double‐acting baking powders more effective in many baking applications than single‐acting baking powders?5 The recipe for a large batch of pancake batter specifies 1 pound of baking soda and MCP as the leaving acid. How much MCP should be used?
6 Vinegar contains about 5% acetic acid (wt/vol). Calculate the normality of vinegar. What volume of vinegar would be required to neutralize 100 ml of 0.1 N sodium hydroxide?
7 You are baking a batch of biscuits and are out of baking powder. You decide to improvise and use vinegar and baking soda. You decide to add 2 teaspoons of baking soda to your dough. What volume of vinegar will you use? Assume that 1 mole of acetic acid will neutralize 1 mole of baking soda. One teaspoon of baking soda weighs 5 g.
8 The published neutralizing value of monocalcium phosphate monohydrate (MCP) is 80. Calculate the expected NV of monocalcium phosphate monohydrate based on stoichiometric relationships. Assume that the MCP is behaving as a monoprotic acid in this system. Does your result agree with the measured value of 80? If not, give a possible explanation. Note: To solve this problem, you will need to write balanced equations for the reactions between MCP and sodium bicarbonate (one with MCP acting as a monoprotic acid and the other with MCP acting as a diprotic acid).
9 What volume of CO2 would be produced from the complete neutralization of 5 g sodium bicarbonate at 80 °C?
10 Draw the structure of potassium acid tartrate. Write an equation to show why it is a leavening acid.
11 What is the main leavening acid in cultured buttermilk? Draw its structure.
12 What is the main leavening acid in lemon juice? Draw its structure.
13 Explain how glucono‐delta‐lactone can act as a leavening acid.
14 What is the minimum percentage of sodium bicarbonate in baking powder necessary to yield 12 g of CO2 per 100 g of powder? (Assume that all of the bicarbonate is converted to CO2 and H2O.)
15 What volume of 1.0 molar sulfuric acid would be required to neutralize 100 ml of 1.0 molar sodium hydroxide?
2.7 Useful Formulas and Values
1 Ideal gas law:PV = nRTwhere: P = pressure in atmospheres (atm)V = volume in liters (l)n = number of moles of gasR = 0.0821 (l) (atm) (mol−1) (K−1)T = temperature in K
2 Volume of 1 mole of CO2 under standard conditions = 22.40 l.
3 Standard temperature and pressure for gases: T = 273 K; P = 1 atm.
4 Baking soda content of baking powder: 28% NaHCO3 (w/w).
5 Formula weight of NaHCO3 = 84.01.
6 Molecular weight of CO2 = 44.0.
2.8 References
1 1 Van Wazer, J.R. and Arvan, P.G. (1954). Chemistry of leavening. Milling Production February–March: 3–7.
2 2 Heidolph, B.B. (1996). Designing chemical leavening systems. Cereal Foods World 41 (3): 118–126.
3 3 Gardner, W.H. (1966). Food Acidulants . Allied Chemical. 185 p.
4 4 Lindsay, R.C. (2017). Food additives. In: Fennema’s Food Chemistry , 5e (eds. S. Damodaran and K.L. Parkin ), 803–864. Boca Raton: CRC Press,Taylor & Francis Group.
5 5 McGee, H. (2004). On Food and Cooking: The Science and Lore of the Kitchen . Completely rev. and updated. New York: Scribner. 884 p.
6 6 AACC method 2‐32 A (1995). Neutralizing value of acid‐reacting materials. In: Approved Methods of the AACC , 9e. St. Paul, MN: The American Association of Cereal Chemists.
7 7 Book, S.L. and Waniska, R.D. (2015). Leavening in flour tortillas. In: Tortillas (eds. L.W. Rooney and S.O. Serna‐Saldivar ), 159–183. St. Paul, MN: AACC International Press.
8 8 Bellido, G.G., Scanlon, M.G., Sapirstein, H.D., and Page, J.H. (2008). Use of a pressuremeter to measure the kinetics of carbon dioxide evolution in chemically leavened wheat flour dough. Journal of Agricultural and Food Chemistry 56 (21): 9855–9861.
9 9 Kichline, T.P. and Conn, T.F. (1970). Some fundamental aspects of leavening agents. Bakers Digest 44 (4): 36–40.
10 10 Conn, J.F. (1981). Chemical leavening systems in flour products. Cereal Foods World 26 (3): 119–123.
11 11 Penfield, M.P. and Campbell, A.M. (1990). Experimental Food Science , 3e. San Diego: Academic Press. 541 p. (Food science and technology).
2.9 Suggested Reading
1 Labaw, G.D. (1982). Chemical leavening agents and their use in bakery products. Bakers Digest. 56 (1): 16.
2 Robinson, J.K., McMurry, J., and Fay, R.C. (2019). Chemistry , 8e. Hoboken, NJ: Pearson Education, Inc. 1200 p.
Answers to Problem Set
1 Volume of CO2 = 99 ml
2 Fast‐acting acids dissolve rapidly, slow‐acting acids dissolve more slowly.
3 Bicarbonate has a high pKa, which means it will not dissociate until the pH is high.
4 Double‐acting powders allow release of some CO2 prior to baking which helps improve batter viscosity.
5 1.25 lb MCP.
6 Normality of vinegar = 0.833 N. It will take 12 ml vinegar to neutralize 100 ml of 0.1 N NaOH.
7 143 ml vinegar.
8 Two equations may be written: Monoprotic: Diprotic: The published value of 80 lies between 67 and 133. This suggests that the sodium bicarbonate reacts nearly completely with the first H on the H2PO4 − but only partially with the second, i.e. the diprotic reaction above does not go to completion.
9 1.72 l CO2.
10
11
12
13 A lactone is an ester formed from the reaction of a carboxyl group and an alcohol group on the same molecule. Glucono‐delta‐lactone slowly hydrolyzes in water to form gluconic acid.
14 22.9%.
15 50 ml.
3 Properties of Sugars
3.1 Learning Outcomes
After completing this exercise, students will be able to:
1 Draw structures of common reducing and nonreducing sugars.
2 Explain the difference between a hemiacetal and an acetal.
3 Distinguish between reducing and nonreducing sugars experimentally.
3.2
