Answer to Question 1
Plant or vegetable fats include cocoa butter, corn oil, sunflower oil, soybean oil, cottonseed oil, peanut oil, olive oil, canola oil, and many others.
Animal fats include lard from pigs, tallow from beef, and butterfat from milk.
Fish oils include cod liver oil, oil from menhaden, and whale oil.
Answer to Question 2
Chemical tests can determine the degree of unsaturation of the fatty acids in a fat. This is expressed as the iodine value of the fat. The test is based on the amount of iodine absorbed by a fat on a per 100 grams basis. The higher the iodine value, the greater the degree of unsaturation.
Another chemical test yields the peroxide value. This indicates the degree of oxidation that has taken place in a fat or oil. The test is based on the amount of peroxides that form at the site of double bonds.