Characterization of a Cabbage Off‐flavor in Whey Protein Isolate

Abstract

Whey 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.

Volatile component change in whey protein concentrate during storage investigated by headspace solid-phase microextraction gas chromatography

“…However, whey protein concentrate typically has a "whey" flavor. As flavor is one of the most important factors affecting consumer choice and acceptance of dairy products [6], much research has been focused on the understanding the chemical nature of this whey offflavor [13,15,16,21,22].…”

Flavor of whey protein concentrates and isolates

“…The volatiles isolated from white WPC products were similar to CWPC and the white WPI products and CWPI differed only by the detection of three additional compounds identified in CWPI: dimethyl trisulfide, 2,6-nonadienal, and benzoic acid. Dimethyl trisulfide is believed to be formed by degradation of sulfur-containing amino acids (Wright et al, 2006) and 2,6-nonadienal is likely formed through lipid oxidation reactions (Frankel, 1985;Hammond, 1989). Low levels of benzoic acid naturally occur in fresh milk and significantly increase during cheese production (Richardson & Gray, 1981).…”

“…Investigations focusing on volatile aroma compounds contributing to flavor of various types of whey protein products were published in the early 1970s and continue to appear (Carunchia Whetstine, Croissant, & Drake, 2005;Feretti & Flanagan, 1971a, b;Gallardo-Escamilla, Kelly, & Delahunty, 2005a, b;Karagul-Yuceer, Drake, & Cadwallader, 2003;Laye, Karleskind, & Morr, 1995;Lee, Laye, Kim, & Morr, 1996;Mahajan, Goddik, & Qian, 2004;Mills, 1986Mills, , 1993Mills & Broome, 1998;Quach, Chen, & Stevenson, 1999;Stevenson & Chen, 1996;Whetstine, Parker, Drake, & Larick, 2003;Wright, Carunchia Whetstine, Miracle, & Drake, 2006;Yang, Li, & Harper, 1998). The products examined in the aforementioned publications include commercially and laboratory prepared whey powders, WPC, sweet whey powder, and liquid whey from cheese production or fermented milk.…”

Odor Components and the Control of Odor Development in Ornamental Cabbage

“…The cut stem was probably the source of these compounds. Dimethyl trisulfide, 4-methylthiobutanenitrile, and methyl methylthiomethyl disulfide have been reported to cause an unpleasant smell in Brassicaceae (Spadone et al, 2006;Wright et al, 2006;Yukawa et al, 2003). However, except for dimethyl disulfide, these compounds were not detected as headspace volatiles of vase water (Table 1).…”

“…Unfortunately, the odor-active components have not been identified so far. In general, sulfur-containing compounds such as dimethyl sulfide, its derivatives, and isothiocyanates are known as unpleasant scent components in Brassicaceae (Spadone et al, 2006;Wright et al, 2006;Yukawa et al, 2003). Levels of unpleasant odor compounds are increased by mechanical damage (Spadone et al, 2006;Tulio et al, 2002) and microbial growth (Cho et al, 2009;Forney et al, 1993) in the plant tissue; in other words, the unpleasant smell intensifies when the plants rot.…”