Evaluating SPCs
May 19/Journal of Farming -- "Milk serum protein concentrates (SPC) are proteins found in cheese whey that are removed directly from milk. Because SPC are not exposed to the cheese-making process, enzymatic or chemical reactions that can lead to off-flavors are reduced," scientists writing in the Journal of Dairy Science report.

"The objectives of this study were to identify and compare the composition, flavor and volatile components of 80% protein SPC and whey protein concentrates (WPC). Each pair of 80% SPC and WPC was manufactured from the same lot of milk, and this was replicated three times. At each replication, spray-dried product from each protein source was collected. Commercial 80% WPC were also collected from several manufacturers for sensory and volatile analyses. A trained sensory panel documented the sensory profiles of the rehydrated powders. Volatile components were extracted by solid-phase microextraction and solvent extraction followed by solvent-assisted flavor evaporation with gas chromatography-mass spectrometry and gas chromatography-olfactometry.

"Consumer acceptance testing of acidified 6% protein beverages made with 80% SPC and WPC produced in the pilot plant and with WPC from commercial sources was conducted. The SPC was lower in fat and had a higher pH than the WPC produced in the pilot plant or commercial WPC. Few sensory differences were found between the rehydrated SPC and WPC manufactured in this study, but their flavor profiles were distinct from the flavor of rehydrated commercial WPC. The pilot-plant WPC had higher concentrations of lipid oxidation products compared with SPC, which may be related to the higher fat content of WPC. There was a large difference in appearance between 80% SPC and WPC: solutions of SPC were clear and those of WPC were opaque. Concentrations of lipid oxidation products in commercial WPC were generally higher than those in pilot-plant SPC or WPC. Sensory profiles of the peach-flavored protein beverage included cereal, free fatty acid, and soapy flavors and bitter taste in beverages made from pilot-plant products, whereas cardboard flavors were detected in those made with commercial WPC," wrote J. Evans and colleagues, North Carolina State University.

The researchers concluded, "Consumer liking scores for the beverages made with SPC were ranked highest or equally high with beverages made with WPC for aroma, appearance and mouthfeel, but the beverages made with SPC had lower flavor and overall liking scores compared with beverages made with three of the four WPC."

Evans and colleagues published their study in the Journal of Dairy Science ("Comparison of Composition and Sensory Properties of 80% Whey Protein and Milk Serum Protein Concentrates." Journal of Dairy Science, 2010;93(5):1824-1843).

Additional information can be obtained by contacting M.A. Drake, North Carolina State University, SE Dairy Foods Research Center, Dept. of Food Bioproc & Nutrition Science, Raleigh, NC 27695.

From the May 24, 2010, Prepared Foods E-dition