Fat interesterification

residues (LARs) and one stearic acid residue (SAR), and another triglyceride (bottom left) with three SARs, yielding two molecules with two SARs and one LAR each (right) Typically the feedstock (starting product) is a mixture of two or more oils. In particular, unsaturated vegetable oil can be interesterified with a fully hydrogenated version thereof, as in the illustration to the right. This procedure yields less saturated fat without creating the trans fat that would be produced by partial hydrogenation. The reaction does not go to completion, and the product will be a mixture of triglycerides with different amounts of saturation. ==Process==

Chemistry In principle, when interesterification is applied to two pure triglycerides, each with three identical fatty acids (AAA and BBB), the result could contain six different triglycerides (AAA, AAB, ABA, ABB, BAB, and BBB). The number is 6, rather than 23 = 8, because of the symmetry of the glycerol backbone. Some enzymes will break and reform ester bonds only at positions 1 and 3 (sp1 and sp3) of the glycerol hub, leaving the acids in position 2 (sp2) fixed. IE has been replacing CIE because it has fewer processing steps, can be carried out at lower temperatures, produces no by-products, and has lower production costs. ==Advantages==

Compared to simple blends, interesterified fats have a wider plasticity range, meaning that they retain their physical properties over a wider temperature range without separation of their components. IE can also use a wider variety of feedstocks, such as soybean oil; they provide a better risk management profile than globally produced palm oil. ==History==

The earliest record of enzymatic interesterification was in 1844, when Théophile-Jules Pelouze published a study on the synthesis of a triglyceride through the esterification of glycerol by butyric acid. In 1920, Wilhelm Normann, who also patented the catalytic hydrogenation of fatty acids, was granted a patent for the chemical interesterification of edible lipids. This process became a viable option for the food industry, as it improved the spreadability and baking properties of the common shortening lard. Enzymatic interesterification was developed in the 1970s by the team at the Unilever Research Center at Colworth House in England. Their work proved that the use of a specific enzyme predictably rearranged the fatty acids on the glycerol backbone of a triglyceride at positions 1 and 3. This provided an expanded range of available triglyceride types. Still, EIE remained largely confined to research laboratories due to high enzyme prices. It was only in the 2000s that general concerns about the health effects of trans fats drove the industry to adopt interesterification as a replacement for partial hydrogenation, which had been the oil hardening method of choice due to its lower cost. Adoption was greatly facilitated by the development of enzymes bound to inert solid substrates like silica, by Novozymes and other companies. ==References==