Trends in research for alternate uses of milk fat

Rapid analysis of acylglycerols in low molecular weight milk fat fractions

A suitable analytical method was required to facilitate development of an industrial-scale short-path distillation (SPD) process. Short-path distillation produces milk fat distillates (MFD) enriched in low molecular weight milk fat components-viz. free fatty acids, monoacylglycerols, diacylglycerols, cholesterol and low molecular weight triacylglycerols. In this case, solid-phase extraction (SPE) was considered a better alternative than thin-layer chromatography for separating polar and apolar lipid components in MFD samples due to its speed and near-complete recoveries. Solid-phase extraction of MFDs yielded two fractions, both of which are sufficiently pure for subsequent analysis by gas chromatography. This procedure provided rapid and complete chemical characterization (including mass balances) of low-molecular weight milk-fat fractions.

Major Advances in Concentrated and Dry Milk Products, Cheese, and Milk Fat-Based Spreads

Advances in dairy foods and dairy foods processing since 1981 have influenced consumers and processors of dairy products. Consumer benefits include dairy products with enhanced nutrition and product functionality for specific applications. Processors convert raw milk to finished product with improved efficiencies and have developed processing technologies to improve traditional products and to introduce new products for expanding the dairy foods market. Membrane processing evolved from a laboratory technique to a major industrial process for milk and whey processing. Ultra-filtration and reverse osmosis have been used extensively in fractionation of milk and whey components. Advances in cheese manufacturing methods have included mechanization of the making process. Membrane processing has allowed uniform composition of the cheese milk and starter cultures have become more predictable. Cheese vats have become larger and enclosed as well as computer controlled. Researchers have learned to control many of the functional properties of cheese by understanding the role of fat and calcium distribution, as bound or unbound, in the cheese matrix. Processed cheese (cheese, foods, spreads, and products) maintain their importance in the industry as many product types can be produced to meet market needs and provide stable products for an extended shelf life. Cheese delivers concentrated nutrients of milk and bio-active peptides to consumers. The technologies for the production of concentrated and dried milk and whey products have not changed greatly in the last 25 yr. The size and efficiencies of the equipment have increased. Use of reverse osmosis in place of vacuum condensing has been proposed. Modifying the fatty acid composition of milkfat to alter the nutritional and functional properties of dairy spread has been a focus of research in the last 2 decades. Conjugated linoleic acid, which can be increased in milkfat by alteration of the cow's diet, has been reported to have anticancer, anti-atherogenic, antidiabetic, and antiobesity effects for human health. Separating milk fat into fractions has been accomplished to provide specific fractions to improve butter spreadability, modulate chocolate meltability, and provide texture for low-fat cheeses.

Chemical and physical properties of butterfat-vegetable oil blend spread prepared with enzymatically transesterified canola oil and caprylic acid

Structured Lipid was synthesized from canola oil and caprylic acid with sn-1,3 specific lipase from Rhizomucor miehei. Cold spreadable butter was made by blending butterfat with the SL at a weight ratio of 80:20. Its chemical and physical properties were compared with pure butter and butterfat-canola oil 80:20 blend spread. The butterfat-SL blend had lower contents of hypercholesterolemic fatty acids (FAs) and the lowest atherogenic index (AI) as compared to the others. Melting and crystallization behaviors of butterfat-SL blend were similar to those of butterfat-canola oil blend above 0 degrees C. It showed solid fat contents (SFCs) similar to butterfat-canola oil blend but lower than pure butterfat. The butterfat-SL blend was shown to crystallize in the beta' form. There were no differences between the hardness of butterfat-SL blend spread and butterfat-canola oil blend spread. Rheological analysis showed that butterfat-SL blend spread lost its elastic behavior at 5 degrees C, a lower temperature than pure butter.

Fractionation of milk fat by short-path distillation

Fractionation of milk fat by short-path distillation changes the chemical composition and physical properties of the resulting fractions. Increases in distillation temperature from 125 to 250 degrees C increased distillate yield from 0.3 to 42.7% (wt/wt). The distillate was enriched in short- and medium-chain fatty acids and low molecular weight acylglycerols, while the retentate was enriched in long-chain saturated and unsaturated fatty acids as well as high molecular weight acylglyerols. As distillation temperature increased, dropping points of the distillate increased. Relative to native milk fat, the solid fat content (SFC) vs. temperature melting profile of the distillate was depressed and that of the retentate was augmented, which correlated with the saturated long-chain fatty acid content in the fractions. Retentate crystallization parameters obtained by fitting the Avrami model to SFC-time data, did not change as a function of distillation temperature, but varied as a function of the degree of undercooling. Changes in microstructure observed by polarized light microscopy also appeared to be solely a function of the degree of undercooling, with no observable differences between retentates obtained at the different distillation temperatures. In addition, no changes in the retentate's free energy of nucleation (deltaGc) as a function of distillation temperature were found. The compressive storage modulus of the crystallized retentate increased as a function of increasing distillation temperature.

The composition of bovine milk lipids: January 1995 to December 2000

Data from recent publications on bovine milk lipids are presented and discussed. This includes extraction of lipids, triacylglycerols, phospholipids, other complex lipids, sterols, isoflavones, and fatty acids. Improved gas-liquid and high performance liquid chromatography were used. Data on the trans and cis isomers of fatty acid and of conjugated linoleic acids are given, and the analyses are described. Papers about the lipids in milks and dairy products from the United States are few; where with the exception of trans-fatty acid isomers and conjugated linoleic acids, almost no research has been reported.