in dough at 2 minutes, per cent

CO2 lost after 15 minutes, per cent of available

Specific volume of biscuits baked immediately

Reduced specific vol-ume due to standing, per cent loss

Phosphate...........

49

4. 0

2. 24

8. 5

S. A. P. P...................

78

6. 5

2. 75

9. 0

Tartrate.............

70

13. 0

2. 65

11. 0

Sulfate phosphate.......

76

6. 5

2. 41

3. 0

* Exception due to effect of acid on colloidal properties of dough.

Barackman's conclusion was that a correlation exists between the carbon dioxide left in doughs after mixing and the volume of the baked product. "The major portion (70 to 80 per cent) of the carbon dioxide generated from baking powders during the mixing of doughs is lost." In the above table the reduced specific volume is due to the biscuits being mixed and allowed to stand 15 minutes before cutting and baking. The controls were baked within 2 to 3 minutes after mixing.

Fineness of division of baking powder. The fineness of division of a baking powder may affect the grain and texture of the baked product. With finely ground powders it seems reasonable to expect that the bubbles of carbon dioxide produced will be smaller than with coarser baking powders, and that a finer grain will thus be produced in cakes and other products. Patterson refers to such a result with finely ground baking powders. Sifting the baking powder with the flour aids in mixing the baking powder more uniformly throughout the batter or dough, and prevents loss of gas that would occur if the baking powder were mixed with the liquid.

Brown spots are often produced on the crust of cookies, biscuits, cakes, and other products when baking powder is used in them. If the baking powder used contains soda that is not finely ground, these spots are more likely to occur. The spots do not develop in the thin batters because of the large proportion of liquid, for solution of the soda is thus obtained. The brown spots appear in the product when the baking powder has been mixed only a short time with the dough. With longer mixing the soda is dissolved and the spots do not appear. If doughs are allowed to stand before baking, the spots may not develop or a smaller number may form. Since cakes are usually mixed longer than biscuits and cookies, the spots develop more frequently in cakes when the baking powder is added after the mixing of the batter is partially completed.