Fat modification processes

Mixtures of triglycerides, triglycerides plus free fatty adds or triglycerides plus fatty acid alkyl esters are used as reactants in fat modification processes. These mixtures are exposed to lipases supported on macroporous particles in the presence of a small amount of water. Liquid substrates (oils) can be reacted without use of a solvent, but with solid reactants (fats) it is necessary to add a solvent to ensure that the reactants and products are completely dissolved in the organic phase. Various water immisdble solvents can be used, but hexane is preferred for commercial operation because this solvent is already used industrially for the processing of oils and fats. 

The fat modification processes can be operated either in batches using stirred tank reactors or continuously with packed bed reactors. 

The main current potential application of lipase-catalyzed fat-modification processes is in the production of valuable confectionery fats for instance, alternative methods of obtaining cocoa-butter equivalents by converting cheap palm-oil fats and stearic acid to cocoa-butter-like fats. The reaction is executed in a water-poor medium, such as hexane, to prevent hydrolysis. At least one commercial apphcation exists. Loders Croklaan (Unilever) has an enzymatic interesterification plant in Wormerveer, the Netherlands. Many other new potential applications of lipases have been proposed of which some will certainly be economically feasible. Examples and details can be found in chapter 9 of this book. 

Timms, R.E. 2005. Fractional crystallization-the fat modification process for the 21st century. Eur. J. Lipid Sci. Technol. 107, 48-57. 

Natural fats and oils can be used directly in products, either individually or as mixtures. In many cases, however, it is necessary to modify their properties, particularly their melting characteristics, to make them suitable for particular applications. Therefore, the oils and fats industry has developed several modification processes using enzyme technology. In particular, lipases (and lately cutinases), phospholipases and pectinases can be used for interesterification processes, ester syntheses and in olive-oil extraction. 

This chapter is focussed on the post-farm modification of milk fat by physical, chemical or enzymic means. The use and control of these processes for differentiation of milk fat to widen its application range or tailor it for specific end-applications (Mortensen, 1983 Mogensen, 1985 Boudreau and Arul, 1991 Rajah and Burgess, 1991) will be discussed. The effects of the modification processes and minor lipid components on the texture and crystallization behavior of milk fat are covered. The potential for applying modification processes to improve the nutritional quality of milk fat is also considered. 

Although the processes of hydrogenation and chemical interesterification that are commonly used in the wider oils and fats industry may be applied to milk fat, there are a number of factors that prevent these being an attractive option for milk fat modification. Apart from the fact that ingredient manufacturers are seeking alternatives to the use of chemicals, milk fat is... 

O Donnell, J.A. (1993). Future of milk fat modification by production or processing Integration of nutrition, food science and animal science. ]. Dairy Sci. 76,1797-1801. 

Interesterification is an interchange of acyl groups between either ester and alcohol (alcoholysis), ester and acid (acidolysis), or between two esters (proper esterification). Esterification is most widely applied to fat modification because it relocates FA in TAG of one or several fat components to be modified, hi this process, acyl groups are repositioned both within TAG molecules (intramolecular esterification) and between different molecules (intermolecular esterification). 

The modification processes which will be described are hydrogenation, fractionation and interesterification. These processes are used to widen the applicability of oils and fats and also, in the case of hydrogenation, to make products of acceptable oxidative and flavour stability from unstable or relatively unstable raw materials. 

The refining processes are used to purify edible oils. The modification processes increase their useability. The latter processes consist of hydrogenation, interesterification and fractionation. They can be used alone or in combination with each other and they can be used on single oils or fats or on blends. Examples of their use are as follows ... 

Similar materials are available based on potato starch, eg, PaseUi SA2 which claims DE below 3 and has unique properties based on its amylose—amylopectin ratio pecuhar to potato starch. The product contains only 0.1% proteia and 0.06% fat which helps stabilize dried food mixes compounded with it. Another carbohydrate raw material is waxy-maize starch. Maltodextrias of differeat DE values of 6, 10, and 15, usiag waxy-maize starch, are available (Staley Co.). This product, called Stellar, is offered ia several physical forms such as agglomerates and hoUow spheres, and is prepared by acid modification (49). Maltodextrias based oa com starch are offered with DEs of 5, 10, 15, and 18 as powders or agglomerates (Grain Processing Corp.). 

Ingredient Additions and Substitutions. Processed meat products have the greatest opportunity for fat reduction for modification because their composition can be altered by reformulation with a fat replacement (see Fat replacers). 

The following factors appear to control the emulsification properties of milk proteins in food product applications 1) the physico-chemical state of the proteins as influenced by pH, Ca and other polyvalent ions, denaturation, aggregation, enzyme modification, and conditions used to produce the emulsion 2) composition and processing conditions with respect to lipid-protein ratio, chemical emulsifiers, physical state of the fat phase, ionic activities, pH, and viscosity of the dispersion phase surrounding the fat globules and 3) the sequence and process for incorporating the respective components of the emulsion and for forming the emulsion. 

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