1. Some proteins dissolves in water, eg. albumen. This coagulates on heating.
2. Most do not dissolve in water, but many are soluble in salt and water mixtures of various strengths.
3. When protein are heated violently their essential qualities are changed. this is usually accompanied by hardening.

Gelatine is an animal protein derived from meat, calves, hoofs,etc. it is completely deficient in at least one of the essential amino acids,and is therefore of little food value unless supplemented by other proteins. Soya beans are a valuable source of high quality vegetable protein; the proteins of soya beans contain all the essential amino acids.

Soya bean flour and soya bean paste are being introduced into the diets of many countries; because of its high protein value - which is comparable to meat it is used as a meat substitute in the diet. Soya beans are now being grown in the United States. They are grown mainly as a source of vegetable oil as soya beans need heat treatment to make them palatable, but new methods of processing them are now being developed.

Also i will still post more about the properties of Protein and there classifications.

http://www.foodchefblog.com/2016/03/sources-of-nutrients.html

http://iniedogist..com.ng/

Ok. Thanks, we are waiting.