Other than a big word that is hard to say at first, interesterification is a process where a fat molecule is broken up into smaller molecules and rearranged. You may see the word on the back of a cookie box or maybe on a margarine box. By the way, the word can be pronounced as “inter-es-tair-eye-fi-cation”.
Why the heck would someone want to rearrange a fat? You know how olive oil is a liquid at room temperature but butter is, for the most part, a solid? That’s because each is made up of different types of fats. By rearranging fats in say vegetable oil, you can make the vegetable oil act more like a butter – that is, change it’s melting point and the way it feels in your mouth when you eat it.
On a more detailed molecular level what is happening is a triglyceride is being broken up into three fatty acids and a glyceride by an enzyme. The fatty acids and glycerides can then be recombined in any combination desired. Thus, you get a brand new fat with the properties you desire.
There’s a lot of debate about whether interesterified fats are any better for you than trans fats. We won’t get into that here – it’s a pretty heated debate. However, it’s important to be aware that sometimes the process of hydrogenation occurs before the interesterification process and sometimes compounds such as hexane are used in the processing of the fats. It’s not necessarily a bad thing (again, heated debate), but it’s important to learn more about the origin of your food so you can make your own conclusions and an informed decision on what to buy and eat!
Let us know what you think about interesterification in the comments below.
[Sources] Edible Oil Processing – Chemical Esterification