Characterization of the key odorants contributing to retronasal olfaction during bread consumption

Flavor release from walnut kernels in an in-vitro mastication model with decoupled oral parameters

Consumer preferences for walnut products are largely determined by the flavors released during mastication. In this study, a peeled walnut kernel (PWK) model was established with oral parameters decoupled using a Hutchings 3D model. The model explored in vitro variations using head-space solid-phase microextraction-gas chromatography-mass spectrometry and intelligent sensory techniques. The fracture strength, hardness, particle size, adhesiveness, springiness, gumminess, and chewiness were significantly reduced during mastication. We identified 61 volatile compounds and found that 2,5-dimethyl-3-ethylpyrazine is a key component, releasing predominantly baking and milky notes. Glutamic acid, alanine, arginine, and sucrose were identified as the key compounds in taste perception. The method can help establish a mastication model for nuts and facilitate breakthroughs in the development of walnut products and processing methods.

Gas chromatography-ion mobility spectrometry (GC-IMS) technique and its recent applications in grain research

Grains are the primary source of food for most people worldwide and constitute a major source of carbohydrates. Many novel technologies are being employed to ensure the safety and reliability of grain supply and production. Gas chromatography-ion mobility spectrometry (GC-IMS) can effectively separate and sensitively detect volatile organic compounds. It possesses advantages such as speed, convenience, high sensitivity, no pretreatment, and wide applicability. In recent years, many studies have shown that the application of GC-IMS technology for grain flavor analysis can play a crucial role in grains. This article elucidates the working principle of GC-IMS technology, reviews the application of GC-IMS in grains in the past 5 years. GC-IMS technology is mainly applied in four aspects in grains. In grain classification, it distinguishes varieties, quality, origin, production year, and processing methods based on the trace differences in volatile organic compounds, thereby fulfilling various grain classification requirements such as origin tracing, geographical indication product recognition, variety identification, production year identification, and detection of counterfeit and inferior grain samples. In optimizing the processing technology of grains and their products, it can improve food flavor, reduce undesirable flavors, and identify better processing parameters. In grain storage, it can determine the storage time, detect spoilage phenomena such as mold and discoloration during storage, eliminate pests affecting storage, and predict the vitality of seeds after storage. In aroma evaluation of grains and their processed products, it can assess the impact of new raw materials, new technologies, fermentation processes, and even oral processing on the quality of grain products. This article also summarizes the characteristics of GC-IMS technology, compiles typical grain flavor compounds, and provides prospects for the future application of GC-IMS. © 2024 Society of Chemical Industry.

Elucidation of key fatty aroma compound contributing to the hepatopancreas of Eriocheir sinensis using sensomics approach by GC-IMS and GC-MS-O

Aroma is one of the most noticeable characteristics when consuming Chinese mitten crab (Eriocheir sinensis) and is crucial for consumer satisfaction and the development of industry. In this study, we utilized fingerprints and the sensomics approach to analyze volatiles in the hepatopancreas of E. sinensis from Chongming and Taixing. GC-IMS indicated that the odor profile was dominated by pungent (-), buttery (+), and fruity (+) from Chongming and was more prone to alcoholic (-), solvent (-), and aldehydic (+) in Taixing. Moreover, PLS-DA modeling identified 2-acetylthiazole and toluene as the primary differential compounds. Subsequently, fifteen active-aroma compounds with FD values of >4 was recombined in an odorless matrix to simulate the odor profile of the hepatopancreas. Notably, removing methional may significantly decrease the intensity of the fatty and toasted odors. The findings reveal the odor profile of hepatopancreas and establish a theoretical foundation for subsequent studies on flavor.

Decoding the Effect of Running on Flavor Perception Changes during Consumption of Sports Drinks

An online survey was conducted to show that most respondents preferred sports drinks with sweet and fruity characteristics. Eleven sports drinks with higher consumers' preferences were further selected for aroma and taste evaluation. Temporal dominance of sensations analysis showed that fruity and fresh attributes were dominant, while sour and fruity sweet were dominant tastes during consumption. β-Damascenone, β-ionone, and linalool contributing to floral perception, γ-decalactone, ethyl cinnamate, and isoamyl acetate contributing to fruity perception, and menthol contributing to fresh perception were confirmed by odor activity value analysis. Running affected the nasal air flow and the saliva secretion, resulting in the flavor perception changing from fruity sweet, sweet, and fruity to sour because the recognition threshold decreased for sweet, fruity, floral, and fresh flavors and increased for saltiness, astringency, and sour tastes.

Effects of different lactic acid bacteria on the characteristic flavor profiles of Chinese rice wine

BACKGROUND

It has been well accepted that lactic acid bacteria (LAB) are the main bacterial genera present during the brewing of Chinese rice wine (CRW). LAB plays a decisive role in the flavor quality of CRW; however, its application in CRW has previously been overlooked. Therefore, effects of different LAB as co-fermenter on the flavor characteristics of CRW were investigated.

RESULTS

Co-fermentation of LAB increased the utilization rate of reducing sugar, concentration of lactic acid, amino acid nitrogen and total acidity, as well as the content of volatile flavor compounds. Different LAB doses had little effect on the flavor profiles of CRW, but the species of LAB greatly affected the flavor characteristic. The flavor of CRW co-fermented with Lactococcus lactis was characterized by long-chain fatty acid ethyl esters, while co-fermentation with Weissella confusa highlighted the ethyl esters of low molecular weight and short carbon chains in the resultant CRW. Alcohol compounds were dominant in the CRW co-fermented using Pediococcus pentosaceus.

CONCLUSION

The co-fermentation of LAB increased the number of volatile flavor compounds, especially esters. LAB exhibited great potential in the application of CRW industry to enrich the flavor characteristics and enhance the flavor diversity of the final product. © 2023 Society of Chemical Industry.

Unveiling innovation in aroma attribute evaluation of Niulanshan Baijiu: An advanced exploration of two different processing methods via food sensory omics and penalty analysis

Niulanshan Baijiu (NLS), a notable variety of Baijiu known for its light flavor and extensive historical legacy, was subjected to a comparative analysis using two different processes: Hunzheng Xucha (HX) and Qingzheng Qingcha (QQ). The study combined sensory-oriented flavor analysis and penalty analysis to assess the differences between the two processes. Aroma compounds in NLS were extracted using liquid-liquid extraction and headspace solid phase microextraction. Gas chromatography-olfactometry-mass spectrometry was employed to identify 46 aroma-active compounds, including the first-time discovery of ethyl isohexanoate and 2,4-nonadienal in NLS. Quantification of 35 compounds with odor activity value (OAV) ≥ 1 was achieved using internal standard curve methods. Sensory assessments by a cohort of 111 participants highlighted the preference for HX-NLS in terms of flavor, while QQ-NLS exhibited a sour-Chen aroma that required improvement. The study further revealed the significant impact of acetic acid, butyric acid, hexanoic acid, octanoic acid, and 3-methylbutanal on the sour-Chen aroma in liquor.

Comprehensive evaluation of aroma and taste properties of different parts from the wampee fruit

Wampee is a tropical fruit having high medicinal value. To fully realize the fruit's potential, it is essential to reveal the flavor characteristics. In this study, a comprehensive analysis of the aroma and taste profiles of different parts from the wampee fruit was conducted. The aroma profile was analyzed by E-nose, and 67 volatile components were identified through HS-SPME-GC-MS. Among them, 11 were considered as crucial compounds. Additionally, 42 volatile components were identified by HS-GC-IMS, with 22 compounds showing a variable importance in projection scores greater than 1.0. Moreover, the taste profile and representative compounds were analyzed by E-tongue and HPLC, and 12 compounds were considered as important taste contributors based on taste activity value. These findings shed light on the various compounds responsible for the unique aroma and taste of the wampee fruit, providing theoretical foundation for exploring ways for its comprehensive utilization and development.

Decoding the Different Aroma-Active Compounds in Soy Sauce for Cold Dishes via a Multiple Sensory Evaluation and Instrumental Analysis

Screening the suitability of soy sauce for specific cooking methods from various products is beneficial for the fine development of the soy sauce industry. Multiple sensory evaluation and gas chromatography-mass spectrometry/olfactometry (GC-MS/O) analysis were combined to decode the suitability of soy sauces for cold dishes and characterize their differential aroma-active compounds. Thirty-two kinds of soy sauce with 42 sensory descriptors were determined via a check-all-that-apply analysis, and werefurther classified into six categories via a cluster analysis. The sensory evaluation results showed that seven soy sauce samples had the highest acceptance in each category. Solid-phase microextraction and solid phase extraction results combined with the GC-MS/O analysis results showed that a total of 38 aroma-active compounds were identified in seven soy sauce samples, among which 2-methoxy-phenol (6-93), ethyl acetate (2-48), 3-methyl-1-butanol (4-30), 3-methyl-butanal (5-24), methional (0-22), dimethyl trisulfide (5-19) and dimethyl disulfide (0-8) showed a higher relative odor activity value (ROAV). A partial least squares regression prediction combined with additional tests further confirmed that 2,5-dimethyl-pyrazine; 2,6-dimethyl-pyrazine; and 2-ethyl-6-methyl-pyrazine significantly contributed to the roasted attributes, methional significantly contributed to the sauce-like notes, ethanol significantly contributed to the alcoholic notes and 2-methoxy-phenol significantly contributed to the smoky notes. 2,5-Dimethyl-pyrazine; methional; 2,6-dimethyl-pyrazine and 2-ethyl-6-methyl-pyrazine significantly contributed to the caramel-like attributes.

Discrimination and characterization of different coconut water (CW) by their phenolic composition and volatile organic compounds (VOCs) using LC-MS/MS, HS-SPME-GC-MS, and HS-GC-IMS

Three varieties of coconut (Cocos nucifera L.) water (CW) at two maturity stages were investigated for physicochemical and nutritional properties. The profile of phenolic compounds and volatile organic compounds (VOCs) was determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS), headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). Most of the properties of CW changed significantly with maturity rather than variety. The five most relevant phenolic compounds in CW were chlorogenic acid, 4-hydroxy-3,5-dimethoxycinnamic acid, L-epicatechin, and procyanidins B2 and B1. Variety played a more important role in phenolic composition than maturity, and Wenye No. 4 can be distinguished from other two varieties. Alcohols and esters were the main VOCs in CW identified by HS-GC-IMS and HS-SPME-GC-MS, respectively. Five and four compounds (VIP scores > 1) were characteristic compounds for CW by HS-GC-IMS and HS-SPME-GC-MS, respectively. The VOCs of Wenye Nos. 2 and 3 were more similar than those of Wenye No. 4. These findings could provide useful information for the selection of raw materials of CW used for different industrial purposes.

Comparison of the volatile organic compounds in Citrus reticulata 'Chachi' peel with different drying methods using E-nose, GC-IMS and HS-SPME-GC-MS

Introduction

Citrus reticulata 'Chachi' peel (CRCP), which is named "Guangchenpi" in China, is a geographical indication product with unique flavor properties. CRCP has been used for centuries as a traditional genuine herb because of its excellent therapeutic effects. In addition, owing to its unique odor and high nutrition, it is widely used in various food preparations. Volatile organic compounds (VOCs) are regarded as an important quality marker for CRCP and are highly susceptible to effects in the drying process due to their thermal instability.

Methods

In the current study, the main VOCs in CRCP were processed using different drying methods, including sun-drying, hot air drying, and vacuum-freeze drying. The VOCs were identified by the electronic nose (E-nose), gas chromatography-ion mobility spectrometry (GC-IMS), and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS).

Results

The results showed that the CRCP dried by vacuum-freeze exhibited the highest VOCs contents and retained the richest compounds compared to those dried by other methods, which indicated that vacuum-freeze drying is the most suitable for CRCP production. Furthermore, the chemometrics analysis revealed that the primary differential metabolites of the samples generated using different drying methods were terpenes and esters.

Discussion

Overall, our study would help better understand the VOCs present in CRCP with different drying methods. The outcomes of the current study would guide the drying and processing of CRCP, which is beneficial for large-scale storage and industrial production of CRCP.

In vivo aroma release and perception of composite foods using nose space PTR–ToF–MS analysis with Temporal-Check-All-That-Apply

In vivo aroma release and perception of complex food matrices have been underexplored. The aims of this study were to investigate the effects of (i) fat and sugar content of chocolate-hazelnut spreads on in vivo aroma release and perception and (ii) carrier addition (bread, wafer) on in vivo aroma release and perception of chocolate-hazelnut spread using dynamic nose space analysis (PTR-ToF-MS) and dynamic sensory analysis (TCATA). Carriers were combined with spreads varying in fat and sugar content and were spiked with five volatile organic compounds (benzaldehyde, filbertone, 2-methylpyrazine, delta-dodecalactone, isovaleraldehyde). TCATA profiles from a consumer panel without in vivo nose space analysis (n = 72) and a trained panel performing in vivo nose space analysis (n = 8, triplicate) were compared. TCATA profiles of the spread-carrier combinations obtained by both panels showed similarly that attributes related to the carriers were perceived at the beginning of consumption, whereas attributes related to the spreads were perceived after swallowing. Significant (p < 0.05) and small differences were observed for the attributes cocoa, creamy, milky, sticky and toffee between both panels. In the evaluated reformulation range, fat and sugar content of chocolate-hazelnut spreads had only a limited effect on in vivo aroma release and perception. In contrast, addition of carriers strongly affected in vivo aroma release and perception for all target molecules. The addition of carriers to spreads generally increased aroma release (duration and intensity of aroma release) and decreased aroma perception. The addition of carriers generally reduced the time to reach maximum intensity compared to when spreads were eaten alone for the five volatile organic compounds while perception decreased. We conclude that the strong effect of carrier addition on in vivo aroma release and perception of chocolate-hazelnut spreads highlights the importance of investigating toppings/spreads accompanied with carriers rather than in isolation.

Unraveling the Difference in the Composition/Content of the Aroma Compounds in Different Tobacco Leaves: For Better Use

The composition/content of aroma compounds in tobacco leaves in the different producing areas varies too much, and it is very meaningful to develop advanced analysis techniques to investigate the composition/content-producing area correlation. Here, gas chromatography-ion mobility spectroscopy (GC-IMS) was used to analyze the composition/content of aroma compounds in tobacco samples from eight different producing areas. With this technique, ion mobility spectrum, differential ion mobility spectrum, and fingerprint spectrum were constructed for two-dimensional analysis. Then, the principal component analysis (PCA) and similarity analysis were performed for the eight tobacco samples. The results showed that the GC-IMS can detect 197 volatile aroma compounds in tobacco leaves and 75 of them are well identified. The fingerprint spectrum directly showed the difference in the composition/content of volatile aroma compounds in tobacco leaves from different producing areas. PCA and similarity analysis can clearly distinguish tobacco samples from different producing areas. This work demonstrated that the application of GC-IMS in analyzing the composition/content of aroma compounds in tobacco leaves is efficient. GC-IMS is a very powerful tool to give a direct and visual comparison of the composition/content of aroma compounds in tobacco leaves from different producing areas. The relationship between the composition/content of aroma compounds and producing areas could be established by this advanced technology. This work offers the possibility of planting or grading tobacco with different taste and smell more precisely in the future.

Characterization of japonica rice aroma profiles during in vitro mastication by gas chromatography-ion mobility spectrometry (GC-IMS) and electronic nose technology

By simulating the aroma changes during in vitro mastication, we can better understand the aroma changes during rice eating, which is helpful in studying people’s sensory preferences. To investigate the rice aroma released during the in vitro mastication, the present study analyzed rice bolus’s odor fingerprints in vitro mastication using electronic nose and gas chromatography-ion mobility spectrometry (GC-IMS). The electronic nose analysis results showed significant differences in the flavor of japonica rice in vitro mastication. In addition, GC-IMS determined 30 volatile organic compounds (VOCs) during rice in vitro mastication. Among these compounds, the most important content was aldehydes, followed by ketones and alcohols. Although the concentration of various chemicals was relatively high in cooked rice, most compounds decreased after mastication. The concentration of propan-2-ol, ethanol, and methanol increased after mastication. Multivariate data analysis showed that isoamyl sovalerate, pentanal, hexanal, acetone, hexanal, and limonene were the main VOCs of japonica rice during in vitro mastication. GC-IMS and e-nose analyses are complementary and recommended for using the two techniques to achieve the VOCs’ rapid and comprehensive detection during in vitro mastication. Results from this study allowed us to understand rice flavor during oral processing.

Identification and Inhibition of the Key Off-Odorants in Duck Broth by Means of the Sensomics Approach and Binary Odor Mixture

To improve the sensory quality and promote the diversified development of duck meat, the identification and inhibition of key off-odorants in duck broth were comparatively characterized by using the sensomics approach and binary odor mixture analysis. Sensory evaluation results showed that Litsea pungens Hemsl (LPH) could strongly inhibit the duck broth off-odorants. Fifty-four aroma-active compounds with flavor dilution factors ranging from 1 to 2048 were identified in duck broth and duck broth stewed by LPH. Recombination and omission tests confirmed that trans-4,5-epoxy-(E)-2-decenal, (E)-2-octenal, p-cresol, 1-octen-3-ol, and 4-methyloctanoic acid were the key off-odorants in duck broth. Additionally, trans-4,5-epoxy-(E)-2-decenal (9.26 μg/L) and p-cresol (718.91 μg/L) were identified as the key off-odorants in duck meat for the first time. The results of binary odor mixture and off-odorants inhibition curves demonstrated that linalool with the lowest theoretical inhibitory concentration (109.65 μg/L) had the best aroma masking ability among the five off-odorants, followed by geraniol (123.03 μg/L), (Z)-3,7-dimethyl-2,6-octadien-1-ol (301.99 μg/L), (E)-3,7-dimethyl-2,6-octadienal (2187.76 μg/L), and (Z)-3,7-dimethyl-2,6-octadienal (2691.53 μg/L). The spiking test verified that these compounds with the lowest theoretical inhibitory concentrations effectively inhibited the off-odorants of duck broth.

Evaluation of key aroma compounds and protein secondary structure in the roasted Tan mutton during the traditional charcoal process

The traditional charcoal technique was used to determine the changes in the key aroma compounds of Tan mutton during the roasting process. The results showed that the samples at the different roasting time were distinguished using GC-MS in combination with PLS-DA. A total of 26 volatile compounds were identified, among which 14 compounds, including (E)-2-octenal, 1-heptanol, hexanal, 1-hexanol, heptanal, 1-octen-3-ol, 1-pentanol, (E)-2-nonenal, octanal, 2-undecenal, nonanal, pentanal, 2-pentylfuran and 2-methypyrazine, were confirmed as key aroma compounds through the odor activity values (OAV) and aroma recombination experiments. The OAV and contribution rate of the 14 key aroma compounds were maintained at high levels, and nonanal had the highest OAV (322.34) and contribution rate (27.74%) in the samples after roasting for 10 min. The content of α-helix significantly decreased (P < 0.05), while the β-sheet content significantly increased (P < 0.05) during the roasting process. The content of random coils significantly increased in the samples roasted for 0-8 min (P < 0.05), and then no obvious change was observed. At the same time, β-turn content had no obvious change. Correlation analysis showed that the 14 key aroma compounds were all positively correlated with the content of α-helix and negatively correlated with the contents of β-sheet and random coil, and also positively correlated with the content of β-turn, except hexanal and 2-methypyrazine. The results are helpful to promoting the industrialization of roasted Tan mutton.

Recent trends in aroma release and perception during food oral processing: A review

The dynamic and complex peculiarities of the oral environment present several challenges for controlling the aroma release during food consumption. They also pose higher requirements for designing food with better sensory quality. This requires a comprehensive understanding of the basic rules of aroma transmission and aroma perception during food oral processing and its behind mechanism. This review summarized the latest developments in aroma release from food to retronasal cavity, aroma release and delivery influencing factors, aroma perception mechanisms. The individual variance is the most important factor affecting aroma release and perception. Therefore, the intelligent chewing simulator is the key to establish a standard analytical method. The key odorants perceived from the retronasal cavity should be given more attention during food oral processing. Identification of the olfactory receptor activated by specific odorants and its binding mechanisms are still the bottleneck. Electrophysiology and image technology are the new noninvasive technologies in elucidating the brain signals among multisensory, which can fill the gap between aroma perception and other senses. Moreover, it is necessary to develop a new approach to integrate the relationship among aroma binding parameters, aroma concentration, aroma attributes and cross-modal reactions to make the aroma prediction model more accurate.

Geographical differentiation of Molixiang table grapes grown in China based on volatile compounds analysis by HS-GC-IMS coupled with PCA and sensory evaluation of the grapes

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Volatile fingerprints of three Molixiang grapes were established using HS-GC-IMS.

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GC-IMS coupled with PCA could distinguished the three Molixiang grapes well.

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Sensory evaluation revealed significant (P ≤ 0.05) difference among the three samples.

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E-2-octenal, styrene and benzaldehyde were potential geographical marker compounds.

In this study, the volatile fingerprints of GC-IMS showed great differences on the volatile profiles of Molixiang grapes collected from three different regions of China, which suggested that aroma of table grapes could be largely impacted by origin areas. Butyl lactate, E-2-octenal and Z-2-pentanol were mainly contained in MLX-A, the grapes sampled from Ningbo, China. High contents of p-cymene, styrene and γ-terpinene were observed in MLX-B grapes sampled from Beizhen, China. In addition, benzaldehyde and methyl benzoate were major contained in MLX-C grapes sampled from Zhangzhou, China. The PCA results revealed effective differentiation of samples from different geographical origin based on the information obtained from GC-IMS. Furthermore, sensory evaluation showed that the aroma characters of grapes from different geographical origin were significantly different (P ≤ 0.05). E-2-octenal, styrene and benzaldehyde might serve as the geographical marker compounds of origin area based on the results of GC-IMS analysis and sensory evaluation.

Characteristics of umami peptides identified from porcine bone soup and molecular docking to the taste receptor T1R1/T1R3

To study the umami peptides derived from porcine bone soup, ultrafiltration fractions with molecular weight less than 1 kDa were screened by sensory analysis which showed higher umami intensity. Four potential umami peptides were identified from the screened fractions by Nano-LC-Q-TOF-MS/MS, among which FSGLDGAK, FAGDDAPR and FSGLDGSK were proved to have dominant umami taste by sensory evaluation and electronic tongue. The threshold of the three peptides ranged from 0.1 mM to 0.89 mM. In addition, FSGLDGSK had the highest umami intensity and exhibited a significant umami-enhancing effect in a 0.35% monosodium glutamate solution. The results of molecular docking simulation showed that the key binding sites of taste receptor type 1 member 1 (His71, Asp108 and Glu301) and taste receptor type 1 member 3 (Glu48, Ser104 and His145) were crucial to the interaction with the umami peptides. Besides, electrostatic interaction and hydrogen bond mainly contributed to the mechanism of umami taste.

Research progress on the formation mechanism and detection technology of bread flavor

With a long history of fermentation technology and rich flavors, bread is widely consumed by people all around the world. The consumer market is huge and the demand is wide. However, the formation mechanism of bread baking flavor has not been completely defined. In order to improve the breadmaking process and the quality of bread, the main flavor substances produced in bread baking, the formation mechanism, and the detection technology of bread baking flavor are carefully summarized in this paper. The generation conditions and formation mechanism of flavor substances during the bread baking process are expounded, and the limitations of some current bread flavor detection technologies are proposed, which will provide theoretical basis for effectively regulating the generation of flavor substances in the bread baking process and making bread with good flavor and rich nutrition in the future.

Discrimination and Characterization of the Volatile Organic Compounds in Schizonepetae Spica from Six Regions of China Using HS-GC-IMS and HS-SPME-GC-MS

Volatile organic compounds (VOCs) are the main chemical components of Schizonepetae Spica (SS), which have positive effects on the quality evaluation of SS. In this study, HS-SPME-GC-MS (headspace solid-phase microextraction-gas chromatography-mass spectrometry) and HS-GC-IMS (headspace-gas chromatography-ion mobility spectrometry) were performed to characterize the VOCs of SS from six different regions. A total of 82 VOCs were identified. In addition, this work compared the suitability of two instruments to distinguish SS from different habitats. The regional classification using orthogonal partial least squares discriminant analysis (OPLS-DA) shows that the HS-GC-IMS method can classify samples better than the HS-SPME-GC-MS. This study provided a reference method for identification of the SS from different origins.

How Different Are Industrial, Artisanal and Homemade Soft Breads?

Soft bread has a significant relevance in modern diets, and its nutritional impact on human health can be substantial. Within this product category, there is an extensive range of ingredients, formulations, and processing methods, which all contribute to the vast diversity found in the final products. This work compared the impact of three different processing methods (industrial, artisanal, and homemade preparation) on the technological (formulation and processing, as they are interconnected in real-life conditions), nutritional, and physicochemical properties of soft bread. In total, 24 types of soft bread were analyzed: 10 industrial, 6 artisanal, and 8 homemade. Although production diagrams were similar among the three methods, industrial recipes contained on average more ingredients and more additives. Industrial bread was lower in saturated fat compared to the other two groups, but contained more sugar than homemade bread. The physical properties of all loaves were comparable, with the exception of higher crumb elasticity in industrial bread compared to homemade. An analysis of volatile molecules revealed more lipid oxidation markers in industrial bread, more fermentation markers in artisanal bread, and fewer markers of Maillard reactions in homemade bread. Chemical reactions during processing seem to be the principal criterion making possible to discriminate the different processing methods. These results offer a quantitative assessment of the differences within a single product category, reflecting the real-world choices for consumers.

In vivo and in vitro aroma release in surimi gel with different cross-linking degrees by proton transfer reaction-mass spectrometry

Transglutaminase-induced cross-linking has been suggested as a strategy to govern surimi gels' texture. To achieve the aroma regulation of surimi gels by cross-links, surimi gels were treated with microbial transglutaminase to get different cross-linking degrees, and in vivo and in vitro aroma releases were investigated by a proton transfer reaction-mass spectrometry (PTR-MS). Seventeen compounds in surimi gels were detected by PTR-MS. The in vitro release curves of odorants were fitted by a pseudo-first-order kinetics model. As the cross-links increased, most aroma compounds' released concentrations and release rates decreased first, and then increased significantly (P < 0.05) when the cross-linking degree exceed around 35.4%, negatively related to the springiness and the gel strength of surimi gels. However, the in vivo aroma release results showed that the harder surimi gel released fewer aroma compounds. In conclusion, texture affected by cross-links could be a strategy to control the aroma release of surimi gels.

Thinned-Young Apple Polyphenols Inhibit Halitosis-Related Bacteria Through Damage to the Cell Membrane

The thinned young apple is a by-product and is generally discarded in the orchard during fruit thinning. The polyphenol content of thinned young apples is about 10 times more than that of ripe apples. In our study, the antibacterial effect of thinned young apple polyphenols (YAP) on the halitosis-related bacteria including Porphyromonas gingivalis, Prevotella intermedius, and Fusobacterium nucleatum was investigated. The minimum inhibitory concentrations of YAP against P. gingivalis, P. intermedia, and F. nucleatum were 8.0, 8.0, and 12.0 mg/ml, while the minimum bactericidal concentrations were 10.0, 10.0, and 14.0 mg/ml, respectively. The scanning electron microscopy and transmission electron microscopy analyses showed that after YAP treatment, the membrane surface of halitosis-related bacterial cells was coarse and the cell wall and membrane were separated and eventually ruptured. The integrity of the cell membrane was determined by flow cytometry, indicating that the cells with the integrity membrane significantly reduced as the YAP concentration treatment increased. The release of proteins and nucleic acids into the cell suspension significantly increased, and the membrane potential reduced after the YAP treatment. This research illustrated the antibacterial mechanism of YAP against halitosis-related bacteria and provided a scientific basis of utilizing the polyphenols from the discarded thinned young apples.

Characterization of key aroma compounds in stewed mutton (goat meat) added with thyme (Thymus vulgaris L.) based on the combination of instrumental analysis and sensory verification

Thyme (Thymus vulgaris L.) is widely used as a traditional spice in the cooking of goat meat (mutton) due to its distinctive flavor and the ability to weaken the "goaty flavor". To investigate the aroma characteristics of stewed mutton with thyme (SMT), four SMT samples prepared using different cooking utensils were analyzed by gas chromatography-mass spectrometry/olfactometry (GC-MS/O). Totally, 26 aroma-active compounds (AACs) were determined by GC-MS/O and further quantified. Among these, 20 AACs exhibited odor activity values (OAV) greater than 1. However, no significant differences existed among the four SMTs, which indicated that different utensils had little effect on the aroma profile of SMTs. Aroma recombination and omission experiments results showed that nonanal, (E)-2-octenal, and (E,E)-2,4-decadienal had the greatest contribution to the aroma profile of SMTs. These three compounds, together with dimethyl trisulfide, 3-methyl-butanal, octanal, (E)-2-decenal, (E)-2-nonenal, methanethiol, hexanal, (E)-2-undecenal, and 1-octen-3-ol, were confirmed as the key aroma compounds in SMTs.

Validation Study on the Simultaneous Quantitation of Multiple Wine Aroma Compounds with Static Headspace-Gas Chromatography-Ion Mobility Spectrometry

A new quantitative method based on static headspace-gas chromatography-ion mobility spectrometry (SHS-GC-IMS) is proposed, which enables the simultaneous quantitation of multiple aroma compounds in wine. The method was first evaluated for its stability and the necessity of using internal standards as a quality control measure. The two major hurdles in applying GC-IMS in quantitation studies, namely, nonlinearity and multiple ion species, were also investigated using the Boltzmann function and generalized additive model (GAM) as potential solutions. Metrics characterizing the model performance, including root mean squared error, bias, limit of detection, limit of quantitation, repeatability, reproducibility, and recovery, were investigated. Both nonlinear fitting methods, Boltzmann function and GAM, were able to return desirable analytical outcomes with an acceptable range of error. Potential pitfalls that would cause inaccurate quantitation, that is, effects of ethanol content and competitive ionization, were also discussed. The performance of the SHS-GC-IMS method was subsequently compared against that of a currently established method, namely, GC-MS, using commercial wine samples. These findings provide an initial validation of a GC-IMS-based quantitation method, as well as a starting point for further enhancing the analytical scope of GC-IMS.

Discrimination and characterization of the volatile organic compounds in eight kinds of huajiao with geographical indication of China using electronic nose, HS-GC-IMS and HS-SPME-GC-MS

Huajiao (Zanthoxylum bungeanum maxim. and Zanthoxylum armatum DC.) is a highly prized spice in China due to its distinctive aroma and taste. The volatile organic compounds (VOCs) of eight kinds of red and green huajiao which varied according to geographical indication of P.R. China were evaluated by electronic nose (E-nose), headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). Results showed that red huajiao emitted more terpenes, esters, and fewer alcohols than green huajiao. Partial least squares-discriminant analysis based on GC-MS and GC-IMS data was revealed a good classifying tool for huajiao from different original habitats. Four and eight aroma substances were selected as the potential markers by the variable importance in projection (VIP) variable selection method, respectively. The results of the current study provide a useful basis in the huajiao aroma difference study. Additionally, a rapid huajiao aroma analysis method using GC-IMS was developed.

Volatile Profile Characterization of Winter Jujube from Different Regions via HS-SPME-GC/MS and GC-IMS

A combined untargeted and targeted approach was established for fingerprinting volatile organic compounds in winter jujubes from eight regions of China. Volatiles, including alcohols, aldehydes, acids, esters, and alkenes, were identified by gas chromatography-ion mobility spectrometry (GC-IMS). Benzyl alcohol, octanoic acid, 2-hexenal, linalool, 2-nonenal, and ethyl decanoate were the most common compounds present in all jujubes. Principal component analysis (PCA) from GC-IMS and untargeted E-nose showed that the main volatile organic compounds (VOCs) of most jujubes were similar. The volatile organic compounds of winter jujubes from Yuncheng city, Shanxi province, and Aksu region, Xinjiang province, were significantly different from those from other regions. 1-Penten-3-ol, ethyl hexanoate, methyl laurate, and 2-formyltoluene were the markers of XJAKS with green and fruity aroma, and SXYC could be labeled by acetone and 2-methoxyphenol with woody and pungent aroma. GC-IMS was an effective method for volatile fingerprinting of jujubes with high sensitivity and accuracy.

Development of meat flavors in peony seed-derived Maillard reaction products with the addition of chicken fat prepared under different conditions

To prepared Maillard reaction products (MRPs) enriched with chicken flavor, the effects of chicken fats on peony seed-derived MRPs were evaluated. The thermal treatments, lipase enzymatic hydrolysis and lipoxygenase with subsequent mild thermal treatments were applied to oxidized chicken fats before their use in the Maillard reaction. Different oxidized chicken fats led to diverse chemical properties and varied volatile compounds. The addition of oxidized chicken fat increased the meaty of MRPs. The chicken fat promoted the Maillard reaction, which produced more oxygenated compounds; however, it reduced the sulfur compounds. Correlation analysis of the chemical properties of chicken fat and the major volatile compounds showed that by controlling the chemical properties of chicken fat, it might be possible to control the content of some volatile compounds of chicken fat and MRPs. Our data elucidated that chicken fat contributes to the development of meat flavors after oxidation and thermal treatments.

Characterization of the Key Aroma Compounds in the Fruit of Litsea pungens Hemsl. (LPH) by GC-MS/O, OAV, and Sensory Techniques

The key aroma compounds in the fruit of Litsea pungens Hemsl. (LPH) were concentrated through solvent-assisted flavor evaporation (SAFE) and characterized by gas chromatography-mass spectrometry-olfactometry (GC-MS/O), quantitative descriptive analysis (QDA), odor activity values (OAVs), and addition test. The results showed that LPH contained 31 aroma-active compounds (flavor dilution, FD = 9). Among them, 30 odorants were quantified by the standard curve method. The OAV analysis results showed that 25 odorants had OAVs ≥ 1, which could be considered as the potent odorants. D-Limonene and 3,7-dimethyl-2,6-octadienal had the highest OAVs (OAV = 9803 and 8399), followed by (Z)-3,7-dimethylocta-2,6-dienal (OAV = 1893), β-myrcene (OAV = 1798), (E)-3-phenyl-2-propenoic acid ethyl (OAV = 1603), and β-caryophyllene (OAV = 1129). Addition experiments further confirmed that 3,7-dimethyl-2,6-octadienal, (Z)-3,7-dimethylocta-2,6-dienal, and D-limonene contributed to lemon attribute, β-myrcene contributed to green attribute, citronellal contributed to mint and fresh note, and eucalyptol contributed to eucalyptus-like note were the key odorants.

An Insight by Molecular Sensory Science Approaches to Contributions and Variations of the Key Odorants in Shiitake Mushrooms

An insight using molecular sensory science approaches to the contributions and variations of the key odorants in shiitake mushrooms is revealed in this study. Odorants were extracted by headspace solid phase microextraction (HS-SPME) and direct solvent extraction combined with solvent-assisted flavor evaporation (DSE-SAFE) in fresh and hot-air-dried shiitake mushrooms. Among them, 18 and 22 predominant odorants were determined by detection frequency analysis (DFA) and aroma extract dilution analysis (AEDA) combined with gas chromatography-olfactometry (GC-O) in the fresh and dried samples, respectively. The contributions of these predominant odorants in the food matrix were determined by quantification and odor activity values (OAVs) with aroma recombination verification. There were 13 and 14 odorants identified as key contributing odorants to overall aroma, respectively. 1-Octen-3-ol and 1-octen-3-one were the most key contributing odorants in the fresh samples in contributing mushroom-like odor. After hot-air-drying, the OAV and concentrations on dry basis of the key contributing odorants changed, due to oxidation, degradation, caramelization and Maillard reactions of fatty acids, polysaccharides and amino acids. 1-Octen-3-ol was reduced most significantly and degraded to 1-hydroxy-3-octanone, while phenylethyl alcohol increased the most and was formed by phenylalanine. In hot-air-dried samples, lenthionine became the most important contributor and samples were characterized by a sulfury odor. Overall contributions and variations of odorants to the aroma of shiitake mushrooms were revealed at the molecular level.