Formation Of Volatile Compounds Research Articles

Impact of Mild Field Drought on the Aroma Profile and Metabolic Pathways of Fresh Tea (Camellia sinensis) Leaves Using HS-GC-IMS and HS-SPME-GC-MS.

Aroma plays a pivotal role in defining tea quality and distinctiveness, and tea producers have often observed that specific drought conditions are closely associated with the formation and accumulation of characteristic aroma compounds in tea leaves. However, there is still limited understanding of the differential strategies employed by various tea cultivars in response to drought stress for the accumulation of key volatile aroma compounds in fresh tea leaves, as well as the associated metabolic pathways involved in aroma formation. In this study, two widely cultivated tea cultivars in China, Fuding Dabai (FD) and Wuniuzao (WNZ), were examined to assess the impact of mild field drought stress on the composition and accumulation of key volatile aroma compounds in fresh leaves using headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) technologies. Results revealed that drought stress led to a substantial increase in the diversity of volatile compounds (VOCs) in FD, while WNZ exhibited a notable rise in low-threshold VOC concentrations, amplifying sweet, floral, fruity, and earthy aroma profiles in post-drought fresh leaves. Through partial least squares discriminant analysis (PLS-DA) of HS-GC-IMS and HS-SPME-GC-MS data, integrating variable importance projection (VIP) scores and odor activity values (OAVs) above 1, 9, and 13, key odor-active compounds were identified as potential markers distinguishing the drought responses in the two cultivars. These compounds serve as crucial indicators of the aromatic profile shifts induced by drought, providing insights into the differential metabolic strategies of the cultivars. Additionally, KEGG enrichment analysis revealed 12 metabolic pathways, such as terpenoid biosynthesis, fatty acid synthesis, cutin, suberine, and wax biosynthesis, and phenylalanine metabolism, which may play crucial roles in the formation and accumulation of VOCs in tea leaves under drought stress. These findings provide a comprehensive framework for understanding the cultivar-specific mechanisms of aroma formation and accumulation in tea leaves under mild drought conditions.

Dry-aged beef quality with the addition of Mucor flavus – Sensory, chemosensory and fatty acid analysis

Dry-aged beef is a premium product known for its unique taste and aroma. These characteristics are thought to partially depend on the composition of the microorganisms present on the meat surface during ageing. Recently several attempts to standardise this process were made. This study aimed to assess the effect of a fungal biostarter application on the profile of volatile compounds, fatty acid composition and sensory quality of dry-aged beef. The Longissimus muscle used in the experiment originated from 20 crossbred (10 heifers and 10 steers) animals from the crossing of Holstein-Friesian cows with beef breed bulls. A fungal biostarter composed of Mucor flavus strain KKP2092p was used for meat inoculation. Half of the material was aged without the use of a biostarter (Control samples). The dry-ageing of the meat was performed at a temperature of 1.5 °C with approximately 80–90 % relative humidity for 28 days. The use of Mucor flavus KKP2092p improved meat quality attributes (aroma liking, flavour and overall liking) as a result of the formation of specific volatile compounds. The profile of volatile compounds in the meat aged with Mucor flavus and control variants was differentiated. This study also indicated that Mucor flavus biostarter had an impact on the specific fatty acid composition. An insignificant effect of Mucor flavus on lipid oxidation expressed as mg/kg of malonaldehyde was also observed.

Changes in flavor profile of vegetable seasonings by innovative drying technologies: A review.

Seasonings like garlic, ginger, and scallion provide spicy and masking flavor or aroma in vegetables. However, the method or technique used for drying these spices can affect the flavor profile. Therefore, this review focuses on vegetable seasonings like ginger, garlic, and scallion, the characteristic flavor of fresh and dehydrated vegetable seasoning, and how drying methods (freeze-drying [FD], convective hot air drying [HAD], infrared drying, microwave drying [MW]), and other recent dryers (swirling fluidized bed [SFB], pulsed-vacuum dryer, relative humidity-convective dryer, etc.) affect the flavor profile of the common vegetable seasonings. HAD increases α-zingiberene, reduces gingerol, and forms β-citral and citral in fresh ginger. FD increased sesquiterpenes, retained terpenoids, sulfides, and other volatiles in fresh ginger, and did not produce new volatile compounds (VOCs) in garlic. SFB drying better preserves 6-gingerol than FD and HAD. MW increases trisulfides and cyclic sulfur compounds in garlic. In general, drying, especially thermal drying reduces the VOCs in fresh garlic, ginger, and scallion and causes the formation of new VOCs.

Contribution of plastic solid components to volatile organic compounds formation during plastics combustion

The combustion of plastic waste releases volatile organic compounds (VOCs) that are harmful to human health. However, information on the micro-mechanisms of VOC formation remains lacking. Here, the study hypothesized and verified the relationship between VOC formation and solid component degradation during plastics combustion. The VOCs released during plastics combustion exhibit characteristics such as low carbon content (nc< 10), volatility (9μgm-3 < log10C0 < 11μgm-3), and medium oxidation degree (−1.5 <OSC¯ < −0.5). The dominant VOCs ketones/aldehydes/acids (33-43%) may be attributed to the depolymerization of the polymer structure of plastics, the oxidation of C-O/C=O groups, and the secondary cleavage of gaseous oxygen-containing macromolecules. The VOCs released from the combustion of polyethylene terephthalate (PET) and poly(butyleneadipate-co-terephthalate) (PBAT) contained more aromatics than polyethylene (PE) and polypropylene (PP). And the temperature response of aromatics released from PET and PBAT lagged other VOCs compared that of PP and PE. However, compared to biomass thermal conversion, combustion of plastics releases fewer aromatics and nitrogenous compounds. Collectively, this work shows that the formation mechanisms of VOCs contributed by the solid components during plastic combustion are similar for PET and PBAT due to their similar chemical structures. The proposed mechanism in this paper will provide insight into the control of contaminants during plastic combustion.

Integrated Metabolomics and Proteomics Analysis Provides Insights into the Formation of Volatile Compounds in Three Different Polyembryonic Mango Cultivars.

Understanding volatile compound formation is critical for enhancing the flavor quality of mangoes. Integrated untargeted metabolomics and proteomics were employed to explore volatile compound formation in three different polyembryonic mango cultivars ("Ah Ping," "Rosa," and "Rosigold"). A total of 87 volatile compounds were identified using SPME-GC-MS. Untargeted metabolomics and proteomics resulted in identification of 508 metabolites and 4481 proteins, respectively. Integrative analysis revealed that the volatile compound formation was influenced by fatty acids, amino acids, pentose, and hexose, as well as terpenoid metabolisms. Specifically, upward expression of core enzymes in lipoxygenanse pathway was responsible for the higher levels of some C6 and C9 volatile compounds in "Ah Ping." The differential expression of key enzymes in fatty acid degradation facilitates the varied contents of straight-chain volatile compounds. The upregulation of glutamate decarboxylase and branched-chain amino acid aminotransferase upstream of butanoate metabolism led to the highest levels of butyl esters in "Ah Ping." Furthermore, the different levels of volatile furan and pyran compounds might be attributed to differential expression of critical enzymes in pentose and hexose metabolism. These findings established a metabolic and proteomic map unraveling the biosynthesis of specific volatile compounds and provided insights into understanding the characteristic flavor of mango.

Effects of heat treatments on the stability, antioxidant activity and volatiles of milk and whey ultrafiltration permeates

Milk (MP) and whey (WP) ultrafiltration permeates were obtained from different dairy processing plants. The effects of pH (4 or 6) and heat treatments (63 °C, 30 min; or 110 °C, 6 min) on permeate stability were measured by the increase of turbidity, and precipitation of nitrogen and calcium. The antioxidant activity and the production of volatiles compounds, as affected by heat treatments, was also evaluated. WP showed a higher sensitivity to heat treatments than MP. Increasing heating temperature reduced the stability of permeates, with an intensified effect at pH 6. Calcium precipitation was the main factor responsible for the increase in turbidity. Lowering the pH to 4 prior to heating strongly limited the development of turbidity. Sterilisation improved antioxidant activity of both permeates, with a greater effect on WP. Sterilisation had no effect on the concentration of volatile aldehydes but promoted the formation of volatile sulfur compounds, and more significantly in WP.

Optimizing Byproduct Processing for Clean Label Foods: Avocado and MSM‐Tambaqui With a Focus on Zero Waste

ABSTRACTAgricultural byproducts, often discarded, possess significant nutritional value and technological potential. This study investigates the efficacy of ethanolic‐water extracts from avocado (Persea americana Mill.) byproducts, obtained with minimal solvent use through optimized extraction, in enhancing the stability of mechanically separated meat‐tambaqui (Colossoma macropomum) burgers, a high‐fat Amazonian fish. 2000 ppm of avocado seed and peel extract were applied in shelf‐life tests conducted under refrigeration and freezing conditions to evaluate the stability of the burgers. The results demonstrated that the bioactive compounds from avocado byproducts resulted in lower TBARS values, indicating strong antioxidant properties, reduced formation of volatile nitrogen compounds, and color maintenance than sodium erythorbate. Monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) were preserved using bioactive ethanolic‐water extracts, and the protein content was improved compared to the control, enhancing nutritional quality. This study highlights the potential of using agri‐food byproducts, especially for application in highly perishable items such as fish, promoting the development of clean label products, thus supporting a more efficient and environmentally friendly food industry focusing on the circular economy.

Volatile compounds and quality changes of lesser mealworm larvae: effect of blanching, storage temperature and time

Abstract The impact of blanching and storage temperature (−20 °C and −80 °C) on the formation of volatile organic compounds and changes in quality characteristics of lesser mealworm (Alphitobius diaperinus) larvae was examined over seven weeks. Acid and peroxide values, pH, and colour of lesser mealworm larvae were significantly affected by the studied variables. The changes in these characteristics as well as in the volatile profile indicated occurring lipid oxidation and lipid hydrolysis processes during the storage. The intensity of these reactions was mostly influenced by blanching treatment and storage time, and a lesser extent by storage temperature. It was proposed that changes in composition and intensity of volatiles can be used for rapid quality assessment of lesser mealworm larvae during frozen storage. Thus, the selection of optimum storage conditions for lesser mealworm larvae is important for the prevention of undesirable chemical reactions and preservation of the quality of insect biomass.

Effect of fatty acid composition on the volatile compounds of pasteurized milk during low-temperature storage

The change in milk fat during storage greatly influences its flavor. This study investigates the effect of fatty acid composition on milk flavor by analyzing volatile compounds in pasteurized whole milk (PWM) and pasteurized skim milk (PSM) during storage at 4 °C. 33 types of volatile compounds were detected and the content of ketones was highest, followed by esters and aldehydes. Based on variable importance in projection and relative odor activity value, 2-hexenal dimer, acetic acid ethyl ester dimer, acetic acid ethyl ester, and butanal were identified as the key differential volatile compounds. These compounds were found in higher concentrations in PWM than in PSM, indicating a close relationship with the changes in the fatty acid composition of milk fat. Among 11 fatty acids detected in PWM, the content of saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) decreased by 0.69 % and 49.1 %, respectively, while the content of monounsaturated fatty acids increased by 46.8 % during 15 days storage, which suggests that the oxidation of SFA and PUFA contributed more to the volatile compound formation. Correlation analysis between fatty acid composition and volatile compounds found that fatty acid C18:2 and C16:0 were strongly associated for 2-hexenal, acetic acid ethyl ester, and butanal. These fatty acids were mainly derived from neutral lipids or phospholipids. These findings provide a new perspective for the formation pathway of milk flavor.

Hydrogen Gas-Grilling in Meat: Impact on Odor Profile and Contents of Polycyclic Aromatic Hydrocarbons and Volatile Organic Compounds.

The effect of fuel (hydrogen vs. butane) on the formation of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) was evaluated for grilled horse meat (very low-fat and low-fat) cooking vertically. Gas chromatography-mass spectrometry was used to analyze PAHs and VOCs. An electronic nose was used to evaluate the odor profile. Total high-molecular-weight PAHs ranged from 19.59 to 28.65 µg/kg with butane and from 1.83 to 1.61 µg/kg with hydrogen. Conversely, total low-molecular-weight PAHs went from 184.41 to 286.03 µg/kg with butane and from 36.88 to 41.63 µg/kg with hydrogen. Aldehydes and alkanes were the predominant family in a total of 59 VOCs. Hydrogen gas-grilling reduced significantly (p < 0.05) the generation of VOCs related to lipid oxidation. The odor profile was not modified significantly despite the change of PAHs and VOCs. The findings indicate that hydrogen is a viable alternative to butane for grilling horse meat. Hydrogen gas-grilling may be regarded as a safe cooking procedure of meat from a PAH contamination point and perhaps sustainable environmentally compared to a conventional technique. The present study provides the basis for the use of hydrogen gas in grilled meat.

Physicochemical Properties of (La,Sr)CoO3 Thick Films on Fe-25Cr Steel under Exposure to SOFC Cathode Operating Conditions.

La0.6Sr0.4CoO3 (LSC) coatings with a thickness of 50-100 µm were deposited on Fe-25Cr ferritic stainless steel (DIN 50049) via screen printing. The required suspension had been prepared using fine LSC powders synthesised using EDTA gel processes. In its bulk form, the LSC consisted entirely of the rhombohedral phase with space group R-3c, and it exhibited high electrical conductivity (~144 S·cm-1). LSC-coated steel was oxidised in air at 1073 K, i.e., under conditions corresponding to SOFC cathode operation, for times of up to 144 h. The in situ electrical resistance of the steel/La0.6Sr0.4CoO3 layered system during oxidation was measured. The products formed on the samples after the oxidation reaction resulting from exposure to the corrosive medium were investigated using XRD, SEM-EDS, and TEM-SAD. The microstructural, nanostructural, phase, and chemical analysis of films was performed with a focus on the film/substrate interface. It was determined that the LSC coating interacts with the oxidised steel in the applied conditions, and a multi-layer interfacial zone is formed. Detailed TEM-SAD observations indicated the formation of a main layer consisting of SrCrO4, which was the reaction product of (La,Sr)CoO3, and the Cr2O3 scale formed on the metal surface. The formation of the SrCrO4 phase resulted in improved electrical conductivity of the investigated metal/ceramics layered composite material, as demonstrated by the low area-specific resistance values of 5 mΩ·cm2, thus making it potentially useful as a SOFC interconnect material operating at the tested temperature. In addition, the evaporation rate of chromium measured for the uncoated steel and the steel/La0.6Sr0.4CoO3 layered system likewise indicates that the coating is capable of acting as an effective barrier against the formation of volatile compounds of chromium.

Cape Gooseberry (Physalis peruviana L.) Volatile Compounds Determination by Vacuum-Assisted Sorbent Extraction (VASE)-Selected Aspects.

Vacuum-Assisted Sorbent Extraction (VASE) is a novel extraction technique that uses vacuum to facilitate the transfer of volatile compounds from the matrix to the sorbent. This technique was explored for extraction of volatiles from cape gooseberry fruit, for both qualitative and quantitative analyses. Selected extraction parameters were tested: sample size, extraction temperature and time, influence of tissue disintegration on release of volatiles, and also addition of Ag+1 ions in the form of AgNO3 to stop enzymatic formation of volatile compounds. For selected conditions (10 g sample, extraction for 30 min. at 40 °C of volatiles from blended fruit) quantitative aspects were explored. Twenty-two compounds of cape gooseberry were tested. The method was characterized with a very good linearity in a range of 10-5000 µg/kg and good reproducibility. The experiments proved the usefulness of VASE in both volatile profiling and quantitative analyses of cape gooseberry and in prospective other fruit.

Integrated metabolomics and microbiome analysis reveal blended oil diet improves meat quality of broiler chickens by modulating flavor and gut microbiota

This study was to evaluate the effects of different dietary oils in chicken diets on meat quality, lipid metabolites, the composition of volatile compounds, and gut microbiota. Nine hundred female 817 crossbred broilers at one day old with an average body weight of 43.56 ± 0.03 g were randomly divided into five treatments, each consisting of 6 replicates of 30 birds. The control group received soybean oil (SO); other groups received diets supplemented with rice bran oil (RO), lard (LO), poultry fat (PO), and blended oil (BO), respectively. All diets were formulated as isoenergic and isonitrogenous. Compared with SO, RO decreased ADG and 42 d BW (P < 0.05). Compared with the RO, BO increased ADG and 42 d BW and decreased FCR (P < 0.05). Compared with SO, BO increased 24 h a* value and reduced the malondialdehyde (P < 0.05), and further improved drip loss of breast muscle. The proportions of C18:0 and saturated fatty acid were the highest in LO, and the proportions of C16:1, C18:1, and monounsaturated fatty acids were the highest in BO. The content of C18:2, C18:3, and polyunsaturated fatty acids were the highest in SO. The contents of glyceryl triglycerides and total esters in BO were significantly higher than those in the SO and LO group (P < 0.05). There was a substantial increment in the relative abundance of PPARα, ACOX1 and CPT1A transcripts in breast of chickens fed BO (P < 0.05). Further, dietary BO increased the relative cecal abundance of Firmicutes phylum, Ruminococcus_torques and Christensenellaceae_R-7 genera, and decreased that of Campylobacterota, Proteobacteria, and Phascolarctobacterium (P < 0.05). Genera g_Lactobacillus and Christensenellaceae_R-7 may mainly be involved in the formation of volatile flavor compounds in breast muscle. In conclusion, dietary BO improved the flavor of chickens by increasing the concentration of triglycerides and volatile flavor compounds, improving gut microbiota structure, and suppressing lipid oxidation. The potential positive effects of BO may be associated with the regulation of lipid metabolism.

Carbonization of bacterial cellulose with structure retention and Nitrogen/Sulfur/Oxygen doping for application in supercapacitors electrode

Bacterial cellulose (BC) presents great potential as an economical and sustainable biomass for the preparation of porous carbon electrodes for electrochemical energy storage. However, it is a challenge to maintain the natural structural advantages of BC and regulate the chemistry during the carbonization, significantly hindering the practical application. This study proposes a straightforward and efficient approach to rationally control the carbonization process of BC for improving structure retention and endowing multiple atomic doping, contributing an advanced electrode for supercapacitors. The addition of ammonium sulfate ((NH4)2SO4) is instrumental in promoting the early dehydration carbonization, forming a carbon layer with thermal insulation. This thermal barrier suppresses the volatile organic compound formation, resulting in the inhibition of volume shrinkage and boosted carbon yield. Moreover, the air activation combined with the addition of (NH4)2SO4 contributes to a Nitrogen/Sulfur/Oxygen-doped carbon electrode. The well-maintained hollow structure and diverse chemistry provide sufficient active sites and enhanced ion diffusion, resulting in a specific capacitance of 268.2 F/g at a current of 0.5 A/g and outstanding capacitance retention of 99.46 % after 10,000 cycles at 5 A/g. This work provides a deep insight into the development of cost-effective biomass in developing advanced carbon electrodes for efficient energy storage.

Mechanisms underlying the formation of main volatile odor sulfur compounds in foods during thermal processing.

Volatile sulfur compounds (VSCs) significantly influence food flavor and garner considerable attention in flavor research due to their low sensory thresholds, diverse odor attributes, and high reactivity. Extensive research studies have explored VSC formation through thermal processes such as the Maillard reaction, thermal pyrolysis, oxidation, and enzymatic reactions. However, understanding of the specific reaction mechanisms and processes remains limited. This is due to the dispersed nature of existing studies, the undefined intermediates involved, and the complexity of the matrices and processing conditions. Given these limitations, the authors have shifted their focus from foods to sulfides. The structure, source, and chemical characteristics of common precursors (sulfur-containing amino acids and derivatives, thiamine, thioglucoside, and lentinic acid) and their corresponding reactive intermediates (hydrogen sulfide, thiol, alkyl sulfide, alkyl sulfenic acid, and thial) are provided, and the degradation mechanisms, reaction rules, and matrix conditions are summarized based on their chemical characteristics. Additionally, the VSC formation processes in several typical foods during processing are elucidated, adhering to these identified rules. This article provides a comprehensive overview of VSCs, from precursors and intermediates to end products, and is crucial for understanding the mechanisms behind VSC formation and managing the flavor qualities of processed foods.

Influence of Drying and Storage Conditions on the Volatile Organic Compounds Profile of Spirulina Platensis

Spirulina platensis (SP) has gained popularity over the last few years, owing to its remarkable nutritional properties and high potential across various industrial sectors. In this study, we analyzed the volatile profile of eight SP samples from the same strain subjected to different drying (oven-drying, air-drying, and spray-drying) and storing conditions (“freshly prepared” and after 12 months of storage) using HS-SPME-GC-MS. Principal component analysis (PCA) was used as a multivariate technique to discern similarities and differences among the samples. The main aim was to assess the impact of the drying technique on the aroma profile and storage life of SP samples. Air-drying leads to the less pronounced formation of by-products related to heat treatment, such as Maillard and Strecker degradation compounds, but promotes oxidative and fermentative phenomena, with the formation of organic acids and esters, especially during storage. Thermal treatment, essential for limiting degradation and fermentation during storage and extending shelf life, alters the aroma profile through the formation of volatile compounds, such as Strecker aldehydes and linear aldehydes, from amino acid and lipid degradation. High temperatures in spray-drying favor the formation of pyrazines. The findings underscore the trade-offs inherent in choosing an appropriate drying method, thereby informing decision-making processes in industrial settings aimed at optimizing both product quality and efficiency.

Effect of thermosonication on the bioactive peptide profile, volatile compounds, and fatty acid profile of Minas Frescal cheese

This study investigated the effect of thermosonication (TS) of milk on the bioactive peptide profile, fatty acid composition, and volatile compounds of Minas Frescal cheese. Five cheese formulations were prepared: raw milk (Control), pasteurized milk (High-Temperature Short-Time or HTST) (72–75 °C/15 s), and milk treated by TS at nominal powers of 160 W (TS160), 400 W (TS400), and 640 W (TS640). The fatty acid profile and health indices did not change significantly after HTST or TS. TS, mainly TS400 treatment, increased the number of bioactive peptides with antihypertensive, antioxidant, immunomodulatory, and antimicrobial activities and promoted the formation of unique volatile organic compounds, mainly from the ester and fatty acid groups. In conclusion, TS can be considered by the dairy industry as an interesting alternative for manufacturing Minas Frescal cheese, resulting in products with greater functional potential and unique volatile compounds and keeping the fatty acid profile unchanged.

Discovery of a temperature-dependent protease spoiling meat from Pseudomonas fragi: Target to myofibrillar and sarcoplasmic proteins rather than collagen

Chilled meat frequently suffered microbial spoilage because bacteria can secrete various proteases that break down the proteins. In this study, Pseudomonas fragi NMC 206 exhibited a temperature-dependent secretion pattern, with the ability to release the specific protease only below 25 °C. It was identified as alkaline protease AprA by LC-MS/MS, with the molecular weight of 50.4 kDa, belonging to the Serralysin family metalloprotease. Its significant potential for meat spoilage in situ resulted in alterations in meat color and sensory evaluation, as well as elevated pH, total volatile basic nitrogen (TVB-N) and the formation of volatile organic compounds (VOCs). The hydrolysis of meat proteins in vitro showed that AprA possessed a considerable proteolysis activity and degradation preferences on meat proteins, especially its ability to degrade myofibrillar and sarcoplasmic proteins, rather than collagen. These observations demonstrated temperatures regulated the secretion of AprA, which was closely related to chilled chicken spoilage caused by bacteria. These will provide a new basis for the preservation of meat products at low temperatures.

The Influence of Cooking Methods and Muscle on Beef Aroma Profile and Consumer Satisfaction: Insights from Volatile Compound Analysis

The objective of this study is to determine the effect of two distinct cooking techniques, namely roasting and stewing, on the formation of volatile compounds in various beef muscles (Semimembranosus, Biceps femoris, and Rectus femoris) and how this relates to consumer acceptance. The research employs the concept of volatile “marker” compounds to discern the influence of cooking techniques on the flavor profile of beef. Eighteen “marker compounds” were selected to represent a number of the mechanisms of formation and quantified in beef subjected to two different cooking methods. While no statistically significant differences were observed in consumer evaluations between the two cooking methods, notable disparities emerged in the consumer assessments of specific muscle cuts. Notably, the Rectus femoris muscle received the highest ratings (p &lt; 0.05) among other evaluated muscles. The utilization of Solid-Phase Microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) methods for the analysis of volatile “marker compounds” in beef proved effective in highlighting significant differences in flavor compound classes between cooking methods, and these differed between muscles. The main effect was of the cooking method with stewed beef aroma having approximately 39× more dimethyl trisulphide, 9× more dimethyl disulphide, 7× more pentanal, 3× more hexanal, and twice as much benzaldehyde and 2-methylthiophene. Dimethyldisulphide, dimethyltrisulphide, hexanal, and heptanal, therefore, emerged as characteristic volatile compounds associated with the stewing cooking technique, suggesting their potential as markers for lipid and other oxidation reactions. This work indicates that certain lipid oxidation compounds, Strecker aldehydes, and sulfur compounds can be markers for the undesirable and/or desirable flavors of cooked beef, but that this depends on the cooking method chosen. It shows that flavor differences may be understood through the analysis of volatile flavor compounds in association with palatability and other chemical measurements.

The potential meat flavoring derived from Maillard reaction products of rice protein isolate hydrolysate-xylose via the regulation of temperature and cysteine

Maillard reaction products (MRPs) derived from rice protein isolate hydrolysate and D-xylose, with or without L-cysteine, were developed as a potential meat flavoring. The combined impact of temperature (80–140 °C) and cysteine on fundamental physicochemical characteristics, antioxidant activity, and flavor of MRPs were investigated through assessments of pH, color, UV–visible spectra, fluorescence spectra, free amino acids, volatile compounds, E-nose, E-tongue, and sensory evaluation. Results suggested that increasing temperature would reduce pH, deepen color, promote volatile compounds formation, and reduce the overall umami and bitterness. Cysteine addition contributed to the color inhibition, enhancement of DPPH radical-scavenging activity and reducing power, improvement in mouthfulness and continuity, reduction of bitterness, and the formation of sulfur compounds responsible for meaty flavor. Overall, MRPs prepared at 120 °C with cysteine addition could be utilized as a potential meat flavoring with the highest antioxidant activity and relatively high mouthfulness, continuity, umami, meaty aroma, and relatively low bitterness.