Milkfat interesterification

Rodrigues, J.N., Gioielli, L.A. 2003. Chemical interesterification ofmilkfat and milkfat-corn oil blends. Food Res. Int. 36, 149-159. 

Frede, E. 1991. Physical and chemical modification of milkfat, 2.3 Interesterification. In Monograph on Utilizations of Milkfat, Bulletin, No. 260 International Dairy Federation, Brussels, p. 12. 

Considerable recent research has defined conditions for successful use of lipases and other enzymes in numerous lipid modification reactions, including a variety of types of interesterifications (69, 71, 76). For edible applications to date, they have been employed at industrial scales for the production of (1) cocoa butter substitutes, for which disaturated, monounsaturated acylglycerols with the unsaturated fatty acid in the sn-2 position are desired (77) (2) to produce human milkfat analogues, where 2-palmitoyl acylglycerols are desired (77) (3) in the synthesis of 1,3- di-acylglycerols (78) and in the production of diacylglycerols for edible applications. These reactions employ vegetable oils as feedstocks. 

Interesterification offers oppoitunities for modifying the glyceride composition of milkfat and recombined butter. The technique confers some positive nutritive value to milkfat. One disadvantage of the interesterification reaction is the loss of flavor during neutralization, interesterification, and subsequent deodorization. Most manufacturers would support that little or no commercial interest will result from using this process. 

Betapol , a human milkfat substitute produced by Loders Croklaan (Wormerveer, the Netherlands), is produced by interesterification of vegetable oils in which the component TAGs have been modified to more closely resemble those found in breast milk. This product closely mimics the specific structure and fatty acid composition of human milkfat and resembles breast milk in terms of its nutritional value and high content of palmitic acid at the sn-2 position than other milkfat substitutes. In addition, the use of Betapol in infant formula can lead to improved mineral and fat absorption and less calcium soap formation within the intestinal lumen resulting in softer stools. 

Kinetic studies of emulsified lipid hydrolysis systems have shown that the interfacial area strongly influences the reaction rate (Benzonana and Desnuelle, 1965). Macrae (1985) showed that rapid interesterification rates were obtained only if there was a large interfacial area between the oil and water phases. Garcia et al. (1991) studied the influence of emulsion particle size on the reaction rate of Aspergillus niger lipase-catalyzed milkfat hydrolysis. An increase in surface area led to greater enzyme activity. 

Much research has been carried out on the chemical interesterification of milkfat. Milkfat, like most fats, does not have a random distribution. Butyric and caproic acids, for example, are predominantly located at the sn-3 position, whereas palmitic acid is mostly at sn-l and sn-2 positions (Kuksis et al., 1973). Interesterification of milkfat can be a powerful means of modifying its functional properties. 

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