Changes in volatile flavor of yak meat during oxidation based on multi-omics

Meat quality differences and protein molecular mechanisms affecting meat flavor in different breeds of Tibetan sheep analyzed by 4D label-free quantitative proteomics

To evaluate the meat quality of the new breed of Panou sheep, the longissimus dorsi (LD) muscles of 1.5-year-old Panou sheep and the local breed of Oula sheep were selected for comparative analysis in terms of meat quality, and the molecular mechanisms influencing flavor were investigated using 4D label-free proteomics technology. The results revealed that the fiber density, tenderness, and brightness of the Panou sheep meat were lower than those of the Oula sheep, and the composition of amino acids and flavor substances made it possible to determine that the Panou sheep meat has a high-quality and distinctive flavor. Proteomic analysis indicated that the metabolic pathways that may be associated with meat flavor are amino acid catabolism and sugar metabolism. This study explored the role of proteins in the regulation of meat flavor in Tibetan sheep, which provides a reference for the identification of meat products and subsequent breed improvement.

Transcriptome analysis reveals the potential mechanism of plateau environment on muscle growth and development in yak

Yak meat plays a significant economic role for yaks. The unique environment of the Qinghai-Tibet plateau profoundly impacts the meat production performance of yaks. Yet, the regulatory mechanisms influencing muscle growth and development in yaks within this plateau environment remain poorly understood. The study investigated the transcriptome gene expression in the buttock muscle tissue of yaks residing at varying altitudes. It revealed 516 differentially expressed genes in the buttock muscle tissue of yaks at high altitude (4500 m) and low altitude (3000 m). The Gene Ontology (GO) annotation indicated that these differentially expressed genes primarily function in RNA binding, identical protein binding, nucleotide binding, pre-mRNA branch point binding, unfolded protein binding, insulin receptor binding, fructose 1,6-bisphosphate 1-phosphatase activity, collagen binding, platelet-derived growth factor receptor binding, and sodium channel inhibitor activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the differentially expressed genes predominantly participated in pathways such as the spliceosome, aminoacyl tRNA biosynthesis, RNA polymerase, cutin, suberin, and wax biosynthesis, ribosome biogenesis in eukaryotes, plant hormone signal transduction, axon guidance, fructose and mannose metabolism, pentose phosphate pathway, and gastric acid secretion. This study unveiled the impact of the plateau environment on transcriptome gene expression in yak buttock muscle tissue, mapping out the gene expression profiles specific to yaks living at varying altitudes (3000 m and 4500 m). The findings offer crucial genomic insights into the mechanisms behind yak muscle adaptation to plateau environments.

Inoculation with autochthonous yeast strains in Harbin dry sausages with partial substitution of NaCl by KCl: Bacterial community structure and flavour profiles

The effects of two autochthonous yeast strains (Pichia kudriavzevii and Debaryomyces hansenii) on the physicochemical characteristics, bacterial community structure, and flavour profile of the dry sausages with 40% substitution of NaCl by KCl were evaluated in this study. The results revealed that the inoculation of yeast strains increased the pH and yeast counts of low-sodium sausages. Higher contents of total esters, aldehydes, and ketones were detected in the inoculated sausages (P < 0.05). Based on the results of high-throughput sequencing, the inoculation of P. kudriavzevii decreased the abundance of Lactobacillus, Weissella, and Leuconostoc. However, the inoculation of D. hansenii increased the abundance of Lactobacillus, Weissella and Staphylococcus, which may help to inhibit the growth of pathogenic microorganisms in sausages. Electronic tongue analysis as well as sensory evaluation revealed that D. hansenii reduced bitter, astringent, and metallic tastes (P < 0.05). Overall, D. hansenii can be used as the prospective stater culture to compensate the flavour defects and improve the safety of the dry sausage with NaCl substitutes.

Exploring the regulation of metabolic changes mediated by different combined starter cultures on the characteristic flavor compounds and quality of Sichuan-style fermented sausages

Comprehensive 2D gas chromatography-mass spectrometry (GC × GC-MS) and non-targeted metabolomics were used in this study to systematically investigate the effects of various fermentation agent combinations on the quality characteristics of Sichuan-style fermented sausages. The results indicate that the inoculation of the combined starter culture significantly improves the sensory score and texture characteristics of Sichuan-style sausages, with the overall acceptability score increasing from 77.6 to 79.9-82.9. Furthermore, substantial improvements were observed in key texture parameters, particularly in hardness (increased from 9050.34 g to 10,625.40-16,633.95 g) and chewiness (elevated from 2231.33 g to 2327.23-4505.71 g). Additionally, it reduces both pH values (from 5.86 to 5.83-5.71) and moisture content (from 31.84 % to 31.72-28.99 %). The combined starter culture facilitates the degradation, transformation, and metabolism of proteins and lipids in the sausages, resulting in the production of more metabolites and volatile flavor compounds. In addition, the combined starter culture may promote the release of flavor substances in the sausage spices, thereby enhancing the overall flavor quality. Compared to the control group, the combined starter culture F, comprising Debaryomyces hansenii, Lactobacillus curvatus, Staphylococcus carnosus, and Staphylococcus vitulinus, significantly increased the levels of 60 volatile flavor substances, such as linalool, β-myrcene, and 3-methyl-1-butanol, in the sausages. The combined starter culture F enhanced the levels of 73 secondary metabolites, including beneficial amino acids, organic acids, fatty acids, and others, demonstrating its superior effectiveness in improving the quality characteristics of Sichuan-style fermented sausages.

Changes in volatile flavor compounds and metabolites during processing of Ginger milk curd from buffalo milk by GC-IMS and LC-MS

Ginger Milk Curd (GMC), a traditional Chinese cheese of Guangdong, remains not fully elucidated regarding the changes of volatile organic compounds (VOCs) across its different processing stages. This study employed electronic nose (E-Nose), electronic tongue (E-Tongue), gas chromatography-ion mobility spectrometry (GC-IMS) and ultra-high performance liquid chromatography-Q-Exactive HF-X mass spectrometer (UHPLC-Q-Exactive HF/MS) to investigate the alterations in VOCs and low molecular weight metabolites throughout the processing of GMC. The results revealed significant alterations in VOCs, resulting in flavor transitioning from the original flavor to fruity, sweet, green, and citrus flavor. The E-Nose and E-Tongue effectively differentiate the aroma and flavor characteristics of samples at four key processing stages. Among them, GMC contains higher levels of alcohols, aldehydes, ketones, and sulfides compared to samples from other stages, and it shows significant differences in umami, saltiness, and astringency taste characteristics. 71 volatile compounds were identified via GC-IMS, with 13 key volatile compounds, including 1-octen-3-one, 1,8-cineole, dimethylsulfide, and methyl 2-methylbutanoate, contributing to the flavor variations in GMC. Meanwhile, protein degradation, lipid oxidation, and the Maillard reaction were identified as key factors significantly impacting the levels of metabolites and VOCs. The enhancement of flavor characteristics in GMC was attributed to the rise in taste-active peptides, aromatic amino acids, and free fatty acids during processing.

Unlocking the chemical basis of fermented golden pompano (Trachinotus ovatus) inoculated with indigenous Bacillus subtilis: Focus on the role of lipid oxidation on volatile flavor formation

Fermented golden pompano is a traditional food valued for its distinctive flavor profile, largely influenced by lipid oxidation. This study evaluated the role of local Bacillus subtilis SCSMX-2 strain in regulating lipid oxidation and improving the flavor profile of the fermented golden pompano. Untargeted metabolomics was used to identify 206 differential metabolites, predominantly lipids, amino acids, and peptides. Enrichment analysis revealed glycerophospholipid metabolism as a key lipid pathway. SCSMX-2 induced moderate lipid oxidation, significantly increasing free fatty acid content, especially omega-3 polyunsaturates. Characterization of 148 volatile compounds revealed a notable increase in lipid oxidation-derived flavor compounds, with 11, including seven lipid derivatives, emerging as distinctive. Correlation analysis showed that secondary lipid oxidation products, such as sn-glycero-3-phosphoethanolamine and lysophosphatidylcholine, are precursors to key flavor compounds. These findings provide a scientific basis for the targeted regulation of flavors in traditional fermented fish.

Impact of Monascus purpureus combined with Lactobacillus plantarum and Saccharomyces cerevisiae fermentation on nutritional and flavor characteristics of Pyropia yezoensis

Fermentation can promote various properties of food. This study investigated the impact of fermentation by Monascus purpureus combined with Lactobacillus plantarum and Saccharomyces cerevisiae on the physicochemical and flavor characteristics of Pyropia yezoensis. Results indicate that the protein and free amino acid content increased threefold. A total of 62 volatile flavor compounds were identified by GC-IMS. Alcohols, ketones and esters were enhanced with 2- to 6-fold, while aldehydes were reduced by 76.56 %, contributing to the enhancement of pleasant fragrances and the reduction of fishy and seawater odors. As for the non-volatile properties, the content of organic acids and free amino acids increased from 2.18 mg/g and 0.19 mg/g to 46.03 mg/g and 4.93 mg/g, respectively, as assessed by HPLC and amino acid analyzer. The metabolic pathways of non-volatile substances were speculated upon. This work provides a basic theory and a practical reference for fermentation food processing of P. yezoensis.

Riboflavin-mediated ultraviolet photosensitive oxidation of beef myofibrillar proteins with different storage times

The study was designed to investigate the mechanism of Riboflavin (RF)-mediated UVA photosensitive oxidation on beef myofibrillar proteins (MP) oxidized at different storage times. To elucidate the direct relationship between RF and protein oxidation, the mechanism of action was analyzed in terms of amino acid and side chain residues, protein structure, and protein oxidative metabolism. Oxidation of MP resulted in significant changes in the levels of carbonyls, sulfhydryls, Lysine, Arginine, Threonin, and Histidine. The oxidized MP secondary structure was changed, fluorescence intensity decreased, and surface hydrophobicity increased. Metabolomics results revealed that RF-mediated UVA photosensitized oxidation is primarily mediated by Riboflavin metabolism and co-regulated with Phenylalanine metabolism. Moreover, with the increase of frozen storage time, Arginine and proline metabolism was inhibited, and the contents of creatine were significantly reduced, which exacerbated MP oxidative damage. The results provide a theoretical basis for unraveling the mechanism of RF-mediated UVA photosensitive oxidation of MP.

A comprehensive analysis of meat quality degradation and identification of spoilage markers in chicken during refrigerated storage using multi-method approach

In order to better understand the stability and safety of chicken meat during its storage, to comprehend the changing law of chicken meat, and to screen markers that could characterize the deterioration of chicken meat. In this study, traditional methods for the determination of physicochemical indicators, gas chromatography-ion mobility spectrometry (GC-IMS), electronic nose, and electronic tongue were used to elucidate the quality profiles of chilled chickens during the shelf-life of 0, 1, 2, 4, 6, 8, and 10 d at 4 °C, and non-targeted and targeted metabolomics were utilized for the screening and validation of deterioration markers of chicken meat. The results indicated that the texture of the chilled chicken changed first, followed by volatile flavors. Important aldehydes degrade and ketones and alcohols increase in chicken during storage. Purine metabolism was identified as the primary pathway influencing the deterioration of meat quality, with IMP and AICAR emerging as potential markers for meat quality deterioration. This study systematically analyzed the change rule of chicken meat during its shelf-life, screened markers that could characterize the deterioration of chicken meat, and these results provided a scientific basis for the quality control and shelf-life prediction of chicken meat. Additionally, it laid a foundation for the development of more effective preservation technology, deterioration early warning systems, and fast and convenient detection methods.

Analysis of the effects of hydroxyl radicals on the volatile flavor composition and lipid profile of sheep meat based on HS-SPME-GC-MS and UPLC-MS/MS studies

In order to investigate the relationship between oxidation and sheep lipids and flavor, this study used hydroxyl radical system, headspace solid phase microextraction and gas-phase coupled methods to analyze the effects of different oxidation times (0, 2, 4, 8 and 12 h) on sheep meat lipids and volatile flavor compounds. Results indicate that conjugated diene increased from 2.89 to 7.93 mmol/kg, and thiobarbituric acid reactive substances increased from 0.31 to 1.26 mg MDA/kg within 12 h. Moreover, the levels of volatile compounds such as pentanal, hexanal, benzaldehyde, octanal, nonanal, 1-octen-3-ol, and 2,3-octanedione increased with the increased levels of hexanal, nonanal, and benzaldehyde associated with rancid odor or acidification. Furthermore, 213 differential lipids were identified, primarily enriched in glycerophospholipid metabolism, glycosylphosphatidylinositol-anchor biosynthesis, sphingolipid signaling, and ether lipid metabolism. These lipids and metabolic pathways may play a role in flavor formation during sheep meat oxidation.

Correlation of lipid hydrolysis, oxidation, and molecular transformation with volatile compound revolution in pork during postmortem wet-aging process

Lipid hydrolysis and oxidation properties, lipid metabolites, and volatile flavors were investigated to elucidate the wet-aging process (1 h to 10 d) on lipid molecule transformation and volatile flavor evolution in pork. Phospholipase A2 (PLA2) activity increased at 12 h, with lipoxygenase (LOX) increasing from 1 h to 7 d (P < 0.05). A total of 546 differential lipids from 997 lipids and 19 aroma-active compounds out of 43 volatiles were identified, with most fatty aldehydes reaching the highest at 10 d. Acyl carnitine (18:2) and hexadecanal are potential markers to predict the wet-aging progress of pork. Correlation analysis indicated that phospholipid molecule hydrolysis by PLA2 and lipid enzymatic oxidation mediated by LOX rather than reactive oxygen species contributed to volatile aldehyde evolution, while phosphatidylcholine (16:2e/22:6) may be the key lipid molecule. These results offer insights into the lipid transformation and aroma evolution in pork during the wet-aging process.

Effect of frozen storage on the untargeted and targeted metabolites of flavored roasted beef using UHPLC-MS/MS and GC-MS

In this study, we investigated the changes in untargeted metabolites using UHPLC-MS/MS and the flavors of nonflavored (BS1) and flavored (BS2) roasted beef using GC-MS throughout a 6-month frozen period. A total of 509, 659, and 496 metabolites met the conditions for differential screening, and 56, 103, and 47 differential metabolites were recognized between BS1 and BS2 at 0, 3, and 6 months of frozen periods, respectively. The total relative abundance of organic nitrogen compounds, phenylpropanoids, polyketides, organic acids and their derivatives, and benzenoids increased during frozen storage at 3 months and then decreased at 6 months. A total of 16 differential metabolites were identified as markers for prolonged freezing, which belong to organic acids and their derivatives (Asp-Val-Lys, Val-Lys, Met-Phe, Tyr-Leu, N(6)-(octanoyl)lysine, and cis-acetylacrylate), lipids and lipid-like molecules (2,3-dimethyl-3-hydroxyglutaric acid, PC(P-16:0/2:0), (S)-17-hydroxy-9,11,13,15-octadecatetraynoic acid, PC(18:1(9Z)/18:1(11Z)), LysoPC (20:4(8Z,11Z,14Z,17Z)/0:0), PC(20:5/0:0), PE(20:3(8Z,11Z,14Z)/18:4(6Z,9Z,12Z,15Z)), and PS(14:1(9Z)/22:0)), and others (putrescine and phenylacetaldehyde). Sixty-three volatile flavor compounds were detected, and their concentrations were decreased along with frozen storage, except for aldehydes. Positive correlations were observed between volatiles and free amino acids. Therefore, frozen storage has a notable effect on the metabolite profiles of roasted beef.

The impact of Sarcocystis infection on lamb flavor metabolites and its underlying molecular mechanisms

Introduction

Meat flavor is a critical factor for consumers to evaluate meat quality and a key determinant of its market value. Sarcocystis spp. are widely distributed parasitic protozoa that infect livestock, leading to reduced meat quality, fur, and fiber, and causing significant economic losses. However, most studies focus on the pathogenic mechanisms and epidemiological characteristics of Sarcocystis, with limited research on its specific impact on meat quality and flavor, particularly the underlying molecular regulatory mechanisms.

Methods

This study investigated the effects of Sarcocystis infection on meat flavor and its molecular mechanisms in Tibetan sheep using flavor metabolite analysis and transcriptomic approaches. Tibetan sheep raised under uniform conditions were divided into four groups based on infection severity: normal, low-infection, moderate-infection, and high-infection. Leg muscle samples were collected for flavor metabolite analysis and transcriptome sequencing. Differentially expressed metabolites (DEMs) and differentially expressed genes (DEGs) were identified, and KEGG pathway enrichment analysis was performed to explore how Sarcocystis infection regulates gene expression, affecting lipid, amino acid, and energy metabolism, ultimately altering the production and accumulation of flavor metabolites.

Results

The results showed that Sarcocystis infection significantly altered the composition of flavor metabolites in Tibetan sheep meat as infection severity increased. Phenolic and acidic metabolites were markedly upregulated, intensifying bitterness and sourness, while ketone and lactone metabolites were downregulated, reducing fatty and creamy aromas. Transcriptomic analysis identified 574 DEGs, including upregulated genes such as MAPK12, COX6A2, and RXRA, which are involved in lipid metabolism, fatty acid oxidation, and thermogenesis, and downregulated genes such as COX2, COX3, and ADIPOQ, which are associated with mitochondrial function and energy metabolism. These gene expression changes disrupted lipid and amino acid metabolism, leading to imbalances in the synthesis and accumulation of flavor compounds.

Discussion

This study systematically revealed the significant effects of Sarcocystis infection on the meat flavor of Tibetan sheep and its underlying molecular mechanisms. The findings provide new insights into the metabolic regulation induced by parasitic infection and offer a theoretical basis for mitigating the adverse effects of Sarcocystis infection on meat quality.

Microstructure observation and flavor substances excavation of Yunyan 87 tobacco leaves with different oil contents

Introduction

The oil content of tobacco leaves is intimately associated with their aromatic characteristics. This study aims to explore the microstructure and distinctive flavor substances of Yunyan 87 high-oil-content tobacco leaves.

Methods

The microstructure and characteristic flavor substances of Yunyan 87 tobacco leaves with different oil contents were analyzed using scanning electron microscope (SEM) and comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOF MS).

Results

The results indicate that the surface of high-oil tobacco leaves was characterized by a high density of glandular hairs, primarily composed of short-stalked glandular hairs featuring enlarged glandular heads. A total of 1551 flavor substances were detected in high-oil tobacco leaves, compared to 1500 metabolites were identified in low-oil tobacco leaves. Among these flavor substances, eight exhibited up-regulated, while three were down-regulated. Notably, the oil-related substances hexadecanoic acid methyl ester and the aroma-related substances nonanoic acid methyl ester and pseudoionone were found to be significantly more abundant in high-oil tobacco leaves compared to their low-oil counterparts. Consequently, hexadecanoic acid methyl ester may serve as a reliable indicator for evaluating the oil content in tobacco leaves, while nonanoic acid methyl ester and pseudoionone could play crucial roles as flavor substances influencing the aroma of tobacco leaves.

Discussion

These findings provide a theoretical foundation for future research on the regulatory mechanisms underlying the synthesis of aroma-producing flavor substances in tobacco leaves.

Serum metabolomics analysis reveals a novel association between maternal metabolism and fetal survival in sows fed diets containing differing methionine levels and sources

Methionine (Met) metabolism is vital for one carbon metabolism, redox status and fetal development. Hence, this study investigated the effects of different levels and sources of Met on maternal metabolism, anti-oxidative capacity and fetal survival in pregnant sows. Forty primiparous sows were assigned to the following four groups: control group (basal diet, CON), 1.5S-OHMet group (supplemented methionine hydroxy analogue [OHMet] at 1.5 g/kg diet), 3.0S-OHMet group (supplemented OHMet at 3.0 g/kg diet), and 3.0S-Met group (supplemented L-Met at 3.0 g/kg diet) (n = 10). The trial lasted from day 60 of gestation to the farrowing day. Maternal 1.5S-OHMet consumption had the lowest stillborn ratio and the highest serum glucose levels during farrowing. Further analysis revealed that dietary 1.5S-OHMet consumption elevated the serum contents of glucose-6-phosphate, citric acid, butyric acid, malic acid, 3-methyladenine, 1-methyladenosine, ferulic acid and salicylic acid, but reduced the serum contents of succinic acid, oxoglutaric acid, 9(S)-hydroperoxylinoleic acid, 13(S)-hydroperoxy-octadecatrienoic acid, uric acid and urea nitrogen when compared to contents observed in the 3.0S-OHMet and 3.0S-Met groups (P < 0.05). Serum metabolomics analysis was conducted to determine the enriched differential metabolites and an enrichment analysis was performed using Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The results showed that the enriched metabolites were mainly associated with central carbon metabolism, amino acid metabolism, lipid metabolism, and nucleotide metabolism. Moreover, maternal 3.0S-OHMet or 3.0S-Met consumption upregulated the trans-methylation pathway by elevating the S-adenosyl-methionine (SAM) level and the ratio of SAM to S-adenosyl-homocysteine (P < 0.05) at day 114 of gestation, while increasing homocysteine concentration (P < 0.001). However, compared to the 3.0S-Met group, maternal 3.0S-OHMet consumption elevated fetal survival and glutathione peroxidase (P < 0.05). Thus, this study provided new insights into the mechanisms through which sows fed with a 1.5S-OHMet diet during mid-to late-gestation period had high fetal survival, such as improvements in maternal amino acid, nucleotide and glycolipid metabolism.

Evaluating the effect of different recycling frequencies on marinade quality, characteristics, and volatile constituents

The quality of marinade is closely related to its recycling frequency, and affects the flavor and quality of leisure dried tofu. The changes in physicochemical parameters, oxidation indicators, and volatile constituents of marinade under different recycling frequencies (0, 3, 6, 9, 12, 15) were systematically investigated in this work. The results showed that the levels of amino acid nitrogen, viscosity, soluble solids, and salinity in the marinade were significantly increased with recycling frequency. The increase in marinade recycling frequency led also to a rise in the peroxide value and thiobarbituric acid reactive substances from 2.13 meq/kg and 0.17 mg/kg to 4.02 meq/kg and 0.94 mg/kg, respectively, suggesting slight oxidation. Marination yielded 101 volatile constituents, mainly including 35 alcohols, 21 hydrocarbons, 15 aldehydes, 9 aromatics. Pearson correlation analysis revealed that the levels of cedrene, cineole, and myrcene were closely related to the quality and flavor of marinade under different recycling times.

Supplementation with mulberry leaves improves growth performance and meat quality of Xiangdong black goats

OBJECTIVE

Mulberry (Morus alba) leaf (ML) is a high-quality feed source for ruminants, while it is unclear whether it can enhance the growth performance and meat quality of Xiangdong black goats.

METHODS

In this study, we investigated the effects of ML supplementation (0%, 5%, 10%, 15%, and 20%) on the growth performance, serum variables, and the profiles of amino acids and fatty acids in the muscle of Xiangdong black goats.

RESULTS

Results showed that the final body weight, initial and final dry matter intake, and average daily gain increased linearly and quadratically with the increasing ML content (p<0.05). The serum concentrations of total antioxidant capacity (T-AOC) increased linearly, while immunoglobulin G (IgG) increased quadratically with the increasing ML content (p<0.05). Conversely, the saturated fatty acids (SFA) content in meat decreased linearly with the increasing ML content (p<0.05). Compared to goats without ML supplementation, goats fed with 15% ML showed significant increases in serum concentrations of T-AOC, superoxide dismutase, catalase, and IgG (p<0.05). Furthermore, goats fed with 20% ML displayed significant decreases in SFA (C18:0) content, compared to goats without ML supplementation (p<0.05).

CONCLUSION

These results suggest that ML supplementation promotes the growth performance of goats. A diet containing 15% ML showed better effects in promoting antioxidant and immunomodulatory activities, while a diet with 20% ML was more effective in enhancing meat flavor in Xiangdong black goats.

Analysis of Potential Markers of Pork Freshness Based on Volatile Organic Compounds

Bacteria and endogenous enzymes generate volatile organic compounds (VOCs), which are posited to be the primary source of undesirable flavors in spoilt pork. Headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) was employed to assess the fluctuations in VOC concentrations in pork stored under tray packaging at 6-8 °C for 10 days, while total volatile basic nitrogen (TVB-N) and total viable counts (TVCs) were used to determine the quality of the pork. During storage, TVCs steadily increased, reflecting the growth of spoilage-related microorganisms, while TVB-N levels surpassed the spoilage threshold early, indicating an acceleration of the degradation process. Nine VOCs associated with pork spoilage were found by partial least squares discriminant analysis (PLS-DA), fold change (FC), and t-tests. The substances comprised ethyl acetate, acetoin, 3-methyl-1-butanol, 3-methylbutanal, 1-octen-3-ol, hexanal, vinyl acetate, 2-methylaziridine, and heptanal. A univariate linear regression analysis revealed a strong positive correlation (p < 0.001) between the gaseous total volatile basic nitrogen (G-TVBN) and the storage duration. Given that G-TVBN accurately reflects changes in pork freshness and the progression of spoilage, these results highlight the potential for dynamically monitoring the freshness and spoilage processes of pork.

A Comprehensive Metabolomic Analysis of Volatile and Non-Volatile Compounds in Folium Artemisia argyi Tea from Different Harvest Times

To develop and utilize Folium Artemisia argyi (FAA) tea resources, UPLC-MS/MS, HS-GC-IMS, and HS-SPME/GC×GC-TOFMS were adopted to analyze its volatile and non-volatile compounds, when harvested from March to June, in combination with its antioxidant activity. Here, 1742 volatile compounds and 8726 non-volatile compounds were identified, with 75 differential volatile metabolites and 36 key flavor compounds screened. Notably, 1-octen-3-one, (E)-2-octenal, (E)-2-undecenal, and heptanal were identified as major contributors to the sweet, fruity, green, and herbal aromas, and the concentration of them was highest in June-harvest FAA tea. Furthermore, metabolomics revealed that there were 154 non-volatile differential metabolites in FAA tea at four harvest times, which were mainly related to amino acid biosynthetic pathways. Samples harvested in June also showed the strongest antioxidant capacity, which was positively correlated with D-xylitol, L-glutamic acid, honokiol, and costunolide. These findings highlight June as the optimal harvest time, providing FAA tea with superior flavor and enhanced antioxidant properties, underscoring its potential as a valuable resource for functional food development.

Effects of water flow treatment on muscle quality, nutrient composition and volatile compounds in common carp (Cyprinus carpio)

This study explored the effects of water flow on the muscle quality, nutrient composition, and volatile compounds in Cyprinus carpio. Fish were exposed to three treatments: sustained water flow (SG, 1 bl/s, 24 h/d), intermittent water flow (IG, 1 bl/s, 8 h/d), and control group (CG, 3 cm/s). Results indicated that SG improved water-holding capacity, muscle fiber density, hardness, and chewiness, while IG enhanced gumminess, springiness, and resilience. Nutritionally, CG exhibited higher crude lipid content and the highest levels of ΣSFA. Conversely, SG showed elevated ∑EPA + DHA and ω-3 fatty acid levels compared to IG. Volatile compound analysis demonstrated that CG contained higher levels of aldehydes and alcohols, associated with off-flavors, whereas IG and SG produced fresher and sweeter aroma profiles, enhancing sensory quality. These findings provide valuable insights into improving the muscle quality, nutritional value, flavor characteristics, processing, and preservation of common carp through water flow treatment.

Unravelling the formation of characteristic aroma of traditional braised pork through untargeted and targeted flavoromics

Untargeted flavoromics and targeted quantitative analysis of key aroma compounds, and analysis of dynamic change of aroma precursors concentration were used to investigate the aroma evolution of traditional braised pork and the underlying mechanism. The results indicated that lipid oxidation dominated at early cooking stage (0th-45th min), resulting in an increased concentration of most aldehydes, alcohols, ketones, such as hexanal, heptanal, octanal, nonanal, (E)-2-octenal, benzaldehyde, 1-octen-3-ol, and 2,3-octanedione, accompanied with an enhanced unpleasant fatty odor. From 45th to 73rd min, the seasonings alleviated excessive oxidation of unsaturated fatty acids accompanied with decreased aldehydes. Moreover, the diffusion of glucose and amino acids from seasonings to lean meat promoted the consumption of endogenous ribose and amino acids in meat through Maillard reaction, and facilitated the formation of dimethyl trisulfide, dimethyl disulfide, methanethiol, and 2-furfural, which contributed to the meaty, sauce-like, and sweety aroma, thus formed the characteristic aroma of traditional braised pork.

Impacts of chitosan/pullulan/carvacrol film on the quality and microbial diversity of refrigerated goat meat

In this study, our previously prepared chitosan/pullulan film (CS/PU) and chitosan/pullulan/carvacrol film (CS/PU/CAR) were applied to goat meat preservation, the dynamic changes in quality and microbial communities of goat meat during chilled storage (4 °C) were investigated, and the fresh-keeping effects of the two biodegradable antibacterial films on goat meat were comprehensively evaluated. The results showed that when the goat meat was wrapped with CS/PU or CS/PU/CAR films during chilled storage, the total plate count and total volatile basic nitrogen (TVB-N) could be inhibited significantly, but the CS/PU/CAR film has a better fresh-keeping effect. Furthermore, during the chilled storage of goat meat, CS/PU/CAR film also could inhibit the production of alcohol compounds and the growth of Pseudomonas spp., thereby slowing down the meat's deterioration and extending the goat meat's shelf life to about 13 days. This study can provide a reference for the application of active packaging film of fresh goat meat.

Feeding systems change yak meat quality and flavor in cold season

Yak meat is in high demand due to its unique flavor. Thus this research utilized GC × GC-ToF-MS to discover important flavor compounds in yak meat raised during the cold season under different feeding systems: traditional grazing (TG), grazing-based supplementation (GS), and stall-feeding (SF). Meat quality results showed that SF significantly improved meat's lightness and tenderness (P < 0.05), as compared to TG. Intramuscular fat (2.7 g/100 g) was highest in the SF, followed by the GS (2.46 g/100 g) and the TG (1.57 g/100 g), whereas protein content was similar in the GS and TG, but again higher in the SF. β-carotene and Vitamin E were highest in the GS and TG groups (P < 0.05), respectively. Essential, fresh, and total amino acids were richer in the SF and TG than in the GS group (P < 0.05). TG exhibited a significantly elevated level of n-3 PUFA compared to the SF and GS systems (P < 0.05). Flavoromics analysis identified 736, 721, and 869 flavor substances in the TG, GS, and SF groups, respectively with six as key flavor compounds (ROAV ≥ 1) in all belonging to aldehydes, ketones, and heterocyclic compounds. The pyruvate, glycolysis/gluconeogenesis, and phenylalanine metabolic pathways significantly contributed to the yak meat flavor. Network analysis showed a complex significant positive correlation between amino acids in meat and Vitamin A in fodder (P < 0.05). Altogether, this study provides a basis for selecting a suitable meat production system that benefits producers and consumers by ensuring an annual supply of fresh meat.

Microbiota dynamics and metabolic mechanisms in fermented sausages inoculated with Lactiplantibacillus plantarum and Staphylococcus xylosus

Lactiplantibacillus plantarum and Staphylococcus xylosus are common starters for fermented sausages. Several studies have demonstrated the impact of these two strains on the quality of fermented sausages. However, the mechanism underlying the effects of these two microorganisms on co-cultivation in sausages remains unclear. This study aimed to investigate the effects of inoculation with various combinations of starters on the microbial communities and metabolic profiles of fermented sausages. High-throughput sequencing revealed that, during sausage fermentation, Firmicutes was the dominant bacterial phylum, and the primary microorganisms were Lactococcus, Staphylococcus, Lactobacillus, and Pseudomonas. On the last day of fermentation, the highest abundance of Staphylococcus was observed in the co-inoculation group. Furthermore, inoculated fermentation effectively inhibited the growth of pathogenic and spoilage bacteria. Metabolomic analysis of the four groups of samples identified 208 metabolites in positive ion mode and 109 in negative ion mode. A total of 31 differential metabolites were identified (P < 0.05, variable importance in the projection >1.5), primarily benzene and substituted derivatives, carboxylic acids and derivatives, and fatty acyls. Five crucial differential metabolites (subaphylline, naringenin, 1-hexadecanol, beta-alanyl-L-lysine, and 3'-AMP) were identified as potential biomarkers for fermented sausages. Key differential metabolite metabolic pathways indicated that L. plantarum YR07 dominated in metabolite regulation during sausage fermentation, and S. xylosus Y-18 downregulated the fatty acid degradation pathway, which also affected the metabolism of fermented sausages. Co-cultivation of the two bacteria exhibited a synergistic effect on the metabolism of the fermented sausages. This study offers further insights into improving the quality of fermented sausages, thereby establishing a theoretical foundation for the production of excellent fermenters.

Characteristic of volatile flavor compounds in 'Fengtangli' plum (Prunus salicina Lindl.) were explored based on GC×GC-TOF MS

Introduction

The 'Fengtangli' plum (Prunus salicina Lindl.) is favoured by consumers for its characteristic flavor. The purpose of this study was to explore the characteristics of volatile flavor compounds in 'Fengtangli' plum.

Methods

The flavor compounds of both 'Fengtangli' and 'Siyueli' plums were analyzed using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-TOF MS).

Results

The results revealed the presence of 495 volatile flavor compounds in 'Fengtangli' plum and 466 in 'Siyueli' plum. The relative concentrations of hydrocarbons, alcohols, ketones, and esters in 'Fengtangli' plum were significantly elevated compared to those detected in 'Siyueli' plum. Moreover, the sensorial attributes of sweetness, citrus, herbal, floral, and fruity notes were more prominent in 'Fengtangli' plum relative to those of 'Siyueli' plum. Through the integration of differential metabolite analysis and relative odor activity assessment, it is hypothesized that furan-2-pentyl; (E)-2-octenal; and 1-octen-3-one may represent the characteristic of volatile flavor compounds in 'Fengtangli' plum.

Discussion

The research results may provide a theoretical reference for the development and application of 'Fengtangli' plum and the study of the synthesis mechanism of characteristic flavor compounds.

Effects of different Lys/Met ratios on the antioxidant capacity, tissue morphology, and fatty acid composition of subcutaneous fat in Tibetan sheep on low-protein diets: a lipidomic analysis

Introduction

This study employed lipidomics to investigate the effects of varying lysine (Lys)- to-methionine (Met) ratios on the antioxidant capacity, tissue morphology, and fatty acid composition of subcutaneous fat in Tibetan sheep fed a low-protein diet.

Methods

Ninety healthy male Tibetan sheep of similar body weight were randomly allocated into three groups. These sheep were fed a low-protein diet containing Lys/Met ratios of 1:1, 2:1, and 3:1. Ultra-High Performance Liquid Chromatography-tandem Mass Spectrometry (UHPLC-MS/MS) was employed to explore the changes in various lipid subclasses in subcutaneous adipose tissue. The expression of genes associated with adipogenesis, antioxidant capacity, and fatty acid metabolism was also examined.

Results

The results indicated that the 1:1 Lys/Met group exhibited significantly higher antioxidant capacity (glutathione peroxidase, GSH-Px), with more orderly adipocyte arrangement, uniform cell size, and a general increase in unsaturated fatty acid levels. Additionally, several lipid molecules associated with the phenotype (Antioxidant index and fatty acid content) were identified, namely, DG(38:3e) + Na, PE(17:1_22:2)-H, PI(17:0_20:3)-H, TG(33:0e) + NH4, Cer(d14:0_17:1) + H, and CL(81:13)-2H. Furthermore, the findings showed that the upregulation of PPARγ, FASN, FAD4, CPT1A, and GPX4 can enhance adipocyte differentiation and lipid accumulation, thereby improving metabolic function in subcutaneous adipose tissue via the regulation of lipid metabolism and oxidative defense mechanisms.

Discussion

In summary, this study provides a theoretical foundation for optimizing precision feeding strategies for Tibetan sheep, offering crucial data to support enhancements in production efficiency and meat quality.

Flavor characterization of pork cuts in Chalu black pigs using multi-omics analysis

The study investigated the flavor variations in four different fresh pork cuts (longissimus thoracis, LT; trapezius muscle, TM; hamstring muscle, HM; Pork Belly, PB) from Chalu black pigs (ten castrated boars) using multi-omics techniques. The research also explored the influence of muscle fiber type on the flavor profiles of these cuts. Results from quantitative real-time PCR (qRT-PCR) indicated significant differences in muscle fiber type across the four pork cuts in various anatomical locations. Each cut exhibited distinctive volatile organic compounds (VOCs) profiles, with HM displaying a sweet and fruity green flavor, LT showcasing a fatty and nutty taste, PB presenting a fresh, citrusy, and green flavor, and TM offering a floral and bitter note. Variations in fatty acid carbon number and saturation were observed among the cuts, with HM, LT, and PB being rich in fatty acids with C16-18, C19-21, and 3 double bonds, respectively. The metabolites specific to each cut were found to play key roles in different metabolic pathways, such as protein-related pathways for HM, arginine biosynthesis for LT, lysine biosynthesis for PB, and D-arginine and D-ornithine metabolism for TM. Differentially expressed genes (DEGs) were associated with amino acid metabolism for HM, glycolysis/gluconeogenesis for LT, and cellular aromatic compound organization for PB. Notably, HM and PB displayed unique flavor characteristics, while TM exhibited relatively neutral features. The study also identified correlations among VOCs, muscle fiber type, lipids, metabolites, and gene patterns specific to each cut, highlighting the complex interplay of factors influencing pork flavor.

Characterization of key off-odor compounds in grass carp cube formed during room temperature storage by molecular sensory science approach

Flavor is a significant factor in determining the popularity of freshwater fish. However, freshwater fish can easily spoil during storage, producing an unpleasant odor. Little research has determined the changes in key off-odor compounds (OOCs) in freshwater fish during storage. In this study, quantitation and odor activity value (OAV) calculations revealed that 19 odorants were important volatile odor compounds in fresh, spoilage, and serious spoilage GCC. Recombination and omission experiments verified that (E)-2-hexenal, acetoin, N,N-dimethyl-benzenamine, trimethylamine (TMA), and ammonia were the key OOCs in spoilage GCC. Additional key OOCs in serious spoilage GCC were cyclohexane isothiocyanato, butylated hydroxytoluene, putrescine, cadaverine and histamine compared to those of spoilage GCC. Correlation analysis showed that 12 amino acids and 10 fatty acids played important roles in the formation of key OOCs. This study provides a theoretical basis for a comprehensive understanding of the formation of key OOCs in GCC during room temperature storage.

Insight into the chemical composition, antioxidant capacity, meat quality, fatty acid profile, and volatile compounds of yellow-feathered chickens fed with fermented pineapple residue

This study aimed to evaluated the effect of dietary fermented pineapple residue (FPR) on the chemical composition, antioxidant capacity, meat quality, fatty acid profile, and volatile compounds in yellow-feathered chickens. GC-IMS technique combined with multivariate analysis were performed to clarify the key volatile compounds. The results showed that dietary FPR improved meat quality by increasing the antioxidant capacity and pH value and decreasing cooking loss of breast muscle. The fatty acid profile was altered in breast muscle of chickens that fed with FPR. GC-IMS detected 43 volatile compounds in breast muscle, including mainly aldehydes, alcohols, esters, and ketones. Among them, 12 volatile compounds could serve as potential aroma markers to distinguish meat flavor of chickens fed with FPR. Correlation analysis revealed that C18:1n9c, C18:2n6, and PUFA are important contributors for meat flavor formation. In conclusion, dietary FPR improved antioxidant capacity, meat quality, fatty acid profile, and volatile compounds of breast muscle in chickens.

Characterization and perceptual interaction of key aroma compounds in Rosa roxburghii Tratt by sensomics approach

Rosa roxburghii Tratt (RRT) is esteemed for its unique aroma and nutritional value. Analyzing RRT juice samples from four elevations using GC-MS and GC-O, 99 volatile compounds were identified with 37 exhibiting aroma activity. 29 compounds including aldehydes, alcohols, and terpenes, were key contributors to RRT's aroma, based on high OAVs. Aroma recombination and omission tests confirmed 18 key aroma compounds in RRT while 2,5-Dimethyl-4-methoxy-3(2H)-furanone, hexanal, furfuryl acetate, furaneol acetate, and benzaldehyde as critical aroma compounds. The σ-τ graph revealed additive interactions among primary aroma compounds, indicating synergistic effects on RRT's overall aroma profile. Longli produced the most fragrant RRT at the lowest elevation of the four producing areas.

The influence mechanism of phospholipids structure and composition changes caused by oxidation on the formation of flavor substances in sturgeon caviar

The oxidation-induced phospholipids (PLs) underwent structural and compositional analysis, alongside the establishment of a simulation system to verify the link between phospholipid oxidation and flavor substances formation in sturgeon caviar. Structural alterations of PLs were tracked using 31P and 1H nuclear magnetic resonance (NMR), electron spin resonance spectroscopy (ESR), and Raman spectroscopy. The findings revealed a reduction in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) from 82.3% and 10.4% to 58.2% and 5.8% respectively. Free radical signals exhibited an initial increase followed by a decrease. The diminished intensity in Raman spectra at 970 and 1080 cm-1 indicated reduced fat unsaturation attributable to PLs oxidation. Correlation analysis highlighted a significant association between PC and PE containing C22:6, C20:5, C20:4, and C18:2 with flavor substances, suggesting their role as key precursors for flavor development. This study established a theoretical basis for understanding the change of flavor quality in sturgeon caviar during storage.

Exploring the correlation of microbial community diversity and succession with protein degradation and impact on the production of volatile compounds during cold storage of grouper (Epinephelus coioides)

Microorganisms, proteins, and lipids play crucial and intricate roles in the aroma generation of aquatic products. To explore the impact of the interaction between microorganisms and proteins on the volatile compounds (VOCs) in grouper, this study employed whey protein isolate (WPI) to inhibit lipid oxidation and reduce mutual interference. Changes in bacterial profiles, metabolites, and VOCs were detected. Eighteen key VOCs associated with the overall flavor of grouper were identified, and the potential relationships among microorganisms, proteins, and VOCs were explored using a correlation network. Five microorganisms (Vibrio, Vagococcus, Pseudomonas, Psychrobacter, and Shewanella) closely related to characteristic flavor compounds were identified. Additionally, 30 differential metabolites related to proteins and six metabolic pathways were screened. Therefore, this study unveils the potential interaction between microorganisms and proteins in flavor formation and provides new insights into the relationships among microorganisms, proteins, and VOCs.

A comprehensive analysis of aroma quality and perception mechanism in ginger-infused stewed beef using instrumental analysis, sensory evaluation and molecular docking

The ginger-infused stewed beef exhibited a satisfactory odor in Chinese cooking meat. This study aimed to reveal its aroma quality and perception mechanism through electronic nose, sensory evaluation and gas chromatography-mass spectrometry (GC-MS), gas chromatography-ion mobility spectrometry (GC-IMS) coupled with chemometric methods and molecular docking. Sensory evaluation and electronic nose analysis indicated ginger could greatly modify aroma profile of beef. Most C6-C10 aldehydes significantly decreased and terpenes increased in ginger-infused stewed beef. Orthogonal partial least squares-discriminant analysis (OPLS-DA) found 7 key markers for distinguishing stewed beef with or without ginger. Ginger additions could reduce fatty acids consumption. Moreover, the key contributors of fatty, bloody, meaty, ginger and mint aroma attributes, namely (E)-2-octenal, 1-octen-3-ol, 2-acetylthiazole, zingiberene and γ-elemene, respectively, selected by partial least squares regression (PLSR) analysis were docked with the olfactory receptor. Hydrogen bonds and hydrophobic interactions were the main interaction forces between olfactory receptor and the five compounds.

Characterization of flavour components and identification of lipid flavour precursors in different cuts of pork by phospholipidomics

The lipids and volatile compounds in pork from different parts, including the loin, belly, shoulder and hind leg were analyzed by triple quadrupole tandem time-of-flight mass spectrometer (Q-TOF/MS) and gas chromatography-olfactometry-mass spectrometry (GC-O-MS), respectively. Partial least squares regression (PLSR) and Pearson correlation analysis were utilized to establish the relationship between the lipids and volatile compounds. A total of 8 main flavour substances, 38 main phospholipids, and 32 main fatty acids were identified. The results showed that the key flavour compounds were mainly derived from unsaturated fatty acids and phospholipids containing unsaturated fatty acids, including oleic acid (C18:2n6c), α-Linolenic acid (C18:3n3), arachidonic acid (C20:4n6), PE O (18:1/20:4), PE O (18:2/20:4), and PE O (18:2/18:2), etc. Understanding the relationship between flavour compounds and lipids of pork will be helpful to control the quality of pork.

Comparative Evaluation of the Nutrient Composition and Lipidomic Profile of Different Parts of Muscle in the Chaka Sheep

Mutton is one of the most popular meats among the public due to its high nutritional value. In this study, we compared and analyzed the nutritional composition and volatile flavor substances in longissimus dorsi (LD), psoas major (PM), and biceps femoris (BF) of the Chaka sheep, and then analyzed the lipid composition using the technique of UHPLC-Q-Exactive Orbitrap MS/MS. Our results indicated that the LD had the highest crude protein content (22.63%), the highest levels of aspartic acid (5.72%) and histidine (2.76%), the BF had the highest contents of glycine (3.40%) and proline (2.88%), the PM had the highest abundance of ω-6 polyunsaturated fatty acids (7.06%), linoleic acid (C18:2n6c; 5.03%), and volatile flavor compounds (alcohols, ketones, and esters). Moreover, our study detected 2,639 lipid molecules classified into 42 classes, among which phospholipids were the major lipids, accounting for nearly half of the total lipids. Among them, phosphatidylethanolamine (PE; 18:2/18:2) and phosphatidylcholine (PC; 25:0/11:3) were the characteristic lipids in LD. Phosphatidylserine (PS; 20:3e/20:4), lysophosphatidylcholine (LPC; 18:3), PE (8:1e/12:3), triacylglycerol (TG; 18:0e/16:0/18:1), TG (18:0/18:0/18:0), TG (18:0e/18:0/18:1), and TG (18:0e/18:1/18:1) were marker lipids in PM. LPC (16:0), LPC (18:1), lysophosphatidylethanolamine (18:1), PC (15:0/22:6), PE (18:1/18:1), Hex1Cer (d24:1/18:1), and PC (10:0e/6:0) were representative lipids in BF. Intermolecular correlations between PC, PE, Hex1Cer, PS, TG, diacylglycerol, and cardiolipid were revealed by correlation analysis. In conclusion, this study provided the interpretation of the specific nutritional indicators and lipid profile in the tripartite muscle of Chaka sheep, which can be used as a guidance for future research on the nutritional qualities and economic benefits of mutton.

The improvement mechanism of volatile for cooked Tibetan pork assisted with ultrasound at low-temperature: Based on the differences in oxidation of lipid and protein

Low-temperature cooking causes flavor weakness while improving the texture and digestive properties of meat. To enhance the flavor of low-temperature cooked Tibetan pork, samples were cooked at low-temperature with or without ultrasound-assisted (UBTP, BTP) for different times (30 min, 90 min) and then analyzed using GC-MS and LC-MS. The results showed that ultrasound-assisted cooking caused a significant increase in lipid oxidation by 9.10% in the early stage of the treatment. Additionally, at the later stage of ultrasound-assisted processing, proteins were oxidized and degraded, which resulted in a remarkable rise in the protein carbonyl content by 6.84%. With prolonged effects of ultrasound and low-temperature cooking, the formation of phenylacetaldehyde in UBTP-90 sample originated from the degradation of phenylalanine through multivariate statistics and correlation analysis. Meanwhile, trans, cis-2,6-nonadienal and 1-octen-3-one originated from the degradation of linolenic acid and arachidonic acid. This study clarified the mechanism of ultrasound-assisted treatment improving the flavor of low-temperature-cooked Tibetan pork based on the perspective of lipids and proteins oxidation, providing theoretical supports for flavor enhancement in Tibetan pork-related products.

Comprehensive characterization of the differences in metabolites, lipids, and volatile flavor compounds between Ningxiang and Berkshire pigs using multi-omics techniques

This study was conducted to comprehensively characterize, metabolites, lipids, and volatile flavor compounds of NingXiang (NX) pigs, Berkshire (BKS) pigs, and their crossbred (Berkshire × Ningxiang, BN) pigs using multi-omics technique. The results showed that NX had high intramuscular fat (IMF) content and meat redness. The metabolite and lipid compositions were varied greatly among three pig breeds. The NX pigs exhibited distinctive sweet, fruity, and floral aroma while BN pigs have inherited this flavor profile. 2-pentylfuran, pentanal, 2-(E)-octenal, and acetic acid were the key volatile flavor compounds (VOC) of NX and BKS pork. The VOCs were influenced by the composition and content of metabolites and lipids. The NX pigs have excellent meat quality traits, unique flavor profiles, and high degree of genetic stability regarding flavor. The study deepens our understanding of the flavor of Chinese indigenous pigs, providing theoretical basis to understand the meat flavor regulation under different feeding conditions.

Targeted metabolomics reveals the contribution of degradation and oxidation of lipids and proteins mediated by pH to the formation of characteristic volatiles in preserved egg yolk during pickling

Targeted metabolomics and flavouromics combined with relative odor activity value were performed to explore the effect of degradation and oxidation of matrix mediated by pH on the formation of characteristic volatiles in preserved egg yolk (PEY) during pickling. It was found that the oxidation of proteins and lipids in PEY induced by pH sequentially occurred in early and later periods, and degradation both mainly occurred in early stage. Moreover, 1-octen-3-one, heptanal, trimethylamine, etc., compounds and 5-HETrE, proline, etc., components were confirmed as up-regulated characteristic volatiles and differential metabolites in PEY during pickling. The formation of octanal-M/D and benzeneacetaldehyde-M was attributed to β-oxidation of hydroxyeicosapentaenoic acid and L-isoleucine catalyzed by strong alkali at early period based on correlation network between them, respectively. Meanwhile, the generation of 1-octen-3-one-M/D mainly depended on L-serine and could be promoted by phosphatidylcholines oxidation. At later stage, the formation of heptanal-M/D was primarily attributed to phosphatidylethanolamines oxidation induced by alkali, and the enrichment of heptanal-M/D and nonanal were both enhanced by oxidized lipids. Lastly, trimethylamine was derived from L-lysine under alkaline conditions and promoted by protein oxidation during the whole process. This manuscript provided insight into the differential contribution of oxidation and degradation from matrix regulated by exogenous factors on the formation pathway for characteristic volatiles in foods.

Lipid degradation contributes to flavor formation during air-dried camel jerky processing

Lipids play an important role in flavor formation in meat products. To determine the contribution of lipids to flavor formation during air-dried camel jerky processing, lipid changes were analyzed by UHPLC-Q-Exactive Orbitrap MS/MS in this study, and volatile compounds were identified by HS-SPME-GC-ToF-MS. Results showed that 606 lipid molecules belonging to 30 subclasses were identified and 206 differential lipid molecules were screened out (VIP > 1, P < 0.05); Cer/NS (d18:1/20:0), LPE (18:1), FA (18:0), GlcADG (12:0/24:1), and PE (18:2e/22:5) were identified as potential lipid biomarkers. A total of 96 volatile compounds were also identified, and 16 of these were identified as key aroma compounds in air-dried camel jerky. Meanwhile, 11 differential lipids significantly, negatively correlated with 7 key aroma compounds (P < 0.05) during processing, indicating that the precursors produced by the degradation of lipid molecules were important sources of volatile flavor substances in air-dried camel jerky.

Effect of cooking methods on volatile compounds and texture properties in millet porridge

To instruct the production of millet porridge, the effect of cooking methods on flavor and texture of millet porridge was investigated. A total of 91 volatiles were detected and most volatile compounds decreased with cooking time, e.g. alcohols. The esters as major volatiles had a high content in electric rice cooker (IC). Multiple chemometric results indicated that volatiles from different cooking methods were distinguished respectively. Texture analysis indicated that the hardness of millet porridge prepared in IC had a more dominant decrease trend than electromagnetic oven and the electric pressure cooker before 40 min. In conclusion, different cooking methods had a more significant influence on the volatiles than cooking time, while the texture is opposite. The comprehensive sensory score reached its peak in IC-30 min. The comprehensive sensory scores of IC and EC decreased with the prolongation of cooking time. This study helps to improve the sensory attributes of millet porridge.

Exploring the influence and mechanism of different frying methods on the flavor quality of low-salt sour meat

To obtain nutritious, healthy, and flavor-enriched sour meat products, the effects of different frying methods (microwave, air-frying, and traditional frying) on the flavor quality of low-salt sour meat were evaluated using metabolomics and other flavor analysis techniques. The pH value of the sour meat rose dramatically, while the TBARS value dropped significantly after frying. E-nose and E-tongue results showed that air-frying could reduce acidity and improve umami. The comprehensive analysis of all samples revealed the identification of 107 volatile flavor compounds, including 10 unique aroma compounds that were specifically detected in the AF group. Additionally, the air frying process notably increased the free amino acid and nucleotide concentrations in sour meat by 53.58% and 159.29%, respectively, while causing a significant reduction in both fatty acid and lactic acid content by 22.84% and 49.29%, respectively. All three frying methods altered the flavor of the samples, but air frying performed better in terms of flavor and texture.

Application of Lactiplantibacillus plantarum hydrogel coating in combination with ice temperature for the preservation of fresh yak meat

Fresh yak meat is highly nutritious and prone to spoilage, so developing suitable preservation methods is crucial. In this study, hydrogel coatings composed of konjac glucomannan, Lactiplantibacillus plantarum and gallic acid (KGX) were applied to preserve fresh yak meat under ice temperature (-1 °C). After 16 days, KGX group showed lowest total viable count (5.3 ± 0.1 log cfu/g) and total volatile basic nitrogen (13.02 ± 1.40 mg/100 g), which did not exceed the relevant standards of fresh meat. Combined assessments of color, texture, pH, drip loss rate, and thiobarbituric acid reactive substances indicated that KGX coating effectively prolonged yak meat preservation. High-throughput sequencing revealed that KGX coating effectively reduced the abundance of Pseudomonas and Candida. The application of L. plantarum hydrogel coatings in conjunction with ice temperature increased the shelf life of fresh yak meat to 16-20 days, suggesting its potential as a viable preservation method for fresh meat.

Research Progress on the Mechanism of the Impact of Myofibrillar Protein Oxidation on the Flavor of Meat Products

Myofibrillar proteins primarily consist of myosin, actin, myogenin, and actomyosin. These proteins form complex networks within muscle fibers and are crucial to the physical and chemical properties of meat. Additionally, myofibrillar proteins serve as significant substrates for the adsorption of volatile flavor compounds, including aldehydes, alcohols, ketones, and sulfur and nitrogen compounds, which contribute to the overall flavor profile of meat products. A series of chemical reactions occur during the processing, storage, and transportation of meat products. Oxidation is one of the most significant reactions. Oxidative modification can alter the physical and chemical properties of proteins, ultimately impacting the sensory quality of meat products, including flavor, taste, and color. In recent years, considerable attention has been focused on the effects of protein oxidation on meat quality and its regulation. This study investigates the impact of myofibrillar protein oxidation on the sensory attributes of meat products by analyzing the oxidation processes and the factors that initiate myofibrillar protein oxidation. Additionally, it explores the control of myofibrillar protein oxidation and its implications on the sensory properties of meat products, providing theoretical insights relevant to meat processing methods and quality control procedures.

Effect of VP, MAP and combined packaging systems on the physicochemical properties and microbiological status of veal from unweaned calves

The packaging system is one of the factors influencing the preservation of the nutritional value, microbiological safety, and sensory attributes of meat. The study investigated changes in physicochemical and microbiological properties taking place during 15-day refrigerated storage of two calf muscles, the longissimus lumborum (LL) and semitendinosus (ST), packaged in three systems, respectively, vacuum packing (VP), modified atmosphere packaging (MAP, 80% O2 + 20% CO2), and a combined system (VP + MAP, 8 d in VP followed by 7 d in MAP). LL and ST stored in VP had significantly lower levels of lipid oxidation, higher α-tocopherol content, and higher instrumentally measured tenderness in comparison with the samples stored in MAP. On the other hand, the MAP samples had lower purge loss at 5 and 15 days, a higher proportion of oxymyoglobin up to 10 days of storage, and a better microbiological status. Calf muscle samples stored in the VP + MAP system had intermediate values for TBARS and α-tocopherol content and at the same time were the most tender and had the lowest counts of Pseudomonas and Enterobacteriaceae bacteria at 15 days. All packaging systems ensured relatively good quality of veal characteristics up to the last day of storage. However, for MAP at 15 days of storage, unfavourable changes in colour (a high level of metmyoglobin and a decrease in oxymyoglobin, redness and R630/580 ratio) and in the lipid fraction (a high TBARS value and a significant decrease in α-tocopherol content) were observed.

Metabolomics, volatolomics, and bioinformatics analyses of the effects of ultra-high pressure pretreatment on taste and flavour parameters of cured Culter alburnus

The effects of ultra-high pressure (UHP) pretreatment (50-250 MPa) on the fish curing were studied. UHP increased the overall volatile compound concentration of cured fish. Among 50-250 MPa five treatment groups, 150 MPa UHP group exhibited the highest total free amino acid content (294.34 mg/100 g) with that of the control group being 92.39 mg/100 g. The activity of cathepsin L was increased under 50-200 MPa UHP treatment (62.28-58.15 U/L), compared with that in the control group (53.80 U/L). UHP treatment resulted in a significant increase in small molecule compounds, especially the amino acid dipeptides and ATP metabolic products. Under UHP treatments, the bacterial phyla Actinobacteriota (1.04-5.25 %), Bacteroidota (0.20-4.47 %), and Deinococcota (0.00-0.05 %) exhibited an increased abundance, and they promoted taste and flavor formation. Our results indicated that UHP is a promising pretreatment method to improve taste and flavour in cured fish by affecting the microorganisms, cathepsin, and proteins.

Volatile Flavor Analysis in Yak Meat: Effects of Different Breeds, Feeding Methods, and Parts Using GC-IMS and Multivariate Analyses

This study investigates the effects of breeds, feeding methods, and parts on the volatile flavor of yak meat. Gas chromatography-ion mobility spectrometry (GC-IMS) and multivariate analysis were used to analyze the volatile organic components (VOCs) in yak meat from various sources. A total of 71 volatile compounds were identified, 53 of which were annotated based on the GC-IMS database. These include 20 alcohols, 16 ketones, 10 aldehydes, four alkenes, one ester, one acid, and one furan. Using VOC fingerprinting and multivariate analysis, yak meats from different sources were distinctly categorized. Breed had the most significant impact on yak meat VOCs, followed by feeding method and then part. Six volatiles with a variable importance in projection value greater than one were identified as potential markers for distinguishing yak meat. This study offers insights into the flavor profile of yak meat from different sources and demonstrates the efficacy of GC-IMS and multivariate analysis in characterizing and discriminating meats.

Identification of Key Volatile Compounds in Tilapia during Air Frying Process by Quantitative Gas Chromatography-Ion Mobility Spectrometry

Air frying as a new roasting technology has potential for roasted fish production. In this study, the changes in volatile compounds (VCs) during air frying of tilapia were studied by quantitative gas chromatography-ion mobility spectrometry, followed by the identification of key VCs based on their odor activity value (OAV). There were 34 verified VCs, of which 16 VCs were identified as the key VCs with OAV ≥ 1. Most of the VCs were improved by air frying and peaked at 20 min. During the air frying, the total sulfhydryl content markedly decreased, while the protein carbonyl and MDA content significantly increased, suggesting the enhancement in the oxidation of lipids and proteins. The correlation network among the chemical properties and key VCs was constructed. The change in total sulfhydryl, protein carbonyl, and MDA showed significant correlation with most of the key VCs, especially 2-methyl butanal, ethyl acetate, and propanal. The results indicated that the oxidation of lipids and proteins contributed the most to the flavor improvement in air-fried tilapia. This study provides a crucial reference for the volatile flavor improvement and pre-cooked product development of roasted tilapia.

Influence of electrohydrodynamics on the drying characteristics, microstructure and volatile composition of apricot abalone mushroom (Pleurotus eryngii)

The study explored the use of current fluid dynamics drying technology for apricot abalone mushroom, examining how different output voltages (15, 25, and 35 kV) affected drying characteristics, microstructure, and volatile components. Comparisons were made with samples dried using hot air drying (HAD) and natural air drying (AD). Results revealed that HAD had the fastest drying rate at 0.29664(g·h-1). However, apricot abalone mushroom treated with electrohydrodynamic drying (EHD) maintained a color closer to fresh samples, exhibited a 21% increase in the ordered structure of protein secondary structure, a 12.5-fold increase in bound water content, and the most stable cell structure compared to HAD and AD treatments. A total of 83 volatile organic compounds were identified in the apricot abalone mushroom, with alcohols and aldehydes being the most prominent in terms of threshold and relative content, peaking in the 35 kV treatment group. These findings provide both experimental and theoretical insights into applying current fluid dynamics for drying apricot abalone mushroom.

Insights into the Flavor Profile of Yak Jerky from Different Muscles Based on Electronic Nose, Electronic Tongue, Gas Chromatography-Mass Spectrometry and Gas Chromatography-Ion Mobility Spectrometry

It is well known that different muscles of yak exhibit distinctive characteristics, such as muscle fibers and metabolomic profiles. We hypothesized that different muscles could alter the flavor profile of yak jerky. Therefore, the objective of this study was to investigate the differences in flavor profiles of yak jerky produced by longissimus thoracis (LT), triceps brachii (TB) and biceps femoris (BF) through electronic nose (E-nose), electronic tongue (E-tongue), gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS). The results indicated that different muscles played an important role on the flavor profile of yak jerky. And E-nose and E-tongue could effectively discriminate between yak jerky produced by LT, TB and BF from aroma and taste points of view, respectively. In particular, the LT group exhibited significantly higher response values for ANS (sweetness) and NMS (umami) compared to the BF and TB groups. A total of 65 and 47 volatile compounds were characterized in yak jerky by GC-MS and GC-IMS, respectively. A principal component analysis (PCA) model and robust principal component analysis (rPCA) model could effectively discriminate between the aroma profiles of the LT, TB and BF groups. Ten molecules could be considered potential markers for yak jerky produced by different muscles, filtered based on the criteria of relative odor activity values (ROAV) > 1, p < 0.05, and VIP > 1, namely 1-octen-3-ol, eucalyptol, isovaleraldehyde, 3-carene, D-limonene, γ-terpinene, hexanal-D, hexanal-M, 3-hydroxy-2-butanone-M and ethyl formate. Sensory evaluation demonstrated that the yak jerky produced by LT exhibited superior quality in comparison to that produced by BF and TB, mainly pertaining to lower levels of tenderness and higher color, taste and aroma levels. This study could help to understand the specific contribution of different muscles to the aroma profile of yak jerky and provide a scientific basis for improving the quality of yak jerky.

Characterization and discrimination of volatile organic compounds and α-glucosidase inhibitory activity of soybeans (Glycine max L.) during solid-state fermentation with Eurotium cristatum YL-1

In this study, the influence of solid-state fermentation (SSF) using probiotic Eurotium cristatum on the change of volatile organic compounds (VOCs) and α-glucosidase inhibition activity of soybeans was investigated. A total of 46 VOCs were characterized via headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS), the majority of which were aldehydes (17), alcohols (10), and ketones (7). SSF by E. cristatum drastically affected the flavor characteristics of soybeans, and the levels of unpleasant beany flavor components, such as hexanal-D, 1-octen-3-ol, 1-hexanol-D, 1-hexanol-M, heptanal-M, 1-pentanol, heptanal-D, and 2-pentyl furan were all substantially decreased by 50% after 15 days of SSF, while volatiles with floral, caramel, and desirable flavors such as pentanal-D, methylpropanal, 2-propanol, and propyl acetate drastically (p < 0.05) increased by 1.1-, 19.2-, 3.6-, and 2.6-fold, respectively. Key aroma-active compounds analysis revealed that 18 VOCs (ROAV, relative odor activity value ≥ 1) play a great role in shaping the flavor characteristics of the soybean samples. After 15 days of SSF, the ROAV values of methylpropanal, 2-propanol, and propyl acetate drastically (p < 0.05) increased to 8.48, 63.88, and 11.29, respectively, which greatly contributed to the desirable flavor characteristics of fermented soybeans. Furthermore, E. cristatum greatly improved the α-glucosidase inhibitory activity of soybean by 22.4% after 15 days fermentation, which was closely correlated with the accumulated phenolic compounds during SSF. Molecular docking showed that genistein and daidzein have high binding affinity for α-glucosidase active sites, primarily driven by hydrogen bonds and hydrophobic interactions. These results demonstrated that soybeans fermented with E. cristatum substantially improved the flavor characteristics and α-glucosidase inhibitory effect, and were greatly helpful to promote the application of soybeans in food products.