This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
Keep a record of the experiments performed in a permanent note book. The experiments should be written up under the following headings. The object of the experiment, what happens, the results, and most important, the conclusion drawn or the application of the results in preparation of food. Suggestive headings for record of what happens are given under most of the experiments.
To determine the relative solubility of the various sugars.
Measure 20 cc. of water for each sugar to be used. Place in a Pyrex cup or a glass. Take the temperature of the water. Weigh the following amounts of sugar.
Add a small portion of the sucrose to one of the containers of water. Stir until all is dissolved. Add another portion of sucrose and continue until you have as much of the sucrose in solution as can be dissolved. Take the temperature of the solution while the sugar is dissolving. The stirring should be continued at intervals for 1 hour. Weigh the sucrose that is left and subtract the amount from 60 grams to obtain the amount dissolved. Your results will be only approximate for solubility should be determined in flasks to prevent evaporation. However, the results that you obtain will show the comparative solubility of the different sugars. If any undissolved sucrose remains after stirring for some time, set the container in warm water and stir until all the sucrose is dissolved. Put the container away in the laboratory and look at it occasionally to watch the growth of crystals. Compare the crystals formed with those of other sugars.
Repeat the above directions for each sugar. For the less soluble dextrose and maltose add smaller portions when dissolving the sugars. Lactose has the least solubility of the above sugars and should be added in very small portions.
Kind of sugar
Temperature of water at first
Temperature while sugar is dissolving
To determine the boiling point of water at the elevation above sea level at which you live.
Place 1 pint of water in a sauce pan. Heat slowly. Notice the temperature at which bubbles begin to form on the sides and bottom of the pan. Of what are these bubbles formed? What becomes of them? At what temperature do the vapor bubbles begin to form? Do the first ones reach the surface of the water? At what temperature does the water boil? Are you at sea level or above it? What is the boiling point of water at sea level? Observe the surface of the liquid and the size of the bubbles. Heat the water so that the bubbles form rapidly. Is the temperature the same as when the bubbles form slowly? How do the surface of the water and the size of the bubbles compare with those of the slow-bubbling liquid? Does the temperature rise? Explain.
Compare the temperatures registered by the thermometer when held in the water so that the thermometer bulb does not touch the bottom of the pan and when it touches it. Compare the temperatures registered when the bulb of the thermometer is only partially immersed and when it is immersed so that there is 1/2 to 1 inch of water above the bulb. How should you apply these results to cooking sirups to a definite temperature in class results? Is the temperature the same when the thermometer bulb touches the bottom at the center and at the sides of the pan? (This may or may not vary according to the type of gas burner or the electric unit used.)
When bulb of thermometer is partially immersed
When bulb touches the bottom of pan
Type of bubble
Results and conclusions.
To determine the effect on the boiling point of water when a soluble sub-stance is added.
To 1 cup of water add a scant 1/4 cup of salt. Heat to the boiling point. Note the temperature. Continue boiling. Does the temperature change? Continue boiling until the temperature remains constant. What other change occurs? What is the effect on the boiling point when salt is added to water? Results and conclusions.
To determine the boiling temperature of sugar sirups corresponding to the "cold-water tests" used in candy making.
A. Sucrose sirup.
Dissolve 1 cup of sucrose (granulated sugar) in 1/2 cup of water. (The proportion of sugar and water used may need to be increased. The quantity of sirup should be sufficient to cover the thermometer stem to a depth of 1/2 inch above the bulb. The amount of sugar needed depends upon the size of the pan and the length of the thermometer bulb.) Bring the solution to boiling. Note rise in temperature with constant boiling. Explain. Why can a higher temperature be obtained with the sugar solution than with the salt solution?
Cook the sirup in sauce pans of the same size and shape. At the temperatures given below remove portions of the sirup. Remove the pan from the stove when making each test. Drop a tablespoon of the sirup in cold water. Note the consistency. Is it easily molded? Does it ring when hit against the side of the container? When do threads or hairs begin to form when a portion of the sirup is allowed to flow from a spoon? How do the character and length of the threads vary at different temperatures? Keep the series of tests on your work tray for comparison with the following experiments and with your neighbors' results. Note the texture at room temperature. Is it soft, firm, or brittle? Put a portion in your mouth. Does it dissolve rapidly on the tongue? To what stage in candy cookery does each of the temperatures given correspond?
Compare with results given in candy and in cook books. Tabulate your results.
Stage of cookery
On the tongue