GC-O-MS technique and its applications in food flavor analysis

The aroma transformation of Japanese sea bass (Lateolabrax japonicas) through endogenous enzyme incubation during the lag phase of attached microorganisms

Endogenous enzymes play a crucial role in determining fish product aroma. However, the attached microorganisms can promote enzyme production, making it challenging to identify specific aromatic compounds resulting from endogenous enzymes. Thus, we investigated the aroma transformation of Japanese sea bass through enzymatic incubation by controlling attached microorganisms during the lag phase. Our results demonstrate that enzymatic incubation significantly enhances grassy and sweet notes while reducing fishy odors. These changes in aroma are associated with increased levels of 10 volatile compounds and decreased levels of 3 volatile compounds. Among them, previous studies have reported enzyme reaction pathways for octanal, 1-nonanal, vanillin, indole, linalool, geraniol, citral, and 6-methyl-5-hepten-2-one; however, the enzymatic reaction pathways for germacrene D, beta-caryophyllene, pristane, 1-tetradecene and trans-beta-ocimene remain unclear. These findings provide novel insights for further study to elucidate the impact of endogenous enzymes on fish product aromas.

The characteristic VOCs of different parts of Artocarpus heterophyllus fruit based on HS-SPME-GC-MS and PTR-TOF-MS

Insight investigation on both edible pulps and inedible parts involving inflorescence axis and shreds of Artocarpus heterophyllus Lam were carried out, a total of 98 VOCs and 201 masses were identified by the combination of HS-SPME-GC-MS and PTR-TOF-MS. Among them, according to the consistency of OAV and results of VIP > 1, p < 0.05, compounds methyl isovalerate (A2), 3-methylbutyl acetate (A5) and octanoic acid, ethyl ester (A21) were recognized as aroma markers to distinguish the pulps, shreds and inflorescence axis. Meanwhile, the inflorescence axis (IC50: 1.82 mg/mL) and shreds (IC50: 16.74 mg/mL) exhibited more excellent antioxidant potency than pulps (IC50: 17.43 mg/mL) in vitro. These findings validated the feasibility of coupling HS-SPME-GC-MS and PTR-TOF-MS for rapid detection of characteristic VOCs of this plant, and offered new prospect of fragrance utilization and waste management of the edible and inedible parts of A. heterophyllus fruit.

Decoding the Qu-aroma of medium-temperature Daqu starter by volatilomics, aroma recombination, omission studies and sensory analysis

Qu-aroma is of great significance for evaluation the quality of Daqu starter. This study aimed to decode the Qu-aroma of medium-temperature Daqu (MT-Daqu) via "top-down" and "bottom-up" approaches. Firstly, 52 aroma descriptors were defined to describe the MT-Daqu aroma by quantitative descriptive analysis. Secondly, 193 volatile organic compounds (VOCs) were identified from 42 MT-Daqu samples by HS-SPME-GC-MS, and 43 dominant VOCs were screened out by frequence of occurrence or abundance. By Thin Film (TF)-SPME-GC-O-MS, 27 odors and 90 VOCs were detected in MT-Daqu mixture, and 14 odor-active VOCs were screened out by odor intensity. Thirdly, a five-level MT-Daqu aroma wheel was constructed by matching 52 aroma descriptors and 37 aroma-active VOCs. Finally, Qu-aroma of MT-Daqu was reconstructed with 37 aroma-active VOCs and evaluated by omission experiments. Hereinto, 26 key aroma-active VOCs were determined by OAV value ≥1, including isovaleric acid, 1-hexanol, isovaleraldehyde, 2-octanone, trimethylpyrazine, γ-nonalactone, 4-vinylguaiacol, etc.

Application Progress of Stable Isotope Dilution Analysis in Volatile Flavor Analysis of Food

Aroma is one of the important indexes to evaluate food quality. The formation of food aroma is based on the interaction of complex substances. The accurate quantification of aroma substances in food has significance in the analysis of aroma substances in food. In this review, the basic principle and significance of stable isotope dilution analysis is introduced, general steps for flavor analysis and its historical progress in food flavor analysis is discussed. Additionally, the application progress of stable isotope dilution analysis in food flavor analysis from 2019 to 2023 has been described in detail, which is also categorized by food. Finally, the accuracy and superiority of stable isotope dilution analysis as an accurate quantitative analysis method were discussed.

HS-SPME-GC-MS untargeted metabolomics reveals key volatile compound changes during Liupao tea fermentation

This study used headspace solid-phase microextraction-gas chromatography-mass spectrometry and multivariate statistical analysis to comprehensively analyze the volatile components in Liupao tea samples throughout fermentation. In total, 1009 volatile organic compounds were detected and identified, including terpenoids, heterocyclic compounds, esters, ketones, hydrocarbons, alcohols, aromatics, and acids. Principal component and hierarchical cluster analyses, characterize the volatile components of Liupao tea samples were characterized at various fermentation stages. Orthogonal partial least squares discriminant analysis identified 248 differentiating compounds (VIP ≥ 1, P < 0.05, and |Log2FC| ≥ 1.0) during fermentation. K-means clustering analysis showed that 11 metabolites increased significantly throughout the fermentation process, whereas 31 metabolites decreased continuously. Annotation of these differential compounds revealed significant changes in sensory flavor characteristics in "green, sweet, fruity, floral, and woody" flavors. The results demonstrated significant variations in the volatile components of Liupao tea fermentation, along with notable changes in flavor characteristics.

Development of analytical "aroma wheels" for Oolong tea infusions (Shuixian and Rougui) and prediction of dynamic aroma release and colour changes during "Chinese tea ceremony" with machine learning

The flavour of tea as a worldwide popular beverage has been studied extensively. This study aimed to apply established flavour analysis techniques (GC-MS, GC-O-MS and APCI-MS/MS) in innovative ways to characterise the flavour profile of oolong tea infusions for two types of oolong tea (type A- Shuixian, type B- Rougui). GC-MS identified 48 aroma compounds, with type B having a higher abundance of most compounds. GC-O-MS analysis determined the noticeable aroma difference based on 20 key aroma compounds, facilitating the creation of an analytical "Aroma Wheel" with 8 key odour descriptors. APCI-MS/MS assessed real-time aroma release during successive brews linked with the "Chinese tea ceremony" (Gongfu Cha). Multivariate Polynomial Regression (MPR) and Long Short-Term Memory (LSTM) network approaches were applied to aroma and colour data from seven successive brews. The results revealed a progressive decline in both colour and aroma with seven repeated brews, particularly notable after the fourth brew.

Enhancing gas chromatography-mass spectrometry resolution and pure analyte discovery using intra-chromatogram elution profile matching

Chemometric decomposition methods like multivariate curve resolution-alternating least squares (MCR-ALS) are often employed in gas chromatography-mass spectrometry (GC-MS) to improve analyte identification and quantitation. However, these methods can perform poorly for analytes with a low chromatographic resolution (Rs) and a high degree of spectral contamination from noise and background interferences. Thus, we propose a novel computational algorithm, termed mzCompare, to improve analyte identification and quantitation when coupled to MCR-ALS. The mzCompare method utilizes an underlying requirement that the retention time and peak shape between mass channels (m/z) of the same analyte should be similar. By discovering the selective m/z for a given analyte in a chromatogram, a pure elution profile can be generated and used as an equality constraint in MCR-ALS. The performance of the mzCompare methodology is demonstrated with both experimental and simulated chromatograms. Experimentally, unresolved analytes with a Rs as low as 0.05 could be confidently identified with mzCompare assisted MCR-ALS. Furthermore, application of the mzCompare algorithm to a complex aerospace fuel resulted in the discovery of 335 analytes, a 44 % increase compared to conventional peak detection methods. GC-MS simulations of target-interferent analyte pairs demonstrated that the performance of MCR-ALS deteriorated below a Rs of ∼0.25. However, mzCompare assisted MCR-ALS showed excellent identification and acceptable quantitative accuracy at a Rs of ∼0.02. These results show that the mzCompare algorithm can help analysts overcome modeling ambiguities resulting from the chemometric multiplex disadvantage.

Characterization of the key differential aroma compounds in five dark teas from different geographical regions integrating GC-MS, ROAV and chemometrics approaches

Dark tea (DT) holds a rich cultural history in China and has gained sizeable consumers due to its unique flavor and potential health benefits. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS), relative odor activity value (ROAV), and chemometrics approaches were used to detect and analyze aroma compounds differences among five dark teas from different geographical regions. The results revealed that the five DTs from different geographical regions differed in types, quantities, and relative concentrations of volatile compounds. A total of 1372 volatile compounds of were identified in the 56 DT samples by HS-SPME-GC-MS. Using ROAV and chemometrics approaches, based on ROAV>1 and VIP>1. Eighteen key aroma compounds can be used as potential indicators for DT classification, including dihydroactinidiolide, linalool, 1,2,3-trimethoxybenzene, geranyl acetone, 1,2,4-trimethoxybenzene, cedrol, 3,7-dimethyl-1,5,7-octatrien-3-ol, β-ionone, 4-ethyl-1,2-dimethoxybenzene, methyl salicylate, α-ionone, geraniol, linalool oxide I, linalool oxide II, 6-methyl-5-hepten-2-one, α-terpineol, 1,2,3-trimethoxy-5-methylbenzene, and 1,2-dimethoxybenzene. These compounds provide a certain theoretical basis for distinguishing the differences in five DTs from different geographical regions. This study provides a potential method for identifying the volatile substances in DTs and elucidating the differences in key aroma compounds. Abbreviations: DT, dark tea; FZT, Fuzhuan tea; LPT, Guangxi Liupao tea; QZT, Hubei Qingzhuan tea; TBT, Sichuan Tibetan tea; PET, Yunnan Pu-erh tea; ROAV, Relative odor activity value; OT, Odor threshold; HS-SPME, Headspace solid-phase microextraction; GC-MS, Gas chromatography-mass spectrometry; PCA, Principal components analysis; PLS-DA, Partial least squares-discriminant analysis; HCA, Hierarchical clustering analysis.

Characterization of Flavor Compounds in Chinese Indigenous Sheep Breeds Using Gas Chromatography-Ion Mobility Spectrometry and Chemometrics

This study analyzed the flavor compounds in the meat of four indigenous breeds of Chinese sheep through the use of gas chromatography-ion mobility spectrometry (GC-IMS). GC-IMS provided information on the characteristics and strength of 71 volatile flavor compounds (monomers and dimers), with aldehydes, alcohols and ketones being the most abundant in all types of sheep meat. The compounds with higher intensity peaks in the sheep meat were aldehydes (n-nonanal, octanal, heptanal, 3-methylbutanal, and hexanal), alcohols (1-octen-3-ol, hexanol, and pentanol), ketones (3-hydroxy-2-butanon, 2-butanone, and 2-propanone), esters (methyl benzoate), and thiazole (trimethylthiazole). The volatile flavor components in the meat of the different breeds of sheep obtained via GC-IMS were further differentiated using principal component analysis. In addition, orthogonal partial least squares discriminant analysis (OPLS-DA) and variable importance on projection (VIP) were used to determine the characteristic flavor compounds in the meats of different breeds of sheep, and 21 differentially volatile components were screened out based on having a VIP above 1. These results indicate that GC-IMS combined with multivariate analysis is a convenient and powerful method for characterizing and discriminating sheep meat.

Recent progress in the extraction of terpenoids from essential oils and separation of the enantiomers by GC-MS

Terpenoids possess significant physiological activities and are rich in essential oils. Some terpenoids have chiral centers and could form enantiomers with distinct physiological activities. Therefore, the extraction and separation of terpenoids enantiomers are very important and have attracted extensive attention in recent years. Meanwhile, the specific distribution and enantiomer excess results (the excess of one enantiomer over the other in a mixture of enantiomers) could be used as quality markers for illegitimate adulteration, origin identification, and exploring component variations and functional interrelations across different plant tissues. In this study, an overview of the progress in the extraction of terpenoids from essential oils and the separation of their enantiomers over the past two decades has been made. Extraction methods were retrieved by the resultant network visualization findings. The results showed that the predominant methods are hydrodistillation, solvent-free microwave extraction, headspace solid-phase microextraction and supercritical fluid extraction methods. GC-MS combined with chiral chromatography columns is commonly used for the separation of enantiomers, while 2D GC is found to have stronger resolution ability. Finally, some prospects for future research directions in the extraction and separation identification of essential oils are proposed.

Research on the brewing technology of Dangshen Huangjiu with low biogenic amines and high functional factors

BACKGROUND

Biogenic amines (BA) are hazardous components in Huangjiu (HJ). To ensure the quality of Dangshen Huangjiu (DSHJ), an orthogonal experiment L9 (33) was proposed to optimize the process by the main brewing factors (pre-fermentation temperature, pre- and post-fermentation time) that may affect BA and functional factors in DSHJ. DSHJ was produced with low BA content and high functional factors. Gas chromatography-ion mobility spectrometry combined with a multivariate statistical method (GC-IMS-MSM) was used to analyze the volatile components in the brewing process of DSHJ.

RESULTS

The optimum brewing process parameters of DSHJ were as follows: pre-fermentation temperature, 28 °C; pre-fermentation time, 9 days; post-fermentation time, 18 days. The average content of BA in DSHJ was 33.12 mg L-1, and the sensory score, total phenol content and DPPH free radical scavenging rate of DSHJ were significantly higher than those of HJ. A total of 14 esters, 7 acids, 7 alcohols, 1 ketone, 5 aldehydes and 1 pyrazine in DSHJ and HJ were identified by GC-IMS. There were no significant differences (P > 0.05) in DSHJ and HJ in the soaking rice and saccharification stage. 11 components, such as ethyl acetate, and 12 components, such as acetic acid, were the different components of HJ and DSHJ in pre-fermentation and post-fermentation stages, respectively. In the post-fermentation stage, the contents of 8 components in DSHJ such as ethyl acetate were higher than in HJ.

CONCLUSION

The preparation process parameters of DSHJ optimized by orthogonal experiments can ensure that DSHJ has the advantages of low BA content, high total phenol content and good antioxidant activity. Sensory score and GC-IMS-MSM analysis found that DSHJ prepared using the optimal process had the characteristics of good taste and rich aroma. © 2024 Society of Chemical Industry.

Ultrasound-induced modifications of beef flavor characteristics during postmortem aging

To investigate the effect of ultrasound treatment on the flavor profile of beef during postmortem aging, a comprehensive analysis of beef flavor was conducted at 0, 7, and 12 d of aging using sensory evaluation and electronic nose. Furthermore, the key volatile flavor compounds were identified using gas chromatography-mass spectrometry (GC-MS), and the odor activity value (OAV) was further evaluated. In addition, the primary pathway involved in flavor formation during beef aging after ultrasound treatment was explored. The results indicated that ultrasound enhanced the flavor profile of beef during postmortem aging by modifying the OAV of hexanal, heptanal, octanal, nonanal, decanal, (Z)-2-nonenal, dodecanal, pentanal, 1-octen-3-ol, octanoic acid, and 2-pentylfuran. Lipid oxidation was a crucial pathway through which ultrasound promoted the generation of volatile flavor compounds in beef, confirmed by the improved oxidation level of fatty acids, particularly monounsaturated ones. The study indicates that ultrasound technology can be regarded as an effective method for enhancing the beef flavor profile during postmortem aging.

Effects of processing methods on the aroma of Poria cocos and its changing regulations during processing

Poria cocos is a natural source of fungal food raw materials. Processing method is a key effecting the aroma of Poria cocos. In this study, the aroma compounds of Poria cocos products processed using sweating-low-temperature drying (SW-LD), sweating-high-temperature drying (SW-HD), steaming-low-temperature drying (ST-LD), and steaming-high-temperature drying (ST-HD) were compared by headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS), and the changes in aroma compounds of Poria cocos products during processing were analyzed. GC-MS analysis showed SW-HD product had highest content of aroma compounds. Aroma activity value (OAV) analysis indicated that 9 aroma compounds contributed to the overall aroma of Poria cocos. Among 9 compounds of Poria cocos, 1-octen-3-ol, hexanal, nonanal, octanal, trans-2-octenal, and heptanal contributed to mushroom, refreshing, sweet and fatty characters. In addition, the aroma compound changes during the processing were analyzed, revealing that steaming and sweating were the key processes affecting the aroma of Poria cocos products. The findings of this study provide valuable theoretical guidance for the development of Poria cocos processing technology.

System Design Based on Biological Olfaction for Meat Analysis Using E-Nose Sensors

The deterioration of food, especially in meat products, can lead to serious health problems. Even with modern preservation technologies, a significant amount of food is lost due to microbial deterioration. As the very first step of the preservation process, the microflora that grows during the storage time and in spoiling foods should be well-known to identify critical levels. Electronic nose and gas chromatography analysis systems can provide sensitive and promising results. Similarly, bacterial analysis is an important process for determining bacterial groups that result in the emergence of such gases in gas chromatography-mass spectrometry (GC-MS) analysis during the degradation time. This study aims to determine the degradation levels for some meat types under different environmental conditions, such as temperature and duration, to compare with other measurement techniques for evaluating the verification of data. E-nose device, developed in this study, can detect carbon monoxide (CO), methane (CH4), ethanol (C2H5OH), and ammonia (NH3) using metal oxide semiconductor (MOS) sensors. In order to test sensory measurements during this period, GC-MS and microbial measurements were used. E-nose measurements show that the results are in accord with each other. This system can easily be made portable, occupying very little space.

Dietary Energy and Protein Levels Influence the Mutton Quality and Metabolomic Profile of the Yunshang Black Goat

This study aimed to evaluate the impact of dietary energy and protein levels on the meat quality and metabolomic profile of Yunshang black goats. For this, 80 Yunshang black goats (male, 6 months old, with a mean live body weight of 35.82 ± 2.79 kg) were used in a completely randomized design with a 2 × 2 factorial dietary arrangement. The dietary treatments were (1) high energy (9.74 MJ/kg) with high protein (12.99%) (HEHP), (2) high energy (9.76 MJ/kg) with low protein (10.01%) (HELP), (3) low energy (8.18 MJ/kg) with high protein (13.04%) (LEHP), and (4) low energy (8.14 MJ/kg) with low protein (10.05%) (LELP). The experiment lasted 64 days, including 14 days for dietary adaptation and a 50-day feeding trial. At the end of the experiment, four animals from each treatment were slaughtered to assess their meat quality and metabolomic profiles. The pH value was greater for the goats fed the LELP diet compared with the other treatments. The LEHP-fed group's meat was brighter (L*) than that of the other three groups. The HEHP-fed group had considerably more tender meat (p < 0.05) compared with the LEHP-fed group. Moreover, 72 and 183 differentiated metabolites were detected in the longissimus muscle samples by using gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry, respectively. The hydropathy and volatilities of raw meat were different (p < 0.05), suggesting changes in the meat flavor because of the dietary treatments. Based on the results, it can be concluded that feeding a high-energy- and high-protein-containing diet improved the tenderness, flavor, and fatty acid contents of mutton.

Odor and taste characteristics, transduction mechanism, and perceptual interaction in fermented foods: a review

Fermentation is a critical technological process for flavor development in fermented foods. The combination of odor and taste, known as flavor, is crucial in enhancing people's perception and psychology toward fermented foods, thereby increasing their acceptance among consumers. This review summarized the determination and key flavor compound screening methods in fermented foods and analyzed the flavor perception, perceptual interactions, and evaluation methods. The flavor compounds in fermented foods could be separated, purified, and identified by instrument techniques, and a molecular sensory science approach could identify the key flavor compounds. How flavor compounds bind to their respective receptors determines flavor perception, which is influenced by their perceptual interactions, including odor-odor, taste-taste, and odor-taste. Evaluation methods of flavor perception mainly include human sensory evaluation, electronic sensors and biosensors, and neuroimaging techniques. Among them, the biosensor-based evaluation methods could facilitate the investigation of the flavor transduction mechanism and the neuroimaging technique could explain the brain's signals that relate to the perception of flavor and how they compare to signals from other senses. This review aims to elucidate the flavor profile of fermented foods and highlight the significance of comprehending the interactions between various flavor compounds, thus improving the healthiness and sensory attributes.

Unraveling the flavor profiles of chicken meat: Classes, biosynthesis, influencing factors in flavor development, and sensory evaluation

Chicken is renowned as the most affordable meat option, prized by consumers worldwide for its unique flavor, and universally recognized for its essential savory flavor. Current research endeavors are increasingly dedicated to exploring the flavor profile of chicken meat. However, there is a noticeable gap in comprehensive reviews dedicated specifically to the flavor quality of chicken meat, although existing reviews cover meat flavor profiles of various animal species. This review aims to fill this gap by synthesizing knowledge from published literature to describe the compounds, chemistry reaction, influencing factors, and sensory evaluation associated with chicken meat flavor. The flavor compounds in chicken meat mainly included water-soluble low-molecular-weight substances and lipids, as well as volatile compounds such as aldehydes, ketones, alcohols, acids, esters, hydrocarbons, furans, nitrogen, and sulfur-containing compounds. The significant synthesis pathways of flavor components were Maillard reaction, Strecker degradation, lipid oxidation, lipid-Maillard interaction, and thiamine degradation. Preslaughter factors, including age, breed/strain, rearing management, muscle type, and sex of chicken, as well as postmortem conditions such as aging, cooking conditions, and low-temperature storage, were closely linked to flavor development and accounted for the significant differences observed in flavor components. Moreover, the sensory methods used to evaluate the chicken meat flavor were elaborated. This review contributes to a more comprehensive understanding of the flavor profile of chicken meat. It can serve as a guide for enhancing chicken meat flavor quality and provide a foundation for developing customized chicken products.

Combined multi-omics approach to analyze the flavor characteristics and formation mechanism of gabaron green tea

Gabaron green tea (GAGT) has unique flavor and health benefits through the special anaerobic treatment. However, how this composite processing affects the aroma formation of GAGT and the regulatory mechanism was rarely reported. This study used nontargeted metabolomics and molecular sensory science to overlay screen differential metabolites and key aroma contributors. The potential regulatory mechanism of anaerobic treatment on the aroma formation of GAGT was investigated by transcriptomics and correlation analyses. Five volatiles: benzeneacetaldehyde, nonanal, geraniol, linalool, and linalool oxide III, were screened as target metabolites. Through the transcriptional-level differential genes screening and analysis, some CsERF transcription factors in the ethylene signaling pathway were proposed might participate the response to the anaerobic treatment. They might regulate the expression of related genes in the metabolic pathway of the target metabolites thus affecting the GAGT flavor. The findings of this study provide novel information on the flavor and its formation of GAGT.

Mechanisms and quality variations of non-volatile and volatile metabolites in black tea from various ages of tea trees: Insights from metabolomics analysis

The sensory quality of black tea (BT) influenced by various factors, among which tree age is particularly significant. People prefer BT produced by fresh leaves from old tea trees, yet the correlation between tree age and tea quality has not been thoroughly investigated. In this study, we analyzed the quality of BT from young trees (H-JYH) and old trees (H-OJYH) using e-tongue technology and sensory evaluation. Our findings revealed that H-OJYH had stronger sweetness and sourness, richer flavor, and diminished bitter-astringency compared to H-JYH. 1231 non-volatile metabolites and 504 volatile metabolites were discovered by ultra-performance liquid chromatography (UPLC) and gas chromatography-mass spectrometry (GC-MS). L-tartaric acid and trans-citridic acid were found to contribute to increase acidity, and 7,8-dihydroxy-6-methoxycoumarin and d-fructose 6-phosphate were associated with enhanced sweetness in H-OJYH. Additionally, lower levels of octyl gallate and vanillic acid in H-OJYH contributed to the diminished bitter-astringency. β-ionone, 2-phenylethanol and phenylacetaldehyde merged as characteristic compounds of older tree BT with stronger floral and sweet aroma. Our study serves as a guideline to explore the relationship between tree age and tea quality.

Characterization of key odorants in 'Baimaocha' black teas from different regions

'Baimmaocha' is a distinctive resource for production of high-quality black tea, and its processed black tea has unique aroma characteristics. 190 volatile compounds were identified by comprehensive two-dimensional gas chromatography-olfactometry-quadrupole-time-of-flight mass spectrometry(GC × GC-O-Q-TOMS), and among them 23 compounds were recognized as key odorants contributing to forming different aroma characteristics in 'Baimaocha' black teas of Rucheng, Renhua, and Lingyun (RCBT, RHBT, LYBT). The odor activity value coupled with GC-O showed that methyl salicylate (RCBT), geraniol (RHBT), trans-β-ionone and benzeneacetaldehyde (LYBT) might be the most definitive aroma compounds identified from their respective regions. Furthermore, PLS analysis revealed three odorants as significant contributors to floral characteristic, four odorants related to fruity attribute, four odorants linked to fresh attribute, and three odorants associated with roasted attribute. These results provide novel insights into sensory evaluation and chemical substances of 'Baimaocha' black tea and provide a theoretical basis for controlling and enhancement tea aroma quality.

Identification of Aroma-active Compounds in Milk by GC×GC-O-TOF-MS Combined with Check-all-that-apply

Understanding consumers' sensory preferences for dairy products is essential. This study employed sensory analysis and instrumental techniques to analyze the flavor of pasteurized milk and ultra-high temperature (UHT) milk. There were 6 milk samples with similar fat content (4.0-4.6 g/100mL) and protein content (3.2-3.8 g/100mL). Sensory data from consumer tests was collected using CATA (n = 100) and 9-point hedonic preferences. Research showed that Chinese consumers could distinguish the flavor of the 2 types of milk, and UHT milk showed a higher preference score, which may be due to the more pronounced milky flavor and sweet taste of UHT milk. A total of 48 aroma-active compounds were sniffed through GC × GC-O-TOF-MS, among which 11 were determined as key aroma-active compounds. Correlation analysis showed that milky odor, sweetness, and aftertaste-milky were positively correlated with γ-dodecalactone and γ-nonanolactone. Cooked and oxidized taste were positively correlated with 1-octen-3-ol and E-2-octenal. This study is important for developing Chinese dairy products and exporting dairy products to China by multinational companies.

Insights into the Volatile Flavor Profiles of Two Types of Beef Tallow via Electronic Nose and Gas Chromatography-Ion Mobility Spectrometry Analysis

In the current study, an electronic nose (E-nose) and gas chromatography-ion mobility spectrometry (GC-IMS) were employed to investigate the volatile flavor compounds (VFCs) of intense flavor beef tallow (L) and ordinary beef tallow (P). The study results indicate that an E-nose combined with an LDA and GC-IMS combined with an OPLS-DA can effectively distinguish between the two types of beef tallow. Compared with ordinary beef tallow, the E-nose sensors of intense flavor beef tallow have stronger response signals to sulfides, terpenes, and nitrogen oxides. A total of 22 compounds contribute to making the flavor of intense flavor beef tallow more typical and richer; in contrast, ethyl acetate was the main aroma-active compound found in the ordinary beef tallow. Sulfur-containing compounds and terpenoids might be the key substances that cause sensory flavor differences between the two types of beef tallow. In conclusion, the results of this study clarify the characteristics and differences of the two types of beef tallow and provide an enhanced understanding of the differences in the flavors of the two types of beef tallow.

Novel animal product substitutes: A new category of plant-based alternatives to meat, seafood, egg, and dairy products

Many consumers are adopting plant-centric diets to address the adverse effects of livestock production on the environment, health, and animal welfare. Processed plant-based foods, including animal product analogs (such as meat, seafood, egg, or dairy analogs) and traditional animal product substitutes (such as tofu, seitan, or tempeh), may not be desirable to a broad spectrum of consumers. This article introduces a new category of plant-based foods specifically designed to overcome the limitations of current animal product analogs and substitutes: novel animal product substitutes (NAPS). NAPS are designed to contain high levels of nutrients to be encouraged (such as proteins, omega-3 fatty acids, dietary fibers, vitamins, and minerals) and low levels of nutrients to be discouraged (such as salt, sugar, and saturated fat). Moreover, they may be designed to have a wide range of appearances, textures, mouthfeels, and flavors. For instance, they could be red, orange, green, yellow, blue, or beige; they could be spheres, ovals, cubes, or pyramids; they could be hard/soft or brittle/pliable; and they could be lemon, thyme, curry, or chili flavored. Consequently, there is great flexibility in creating NAPS that could be eaten in situations where animal products are normally consumed, for example, with pasta, rice, potatoes, bread, soups, or salads. This article reviews the science behind the formulation of NAPS, highlights factors impacting their appearance, texture, flavor, and nutritional profile, and discusses methods that can be used to formulate, produce, and characterize them. Finally, it stresses the need for further studies on this new category of foods, especially on their sensory and consumer aspects.

Enhancing Odor Analysis with Gas Chromatography-Olfactometry (GC-O): Recent Breakthroughs and Challenges

Gas chromatography-olfactometry (GC-O) has made significant advancements in recent years, with breakthroughs in its applications and the identification of its limitations. This technology is widely used for analyzing complex odor patterns. The review begins by explaining the principles of GC-O, including sample preparation, separation methods, and olfactory evaluation techniques. It then explores the diverse range of applications where GC-O has found success, such as food and beverage industries, environmental monitoring, perfume and aroma development, and forensic analysis. One of the major breakthroughs in GC-O analysis is the improvement in separation power and resolution of odorants. Techniques like rapid GC, comprehensive two-dimensional GC, and multidimensional GC have enhanced the identification and quantification of odor-active chemicals. However, GC-O also has limitations. These include the challenges in detecting and quantifying trace odorants, dealing with matrix effects, and ensuring the repeatability and consistency of results across laboratories. The review examines these limitations closely and discusses potential solutions and future directions for improvement in GC-O analysis. Overall, this review presents a comprehensive overview of the recent advances in GC-O, covering breakthroughs, applications, and limitations. It aims to promote the wider usage of GC-O analysis in odor analysis and related industries. Researchers, practitioners, and anyone interested in leveraging the capabilities of GC-O in analyzing complex odor patterns will find this review a valuable resource. The article highlights the potential of GC-O and encourages further research and development in the field.

Application of PLSR in correlating sensory and chemical properties of middle flue-cured tobacco leaves with honey-sweet and burnt flavour

Among the eight types of aroma and flavour characteristics of Chinese flue-cured tobacco (FCT), tobacco grown in Shandong is classified as having a honey-sweet and burnt aroma. To elucidate the key chemical components that determine the characteristics of the honey-sweet and burnt aroma styles of Shandong FCT, we qualitatively and quantitatively evaluated the smoke flavour quality and five categories of flavour-related chemical components (routine components, water-soluble sugars, free amino acids, Amadori compounds and key aroma-active compounds) in Shandong middle FCT leaves using sensory analysis and modern instrumental analysis techniques. The association between the chemical components and sensory quality was analysed. Our results showed that the total sugars, reducing sugars (fructose, glucose, and psicose), total sugar-nicotine ratio, proline-total amino acid ratio, sulphur-containing amino acid-total amino acid ratio and fructosyl-proline (Fru-Pro) were high in premium FCT leaves. The aroma-active compounds associated with the honey-sweet burnt flavour style of the Shandong Middle FCT included sweet-scented 2,3-pentanedione, 2,3-butanedione, butyrolactone, 2-furanmethanol, roasted-like 2-pentylfura, and green-like 1-penten-3-one. Partial least squares regression (PLSR) analysis revealed that 29 aroma precursors were positively correlated with the sensory quality characteristics of Shandong FCT. The results of our study can provide guidance for the targeted improvement and precise regulation of the flavour-style characteristics of Shandong FCT.

GC-IMS and multivariate analyses of volatile organic components in different Chinese breeds of chickens

This study examined the difference in volatile flavor characteristics among four different local breeds of chicken by headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) combined with multivariate analysis. In total, 65 volatile organic compounds (VOCs) were identified (17 aldehydes, 12 alcohols, 7 ketones, 5 esters, 2 acids, and 22 unidentified, i.e., 26.15% aldehydes, 18.46% alcohols, 10.77% ketones, 7.69% esters, 3.08% acids, and 33.84% unidentified), of which 43 were annotated. The chicken meats from the four breeds exhibited good separation in topographic plots, VOC fingerprinting, and multivariate analysis. Meanwhile, 20 different volatile components, with variable importance in projection value > 1, were selected as potential markers to distinguish different breeds of chicken by partial least squares discriminant analysis (PLS-DA). These findings provide insights into the flavor traits of chicken meat. Also, HS-GC-IMS combined with multivariate analysis can be a convenient and powerful method for characterizing different meats.

Recent advances and challenges in the interaction between myofibrillar proteins and flavor substances

Myofibrillar proteins are an important component of proteins. Flavor characteristics are the key attributes of food quality. The ability of proteins to bind flavor is one of their most fundamental functional properties. The dynamic balance of release and retention of volatile flavor compounds in protein-containing systems largely affects the sensory quality and consumer acceptability of foods. At present, research on flavor mainly focuses on the formation mechanism of flavor components, while there are few reports on the release and perception of flavor components. This review introduces the composition and structure of myofibrillar proteins, the classification of flavor substances, the physical binding and chemical adsorption of myofibrillar proteins and volatile flavor substances, as well as clarifies the regulation law of flavor substances from the viewpoint of endogenous flavor characteristics and exogenous environment factors, to provide a theoretical reference for the flavor regulation of meat products.

Detection and Analysis of VOCs in Cherry Tomato Based on GC-MS and GC×GC-TOF MS Techniques

Volatile organic compounds (VOCs) play a significant role in influencing the flavor quality of cherry tomatoes (Solanum lycopersicum var. cerasiforme). The scarcity of systematic analysis of VOCs in cherry tomatoes can be attributed to the constraints imposed by detection technology and other contributing factors. In this study, the cherry tomato cultivar var. 'Zheyingfen1' was chosen due to its abundant fruit flavor. Two detection technology platforms, namely the commonly employed headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and the most advanced headspace solid-phase microextraction-full two-dimensional gas chromatography-time-of-flight mass spectrometry (HS-SPME-GC×GC-TOFMS), were employed in the analysis. The VOCs of cherry tomato cultivar var. 'Zheyingfen1' fruits at red ripening stage were detected. A combined total of 1544 VOCs were detected using the two aforementioned techniques. Specifically, 663 VOCs were identified by through the HS-SPME-GC-MS method, 1026 VOCs were identified by through the HS-SPME-GC×GC-TOFMS, and 145 VOCs were identified by both techniques. The identification of β-ionone and (E)-2-nonenal as the principal VOCs was substantiated through the application of the relative odor activity value (rOAV) calculation and subsequent analysis. Based on the varying contribution rates of rOAV, the analysis of sensory flavor characteristics revealed that cherry tomato cultivar var. 'Zheyingfen1' predominantly exhibited green and fatty attributes, accompanied by elements of fresh and floral flavor characteristics. In conclusion, our study conducted a comprehensive comparison of the disparities between these two methodologies in detecting VOCs in cherry tomato fruits. Additionally, we systematically analyzed the VOC composition and sensory flavor attributes of the cherry tomato cultivar var. 'Zheyingfen1'. This research serves as a significant point of reference for investigating the regulatory mechanisms underlying the development of volatile flavor quality in cherry tomatoes.

Key components, formation pathways, affecting factors, and emerging analytical strategies for edible mushrooms aroma: A review

Aroma is one of the decisive factors affecting the quality and consumer acceptance of edible mushrooms. This review summarized the key components and formation pathways of edible mushroom aroma. It also elaborated on the affecting factors and emerging analytical strategies of edible mushroom aroma. A total of 1308 volatile organic compounds identified in edible mushrooms, 61 were key components. The formation of these compounds is closely related to fatty acid metabolism, amino acid metabolism, lentinic acid metabolism, and terpenoid metabolism. The aroma profiles of edible mushrooms were affected by genetic background, preharvest factors, and preservation methods. Molecular sensory science and omics techniques are emerging analytical strategies to reveal aroma information of edible mushrooms. This review would provide valuable data and insights for future research on edible mushroom aroma.

Comparative key aroma compounds and sensory correlations of aromatic coconut water varieties: Insights from GC × GC-O-TOF-MS, E-nose, and sensory analysis

Aroma is a key criterion in evaluating aromatic coconut water. A comparison regarding key aroma compounds and sensory correlations was made between Thailand Aromatic Green Dwarf (THD) and Cocos nucifera L. cv. Wenye No. 4 coconut water using E-nose and GC × GC-O-TOF-MS combined with chemometrics. Twenty-one volatile components of coconut water were identified by GC × GC-O-TOF-MS, and 5 key aroma compounds were analyzed by relative odor activity value and aroma extract dilution analysis. Moreover, the combination of the E-nose with orthogonal partial least squares was highly effective in discriminating between the two coconut water samples and screened the key sensors responsible for this differentiation. Additionally, the correlation between volatile compounds and sensory properties was established using partial least squares. The key aroma compounds of coconut water exhibited positive correlations with the corresponding sensory properties.

Chemosensory of hemp seed oil extracted with hemp seed(Cannabis sativa L.) roasted under various conditions using electronic sensors and GC-MS/Olfactometry

This study analyzed the flavor of six types of hemp seed oil (HSO) extracted with roasted hemp seed (RHS) under various conditions (Raw, 140 °C_9 min, 140 °C_12 min, 160 °C_12 min, 180 °C_6 min). Electronic tongue (E-tongue), electronic nose (E-nose), GC-MS (gas chromatography-mass spectrometry), and GC-O (gas chromatography-olfactometry) were used for HSO flavor analysis. As a result of the E-tongue analysis, the sweetness tends to increase in most samples as roasting. A total of 89 and 77 volatile compounds were detected through E-nose and GC-MS, and the main volatile compounds were identified as Maillard reaction products. A total of 16 odor active compounds were detected in the GC-O analysis, and in the case of 160 ℃_12 min and 180 ℃_6 min, the scent of Roasted hemp seed oil was more dominant than other aroma profiles. The results of this study are basic data on the flavor characteristics of HSO.

Characterization of Evodia rutaecarpa (Juss) Benth honey: volatile profile, odor-active compounds and odor properties

BACKGROUND

Aroma is one of the most important quality criterion of different honeys and even defines their merchant value. The composition of volatile compounds, especially the characteristic odor-active compounds, contributes significantly to the aroma of honey. Evodia rutaecarpa (Juss) Benth honey (ERBH) is a special honey in China with unique flavor characteristics. However, no work in the literature has investigated the volatile compounds and characteristic odor-active compounds of ERBHs. Therefore, it is imperative to conduct systematic investigation into the volatile profile, odor-active compounds and odor properties of ERBHs.

RESULTS

The characteristic fingerprint of ERBHs was successfully constructed with 12 characteristic peaks and a similarity range of 0.785-0.975. In total, 297 volatile compounds were identified and relatively quantified by headspace solid-phase microextraction coupled with gas chromatography quadrupole time-of-flight mass spectrometry, of which 61 and 31 were identified as odor-active compounds by relative odor activity values and GC-olfactometry analysis, respectively, especially the common 22 odor-active compounds (E)-β-damascenone, phenethyl acetate, linalool, cis-linalool oxide (furanoid), octanal, hotrienol, trans-linalool oxide (furanoid), 4-oxoisophorone and eugenol, etc., contributed significantly to the aroma of ERBHs. The primary odor properties of ERBHs were floral, followed by fruity, herbaceous and woody aromas. The partial least-squares regression results showed that the odor-active compounds had good correlations with the odor properties.

CONCLUSION

Identifying the aroma differences of different honeys is of great importance. The present study provides a reliable theoretical basis for the quality and authenticity of ERBHs. © 2023 Society of Chemical Industry.

Exploring the visualization of human milk odor profiles: Intuitive characterization and construction of the link between odor compounds and sensory attributes

Studies on odor are not negligible in the human milk (HM) science field because it plays an irreplaceable role in the feeding process of infants. This study aimed to investigate the odor skeleton components (OSCs) in HM and verify and construct an intuitive link between them and the HM odor attributes. A total of 72 odor-active compounds were identified from 32 HMs using the comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry. Twenty of these compounds were identified as OSCs (average FD ≥ 1 and average OAV ≥ 1), and their actual odor contribution was clarified. Furthermore, the connection of the 20 OSCs with their corresponding eight odor attributes was visualized by constructing a molecular sensory odor wheel. Of them, 2,3-butanedione, (E)-2-decenal, nonanal, (E)-2-nonenal, octanal, 1-octen-3-one, hexanal, methional, and butanoic acid were the most important contributors to dairy-sweet, fishy, dairy-fat, metallic/iron, flour, grassy/green, cooked, and sweaty/rancid odor of HM.

Volatilome: Smells like microbial spirit

In recent years, the study of volatile compounds has sparked interest due to their implications in signaling and the enormous variety of bioactive properties attributed to them. Despite the absence of analysis methods standardization, there are a multitude of tools and databases that allow the identification and quantification of volatile compounds. These compounds are chemically heterogeneous and their diverse properties are exploited by various fields such as cosmetics, the food industry, agriculture and medicine, some of which will be discussed here. In virtue of volatile compounds being ubiquitous and fast chemical messengers, these molecules mediate a large number of interspecific and intraspecific interactions, which are key at an ecological level to maintaining the balance and correct functioning of ecosystems. This review briefly summarized the role of volatile compounds in inter- and intra-specific relationships as well as industrial applications associated with the use of these compounds that is emerging as a promising field of study.

Chemometric approach for an application of Atlantic salmons (Oncorhynchus keta) by-product for potential food sources

This study identified the aroma profile of salmon by-product for high utilization of by-products, including hydrolysates of head, frame, and skin were treated with reducing sugars and thermal processing. Electronic nose (E-nose) and gas chromatography-mass spectrometry (GC-MS) coupled with gas chromatography-olfactometry (GC-O) were used to analyzed the aroma profile. A total of 140 and 90 volatile compounds were detected through E-nose and GC-MS respectively, and the main volatile compounds were aldehydes. A total of 23 odor active compounds were recognized using GC-O, and 3-methyl-butanal, heptanal, benzaldehyde, octanal, furfural, and methoxy-phenyl-oxime were identified as the aroma of salmon. Using multivariate analysis, the pattern between the pretreated samples and aroma profiles was confirmed, and there were clear separations among the samples. The results of this study provide the aroma profile of salmon by-products and are expected salmon by-products to be used as a potential food source.

Food off-odor generation, characterization and recent advances in novel mitigation strategies

The pronounced perception of off-odors poses a prevalent issue across various categories of food ingredients and processed products, significantly exerting negative effects on the overall quality, processability, and consumer acceptability of both food items and raw materials. Conventional methods such as brining, marinating, and baking, are the main approaches to remove the fishy odor. Although these methods have shown notable efficacy, there are simultaneously inherent drawbacks that ultimately diminish the processability of raw materials, encompassing alterations in the original flavor profiles, the potential generation of harmful substances, restricted application scopes, and the promotion of excessive protein/lipid oxidation. In response to these challenges, recent endeavors have sought to explore innovative deodorization techniques, including emerging physical processing approaches, the development of high-efficiency adsorbent material, biological fermentation methods, and ozone water rinsing. However, the specific mechanisms underpinning the efficacy of these deodorization techniques remain not fully elucidated. This chapter covers the composition of major odor-causing substances in food, the methodologies for their detection, the mechanisms governing their formation, and the ongoing development of deodorization techniques associated with the comparison of their advantages, disadvantages, and application mechanisms. The objective of this chapter is to furnish a theoretical framework for enhancing deodorization efficiency through fostering the development of suitable deodorization technologies in the future.

Characterization of odor properties of human milk: Effect of inter-individual nutrient differences on key odor-active compounds and odor attributes

Odor is an important indicator of human milk (HM) quality, with a proven function. Here, the effect of inter-individual nutrient differences on key odor-active compounds (OACs) and odor attributes of HM samples was investigated using flavor analysis techniques and correlation network analysis. A total of ninety-four OACs were identified from 30 HMs, of which 24 key OACs could represent the basic odor characteristics of HMs. Fat content was closely related to the amounts of OACs, with aldehydes being the most abundant species and having the highest correlation with fat content. Of them, nonanal and octanal were the most important OACs in HM, having both high flavor dilution factor (2 ∼ 64, 4 ∼ 128) and odor activity values (<1 ∼ 37, 2 ∼ 36) in most samples. Additionally, different pattern of synergism between key OACs contribute to each odor attribute of HM. These findings will provide insights for subsequent in-depth studies of HM flavor.

Effects of Fermentation with Tetragenococcus halophilus and Zygosaccharomyces rouxii on the Volatile Profiles of Soybean Protein Hydrolysates

The effects of fermentation with lactic acid bacteria (LAB) and yeast on the aroma of samples were analyzed in this work. The volatile features of different soybean hydrolysates were investigated using both GC-MS and GC-IMS. Only 47 volatile flavor compounds (VFCs) were detected when using GC-IMS, while a combination of GC-MS and GC-IMS resulted in the identification of 150 compounds. LAB-yeast fermentation could significantly increase the diversity and concentrations of VFCs (p < 0.05), including alcohols, acids, esters, and sulfurs, while reduce the contents of aldehydes and ketones. Hierarchical clustering and orthogonal partial least squares analyses confirmed the impact of fermentation on the VFCs of the hydrolysates. Seven compounds were identified as significant compounds distinguishing the aromas of different groups. The partial least squares regression analysis of the 25 key VFCs (ROAV > 1) and sensory results revealed that the treatment groups positively correlated with aromatic, caramel, sour, overall aroma, and most of the key VFCs. In summary, fermentation effectively reduced the fatty and bean-like flavors of soybean hydrolysates, enhancing the overall flavor quality, with sequential inoculation proving to be more effective than simultaneous inoculation. These findings provided a theoretical basis for improving and assessing the flavor of soybean protein hydrolysates.

Characterization of the odor compounds in human milk by DHS/GC × GC-O-MS: A feasible and efficient method

Odor analysis of human milk (HM) is often challenging. Here, a new strategy for the analysis of odorants in HM using dynamic headspace sampling combined with comprehensive two-dimensional gas chromatography-olfactometry-mass spectrometry (DHS/GC × GC-O-MS) was established based on the comparison of different extraction methods and instrument modes. Overall, DHS/GC × GC-O-MS was proved to be able to provide higher extraction efficiency and better analytical results of the odor-active compounds (OACs) in HM, meanwhile, the salt addition during the extraction further promoted the release of the odorants. Twenty key OACs in HM were identified by flavor dilution analysis and odor activity calculation, of which 1-octen-3-one, 2,3-butanedione, (E)-2-nonenal, and nonanal contributed significantly to the odor of HM. In addition, 2,3-pentanedione was detected as a key OAC in HM for the first time. This study provided a powerful analytical strategy for the comprehensive odor analysis of HM.

Effect of shaking manners on floral aroma quality and identification of key floral-aroma-active compounds in Hunan black tea

Shaking is a key process effecting the floral aroma of Hunan black tea (HBT). In this study, the aroma composition of HBTs shaken in the early withering stage (ES1, ES1 + LS1, and ES2), shaken in the late withering stage (LS1), and not shaken (NS), and the identification of main floral aroma compounds were analyzed using sensory evaluation combined with gas chromatography-mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), and aroma recombination experiments. Sensory evaluation results showed that the floral aroma of HBT shaken in the early withering stage was with high intensity, whereas HBT shaken in the late withering stage had low-intensity floral aroma. GC-MS identified a total number of 81 differential volatile compounds in HBT, including 30 esters, 18 aldehydes, 15 alcohols, 12 terpenes, 4 ketones, and 2 nitrogen-containing compounds. Further screening of important floral aroma differential compounds was performed using sensory-guided, odor activity value (OAV), and GC-O analysis, which identified three critical floral aroma differential compounds. Eventually, absolute quantification analysis and aroma recombination experiments confirmed that indole and methyl jasmonate were the most critical compounds of HBT determining floral aroma intensity. The findings of this study provide valuable guidance for the production of HBT with rich floral aroma attributes.

Headspace stir-bar sorptive extraction combined with gas chromatography-mass spectrometry for trace analysis of volatile organic compounds in Schisandra chinensis Baillon (omija)

Analyzing volatile organic compounds (VOCs) in food is crucial but challenging. Schisandra chinensis Baillon (omija) is an herbal plant with various functional health activities. Previous VOC analyses focused on S. chinensis fruit but not its leaves. Therefore, VOCs in S. chinensis fruit and leaves were analyzed using headspace stir-bar sorptive extraction (HS-SBSE)-GC-MS, and optimal conditions were established. Various factors, such as the sample preparation method, twister stir-bar type, sample amount, extraction temperature, and extraction time, expected to affect extraction were carefully optimized. Under the optimal conditions, 35 and 40 VOCs were identified in S. chinensis fruit and leaves, respectively. This HS-SBSE method is capable of rapid analysis and a low contamination rate without requiring organic solvents. These findings provide practical guidelines for HS-SBSE applications in various food matrices by providing analytical methods for VOC detection.

A Review of Plant-Based Drinks Addressing Nutrients, Flavor, and Processing Technologies

Plant-based drinks have garnered significant attention as viable substitutes for traditional dairy milk, providing options for individuals who are lactose intolerant or allergic to dairy proteins, and those who adhere to vegan or vegetarian diets. In recent years, demand for plant-based drinks has expanded rapidly. Each variety has unique characteristics in terms of flavor, texture, and nutritional composition, offering consumers a diverse range of choices tailored to meet individual preferences and dietary needs. In this review, we aimed to provide a comprehensive overview of the various types of plant-based drinks and explore potential considerations including their nutritional compositions, health benefits, and processing technologies, as well as the challenges facing the plant-based drink processing industry. We delve into scientific evidence supporting the consumption of plant-based drinks, discuss their potential roles in meeting dietary requirements, and address current limitations and concerns regarding their use. We hope to illuminate the growing significance of plant-based drinks as sustainable and nutritious alternatives to dairy milk, and assist individuals in making informed choices regarding their dietary habits, expanding potential applications for plant-based drinks, and providing necessary theoretical and technical support for the development of a plant-based drink processing industry.

Volatile compounds and aroma characteristics of mushrooms: a review

Mushrooms are popular due to their rich medicinal and nutritional value. Of the many characteristics of mushrooms, aroma has received extensive attention and research as a key determinant of consumer preference. This paper reviews the production, role and contribution of common volatile compounds (VCs) in wild and cultivated mushrooms, and explores the methods used to characterize them and the factors influencing aroma. To date, more than 347 common VCs have been identified in mushrooms, such as aldehydes, ketones, alcohols and sulfur-containing compounds. Extraction and identification of VCs is a critical step and combining multiple analytical methods is an effective strategy in mushroom aroma studies. In addition, the VCs and the aroma of mushrooms are affected by a variety of factors such as genetics, growing conditions, and processing methods. However, the mechanism of influence is unknown. Further studies on the production mechanisms of VCs, their contribution to aroma, and the factors influencing their formation need to be determined in order to fully elucidate aroma and flavor of mushrooms.

Review of technology advances to assess rice quality traits and consumer perception

The increase in rice consumption and demand for high-quality rice is impacted by the growth of socioeconomic status in developing countries and consumer awareness of the health benefits of rice consumption. The latter aspects drive the need for rapid, low-cost, and reliable quality assessment methods to produce high-quality rice according to consumer preference. This is important to ensure the sustainability of the rice value chain and, therefore, accelerate the rice industry toward digital agriculture. This review article focuses on the measurements of the physicochemical and sensory quality of rice, including new and emerging technology advances, particularly in the development of low-cost, non-destructive, and rapid digital sensing techniques to assess rice quality traits and consumer perceptions. In addition, the prospects for potential applications of emerging technologies (i.e., sensors, computer vision, machine learning, and artificial intelligence) to assess rice quality and consumer preferences are discussed. The integration of these technologies shows promising potential in the forthcoming to be adopted by the rice industry to assess rice quality traits and consumer preferences at a lower cost, shorter time, and more objectively compared to the traditional approaches.

Comparative characterization of flavor precursors and volatiles of Taihe black-boned silky fowl and Hy-line Brown yolks using multiomics and GC-O-MS-based volatilomics

Eggs are nutritious and highly valued by consumers. However, egg flavor varies greatly among different hen breeds. The present study used gas chromatography-olfactometry-mass spectrometry-based volatilomics to identify and compare volatile compounds in Taihe black-boned silky fowl (TS) and Hy-line Brown (HL) egg yolks. In addition, the relationships between the levels of different metabolites and lipids and flavor-associated differences were investigated using multiomics. Twenty-eight odorants in total were identified; among them, the levels of 3-methyl-butanal, 1-octen-3-ol, 2-pentylfuran, and (E, E)-2,4-decadienal differed significantly (P < 0.05) between TS and HL egg yolks. The difference in flavor compounds results in TS egg yolks having a stronger overall odor and flavor and a higher acceptance level than HL egg yolks. Metabolomic analysis revealed that 112 metabolites in the egg yolks were significantly different between the two breeds. Furthermore, these different metabolites in the egg yolks of both breeds were significantly enriched in phenylalanine, tyrosine, and tryptophan biosynthesis pathways and phenylalanine metabolism, alanine, aspartate, and glutamate metabolism pathways (P < 0.05), as identified by both metabolite set enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses. Lipidomic analysis revealed significant differences in the lipid subclasses, lipid molecules, and fatty acid profiles between the egg yolks from the two breeds. As a result, 48 lipid molecules had variable influence in projection values > 1 based on the partial least squares regression model, which may play a role in the differences in aroma characteristics between the two breeds through oxidative degradation of fatty acids. Our study revealed the metabolite, lipid, and volatility profiles of TS and HL egg yolks and may provide an important basis for improving egg flavor to satisfy various consumer preferences.

Comparative Analysis of Key Odorants and Aroma Characteristics in Hot-Pressed Yellow Horn (Xanthoceras sorbifolia bunge) Seed Oil Via Gas Chromatography-Ion Mobility Spectrometry and Gas Chromatography-Olfactory-Mass Spectrometry

Volatile compounds (VOCs) present in the oil extracted from yellow horn seeds were first analyzed using GC-IMS and GC-O-MS at varying roasting temperatures. A total of 97 VOCs were detected using GC-IMS, while 77 were tentatively identified using GC-O-MS. Moreover, both methods allowed the identification of 24 VOCs, of which the type of aldehydes is the most abundant. Combining the results of GC-IMS, GC-O-MS, OAVs, and VIP, it was concluded that hexanal, 2,5-dimethylpyrazine, heptanal, 2-pentylfuran, 1-hexanol, and 1-octen-3-ol were the key aroma compounds. The PLS-DA and OPLS-DA models have demonstrated the ability to discriminate between different oil roasting temperatures with high accuracy. The roasting temperature of 160 °C was found to yield the highest content of main aroma substances, indicating its optimality for yellow horn seed oil production. These findings will prove beneficial for optimizing industrial production and enhancing oil aroma control.

Changes in the aroma and key odorants from white garlic to black garlic using approaches of molecular sensory science: A review

Black garlic is a relatively new product that has become very popular in recent years. It is obtained by fermenting raw (white) garlic by the application of heat treatment. The undesirable pungent odor of the white garlic disappears and the black garlic product with a sweet-sour flavor is formed after various reactions during the applied heat process. As a result, black garlic is more preferred and easily consumed by the consumers compared to white garlic. This review aims to summarize the studies on the changes in the odorants during the heat treatment employed in the production of black garlic as well as the factors affecting the changes in the aroma and aroma-active compounds and the use of molecular sensory science (MSS) approach, which has been applied in recent years as a new method for the determination of the aroma compounds. This work revealed that the use of the MSS on the aroma changes in black garlic is quite limited in the literature. Thus, more studies are needed to understand the aroma changes that occur during the formation of black garlic from white garlic in more detail.

Evaluation of the Chemosensoric Properties of Commercially Available Dog Foods Using Electronic Sensors and GC-MS/O Analysis

Pet owners think of their animals as part of their family, which further promotes the growth of the pet food market, encouraging pet owners to select nutritious, palatable, and high-quality foods for pets. Therefore, the evaluation of taste and volatile compounds in pet foods is essential to improve palatability. In this study, the sensory characteristics of taste and odor compounds in 10 commercially available dry dog foods were investigated using electronic tongue (E-tongue), electronic nose (E-nose), gas chromatography-mass spectrometry (GC-MS), and gas chromatography-olfactometry (GC-O). Dry dog foods were separated based on the sensory properties of taste and volatile compounds through the multivariate analysis of integrated results of the E-tongue and E-nose. A total of 67 odor active compounds were detected through GC-MS and GC-O, and octanal, nonanal, 2-pentyl furan, heptanal, and benzaldehyde were identified as key odor compounds which may have positive effects on food intake. The multivariate analysis was used to classify samples based on key odor compounds. Volatile compounds responsible for aroma properties of samples were evaluated using GC-O and multivariate analysis in this present study for the first time. These results are expected to provide fundamental data for sensory evaluation in producing new dog foods with improved palatability.

Enantiomeric separation and precise quantification of chiral volatiles in Wuyi rock teas using an efficient enantioselective GC × GC-TOFMS approach

Chiral volatiles play important roles in the formation of aroma quality of foods. To date, enantiomeric characteristics of chiral volatiles in Wuyi rock tea (WRT) and their aroma contributions are still unclear. In this study, an efficient enantioselective comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (Es-GC × GC-TOFMS) approach to separate and precisely quantitate 24 pairs of chiral volatiles in WRTs was established, and the enantiomeric distribution and aroma contribution of chiral volatiles among WRTs from four representative cultivars were investigated. Enantiomeric ratio (ER) of R-α-ionone (80%) in Dahongpao (DHP), ER of S-α-terpineol (57%) in Jinfo (JF), ERs of R-γ-heptanolactone (69%), S-γ-nonanolactone (55%), (2R, 5S)-theaspirane B (91%), concentration of S-(E)-nerolidol (313.37 ng/mL) in Rougui (RG) and concentration of R-α-ionone (33.01 ng/mL) in Shuixian (SX) were unique from other types of WRTs, which were considered as the potential chemical markers to distinguish WRT cultivars. The OAV assessment determined 7 volatile enantiomers as the aroma-active compounds, especially R-α-ionone and R-δ-octanolactone in SX, as well as S-(E)-nerolidol and (1R, 2R)-methyl jasmonate in RG contribute much to aroma formation of the corresponding WRTs. The above results provide scientific references for discrimination of tea cultivars and directed improvement of the aroma quality of WRT.