@article{wright_zevchak_wright_drake_2009, title={The Impact of Agglomeration and Storage on Flavor and Flavor Stability of Whey Protein Concentrate 80% and Whey Protein Isolate}, volume={74}, ISSN={["1750-3841"]}, DOI={10.1111/j.1750-3841.2008.00975.x}, abstractNote={ABSTRACT:  The impact of agglomeration on flavor and flavor stability of whey protein concentrates 80% (WPC80) and whey protein isolates (WPI) has not been widely addressed. This study examined the impact of agglomeration on the flavor and flavor stability of commercial WPC80 and WPI across 18 mo of storage. Duplicate agglomerated and nonagglomerated WPC80 and WPI were collected from 4 facilities and stored at 21 °C, 50% relative humidity. Volatile analysis using solid phase microextraction (SPME) with gas chromatography‐mass spectrometry (GC‐MS) and descriptive sensory analysis were conducted every 2 mo. Solubility index, bulk volume, dispersibility, moisture, and color (L, a, b) were tested every 3 or 6 mo. Consumer acceptance testing with protein beverages was conducted with fresh and stored whey proteins. Higher intensities and more rapid development of lipid oxidation flavors (cardboard, raisin/brothy, cucumber, and fatty) were noted in agglomerated powders compared to nonagglomerated powders (P < 0.05). Volatile analysis results confirmed sensory results, which indicated increased formation of aldehydes and ketones in agglomerated products compared to nonagglomerated powders (P < 0.05). Consumer acceptance scores for protein beverages were lower for beverages made with agglomerated WPC80 stored for 12 mo and agglomerated or nonagglomerated WPI stored for 18 mo compared to fresh products while trained panelists detected differences among beverages and rehydrated proteins earlier. Agglomeration with or without lecithin decreased the storage stability of whey proteins. These results indicate that the optimum shelf life at 21 °C for nonagglomerated whey proteins is 12 to 15 mo and 8 to 12 mo for agglomerated whey proteins.}, number={1}, journal={JOURNAL OF FOOD SCIENCE}, author={Wright, B. J. and Zevchak, S. E. and Wright, J. M. and Drake, M. A.}, year={2009}, pages={S17–S29} }
 @article{wright_whetstine_miracle_drake_2006, title={Characterization of a cabbage off-flavor in whey protein isolate}, volume={71}, ISSN={["1750-3841"]}, DOI={10.1111/j.1365-2621.2006.tb08887.x}, abstractNote={ABSTRACTWhey protein isolate (WPI) is a value‐added protein with multiple ingredient applications. A bland flavor is expected in WPI, and off‐flavors can limit its use in foods. Recently, a cabbage off‐flavor was noted in some WPI. The objective of this study was to characterize the source of cabbage flavor in WPI. WPI with and without cabbage flavor were collected, and descriptive sensory analysis was conducted on the rehydrated WPI using a trained panel and a previously identified sensory language. Volatile compounds were extracted by solvent extraction followed by solvent‐assisted flavor evaporation (SAFE), followed by gas chromatography‐mass spectrometry (GC‐MS) and gas chromatography‐olfactometry (GCO), to identify and characterize aroma‐active compounds. Dimethyl trisulfide (DMTS) (cabbage aroma) was identified by GCO and GC‐MS in WPI with the cabbage flavor. DMTS was quantified by solid‐phase microextraction (SPME) with GC‐MS. Orthonasal thresholds of DMTS in deodorized water and WPI were determined by ascending forced choice analysis, and descriptive analysis of model systems was used to confirm instrumental results. DMTS levels were 1.94 ± 0.26 and 3.25 ± 0.61 parts per billion (ppb) in WPI with cabbage flavor, and 0.44 ± 0.25 and 0.43 ± 0.18 ppb in those without cabbage flavor. The orthonasal thresholds for DMTS in water and WPI were 0.07 ± 1.28 parts per trillion (ppt) and 0.80 ± 0.45 ppb, respectively. Descriptive analysis of model systems confirmed the role of DMTS in the cabbage off‐flavor. Knowledge of the source of this flavor will aid in identification of ways to minimize or prevent DMTS formation in WPI.}, number={2}, journal={JOURNAL OF FOOD SCIENCE}, author={Wright, JM and Whetstine, MEC and Miracle, RE and Drake, M}, year={2006}, month={Mar}, pages={C86–C90} }