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.

Dried whey and whey protein are important food ingredients. Functionality of whey products has been studied extensively. Flavor inconsistency and flavors which may carry through to the finished product can limit whey ingredient applications in dairy and nondairy foods. The goal of this research was to determine the flavor and flavor variability of commercially produced liquid Cheddar cheese whey. Liquid Cheddar cheese whey from five culture blends from two different stirred-curd Cheddar cheese manufacturing facilities was collected. Whey flavor was characterized using instrumental and sensory methods. Wide variation in whey headspace volatiles was observed between different manufacturing facilities (P < 0.05). Hexanal and diacetyl were two key volatiles that varied widely (P < 0.05). FFA profiles determined by solid-phase microextraction and degree of proteolysis of the whey samples were also different (P < 0.05). Differences in whey flavor profiles were also confirmed by descriptive sensory analysis (P < 0.05). Differences in liquid whey flavor were attributed to differences in milk source, processing and handling and starter culture blend. The flavor of liquid Cheddar cheese whey is variable and impacted by milk source and starter culture rotation. Results from this study will aid future studies that address the impact of liquid whey flavor variability on flavor of dried whey ingredients.

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.

Umami plays an important role in the flavor of many cheese varieties. The purpose of this study was to identify the compound(s) responsible for umami taste in Cheddar and Swiss cheeses. Four Cheddar and 4 Swiss cheeses (two with low umami intensity and two with high umami intensity from each type) were selected using a trained sensory panel. Monosodium glutamate (MSG), disodium 5'-inosine monophosphate (IMP), disodium 5'-guanosine monophosphate (GMP), sodium chloride, lactic acid, propionic acid, and succinic acid were quantified in the cheeses instrumentally. Taste thresholds (best estimate thresholds, BETs) were determined for each compound in water. Subsequently, a trained descriptive sensory analysis panel evaluated each compound in odor-free water across threshold concentrations to confirm that the thresholds were based on umami and not some other stimuli. Model system studies with trained panelists were then conducted with each compound individually or all compounds together. Comparison of analytical data and sensory thresholds indicated that IMP and GMP thresholds were 100-fold higher than their concentrations in cheese. All other compounds contributed some umami taste within their concentration range in umami cheeses. Sensory analysis of model cheeses revealed that glutamic acid played the largest role in umami taste of both Cheddar and Swiss cheeses while succinic and propionic acids contributed to umami taste in Swiss cheeses. Knowledge of the key compounds associated with umami taste in cheeses will aid in the identification of procedures to enhance formation of this taste in cheese.

Many consumers are concerned with fat intake. However, many reduced-fat foods, including reduced-fat cheese, lack robust flavors. The objectives of this study were to characterize the flavors found in full-fat cheese, cheese fat, and reduced-fat cheese made from aged Cheddar using a novel process to remove the fat (Nelson and Barbano, 2004). Two full-fat, aged cheeses (9 and 39 mo) were selected, and the fat was removed using the novel fat removal process. Full-fat cheeses, shredded and reformed full-fat cheeses, corresponding reduced-fat cheeses, and cheese fats were then analyzed using descriptive sensory and instrumental analysis followed by consumer acceptance testing. Cheeses were extracted with diethyl ether followed by isolation of volatile material by high vacuum distillation. Volatile extracts were analyzed using gas chromatography/ olfactometry with aroma extract dilution analysis. Selected compounds were quantified. The 39-mo cheese was characterized by fruity and sulfur notes, and the 9-mo-old cheese was characterized by a spicy/brothy flavor. Reduced-fat cheeses had similar flavor profiles with no difference in most sensory attributes to corresponding full-fat cheeses. Sensory profiles of the cheese fats were characterized by low intensities of the prominent flavors found in the full-fat cheeses. Instrumental analysis revealed similar trends. Consistent with sensory analysis, there were lower concentrations and log(3) flavor dilution factors for most compounds in the cheese fats compared with both the reduced- and full-fat cheeses, regardless of compound polarity. Consumers found the intensity of flavor in the reduced-fat cheese to be equal to the full-fat cheeses. This study demonstrated that when fat was removed from aged full-fat Cheddar cheese, most of the flavor and flavor compounds remained in the cheese and were not removed with the fat.