U.S. Milkfat Processors Look to New Technology for Market Growth
Grassland Dairy Products, Inc. of Greenwood, Wis. expects to have a Grassland spreadable butter product on the market by the middle of 1998. To do this, they have had to master the technique of fractionation, the process by which milkfat is separated into fractions with different physical and chemical properties. When low-melting fractions are combined with custom blending and appropriate texturization, the result is a butter that is spreadable straight from the refrigerator.
The Northland Dairy Company in New Zealand offers a spreadable butter product, Anchor, to consumers there and in the U.K., Chile, Portugal and Australia. In New Zealand alone, it is anticipated that local retail sales will run close to $7 million this year. Like Grassland, Northland Dairy relies on the same fractionation technique to produce Anchor. But unlike Grassland, European dairy producers have been successfully applying fractionation technology to develop milkfat ingredients for more than two decades.
Because surplus butter (a.k.a.: milkfat) had been bought up by the U.S. government, dairy producers here had no strong incentive to explore new applications for the product. But recently, as U.S. dairy producers have had to assume the responsibility for excess butter supplies, they have begun to look at new uses for their milk byproduct.
The commercialization of fractionation technology in this country was based on 10 years of dairy farmer-funded research by the University of Wisconsin-Madison's Center for Dairy Research (CDR), which Grassland Dairy's spreadable butter product depended on. Researchers at the Milkfat Fractionation Pilot Plant and Applications Lab at the CDR have been studying the development and application of milkfat ingredients for baked goods, confectionery products, butter spreads and flavors. The pilot plant facilities include a Tirtiaux fractionation unit and a Gerstenberg & Agger Perfector texturization unit. Analytical and applications labs allow the center to develop, produce, analyze, and evaluate a wide range of milkfat ingredients in foods.
Fractionation: The Technique
The most common method used to fractionate milkfat is dry crystallization. Anhydrous milkfat, which is 99.9 percent fat, is the starting material. Fractionation equipment generally consists of a control panel, a chiller for the cooling liquid, a stainless steel jacketed tank (crystallizer) with an agitator, and a means to separate the fractions—either by vacuum or pressure filtration, or by centrifugation. Milkfat is placed in the crystallizer and then heated until it is fully melted to ensure good crystallization. The milkfat is cooled and stirred using controlled conditions until the crystallization process is completed, yielding solid milkfat crystals suspended in liquid milkfat. The milkfat slurry is pumped to the filter and the liquid and solid fractions are separated. Several variables can be manipulated during the fractionation process to influence the properties of the fractions.
Milkfat ingredients are made by blending milkfat fractions and intact milkfat to meet the desired specifications for a selected application. The milkfat blend is then mixed with skim milk and other desired ingredients, such as salt. The final mixture is recrystallized using a texturizer in a manner similar to recombined butter or margarine. The texturizer consists of swept-surface heat exchangers to cool the mixture and initiate crystallization, a pin-worker to continue the crystallization under high-shear conditions, and resting tubes to allow the product to set and equilibrate. The texturizer produces a high quality finished product. The texturization process improves the functionality of milkfat ingredients designed for bakery use by increasing the plasticity of the products.
Grassland Dairy Products is producing milkfat fractions with various melting points, from 15ºC to 45°C. The melting point of milkfat is from 32ºC to 36°C. The products maintain the flavor of butter while modifying the functional attributes of aeration, layering, plasticity, solid fat content, firmness and softness.
Further Milkfat Applications
Beyond spreadable butters, milkfat fractions offer a host of other food applications. Bakery applications such as cakes, puff pastries and Danish butter cookies can benefit from milkfat fractions. Pastry butter that performs like vegetable fats and oils can be created, without compromising the rich taste of butter. European bakers have been using milkfat fractions to give their croissants and puff pastries lighter and flakier texture. The ingredient also has been used for flavor enhancement in cheeses and other products.
Milkfat fractions that melt at higher temperatures can increase storage stability of preventing fat bloom, a whitish discoloration and texture change caused by unstable cocoa crystals. Fractions that melt at lower temperatures can be used in softer chocolates for coating ice cream bars, and as cocoa butter extenders to save costs for chocolate producers.
In addition to the Pilot Plant and Applications Lab, CDR is also headquarters for the Milkfat Fractionation Consortium. The Consortium provides its members access to technical assistance, research expertise, product samples, and overall support. Members include both prospective manufacturers and potential users of milkfat fractions across a wide range of food products.
By Pam Ahlberg
For more information, contact:
Kerry E. Kaylegian, Wisconsin Center for Dairy Research, 1605 Linden Dr., Madison, WI 53706. Tel: 608-265-3086; Fax: 608-262-1578.
Grassland Dairy Products, Inc., 8790 Fairground Ave, Greenwood, WI 54437-7668. Tel: 715-267-6182; Fax: 715-267-6044.
Gerstenberg & Agger A/S, 21850 Watertown Rd., Suite 21, Waukesha, WI 53186.
Fractionnement Tirtiaux S.A., Rue De Fleurjoux 8, Fleurus 6220, Belgium. Tel: 32 71-813 787.