“Food and the Principles of Dietetics,” by Hutchison, gives, on page 378, a list of different starches and the temperatures at which they gelatinize.

In a bulletin entitled “Digestibility of Starch of Different Sorts as Affected by Cooking,” by Edna D. Day, Ph.D. (U. S. Dept, of Agriculture, Office of Experiment Stations, Bulletin No. 202, page 40), we read that starch takes up water at 60 degrees to 80 degrees Centigrade (140 degrees to 176 degrees Fahrenheit) and forms a sticky, colloidal substance known as starch paste, in which form it is very easily digested. Long boiling, at least to the extent of three hours, does not make it more quickly digestible.

There is something to be considered besides the mere starch in cooking starchy foods, and the fact that potato starch will form paste at 149 degrees while rice starch requires 176 degrees does not mean that less cooking will be needed for potatoes than for rice. The woody fibre or other constituents of foods, as well as their density and difference in size, must be taken into account.

11. Cooking temperatures of proteids.

Egg Albumen

In the bulletin entitled “Eggs and Their Uses as Food,” by C. F. Langworthy, Ph.D., published as Farmers’ Bulletin, No. 128, by the U. S. Department of Agriculture, the statement is made that “egg white begins to coagulate at 134 degrees Fahrenheit. White fibres appear which become more numerous until at about 160 degrees Fahrenheit the whole mass is coagulated, the white almost opaque, yet it is tender and jelly-like. If the temperature is raised to 212 degrees Fahrenheit, and continued, the coagulated albumen becomes much harder and eventually more or less tough and horn-like; it also undergoes shrinkage. It has been found by experiment that the yolk of egg coagulates firmly at a lower temperature than the white.”

It also says that these changes in the albumen suggest the idea that it is not advisable to cook eggs in boiling water in order to secure the most desirable result.

Experiment A: To show the changes that take place in egg white at various temperatures.
Materials: