Characterization of Dried Whey Protein Concentrate and Isolate Flavor

Abstract

The flavor of whey protein concentrates (WPC 80) and whey protein isolates (WPI) was studied using instrumental and sensory techniques. Four WPC 80 and 4 WPI, less than 3 mo old, were collected in duplicate from 6 manufacturers in the United States. Samples were rehydrated and evaluated in duplicate by descriptive sensory analysis. Duplicate samples with internal standards were extracted with diethyl ether. Extracts were then distilled to remove nonvolatile material using high vacuum distillation. Volatile extracts were analyzed using gas chromatography/olfactometry with post peak intensity analysis and aroma extract dilution analysis. Compounds were identified by comparison of retention indices, odor properties, and gas chromatography/mass spectrometry against reference standards. Whey proteins exhibited sweet aromatic, cardboard/wet paper, animal/wet dog, soapy, brothy, cucumber, and cooked/milky flavors, along with the basic taste bitter, and the feeling factor astringency. Key volatile flavor compounds in WPC 80 and WPI were butanoic acid (cheesy), 2-acetyl-1-pyrroline (popcorn), 2-methyl-3-furanthiol (brothy/burnt), 2,5-dimethyl-4-hydroxy-3-(2H)-furanone (maple/spicy), 2-nonenal (fatty/old books), (E,Z)-2,6-nonadienal (cucumber), and (E,Z)-2,4-decadienal (fatty/oxidized). This baseline data on flavor and flavor sources in whey proteins will aid ongoing and future research and will help to identify the most appropriate whey ingredients to use to control or minimize flavor variability in whey enhanced products.

Flavor of whey protein concentrates and isolates

“…It is likely that the higher lactose and fat content (Table 4) of the WPC samples led to more Maillard reaction and lipid oxidation product formation. All sample pairs, with the exception of mozzarella WPC and WPI, had between 4 and 11 fewer compounds detected for WPI products; Carunchia Whetstine et al (2005) also reported fewer compounds derived from lipid oxidation in WPI as compared with WPC. Additionally, the MF and UF procedures during WPI manufacture were not only methods of whey component fractionation, but also probable sources of volatile loss.…”

“…Based on prior research (Carunchia Whetstine et al, 2005;Gallardo-Escamilla et al, 2005b), we had expected to find more differences within the WPC and WPI groups due to the different cheese types and processing methodologies. One reason for the lack of these differences may be because we processed, spray dried, and stored all the wheys under the same controlled conditions in our pilot plant (except for IEX) and thus removed many sources of variability.…”

“…Also, we hypothesized that WPC made from cottage cheese whey will be more acidic than WPC made with other production methodologies (Scott, 1981), and thus be more sour. Other researchers (Carunchia Whetstine et al, 2005;Gallardo-Escamilla et al, 2005b) have shown that cheese type and processing methodologies affect liquid whey flavor and, therefore, we expected to see differences among dried WPC and WPI in this study due to cheese type and processing methodology.…”

“…In total, for all fresh samples, 30 compounds were identified by GC-O and GC-MS. The majority of these compounds have been identified in other dry whey protein products and referenced appropriately in Table 3 (Carunchia Whetstine et al, 2005;Feretti & Flanagan, 1971a;Lee et al, 1996;Mahajan et al, 2004;Mills, 1993;Mills & Broome, 1998;Quach et al, 1999;Stevenson & Chen, 1996;Yang et al, 1998). The reader is referred to the aforementioned references for discussion of aroma compound formation in whey products.…”

“…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.…”