Fat interesterification

In the food industry and biochemistry, interesterification (IE) is a process that rearranges the fatty acids of a fat product, typically a mixture of triglycerides. The process implies breaking and reforming the ester bonds C–O–C that connect the fatty acid chains to the glycerol hubs of the fat molecules. The reactions involve catalysts, either inorganic chemicals (chemical interesterification, CIE) or enzymes (enzymatic interesterification, EIE).^[1]

This process is typically used to adjust the physical characteristics of the fat, such as melting point and plasticity, for specific uses. It can be used, for instance, to turn oils into solid or semisolid products by combining them with other solid fats. It can also be used to prevent separation of solid fractions in palm oil and lauric fats,^[2] or slow rancidification, or to create oils more suitable for deep frying.

In contrast to hydrogenation, interesterification itself generally retains the original distribution of fatty acids in the product and hence is expected to preserve its nutritional and health attributes. However, hydrogenation and other techniques may still be applied to the starting fats or to the products of IE, and the products may be blended with other fats. Also, some of the new triglycerides produced by IE may be fractionated (separated) through controlled crystallization.^[3]

Interesterified fats are used in many industrial food products, including cookies, crackers, biscuits, cakes and icings, dairy fat replacers, pie crust, popcorn, flatbread and tortillas.^[4]