Descriptive sensory evaluation, gas chromatography-olfactometry (GC-O), and gas chromatography-mass spectrometry (GC-MS) were used to determine whether cheese variety and processing techniques influenced the flavor of reconstituted whey protein concentrate (WPC) and whey protein isolate (WPI). Five different raw whey streams were used to produce a total of 12 different pilot-scale WPC and WPI products using membrane filtration, ion exchange, instantizing, and bleaching operations. Panelists rated WPC higher than WPI for milky, sweet, and caramel flavors; instrumental analysis showed that WPC products had a greater number of volatiles than WPI products. Neither the WPC samples (other than cottage cheese) nor the WPI samples differed significantly on the sensory attributes tested. Contrary to expectations, sensory results indicated that the flavor of WPC and WPI was not affected by instantizing, ion exchange, or bleaching; alternatively, instrumental results indicated slight differences in numbers of volatiles identified for each aforementioned process.
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The authors would like to thank Dairy Management Inc., for their financial support. We would also like to thank: PTI Advanced Filtration Inc. (Oxnard, CA, USA) for developing and implementing the scheme for processing WPI; our whey suppliers Davisco Foods International Inc. (LeSueur, MN, USA) and Kemps LLC (St. Paul, MN, USA); and Ray Miller of the University of Minnesota pilot plant for his advice and assistance. Finally, we extend a great deal of gratitude to Monica Coulter and The Sensory Center in the Department of Food Science and Nutrition, University of Minnesota.