Читать книгу Food Chemistry - Dennis D. Miller - Страница 39

Note: This is a standard protocol for measuring leavening rates in a model system.

1 Add 60 ml distilled water and a magnetic stir bar to a filter flask.

2 Fill a 100 ml graduated cylinder with tap water and invert it in a pan of water as shown in Figure 2.2 (take care to avoid allowing air to get into the cylinder).

3 Weigh out the specified amounts of each of the leavening agents (see Section 2.5.1.2).

4 With the stirrer running on low speed, transfer the leavening agent to the flask and stopper immediately. (Note: The rate of stirring will affect the rate of the reaction, so always use the same setting on the stirrer.)

5 Record the volume of displaced water in the cylinder every 30 seconds for five minutes.

6 Now, set the flask in a water bath held at 65 °C and continue recording the volume for an additional five minutes. (Note: Temperature can have a marked effect on CO2 generation, so regulate the temperature carefully.)

7 Measure the final pH of the solution in the filter flask.