In this study, 2 different extraction methods, namely solvent-assisted flavor evaporation (SAFE) and solid-phase microextraction (SPME), were employed to investigate the comprehensive volatile profile of Doenjang (one of Korean fermented soybean pastes) efficiently. Quantitatively, major volatiles of Doenjang isolated by SAFE were 3-methylbutanoic acid, butanoic acid, 3-hydroxy-2-methyl-4H-pyran-4-one (maltol), ethyl 2-methylbutanoate, 2-methylpropanoic acid, tetramethylpyrazine, and 4-ethyl-2-methoxyphenol, while ethanol, ethenylbenzene, ethyl benzoate, ethyl linoleate, ethyl acetate, ethyl butanoate, tetramethylpyrazine, and ethyl 2-methylpropanoate extracted by SPME. In addition, volatile profiling that applied principal component analysis to gas chromatography-mass spectrometry datasets allowed Doenjang samples that had been prepared using different traditional and commercial methods to be discriminated, and the volatile compounds that contributed to their discrimination were assigned. The major volatiles that were related to differentiation of traditional and commercial Doenjang samples were 2-pentylfuran, 4-ethylphenol, dihydro-5-methyl-2(3H)-furanone, butanoic acid, pyrazines (for example, 2-ethyl-5-methylpyrazine and 2,3-dimethylpyrazine), esters (for example, ethyl 4-methylpentanoate and diethyl succinate), maltol, dimethyl disulfide, 2- and 3-methylbutanal, hexanal, 4-vinylphenol, and ethanol.

Typical high-temperature, short-time (HTST) pasteurization encompasses a lower heat treatment and shorter refrigerated shelf life compared with ultra-pasteurization (UP) achieved by direct steam injection (DSI-UP) or indirect heat (IND-UP). A greater understanding of the effect of different heat treatments on flavor and flavor chemistry of milk is required to characterize, understand, and identify the sources of flavors. The objective of this study was to determine the differences in the flavor and volatile compound profiles of milk subjected to HTST, DSI-UP, or IND-UP using sensory and instrumental techniques. Raw skim and raw standardized 2% fat milks (50 L each) were processed in triplicate and pasteurized at 78°C for 15 s (HTST) or 140°C for 2.3 s by DSI-UP or IND-UP. Milks were cooled and stored at 4°C, then analyzed at d 0, 3, 7, and 14. Sensory attributes were determined using a trained panel, and aroma active compounds were evaluated by solid-phase micro-extraction or stir bar sorptive extraction followed by gas chromatography-mass spectrometry, gas chromatography-olfactometry, and gas chromatography-triple quad mass spectrometry. The UP milks had distinct cooked and sulfur flavors compared with HTST milks. The HTST milks had less diversity in aroma active compounds compared with UP milks. Flavor intensity of all milks decreased by d 14 of storage. Aroma active compound profiles were affected by heat treatment and storage time in both skim and 2% milk. High-impact aroma active compounds were hydrogen sulfide, dimethyl trisulfide, and methional in DSI-UP and 2 and 3-methylbutanal, furfural, 2-heptanone, 2-acetyl-1-pyrroline, 2-aminoacetophenone, benzaldehyde, and dimethyl sulfide in IND-UP. These results provide a foundation knowledge of the effect of heat treatments on flavor development and differences in sensory quality of UP milks.

Gouda cheese is a washed-curd cheese that is traditionally produced from bovine milk and brined before ripening for 1 to 20 mo. In response to domestic and international demand, US production of Gouda cheese has more than doubled in recent years. An understanding of the chemical and sensory properties of Gouda cheese can help manufacturers create desirable products. The objective of this study was to determine the chemical and sensory properties of Gouda cheeses. Commercial Gouda cheeses (n = 36; 3 mo to 5 yr; domestic and international) were obtained in duplicate lots. Volatile compounds were extracted by solid-phase microextraction and analyzed by gas chromatography-olfactometry and gas chromatography-mass spectrometry. Composition analyses included pH, proximate analysis, salt content, organic acid analysis by HPLC, and color. Flavor and texture properties were determined by descriptive sensory analysis. Focus groups were conducted to document US consumer perception followed by consumer acceptance testing (n = 149) with selected cheeses. Ninety aroma-active compounds in Gouda cheeses were detected by solid-phase microextraction/gas chromatography-olfactometry. Key aroma-active volatile compounds included diacetyl, 2- and 3-methylbutanal, 2-methylpropanal, methional, ethyl butyrate, acetic acid, butyric acid, homofuraneol, δ-decalactone, and 2-isobutyl-3-methoxypyrazine. Aged cheeses had higher organic acid concentrations, higher fat and salt contents, and lower moisture content than younger cheeses. Younger cheeses were characterized by milky, whey, sour aromatic, and diacetyl flavors, whereas aged cheeses were characterized by fruity, caramel, malty/nutty, and brothy flavors. International cheeses were differentiated by the presence of low intensities of cowy/barny and grassy flavors. Younger cheeses were characterized by higher intensities of smoothness and mouth coating, whereas aged cheeses were characterized by higher intensities of fracture and firmness. American consumers used Gouda cheese in numerous applications and stated that packaging appeal, quality, and age were more important than country of origin or nutrition when purchasing Gouda cheeses. Young and medium US cheeses ≤6 mo were most liked by US consumers. Three distinct consumer segments were identified with distinct preferences for cheese flavor and texture. Findings from this study establish key differences in Gouda cheese regarding age and origin and identify US consumer desires for this cheese category.

Ready-to-mix (RTM) whey protein beverages are an expanding product category, and sensory properties strongly affect consumer acceptance and purchase intent. Because consumers themselves prepare RTM whey protein beverages, understanding possible gaps between central location test (CLT) and home usage test (HUT) results is critical. The objectives of this study were to compare results obtained from a CLT and a HUT and to identify the drivers of liking and disliking vanilla-flavored RTM whey protein beverages. Fourteen commercial vanilla-flavored RTM whey protein beverages were rehydrated with spring water at 15% solids (wt/vol) and evaluated by a trained panel (n = 8). Ten representative products were selected for consumer testing. Rehydrated beverages were subsequently evaluated by protein beverage consumers (n = 160) in a CLT. Nine representative products were selected for the HUT. Consumers prepared and evaluated individual beverages over 3 consecutive weeks, trying 3 samples each week. Overall liking and other attributes were scored by consumers in both tests. Data were evaluated by univariate and multivariate statistical analyses. Overall liking scores from the HUT were higher than scores from the CLT. The products with the highest and lowest overall liking scores were consistent between the CLT and HUT. More differences were observed among beverages by CLT compared with HUT when liking was averaged across all consumers. Both methods identified 2 distinct consumer clusters. Fruity flavor and sweet taste were drivers of liking, whereas cardboard flavor and bitter taste were drivers of disliking in both methods. The HUT exclusively identified thickness (viscosity) as a driver of liking and astringency as a driver of disliking. These results sug-gest that a CLT can be used to differentiate consumer acceptance among vanilla-flavored RTM whey protein beverages. A HUT should be used to provide more intensive insights for mouthfeel and mixing experiencerelated attributes.

A greater understanding of the nature and source of dried milk protein ingredient flavor(s) is required to characterize flavor stability and identify the sources of flavors. The objective of this study was to characterize the flavor and flavor chemistry of milk protein concentrates (MPC 70, 80, 85), isolates (MPI), acid and rennet caseins, and micellar casein concentrate (MCC) and to determine the effect of storage on flavor and functionality of milk protein concentrates using instrumental and sensory techniques. Spray-dried milk protein ingredients (MPC, MPI, caseins, MCC) were collected in duplicate from 5 commercial suppliers or manufactured at North Carolina State University. Powders were rehydrated and evaluated in duplicate by descriptive sensory analysis. Volatile compounds were extracted by solid phase microextraction followed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry. Compounds were identified by comparison of retention indices, odor properties, and mass spectra against reference standards. A subset of samples was selected for further analysis using direct solvent extraction with solvent-assisted flavor extraction, and aroma extract dilution analysis. External standard curves were created to quantify select volatile compounds. Pilot plant manufactured MPC were stored at 3, 25, and 40°C (44% relative humidity). Solubility, furosine, sensory properties, and volatile compound analyses were performed at 0, 1, 3, 6, and 12 mo. Milk proteins and caseins were diverse in flavor and exhibited sweet aromatic and cooked/milky flavors as well as cardboard, brothy, tortilla, soapy, and fatty flavors. Key aroma active compounds in milk proteins and caseins were 2-aminoacetophenone, nonanal, 1-octen-3-one, dimethyl trisulfide, 2-acetyl-1-pyrroline, heptanal, methional, 1-hexen-3-one, hexanal, dimethyl disulfide, butanoic acid, and acetic acid. Stored milk proteins developed animal and burnt sugar flavors over time. Solubility of MPC decreased and furosine concentration increased with storage time and temperature. Solubility of MPC 80 was reduced more than that of MPC 45, but time and temperature adversely affected solubility of both proteins, with storage temperature having the greatest effect. Flavor and shelf stability of milk proteins provide a foundation of knowledge to improve the flavor and shelf-life of milk proteins.

Fluid milk consumption in the United States continues to decline. As a result, the level of dietary vitamin D provided by fluid milk in the United States diet has also declined. Undesirable flavor(s)/off flavor(s) in fluid milk can negatively affect milk consumption and consumer product acceptability. The objectives of this study were to identify aroma-active compounds in vitamin concentrates used to fortify fluid milk, and to determine the influence of vitamin A and D fortification on the flavor of milk. The aroma profiles of 14 commercial vitamin concentrates (vitamins A and D), in both oil-soluble and water-dispersible forms, were evaluated by sensory and instrumental volatile compound analyses. Orthonasal thresholds were determined for 8 key aroma-active compounds in skim and whole milk. Six representative vitamin concentrates were selected to fortify skim and 2% fat pasteurized milks (vitamin A at 1,500-3,000 IU/qt, vitamin D at 200-1,200 IU/qt, vitamin A and D at 1,000/200-6,000/1,200 IU/qt). Pasteurized milks were evaluated by sensory and instrumental volatile compound analyses and by consumers. Fat content, vitamin content, and fat globule particle size were also determined. The entire experiment was done in duplicate. Water-dispersible vitamin concentrates had overall higher aroma intensities and more detected aroma-active compounds than oil-soluble vitamin concentrates. Trained panelists and consumers were able to detect flavor differences between skim milks fortified with water-dispersible vitamin A or vitamin A and D, and unfortified skim milks. Consumers were unable to detect flavor differences in oil-soluble fortified milks, but trained panelists documented a faint carrot flavor in oil-soluble fortified skim milks at higher vitamin A concentrations (3,000-6,000 IU). No differences were detected in skim milks fortified with vitamin D, and no differences were detected in any 2% milk. These results demonstrate that vitamin concentrates may contribute to off flavor(s) in fluid milk, especially in skim milk fortified with water-dispersible vitamin concentrates.

Background Unique among cnidarians, jellyfish have remarkable morphological and biochemical innovations that allow them to actively hunt in the water column and were some of the first animals to become free-swimming. The class Scyphozoa, or true jellyfish, are characterized by a predominant medusa life-stage consisting of a bell and venomous tentacles used for hunting and defense, as well as using pulsed jet propulsion for mobility. Here, we present the genome of the giant Nomura’s jellyfish ( Nemopilema nomurai ) to understand the genetic basis of these key innovations. Results We sequenced the genome and transcriptomes of the bell and tentacles of the giant Nomura’s jellyfish as well as transcriptomes across tissues and developmental stages of the Sanderia malayensis jellyfish. Analyses of the Nemopilema and other cnidarian genomes revealed adaptations associated with swimming, marked by codon bias in muscle contraction and expansion of neurotransmitter genes, along with expanded Myosin type II family and venom domains, possibly contributing to jellyfish mobility and active predation. We also identified gene family expansions of Wnt and posterior Hox genes and discovered the important role of retinoic acid signaling in this ancient lineage of metazoans, which together may be related to the unique jellyfish body plan (medusa formation). Conclusions Taken together, the Nemopilema jellyfish genome and transcriptomes genetically confirm their unique morphological and physiological traits, which may have contributed to the success of jellyfish as early multi-cellular predators. Electronic supplementary material The online version of this article (10.1186/s12915-019-0643-7) contains supplementary material, which is available to authorized users.

Volatile sulfur compounds in ultra-pasteurized (UP) milk are the major contributors to sulfur/burnt and eggy flavors, and these flavors are disliked by consumers. Previous research has established distinct differences in flavor profiles of fluid milk processed by high temperature, short time pasteurization (HTST) and UP by direct steam injection (DSI-UP) or indirect heat (IND-UP). An understanding of the contribution of the individual milk proteins to sulfur off-flavors would clarify the source of sulfur flavors in UP milks. The objective of this study was to determine the source of volatile sulfur compounds in fluid milk with a specific focus on the comparison of heat treatment effects on milks by HTST and UP. Formulated skim milks (FSM) were manufactured by blending micellar casein concentrate and serum protein isolate (SPI). Three different caseins as a percentage of true protein (FSM95, FSM80, and FSM60) were formulated to determine the source of sulfur/burnt and eggy flavors. Freshly processed micellar casein concentrate or SPI were blended to achieve a true protein content of about 3.2%. Raw skim milk served as a control. Skim milk and FSM were pasteurized at 78°C for 15 s (HTST) or 140°C for 2.3 s by IND-UP or DSI-UP. The experiment was replicated twice. Sensory properties of milks and FSM were documented by descriptive sensory analysis. Volatile sulfur compounds in milks and FSM were evaluated using solid-phase microextraction followed by gas chromatography-triple quadrupole mass spectrometry combined with a sulfur selective flame photometric detector. The FSM with higher SPI as a percent of true protein had higher sensory sulfur/burnt and eggy flavors along with elevated concentrations of hydrogen sulfide and carbon disulfide compared with skim milk or FSM with lower proportions of SPI. Sulfur compounds including dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, dimethyl sulfoxide, and methional were not associated with sulfur/burnt and eggy flavors, which suggests that these compounds may not specifically contribute to the sulfur/burnt and eggy off-flavors of UP milks. Sensory panelists found higher overall aroma impact, and cooked, sulfur/burnt, and eggy flavors for DSI-UP, followed by IND-UP and HTST. The combination of sensory and instrumental methods used in the current study effectively identified that milk serum proteins are the source of sulfur compounds in milk, and further confirmed the contribution of hydrogen sulfide and carbon disulfide to eggy and sulfur/burnt flavors, respectively.