Flavor Dilution Research Articles

Analysis of key precursor peptides and flavor components of flaxseed derived Maillard reaction products based on iBAQ mass spectrometry and molecular sensory science

Flaxseed derived Maillard reaction products (MRPs) have typical meaty flavor, but there is no report on comparison of their amino acids and peptides reactivity. The peptides and amino acids of flaxseed protein hydrolysates were separately collected by G-15 gel chromatography. Taste dilution analysis (TDA) showed that peptides-MRPs had high umami, mouthfulness, and continuity enhancement. Further, LC-MS/MS revealed that flaxseed protein hydrolysates consumed 41 peptides after Maillard reaction. Particularly, DLSFIP (Asp-Leu-Ser-Phe-Ile-Pro) and ELPGSP (Glu-Leu-Pro-Gly-Ser-Pro) accounted for 42.22% and 20.41% of total consumption, respectively. Aroma extract dilution analysis (AEDA) indicated that formation of sulfur-containing flavors was dependent on cysteine, while peptides were more reactive than amino acids for nitrogen-containing heterocycles. On the other hand, 11 flavor compounds with flavor dilution (FD) ≥ 64 were identified for flaxseed derived MRPs, such as 2-methylthiophene, 2-methyl-3-furanthiol, furfural, 2-furfurylthiol, 3-thiophenethiol, thieno[3,2-b] thiophene, 2,5-thiophenedicarboxaldehyde, 2-methylthieno[2,3-b] thiophene, 1-(2-methyl-3-furylthio)-ethanethiol, 2-methylthieno[3,2-b] thiophene, and bis(2-methyl-3-furyl)-disulfide. In addition, we further demonstrated the flavors formation mechanism of flaxseed derived MRPs.

Effect of Wort Boiling on Volatiles Formation and Sensory Properties of Mead.

Mead is an alcoholic beverage based on bee honey, which can be prepared in different variations such as modified honey-water compositions, the addition of spices, and the use of different yeast strains. Moreover, the technological process of mead production such as the step of wort preparation (with or without boiling of wort before fermentation) can be modified. All these factors might have a significant impact on the formation of aroma-active compounds, and therefore, sensory acceptance by consumers. High vacuum distillation, using the so-called solvent assisted flavor evaporation (SAFE) technique, or headspace-solid phase microextraction (HS-SPME) were applied for the isolation of the odorants. A sensory profile was used to monitor the changes in the aroma of the mead samples. Twenty-eight aroma-active compounds were detected during aroma extract dilution analysis (AEDA) based on gas chromatography-olfactometry (GC-O) and were finally identified by gas chromatography-mass spectrometry (GC-MS) using authentic reference compounds, including methyl propanoate, methyl 3-(methylthio)propanoate, and methional, all of them were identified for the first time in mead. Compounds with high flavor dilution (FD) factors were quantitated via stable isotope dilution analysis (SIDA) and revealed ethyl acetate (16.4 mg/L) to be the most abundant volatile compound, increasing to 57 mg/L after wort boiling, followed by ethyl hexanoate (both 1.2 mg/L). Furthermore, key aroma compounds were esters such as ethyl hexanoate, ethyl octanoate, and ethyl 3-methylbutanoate. The sensory panel evaluated ethanolic, honey-like, clove-like, sweet, and fruity notes as the main aroma descriptors of mead. The significant change in sensory evaluation was noted in the sweet odor of the heat-treated mead.

Changes in key aroma-active compounds and sensory characteristics of sunflower oils induced by seed roasting.

This study investigated the changes in aroma composition and perception of sunflower oils induced by seed roasting using sensory-oriented flavor analysis. Volatile compounds were extracted by solvent-assisted flavor evaporation and headspace solid-phase microextraction. Odorants were characterized by gas chromatography-olfactometry-mass spectrometry and aroma extract dilution analysis. The cold-pressed and roasted sunflower oils contained 13 and 50 odorants, respectively, with the flavor dilution factors between 1 and 256. Fifty-six odorants were newly identified in sunflower oils. Quantification of 26 important odorants by the external standard method revealed apparent changes induced by seed roasting in loss of terpenes, formation of Maillard reaction products, and the increase in lipid oxidation products. The most important odorants (odor active values, OAVs=1-1857) in the cold-pressed sunflower oil included α-pinene (11,145µg/kg), β-pinene (4068µg/kg), linalool (56µg/kg), hexanal (541µg/kg), octanal (125µg/kg), α-phellandrene (36µg/kg), and (E)-2-octenal (69µg/kg), contributing to the raw sunflower seed, woody, green, earthy, and sweet aromas of the oil. The most important contributors (OAVs=1-884) to the roasted, smoky, and burnt aromas of the roasted sunflower oil were 2- and 3-methylbutanal (6726 and 714µg/kg), 2,6-dimethylpyrazine (2329µg/kg), 2,5-dimethylpyrazine (12,228µg/kg), 2,3-dimethylpyrazine (238µg/kg), 2,3-pentanedione (1456µg/kg), 2-pentylfuran (1332µg/kg), 2,3-dimethyl-5-ethylpyrazine (213µg/kg), and 1-pentanol (693µg/kg). Aroma recombination of the key odorants in odorless sunflower oil adequately mimicked the general aroma profiles of sunflower oils. This study provides an important foundation for understanding the relationship between oil processing and aroma molecules of sunflower oils. PRACTICAL APPLICATION: The clear changes observed in the composition and concentrations of key aroma compounds explained the changes in sensory characteristics of sunflower seed oils induced by seed roasting on a molecular basis. Characterizing the key aroma-active composition of sunflower oil and investigating its relationship with oil processing could provide important practical applications for the sunflower oil industry in flavor regulation, quality control, product development, and process optimization.

Production of an Anise- and Woodruff-like Aroma by Monokaryotic Strains of Pleurotus sapidus Grown on Citrus Side Streams.

The production of natural flavors by means of microorganisms is of great interest for the food and flavor industry, and by-products of the agro-industry are particularly suitable as substrates. In the present study, Citrus side streams were fermented using monokaryotic strains of the fungus Pleurotus sapidus. Some of the cultures exhibited a pleasant smell, reminiscent of woodruff and anise, as well as herbaceous notes. To evaluate the composition of the overall aroma, liquid/liquid extracts of submerged cultures of a selected monokaryon were prepared, and the volatiles were isolated via solvent-assisted flavor evaporation. Aroma extract dilution analyses revealed p-anisaldehyde (sweetish, anisic- and woodruff-like) with a flavor dilution factor of 218 as a character impact compound. The coconut-like, herbaceous, and sweetish smelling acyloin identified as (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone also contributed to the overall aroma and was described as an aroma-active substance with an odor threshold in air of 0.2 ng L−1 to 2.4 ng L−1 for the first time. Supplementation of the culture medium with isotopically substituted l-tyrosine elucidated this phenolic amino acid as precursor of p-anisaldehyde as well as of (2S)-hydroxy-1-(4-methoxyphenyl)-1-propanone. Chiral analysis via HPLC revealed an enantiomeric excess of 97% for the isolated product produced by P. sapidus.

Reconstitution of the Flavor Signature of Laobaigan-Type Baijiu Based on the Natural Concentrations of Its Odor-Active Compounds and Nonvolatile Organic Acids.

Nonvolatile organic acids (NVOAs) associated with the Laobaigan flavor type of Baijiu were analyzed by a derivatization method, and 37 NVOAs were quantified. In addition, 33 odorants were judged to have high flavor dilution factors by application of aroma extract dilution analysis and quantification by gas chromatography coupled with mass spectrometry (GC-MS) and GC combined with quadrupole time-of-flight MS. The quantitative data obtained for the odorants and NVOAs were used to recombine the overall flavor of Baijiu. The odor of the reconstitution of the odor-active volatiles and the NVOAs was more similar to that of the original Baijiu sample than the sample that only contained odor-active volatiles, and the alcoholic and sweety flavor odor characters were reduced, while others, that is, fruity, acidic, floral, jujube and grain, were amplified. It was shown for the first time that NVOAs have effects on the volatiles in Baijiu and might obviously influence the intensity of certain aroma qualities.

Characterization of Key Aroma-Active Compounds in Rough and Moderate Fire Rougui Wuyi Rock Tea (Camellia sinensis) by Sensory-Directed Flavor Analysis and Elucidation of the Influences of Roasting on Aroma.

Rougui Wuyi rock tea (WRT) with the premium aroma is a subcategory of oolong tea. Roasting is a unique process that provides a comprehensive aroma to WRT. The key aroma-active compounds of rough Rougui WRT (RR) and Rougui WRT with moderate fire (RM) were characterized by sensory-directed flavor analysis. A total of 80 aroma-active compounds were identified by gas chromatography-olfactometry-time-of-flight-mass spectrometry (GC-O-TOF-MS) and two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry (GC × GC-O-MS), and 42 of them revealing high flavor dilution (FD) factors (16-4096) during aroma extract dilution analysis were quantitated. Finally, the aroma recombination and omission experiments confirmed 26 odorants as key aroma-active compounds in Rougui WRT. Roasting enhanced the aroma of roasted, woody, burnt/smoky, and cinnamon-like odor impressions in RM evoked by 2- and 3-methylbutanal, furaneol, 3-methylbutanoic acid, propanoic acid, methional, β-myrcene, 2-pentylfuran, 5- and 6-methyl-2-ethylpyrazine, and furfural. In contrast, hexanal, linalool, (Z)-3-hexen-1-ol, (Z)-4-heptenal, (E)-2-heptenal, geraniol, pentanal, and β-nerolidol were responsible for the more intense floral, fruity, and grassy/fresh leaf-like aroma attributes in RR.

Contribution of aroma‐active compounds to the aroma of Lu'an Guapian tea

AbstractIn China, Lu'an Guapian (LAGP) tea consists of tea leaves without tea buds or stems. In this study, we evaluated the aromatic characteristics of LAGP by sensory analysis, aroma extract dilution analysis (AEDA), and odor activity values. The sensory analysis revealed that LAGP had cooked soybean‐like, cooked chestnut‐like, roasted, cooked corn‐like, fishy, fruity, floral, and grass aromas. Aroma‐active compounds from LAGP were identified by solvent extraction‐solid phase extraction (SE‐SPE) and headspace‐solid phase microextraction (HS‐SPME), and subjected to AEDA. A total of 91 aroma‐active compounds were identified by SE‐SPE‐AEDA with flavor dilution (FD) factors ranging from 1 to 4096. A total of 66 aroma‐active compounds were identified by HS‐SPME‐AEDA with FD of 1 to 128. Nine compounds with FD ≥64 and OAVs ≥1 were major aroma‐active compounds to the aroma of LAGP tea: raspberry ketone (raspberry), (E)‐β‐ionone (floral, raspberry), dimethyl sulfide (cooked corn‐like), indole (animal), phenylacetaldehyde (floral, honey‐like), 2‐ethyl‐3,5‐dimethylpyrazine (roasted), (Z)‐4‐heptenal (cooked soybean‐like, fishy), (Z)‐jasmone (jasmine), and geraniol (rose).

Applications of the Partial Molar Volume Concept in Whisky and Gin Dilutions with Water

The meaning of the partial molar volume, the analytical methods for finding the partial molar volumes and the additivity theorem of the partial molar volumes are explained. The additivity theorem of the partial molar volume is used for whisky alcohol strength dilutions and for single shot or multi-shots for gin in both flavor dilution with GNS and alcohol strength dilution.

Characterization of Six Lactones in Cheddar Cheese and Their Sensory Interactions Studied by Odor Activity Values and Feller's Additive Model.

To evaluate the perceptual interactions among important lactone compounds in cheddar cheese, a molecular-level flavoromic approach, in combination with perceptual interaction analysis, was applied. Six aroma-active lactones with flavor dilution factors ranging from 4 to 128 were identified in three cheddar samples by gas chromatography-olfactometry-mass spectrometry. Odor thresholds of these six aroma-active lactones were determined with values from 7.16 to 30.03 μg/kg using a deodorized cheddar matrix. The odor activity value approach demonstrated complicated interactions among the 15 binary mixtures of six important lactones, including additive, synergistic, or masking effects. Based on partial differential odor intensities, each lactone with similar degrees of perceptual interactions in binary mixtures tends to present synergistic or masking effects. Owing to the difference in the chemical structure and mixture composition, δ-dodecalactone and γ-dodecalactone caused promotive and inhibitory effects on the expression of lactone fruity aroma, respectively.

Characterization of odor-active compounds in moso bamboo (Phyllostachys pubescens Mazel) leaf via gas chromatography-ion mobility spectrometry, one- and two-dimensional gas chromatography-olfactory-mass spectrometry, and electronic nose

The leaf of moso bamboo (Phyllostachys pubescens Mazel) is rich in odorant compounds, which is important natural materials for the production of flavor. It also contains phenolic acids, amino acids and peptides, which is a potential source of natural bioactive compounds. The study of odor-active compounds in bamboo leaves can provide a basis for the discovery of natural flavor. The leaf, stem, and powder of moso bamboo were analyzed by gas chromatography-ion mobility spectrometry (GC-IMS). Main odor-active compounds in moso bamboo leaf were analyzed and characterized by (1) a gas chromatography olfactory mass spectrometry (GC-O-MS), (2) two-dimensional gas chromatography olfactory mass spectrometry (GC × GC-O-MS) and (3) electronic nose (E-nose). Based on aroma extract dilution analysis (AEDA), 13 key odor-active compounds with high flavor dilution (FD) factor (≥27), including 3-methyl-1-butanol, (E)-2-hexenal, ethyl hexanoate, (Z)-4-heptenenal, 6-methyl-5-hepten-2-one, octanal, ethyl (Z)-3-hexenoate, 1-hexanol, (Z)-3-hexen-1-ol, (E, E)-2,4-heptadienal, (Z)-2-hexen-1-ol, 1-octen-3-ol and benzaldehyde, were further analyzed. The compounds detected by the above four methods were (E)-2-hexenal, 6-methyl-5-hepten-2-one, octanal, (E, E)-2,4-heptadienal, 1-octen-3-ol and benzaldehyde, and all of which were the main and potential odorants of moso bamboo leaf.

Profiling of Aroma-Active Compounds in Ylang-Ylang Essential Oils by Aroma Extract Dilution Analysis (AEDA) and Chemometric Methods.

The aroma-active compounds in the extra, first, and third grades of ylang-ylang essential oils (YYEO) from Comoros and Madagascar were identified by gas chromatography-mass spectrometry with olfactometry (GC-MS/O) using an aroma extract dilution analysis (AEDA) technique. In the previous study, the authors investigated differences in volatile compound profiles between YYEO of different grades and regions using GC coupled with a flame ionization detector (FID) and GC-MS. This study follows up with identification of the aroma-active compounds present in YYEO of various grades from both origins and to profile the aroma of those oils. For the first time, principal component analysis (PCA) on AEDA logarithmic flavor dilution (LFD) data was performed, in comparison with the corresponding PCA on GC-FID-MS data. Based on AEDA data, 21 aroma-active compounds were found across all samples and grades of YYEO, with 8 common ones previously identified by GC-FID. Linalool had the highest odor activity and is the major component of YYEO, followed by geraniol, although the latter only appeared as a much smaller peak in the chromatogram. Other trace compounds such as eugenol and vanillin were also found to be significant to the aroma of YYEO. Using PCA on resulting LFD data, YYEO from Comoros were found to have spicier odor qualities as compared to those from Madagascar. The main contributors that determine the difference in a spicy aroma profile of Comoros and Madagascar oils are vanillin, methyl eugenol, and trans-cinnamyl acetate.

Comparison of aroma, aroma‐active, and phenolic compounds of crude and refined hazelnut oils

AbstractHazelnut (Corylus avellana L.) is an important shelled nut with its pleasant aroma. The refining process causes significant changes in the quality attributes of hazelnut oil. The aim of this study was to assess the aroma, aroma‐active, and phenolic compounds of the crude and refined hazelnut oils by using gas chromatography–mass spectrometry (GC–MS), GC–MS‐olfactometry (GC–MS‐O), and liquid chromatography–mass spectrometry (LC–MS/MS). The antioxidant capacities were also determined by DPPH and ABTS methods. Results showed that terpenes and aldehydes constituted a significant portion of the aroma profile. Refining process dramatically reduced the numbers (from 63 to 25) and amounts of aroma compounds (from 36,769 to 4461 μg/kg). Similarly, the numbers of aroma‐active compounds were reduced from 22 to 8 by the refining process. Their flavor dilution factors ranged from 2 to 1024 for crude oil and from 2 to 32 in the refined oil. As of the phenolics, five and two compounds were quantified in the crude and refined oil samples, respectively. In sum, the refining process had a considerable adverse effect on the aroma, aroma‐active, and phenolic constituents of the hazelnut oil; hence, the refining process has to be planned with minimal negative effect on its organoleptic properties.

Characterization of Key Odorants in Scallion Pancake and Investigation on Their Changes during Storage.

To characterize key odorants in scallion pancake (SP), volatiles were extracted by solvent extraction-solvent assisted flavor evaporation. A total of 51 odor-active compounds were identified by gas chromatography-olfactometry (GC-O) and chromatography–mass spectrometry (GC-MS). (Z/E)-3,6-Diethyl-1,2,4,5-tetrathiane was detected for the first time in scallion food. Application of aroma extract dilution analysis to extracts showed maltol, methyl propyl disulfide, dipropyl disulfide and 2-pentylfuran had the highest flavor dilution (FD) factor of 4096. Twenty-three odorants with FD factors ≥ 8 were quantitated, and their odor active values (OAVs) were calculated. Ten compounds with OAVs ≥ 1 were determined as the key odorants; a recombinate model prepared from the key odorants, including (E,E)-2,4-decadienal, dimethyl trisulfide, methyl propyl disulfide, hexanal, dipropyl trisulfide, maltol, acetoin, 2-methylnaphthalene, 2-pentylfuran and 2(5H)-furanone, successfully simulated the overall aroma profile of SP. The changes in odorants during storage were investigated further. With increasing concentrations and OAVs during storage, hexanal became an off-flavor compound.

Effect of sourdough fermented with corn oil and lactic acid bacteria on bread flavor

Corn oil and Lactococcus lactis (L. lactis) were selected for improving the sourdough bread aroma, and their effect on bread flavor was studied. Volatile compounds (VOCs) in sourdough and bread crumbs were determined by gas chromatography−mass spectrometry. The results demonstrated that the VOC profiles appeared mainly dominated by alcohols, aldehydes, ketones, acids, esters, and heterocyclic compounds. Principal component analysis and cluster analysis showed that the formation of most alcohols were promoted by L. lactis, while corn oil addition yielded more aldehydes, ketones, and furans. Further analysis of odor-active components in bread was characterized by aroma extract dilution analysis and odor activity value (OAV). In the sourdough bread obtained with the addition of corn oil and lipase, (E,E)-2,4-decadienal, 2-pentylfuran, 1-octen-3-ol, 3-methylthio-1-propanol, and (E)-2-nonenal had higher flavor dilution factors and OAV, which were the key aroma compounds distinguished from other varieties of breads.

Characterization of the Key Odorants Causing the Musty and Fusty/Muddy Sediment Off-Flavors in Olive Oils.

Microbial spoilage of olive fruits is among the most frequent reasons for two types of off-flavors in olive oils, assigned as musty and fusty/muddy sediment. To characterize both off-flavors on a molecular level by means of the sensomics approach, the key aroma compounds in a premium extra virgin olive oil (PreOO1) eliciting the typical sensory properties were compared to those identified in two off-flavor olive oils obtained from the International Olive Council (IOC). A comparative aroma extract dilution analysis (cAEDA) followed by identification experiments revealed 53 odorants in the musty reference olive oil (MusOO1) and 48 odorants in the fusty/muddy sediment one (FusOO1). Odorants, differing in flavor dilution (FD) factors or showing a high FD factor in at least one of the olive oils, were quantitated by stable isotope dilution analysis (SIDA), followed by the calculation of odor activity values (OAVs; ratio of concentration of an odorant to the respective odor threshold in odorless refined sunflower oil). Aroma recombination and omission experiments revealed 13 key aroma compounds in MusOO1 and 12 in FusOO1. To demonstrate the importance of volatile phenols, 10 phenolic smelling odorants were quantitated in further 13 extra virgin olive oils, in 3 musty and in 13 fusty/muddy sediment defective olive oils, and in 8 olive oils with other off-flavors. Both sensory defects could successfully be discriminated from extra virgin olive oils by applying either a principal component analysis or a hierarchical cluster analysis. Considering possible reaction pathways and all results obtained including Pearson coefficients between the odorant concentrations and the intensities of the defects, specifically 2-methoxyphenol and 4-ethylphenol were proposed as marker compounds for the quality assignment of both types of off-flavors induced by microbial spoilage among the identified key aroma compounds.

Identification of Light-Induced Key Off-Flavors in Ponkan Mandarin Juice Using MDGC-MS/O and GC-MS/PFPD.

Light-induced off-flavor compounds in Ponkan mandarin juice were investigated during its shelf-life by headspace solid-phase microextraction multidimensional gas chromatography-mass spectrometry/olfactometry (MDGC-MS/O) and a GC-MS/pulsed flame photometric detector (GC-MS/PFPD). A total of 34 aroma-active compounds with flavor dilution (FD) factors from 2 to 128 were tentatively identified by aroma extract dilution analysis-MDGC-MS/O. Among them, a light-induced off-flavor compound with a high FD factor, methional (cooked potato), was positively identified in the Ponkan mandarin juice at the end of the shelf-life. In addition, 11 volatile sulfur compounds (VSCs), including 6 screened shelf-markers (variable identification, VID > 0.80), were identified in Ponkan mandarin juice by a sulfur detector (PFPD). Four VSCs exhibited odor activity values exceeding 1. Three VSCs (methanethiol, dimethyl trisulfide, and methional) were confirmed as key light-induced off-flavor compounds in Ponkan mandarin juice based on addition/omission experiments. Furthermore, light irradiation accelerated the degradation of sulfur precursors (methionine and MMS) and the formation of these VSCs leading to an increase in off-flavor intensity.

Comparison of key aroma-active compounds between roasted and cold-pressed sesame oils

This was the first study to compare the key aroma-active compounds that contributed to the different aroma profiles between roasted and cold-pressed sesame oils. Aroma compounds were extracted by headspace solid-phase micro-extraction (HS-SPME) and simultaneous distillation extraction (SDE) and were analysed using gas chromatography–olfactometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA). The numbers of aroma-active compounds with the flavour dilution (FD) factors between 1 and 2048 were 57 and 16 in the roasted and cold-pressed sesame oils, respectively. A total of 28 volatile compounds were identified as aroma-active compounds in sesame oils for the first time. Important aroma compounds (FD ≥ 8) were quantified by the external standard method, and their odour activity values (OAV) were calculated as the ratio of their concentrations to odour thresholds in oil. The numbers of key aroma-active compounds defined by OAVs ≥ 1 were 23 (OAVs = 1–385) and 8 (OAVs = 1–42), respectively, in the roasted and cold-pressed sesame oils. 2-Methoxy-4-vinylphenol (smoked, 1924 µg/kg, OAV = 385), 2-methoxyphenol (smoked, 1488 µg/kg, OAV = 114) and pyrazines (roasted and nutty, 578–22750 µg/kg, OAV = 1–67) were the most important aroma-active compounds in the roasted sesame oil, whereas hexanal (green and fruity, 3094 µg/kg, OAV = 42) was the most important aroma-active compound in the cold-pressed sesame oil, followed by (E,E)-2,4-decadienal (earthy, 4170 µg/kg, OAV = 31), dimethyl sulfone (sulphur-like, 406 µg/kg, OAV = 20) and octanal (green and fruity, 901 µg/kg, OAV = 16). This study provides valuable information for manufacturers to achieve precise flavour control of sesame oil products.

Identification of odor compounds and odor-active compounds of yogurt using DHS, SPME, SAFE, and SBSE/GC-O-MS

Yogurt is widely acknowledged as a healthy dairy product with unique aroma. However, the changes in the odor compounds often affect the storage and shelf life of yogurt. Besides, the complex colloidal system and low concentration levels of most of odorants make it more difficult to be analyzed. Therefore, this study extracted the odor compounds of yogurt through four extraction methods, including dynamic headspace sampling (DHS), solid phase micro-extraction (SPME), solvent-assisted flavor evaporation (SAFE), and Stir bar sorptive extraction (SBSE). A total of 117 odorants, including 27 esters, 27 alcohols, 22 ketones, 16 acids, 15 aldehydes, 5 sulfides, and 5 other compounds, were identified. Of which, 31 odor-active compounds were perceived, and 12 compounds were smelled for the first time in yogurt. Of the four methods, DHS showed the most outstanding extraction effect by obtaining 88 odor compounds. Around 13 volatiles were characterized as the key odor-active compounds of yogurt. Similarly, acetophenone and butyl acrylate were detected as the key odor-active compounds of yogurt for the first time. 2,3-Butanedione was the vital odor-active compound with the highest flavor dilution (FD) factor in yogurt. The results concluded that the odor-active compounds in yogurt might have synergistic and masking effects between them.

Characterization of odor-active compounds in high-salt liquid-state soy sauce after cooking

GC × GC–O–MS was used for the aroma extract dilution analysis of cooked high-salt liquid-state soy sauce (HLS), wherein a number of components exhibited high flavor dilution (FD) factors. Electronic nose analysis showed that the heating temperature had a greater influence on the odor characteristics of soy sauce than the heating time. Sensory evaluation and the FD factor of odor-active compounds suggested that the caramel-like/sweet, roasted/roasted nut-like and spicy/burnt odor intensities of the boiled soy sauce were stronger than following heating at a higher temperature. These results indicate that different heating conditions could change the intensities of caramel-like/sweet, roasted/roasted nut-like and spicy/burnt in soy sauce during cooking by the concentrations changing of corresponding odor-active compounds. This study can provide basic data for the application of HLS aroma in food processing, and provides a reference for the application of HLS aroma in daily cooking and diet.

Characterization of the key aroma compounds in pork broth by sensory-directed flavor analysis.

The solvent-assisted flavor evaporation, sensory evaluation, and partial least squares regression analysis were used to screen the relatively better flavor of pork broth among different stewing time (1, 2, 4, 6, and 8 h). A total of 48 volatile compounds were successfully characterized by gas chromatography-mass spectrometry in the pork broth, which stewed for 4 h. The dominant volatiles were confirmed by aroma extract dilution analysis. Twenty-seven odorants with flavor dilution factors between 2 and 1,024 were identified. Among them, odor activity values of 19 components were greater than or equal to 1. An aroma recombination test was performed, and a similar flavor (93.04 %) was simulated. Omission test further confirmed that 4-hydroxy-2,5-dimethyl-3(2H)-furanone, hexanal, 1-octen-3-ol, (E)-2-octenal, (E)-2-decenal, (E)-2-undecanal, (E, E)-2,4-decadienal, nonanoic acid, decanoic acid, 2-heptanone, 3-hydroxy-2-butanone, δ-decanolactone, and 2-acetylpyrrole were the key odorants of the aroma profile of pork broth. PRACTICAL APPLICATION: Pork broth is popular in China, but lacks the study of its key aroma compounds, which restricts its industrial production. This study researched the optimum stewing time of pork broth and analyzed its key aroma compounds. Finally, the flavor profile can be obtained and understood. This study could provide a reference and further promote research on pork flavor.