Fat Products Using Fractionation and Hydrogenation

Abstract

Fractionation and hydrogenation are two widely used processes which help to alter the melting profile, physical properties and chemical composition of the feed oil or fat and the products so produced are in effect new ingredients suitable for use in applications in which the original oil/fat could never have been used or would have performed poorly. Fractionation is a thermomechanical process which eventually leads to two new products, an olein and a stearin. The olein can be used in further fractionations. Three types of fractionation systems are available, dry, solvent and detergent. Stages within each process such ilS nucleation and crystallisation and the conditions under which these are carried out are critical in determining the quality of the fractions. Equally, the separation efficiency of the filters also decides the yield of each fraction. Vacuum filters (e.g. Florentine, Vacuband, Stockdale) are being challenged by positive pressure membrane filters. Recent innovation with respect to the latter is a membrane filter by Krupp used in dry fractionation of fats for cocoa butter replacers. During filtration the pressure can be increased up to an end pressure of more than 50 bar. Fractionation has enabled the introduction of many fats, particularly milkfat, into new food applications. These fats are now used to better effect in areas such as in the manufacture of stable creams, buttercreams, sauces, infant feed, ice-cream, bakery products and chocolate. The use of fractionated milkfat in yellow fat spreads is increasing, particularly in the production of spreadable butters. Fractionated fats are also used as stable frying oils and salad oils. The fractionated oils or fats can be incorporated directly into some recipes but in others they are used in blends with other oils. Some are also treated in further processes such as texturisation, in this case to make them suitable for use in bakery products. The measurement of solid fat content at 20C by pulse NMR is a useful aid for determining suitability of milkfats for specific food applications. Hydrogeneration decreases the unsaturation of triacylglycerol oils and thereby increases their melting points. The chemical composition of the feed and the conditions under which the reaction is carried out, together with the type of catalyst used, help to determine the physical properties of the fat and the way in which it melts over a temperature range. The choice of the D. P. J. Moran et al. (eds.), Fats in Food Products