In margarine water is not uniformly distributed so it must be homogenized before the determination. However, it must not be heated above 25C as otherwise phase separation could occur.
Water determination in margarine by Karl Fischer
Margarine was created in the early 1800s as an inexpensive substitute for butter.
Early margarines were made from animal fat.
In the 1900s, chemists discovered how to harden liquid oils and vegetable oil replacing animal fat.
Today, margarine is manufactured through a multi-step process.
One of them is having hydrogen gas bubbling through liquid oil in the presence of a catalyst (usually nickel). This forces unsaturated fatty acids to become saturated and solid.
The more complete the hydrogenation process, the firmer the finished product will be. Margarine undergoes partial hydrogenation to make it semi-solid.
Partial hydrogenation produces lumpy grey grease and results in the formation of trans-fats.
Emulsifiers are then added to remove lumps; bleach to remove the grey color.