Comparison of Composition, Sensory Properties and Volatile Components of Whey Protein and Serum Protein Concentrates

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Title: Comparison of Composition, Sensory Properties and Volatile Components of Whey Protein and Serum Protein Concentrates
Author: Evans, Joshua Peter
Advisors: Dr. MaryAnne Drake, Committee Chair
Dr. Lynn Turner, Committee Member
Dr. E. Allen Foegeding, Committee Member
Abstract: EVANS, JOSHUA PETER. Comparison of Composition, Sensory and Volatile Components of Whey Protein and Serum Protein Concentrates. (Under the direction of Dr. MaryAnne Drake.) Whey proteins are highly functional and nutritious proteins used in a variety of products. Whey protein concentrate (WPC) is one of the most commonly used value-added forms of whey protein. Whey proteins should ideally have a bland flavor to facilitate application in foods, but flavor of these products is highly variable due to the original whey source, processing, and storage. Recent research has highlighted removal of whey proteins from skim milk prior to cheese making. These proteins removed from milk before the cheese making process are referred to as serum or “native†whey proteins and serum protein concentrate (SPC) when further processed to 34-89% protein. Since SPC are not exposed to the cheese make-process, enzymatic and/or chemical reactions that can lead to off-flavors are reduced. The objectives of this research were to characterize and compare the composition, sensory properties, and flavor chemistry of both whey protein concentrate and serum protein concentrate at protein concentrations of 34 and 80% (SPC34, WPC34, SPC80, WPC80). A second objective was to compare the composition, sensory properties and flavor chemistry of the serum protein and whey protein concentrates made in our study with those of commercial WPC34 and WPC80. SPC and WPC were manufactured in triplicate with each pair of serum and traditional whey protein manufactured from the same lot of milk. At each replication, spray-dried (SD) product from each protein source was collected. Commercial WPC34 and WPC80 were also collected for sensory and volatile analyses. A trained sensory panel documented the sensory profiles of the rehydrated powders. Volatile components were extracted by solid phase micro-extraction (SPME) and solvent extraction followed by solvent assisted flavor evaporation (SAFE) with gas chromatography-mass spectrometry and gas chromatography-olfactometry. Consumer acceptance testing with 6 % protein beverages was conducted with SPC80 and WPC80, as well as commercial WPC80. Fat content of SPC34 and SPC80 was lower and pH was higher than WPC34 and WPC80 (p<0.05). Few sensory differences were documented between the rehydrated SPC and WPC at both protein levels manufactured in this study, but their flavor profiles were distinct from flavor profiles of rehydrated commercial WPC (p<0.05). WPC34 and WPC80 generally had higher concentrations of lipid oxidation products than SPC34 and SPC80 (p<0.05). Lipid oxidation product concentrations were also higher in commercial products compared to pilot plant products (p<0.05). Fifty-six aroma active compounds were identified in the four products manufactured in this study (WPC34, SPC34, WPC80, SPC80), eighteen of these compounds were found in all four products. Overall, aroma active compounds were primarily lipid oxidation products, followed by fermentation, Strecker degradation, Maillard browning, and caramelization products. More aroma-active compounds were identified in the 80% protein samples (46) than in the 34% protein samples (29). Free fatty acid and soapy flavors and bitter taste were identified in beverages made with SPC80, and soapy flavor and bitter taste were documented in beverages made with WPC80 manufactured in this study; these flavors were not present in beverages made with commercial WSPC80. Overall consumer acceptance scores were highest for beverages made with one commercial WPC80 followed by beverages made with the WPC80 manufactured in this study. Differences between products manufactured in this study and commercial samples, as well as variability among commercial samples alone, suggests that additional processing parameters contribute to flavor and flavor variability in WPC. Composition, physical properties and volatile compound composition of SPC are distinct from WPC, and these differences may contribute to flavor differences in ingredient applications.
Date: 2009-03-11
Degree: MS
Discipline: Food Science

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