Identification of the main aroma compounds in Chinese local chicken high-quality meat

Integrating lipidomics and metabolomics to reveal biomarkers of fat deposition in chicken meat

Local chicken breeds in China are highly regarded for their superior meat flavor. This study utilized lipidomics and non-targeted metabolomics to identify biomarkers influencing intramuscular fat (IMF) deposition in the breast muscle of 42- and 180-day-old Jingyuan chickens. Results revealed that IMF content was higher in the breast muscle of 180-day-old Jingyuan chickens compared to 42-day-old chickens (P < 0.01). We identified 248 differentially expressed lipids (DELs) and 1042 differentially expressed metabolites (DEMs). The breast muscle of 180-day-old chickens contained higher levels of TG, fatty acid (FA) and cholesteryl ester (CE), with C16:1 and C18:1 being particularly abundant. Integration of non-targeted metabolomic analyses emphasized glycerolipid metabolism and vitamin digestion and absorption as the main pathways distinguishing between 42- and 180-day-old chickens. Additionally, the differential metabolites LysoPS 18:1, LysoPC 20:3, LysoPC 18:2, LysoPI 20:3, and Pantothenic acid contributed to enhanced meat flavor in Jingyuan chickens.

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.

Integrative analysis of the transcriptome, proteomics and metabolomics reveals key genes involved in the regulation of breast muscle metabolites in capons

Castration is widely used in poultry and livestock to enhance fat metabolism and improve the flavor, tenderness and juiciness of meat. However, the genetic regulatory mechanism underlying castration consequences have not been clarified. To investigate the key metabolites affecting the quality of capons and the key regulatory mechanisms, Qingyuan partridge roosters were subjected to castration. Metabolic profiling was used to detect differential metabolites in the breast muscle of both capon and control groups. Additionally, an integrative analysis of transcriptomics and proteomics was conducted to explore the genetic regulation mechanisms influencing meat quality. The results indicated that the muscle fiber density and shear force of capons was lower than that of normal chickens, and the fat percentage of capon group (CAM) was higher than control group (COM). The expression of the metabolite inostine-5'-monophosphate (IMP) was lower in capons, and lipid metabolites (PC (10:0/10:0), PC (6:0/13:1), LPC 22:6, LPC 18:2, LPE 18:1, LPE 20:4) were higher in capons. Metabolic pathways were found to be a common signaling pathway in all omics. Glutamate-ammonia ligase (GLUL), acetyl-CoA carboxylase beta (ACACB), 1-acylglycerol-3-phosphate O-acyltransferase 2 (AGPAT2), 4-hydroxy-2-oxoglutarate aldolase 1 (HOGA1) and glutathione S-transferase alpha 2 (GSTA2) regulate the expression of citric acid, arachidonic acid, palmitic acid, isocitric acid, and betaine. These findings highlight the key mechanisms contributing to the meat quality differences between capons and normal chickens.

Modulating the aroma and taste profile of soybean using novel strains for fermentation

A key factor influencing consumer acceptance of soybean products is the aroma and taste profile, which can be modulated through fermentation using unique microbial strains. This study aimed to identify and characterize novel microbial strains with the potential to enhance flavour profiles including umami, while reducing undesirable flavour notes such as beany aromas. The results showed an 800% (8-fold) increase in free amino acids in samples fermented with Rhizopus oryzae, which correlated with an increase in umami intensity as measured using an E-tongue. Samples fermented with Neurospora crassa also demonstrated an increase in methionine and cysteine, sulfur-containing amino acids that are deficient in raw soybean. Fermentation additionally resulted in a significant increase in fatty acids and alterations to the fatty acid profile. Notably, samples fermented with Penicillium camemberti, Penicillium nalgiovense, Penicillium chrysogenum, and Leuconostoc mesenteroides containing omega-3 fatty acids. Lastly, fermentation introduced desirable aroma compounds, including 'smoky', 'cheesy' and 'floral' notes, enhancing the sensory appeal of certain samples. This study demonstrates the innovative use of novel microbial strains in soybean fermentation as a promising strategy to modulate the aroma and taste profile of soybean products.

Effect of chilled storage period on the volatile organic compounds and bacterial community in goose meat

Storage time is considered to be one of the most important factors affecting the obnoxious odor and microbial spoilage of fresh meat. In this study, volatile organic compounds (VOCs) and bacterial community structure of chilled goose meat during storage were investigated. The results showed that numerous VOCs were produced during the fresh goose meat storage, including aldehydes (nonanal, (E)-2-octenal, hexanal, tetradecanal), alcohol (1-octen-3-ol), furan (2-pentylfuran), and carboxylic acids (methyl diethyldithiocarbamate), which might be a breakdown product during spoilage. In addition, there were slight fluctuations in fatty acid profiles and amino acid contents. Furthermore, bacterial community diversity decreased with prolonged storage. Also, Pseudomonas and Acinetobacter were the dominant spoilage bacteria contributing to nonanal and methyl diethyldithiocarbamate generation. Taken together, these data provide insights into the characterization of VOCs and the bacterial community of chilled goose meat, which will help to further control the microbial quality of chilled meat.

Aroma component analysis by HS-SPME/GC-MS to characterize Lager, Ale, and sour beer styles

The world of beer is a rich tapestry woven with diverse styles, each with its unique character. Lager, known for its crispness, ferments at lower temperatures, while ale, at warmer ones, boasts a wide spectrum of aromas. Belgian beers dazzle with their complexity, from fruity Trappist ales to sour lambics. German wheat beers, like hefeweizens, charm with their effervescence and fruity undertones. India Pale Ales (IPAs) showcase a hoppy burst, while sour ales tantalize with their tanginess. Craftsmanship, history, and regional ingredients intertwine in this world of brewing, offering aficionados an array of delightful experiences. Research on craft beer aromas is limited, and molecular fingerprint could be crucial. To date, there have been no studies focused on characterizing compound profiles to differentiate beer styles. The Headspace Solid Phase Microextraction (HS-SPME) method provides a rapid and solvent-free approach to volatile compound. The present study aims to characterize the aroma profile of a wide range of beers by using HS-SPME/GC-MS technique combined with multivariate data processing. A total of 120 beer samples were collected and divided into five categories: Pilsen (n = 28); Lager (n = 23); Ale (n = 32); Sour (n = 24); and Belgian Ales (n = 13). Among the Pilsen beers, 18 unique compounds were found for beers with hop extract and hops, and 2 for beers with hop extract (Octyl acetate; and alpha-Terpineol). When comparing the remaining groups to each other, Belgian beers exhibited 5 unique compounds, and Lagers had one (nonanal). Sours and Ales did not have unique compounds but shared 2 distinct compounds with the Belgian group each. We concluded that Belgian beers are the most complex in terms of various aroma-related compounds, and that it is possible to distinguish beers that use pure hops from hop extract.

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

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

The effect of instant tea on the aroma of duck meat

Tea products, such as instant tea, have been shown to improve the aroma of meat products. However, the mechanisms by which tea products enhance meat aroma have not been adequately explained. In this study, we analyzed the impact of instant tea on the aroma of duck meat. Our results showed that treatment with instant tea led to increases in floral, baked, and grassy notes while reducing fishy and fatty notes. Several alcohols, aldehydes, ketones, indole and dihydroactinidiolide exhibited significantly increased OAVs. Conversely, certain saturated aldehydes, unsaturated aldehydes and alcohols displayed significantly decreased OAVs. The enhanced floral, baked and grassy notes were attributed to volatile compounds present in instant tea. The reduction in fishy and fatty notes was linked to polyphenols in instant tea interacting with nonanal, undecanal, (E)-2-octenal, (E)-2-nonenal, (E)-2-decenal, and 2,4-decadienal through hydrophobic interactions and electronic effects. This study enhances our understanding of how tea products improve meat aromas.

Dietary effect of Dendrobium officinale leaves on chicken meat quality, fatty acid composition, and volatile compounds profile

Dendrobium officinale leaves (DOL) contain many active ingredients with various pharmacological effects, but are still ineffectively utilized. To investigate the feasibility of developing DOL as a feed additive, it is necessary to determine whether dietary supplementing DOL had any effect on meat quality and flavor. Our results showed that supplementation with DOL decreased the shear force while increased the pH and fat content in breast meat. Meat from DOL-fed chickens had higher levels of n-3 polyunsaturated fatty acids (PUFAs) and n-6 PUFAs, but lower n-6/n-3 ratios. Moreover, volatile compounds profile indicated that contents of aldehydes, including hexanal, pentanal, and heptanal, etc.), which were identified as the key volatile compounds in chicken meat, exhibited noteworthy rise in DOL intake groups. Octanal, 1-octen-3-ol, and 2-pentylfuran also contributed greatly to the meat overall aroma. These data provide a foundation for the comprehensive utilization of DOL as a feed additive with antibiotic substitution potential.

RNA-Seq Reveals Pathways Responsible for Meat Quality Characteristic Differences between Two Yunnan Indigenous Chicken Breeds and Commercial Broilers

Poultry is a source of meat that is in great demand in the world. The quality of meat is an imperative point for shoppers. To explore the genes controlling meat quality characteristics, the growth and meat quality traits and muscle transcriptome of two indigenous Yunnan chicken breeds, Wuding chickens (WDs) and Daweishan mini chickens (MCs), were compared with Cobb broilers (CBs). The growth and meat quality characteristics of these two indigenous breeds were found to differ from CB. In particular, the crude fat (CF), inosine monophosphate content, amino acid (AA), and total fatty acid (TFA) content of WDs were significantly higher than those of CBs and MCs. In addition, it was found that MC pectoralis had 420 differentially expressed genes (DEGs) relative to CBs, and WDs had 217 DEGs relative to CBs. Among them, 105 DEGs were shared. The results of 10 selected genes were also confirmed by qPCR. The differentially expressed genes were six enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) biological pathways including lysosomes, phagosomes, PPAR signaling pathways, cell adhesion molecules, cytokine-cytokine receptor interaction, and phagosome sphingolipid metabolism. Interestingly, four genes (LPL, GK, SCD, and FABP7) in the PPAR signal pathway related to fatty acid (FA) metabolism were elevated in WD muscles, which may account for higher CF, inosine monophosphate content, and AA and FA contents, key factors affecting meat quality. This work laid the foundation for improving the meat quality of Yunnan indigenous chickens, especially WD. In future molecular breeding, the genes in this study can be used as molecular screening markers and applied to the molecular breeding of chicken quality characteristics.

Use of GC-IMS and Stoichiometry to Characterize Flavor Volatiles in Different Parts of Lueyang Black Chicken during Slaughtering and Cutting

Chilled and cut chicken is preferred by consumers for its safeness and readiness to cook. To evaluate the quality characteristics of various chilled chicken products, differences in volatile organic components (VOCs) of six different cut parts (breast, back, leg, heart, liver, and gizzard) of Lueyang black chicken were characterized through gas chromatography-ion mobility spectroscopy (GC-IMS) combined with stoichiometry. A total of 54 peaks in the signal of VOCs were detected by GC-IMS, and 43 VOCs were identified by qualitative analysis. There were 22 aldehydes (20.66-54.07%), 8 ketones (25.74-62.87%), 9 alcohols (4.17-14.69%), 1 ether (0.18-2.22%), 2 esters (0.43-1.54%), and 1 furan (0.13-0.52%), in which aldehydes, ketones, and alcohols were the main categories. Among the six cut parts, the relative content of aldehydes (54.07%) was the highest in the gizzard, and the relative content of ketones (62.87%) was the highest in the heart. Meanwhile, the relative content of alcohols (14.69%) was the highest in the liver. Based on a stable and reliable predictive model established by orthogonal partial least squares-discriminant analysis (OPLS-DA), 3-hydroxy-2-butanone (monomer and dimer), acetone, 2-butanone monomer, hexanal (monomer and dimer), isopentyl alcohol monomer, and n-hexanol monomer were picked out as characteristic VOCs based on variable importance in projection (VIP value > 1.0, p < 0.05). Principal component analysis (PCA) and the clustering heatmap indicated that the characteristic VOCs could effectively distinguish the six cut parts of Lueyang black chicken. The specific VOCs responsible for flavor differences among six different cut parts of Lueyang black chicken were hexanal (monomer and dimer) for the gizzard, 2-butanone monomer and hexanal dimer for the breast, hexanal monomer for the back, 3-hydroxy-2-butanone monomer for the leg, 3-hydroxy-2-butanone (monomer and dimer) for the heart, and acetone and isopentyl alcohol monomer for the liver. These findings could reveal references for quality assessment and development of chilled products related to different cut parts of Lueyang black chicken in the future.

Application of UV-Vis-NIR and FTIR spectroscopy coupled with chemometrics for quality prediction of katsuobushi based on the number of smoking treatments

Katsuobushi, a smoked, dried skipjack tuna, is a traditional Japanese food additive with a unique flavor and taste. Gas chromatography mass spectrometry (GC-MS), fourier transform infrared (FTIR), and ultraviolet-visible-near infrared spectroscopy (UV-Vis-NIR) combined with chemometric methods were evaluated the quality of katsuobushi according to the number of smoking treatments. Using GC-MS, 46 metabolites were identified and five metabolites were selected as key compounds. All samples were classified according to their smoking number via principal component analysis (PCA), partial least squares-discriminate analysis (PLS-DA) and hierarchical cluster analysis (HCA) of the FTIR and NIR spectra. Partial least squares regression (PLSR) analysis revealed that the FTIR and NIR spectra were highly correlated with the metabolites by GC-MS. These results demonstrated the potential of using the FTIR and NIR spectroscopy combined with chemometrics to assess the quality of katsuobushi based on the smoking treatments, with NIR spectroscopy showed particularly promising.

Large-scale transcriptomic and genomic analyses reveal a novel functional gene SERPINB6 for chicken carcass traits

BACKGROUND

Carcass traits are crucial indicators of meat production efficiency. However, the molecular regulatory mechanisms associated with these traits remain unclear.

RESULTS

In this study, we conducted comprehensive transcriptomic and genomic analyses on 399 Tiannong partridge chickens to identify key genes and variants associated with carcass traits and to elucidate the underlying regulatory mechanisms. Based on association analyses with the elastic net (EN) model, we identified 12 candidate genes (AMY1A, AP3B2, CEBPG, EEF2, EIF4EBP1, FGFR1, FOXD3, GOLM1, LOC107052698, PABPC1, SERPINB6 and TBC1D16) for 4 carcass-related traits, namely live weight, dressed weight, eviscerated weight, and breast muscle weight. SERPINB6 was identified as the only overlapping gene by 3 analyses, EN model analysis, weighted gene co-expression network analysis and differential expression analysis. Cell-level experiments confirmed that SERPINB6 promotes the proliferation of chicken DF1 cells and primary myoblasts. Further expression genome-wide association study and association analysis indicated that rs317934171 is the critical site that enhances SERPINB6 expression. Furthermore, a dual-luciferase reporter assay proved that gga-miR-1615 targets the 3'UTR of SERPINB6.

CONCLUSIONS

Collectively, our findings reveal that SERPINB6 serves as a novel gene for chicken carcass traits by promoting fibroblast and myoblast proliferation. Additionally, the downstream variant rs317934171 regulates SERPINB6 expression. These results identify a new target gene and molecular marker for the molecular mechanisms of chicken carcass traits.

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

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

Identification and comparison of aroma and taste-related compounds from breast meat of three breeds of Korean native chickens

This study was aimed to identify and compare the taste-related compounds (nucleotide-related compounds, free amino acid contents, and fatty acid composition) and aroma (volatile organic compounds [VOC]) compounds in the chicken breast meat from 3 kinds of Korean native chicken (KNC), namely Hanhyup 3 (HH3), Woorimatdag 1 (WRMD1) and Woorimatdag 2 (WRMD2). Among the 3 breeds, WRMD1 had significantly higher IMP and AMP contents than HH3. WRMD2 exhibited higher levels of umami and sweet-taste amino acids and oleic acid composition compared to HH3 (P < 0.05). HH3 showed a higher composition of unsaturated fatty acids than WRMD2 (P < 0.05). On their discrimination by flavor composition, some compounds including aspartic acid were analyzed as important compounds. Regarding aroma compounds, unique aroma compounds were detected for each breed and some compounds such as isopropyl myristate, p-cresol, (S)-(+)-3-Methyl-1-pentanol, and cyclic octa-atomic sulfur were expected to be utilized as key compounds in discrimination of the 3 breeds. From the result of this study, the differences on the flavor compounds of three breeds were elucidated and key compounds for their discrimination were presented.

Identification and biotransformation analysis of volatile markers during the early stage of Salmonella contamination in chicken

Salmonella is one of the most prevalent foodborne pathogens in poultry and its products. Its rapid detection based on volatile organic compounds (VOC) has been widely accepted. However, the variation in the VOCs of Salmonella-contaminated chicken during the early stage (48 h) remains uncertain. Headspace-SPME-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace-gas chromatography-ion migration spectroscopy (HS-GC-IMS) were used to identify VOCs and their variations after the chicken meat was contaminated with Salmonella. Chemometric and KEGG enrichment analyses were performed to identify VOC markers and their potential metabolic pathways. A total of 64 volatile compounds were detected using HS-GC-IMS, which showed a better differentiation than HS-SPME-GC-MS (45 volatile compounds) based on principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA). Fatty acid degradation was the main cause of VOC variation. 2-Propanol, hexadecane, 3-methylbutanol, acetic acid, propyl acetate, acetic acid methyl ester, and 3-butenenitrile were identified as VOC markers in the middle stage of decomposition, and 1-octen-3-ol was recognized as a VOC marker of Salmonella-contaminated chicken during the first 48 h of contamination. This provides a theoretical basis for the study of Salmonella contamination VOC markers in poultry meat.

Cultured meat with enriched organoleptic properties by regulating cell differentiation

Research on cultured meat has primarily focused on the mass proliferation or differentiation of muscle cells; thus, the food characteristics of cultured meat remain relatively underexplored. As the quality of meat is determined by its organoleptic properties, cultured meat with similar sensory characteristics to animal-derived meat is highly desirable. In this study, we control the organoleptic and nutritional properties of cultured meat by tailoring the 2D differentiation of primary bovine myoblasts and primary bovine adipose-derived mesenchymal stem cells on gelatin/alginate scaffolds with varying stiffness. We assess the effect of muscle and adipose differentiation quality on the sensory properties of cultured meat. Thereafter, we fabricate cultured meat with similar sensory profiles to that of conventional beef by assembling the muscle and adipose constructs composed of highly differentiated cells. We introduce a strategy to produce cultured meat with enriched food characteristics by regulating cell differentiation with scaffold engineering.

Identification of characteristic aroma compounds in chicken meat and their metabolic mechanisms using gas chromatography-olfactometry, odor activity values, and metabolomics

Aroma has an important influence on the aroma quality of chicken meat. This study aimed to identify the characteristic aroma substances in chicken meat and elucidate their metabolic mechanisms. Using gas chromatography-olfactometry and odor activity values, we identified nonanal, octanal, and dimethyl tetrasulfide as the basic characteristic aroma compounds in chicken meat, present in several breeds. Hexanal, 1-octen-3-ol, (E)-2-nonenal, heptanal, and (E,E)-2,4-decadienal were breed-specific aroma compounds found in native Chinese chickens but not in the meat of white-feathered broilers. Metabolomics analysis showed that L-glutamine was an important metabolic marker of nonanal, hexanal, heptanal, octanal, and 1-octen-3-ol. Exogenous supplementation experiments found that L-glutamine increased the content of D-glucosamine-6-P and induced the degradation of L-proline, L-arginine, and L-lysine to enhance the Maillard reaction and promote the formation of nonanal, hexanal, heptanal, octanal, and 1-octen-3-ol, thus improving the aroma profile of chicken meat.

Characterization of Volatile Compounds in Donkey Meat by Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) Combined with Chemometrics

Volatile compounds (VOCs) are an important factor affecting meat quality. However, the characteristic VOCs in different parts of donkey meat remain unknown. Accordingly, this study represents a preliminary investigation of VOCs to differentiate between different cuts of donkey meat by using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) combined with chemometrics analysis. The results showed that the 31 VOCs identified in donkey meat, ketones, alcohols, aldehydes, and esters were the predominant categories. A total of 10 VOCs with relative odor activity values ≥1 were found to be characteristic of donkey meat, including pentanone, hexanal, nonanal, octanal, and 3-methylbutanal. The VOC profiles in different parts of donkey meat were well differentiated using three- and two-dimensional fingerprint maps. Nine differential VOCs that represent potential markers to discriminate different parts of donkey meat were identified by chemometrics analysis. These include 2-butanone, 2-pentanone, and 2-heptanone. Thus, the VOC profiles in donkey meat and specific VOCs in different parts of donkey meat were revealed by HS-GC-IMS combined with chemometrics, whcih provided a basis and method of investigating the characteristic VOCs and quality control of donkey meat.

Effects of Lactiplantibacillus plantarum on oxidative stress, mitophagy, and NLRP3 inflammasome activation in broiler breast meat

Poultry meat has a high polyunsaturated fatty acids content, making it vulnerable to oxidative stress. Mitophagy participates in the regulation of oxidative stress and the nucleotide-binding and oligomerization domain (NOD)-like receptor family as well as pyrin domain-containing protein 3 (NLRP3) inflammasome activation. Lactiplantibacillus plantarum P8 (P8) is a probiotic strain with an antioxidant capacity. In the present study, we investigated the effects of P8 on oxidative stress, mitochondrial function, mitophagy, and NLRP3 inflammasome in the breast meat of oxidatively stressed broilers. Four hundred 1-day-old male broilers were assigned to a 2 × 2 factorial design with 2 P8 levels (0 or 1 × 108 cfu/g), either with or without dexamethasone (DEX) injection, for a 21-day experimental period. DEX was injected intraperitoneally once daily from d 16 to 21. The breast meat was collected on d 21. The results showed that P8 supplementation decreased malondialdehyde (MDA) levels, increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and activated the Keap1-Nrf2 pathway in DEX-injected broilers. Moreover, P8 supplementation downregulated mitochondrial DNA (mtDNA) copy number and increased the expressions of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), silent information regulator 1 (SIRT1), mitochondrial fusion protein 1 (Mfn1), and optic atrophy protein 1 (OPA1) in DEX-treated broilers. In addition, the decreased mitophagy level in DEX-treated broilers was elevated with P8 supplementation, as reflected by the increased gene expression of autophagy-related gene 5 (ATG5), Bcl-2-interacting protein (Becline-1), Parkin, PTEN-induced kinase 1 (PINK1), light chain 3 II (LC3II)/LC31, and the protein expression of Parkin as well as decreased p62 expression. In addition, P8 supplementation inhibited NLRP3 inflammasome activation by decreasing the transcription of NLRP3, IL-18, cysteinyl aspartate-specific proteinase-1 (Caspase-1), and the expression of NLRP3 and IL-18 in DEX-treated broilers. In conclusion, dietary P8 supplementation alleviates oxidative stress, improves mitophagy, and inhibits NLRP3 inflammasome activation in the breast meat of oxidatively stressed broilers.

Comparative flavor precursors and volatile compounds of Wenchang chickens fed with copra meal based on GC-O-MS

In the Wenchang chicken (WC) feeding process, copra meal is often added to improve chicken quality. To determine the effect of feeding with copra meal on the flavor formation of WCs, the experimental subjects were fed with 4.5 % and 7.5 % copra meal, and the control group was fed without copra meal. The electronic nose combined with gas chromatography-olfactometry mass spectrometry (GC-O-MS) was used to identify the volatile compounds from the samples. Compared with the control group, the pH of chickens fed copra meal was significantly decreased (P < 0.05) after slaughter. Aldehydes and alcohols were the main volatile compounds in muscle, among which hexanal and 1-octen-3-ol were the highest. Thirty-two and thirty-six compounds were identified in breast muscle and drumstick muscle, respectively. Twelve new volatile compounds were added, including 1-octanol, butanal, 1-heptanol, 3-ethylbenzaldehyde, 2,2-dimethylpentanal, hexanoic acid, 3-heptanone, 2,5-heptanedione, 2-ethylfuran, 2-propylfuran, 2-ethynylpyridine, and 1,2,4,5-tetrazine. The types and contents of volatile compounds in drumstick muscle increased with an increasing proportion of copra meal in the diet. In summary, the addition of copra meal changed the quality of WCs and increased the types and contents of volatile compounds. This study provides a reference for understanding the flavor profile of WC fed copra meal.

Characteristics and potential biomarkers of flavor compounds in four Chinese indigenous chicken breeds

Chinese indigenous chickens have a long history of natural and artificial selection and are popular for their excellent meat quality and unique flavor. This study investigated six meat quality-related traits in Ningdu yellow, Baier yellow, Kangle, and Shengze 901 chickens. Two-dimensional gas chromatography-time-of-flight mass spectrometry was used to detect unique flavors in 24 breast muscle samples from the same phenotyped chickens. Overall, 685, 618, 502, and 487 volatile organic compounds were identified in Ningdu yellow, Baier yellow, Kangle, and Shengze 901 chickens, respectively. The flavor components were separated into eight categories, including hydrocarbons and aldehydes. Multivariate analyses of the identified flavor components revealed some outstanding features of these breeds. For example, the hydrocarbons (22.09%) and aldehydes (14.76%) were higher in Ningdu yellow chickens and the highest content of N, N-dimethyl-methylamine was in Ningdu yellow, Baier yellow, and Shengze 901 chickens, indicating the maximum attribution to the overall flavor (ROAV = 439.57, 289.21, and 422.80). Furthermore, we found that 27 flavor compounds differed significantly among the four Chinese breeds, including 20 (e.g., 1-octen-3-ol), two (e.g., 2-methyl-naphthalene), four (e.g., 2,6-lutidine), and one (benzophenone) flavor components were showed significant enrichment in Ningdu yellow, Baier yellow, Kangle, and Shengze 901 chickens, respectively. The flavor components enriched in each breed were key biomarkers distinguishing breeds and most were significantly correlated with meat quality trait phenotypes. These results provide novel insights into indigenous Chinese chicken meat flavors.

Integrated LC/MS-based lipidomics and transcriptomics analyses revealed lipid composition heterogeneity between pectoralis intramuscular fat and abdominal fat and its regulatory mechanism in chicken

Intramuscular fat (IMF) content is conducive to multiple meat quality properties, while abdominal fat (AF) is treated as waste product in chicken industry. However, the heterogeneity and distinct regulatory mechanisms of lipid composition between the IMF and AF are still unclear. In this study, we carried out non-targeted lipidomics analyses of pectoralis IMF and AF, and detected a total of 423 differential lipid molecules (DLMs) between chicken IMF and AF, including 307 up-regulated and 116 down-regulated DLMs in pectoral IMF. These DLMs exhibited the definite alteration of lipid composition. The up-reglated DLMs in IMF were mainly glycerophospholipids (GPs), including the bulk of phosphatidylcholines (PC, PC (P) and PC (O)), phosphatidylethanolamines (PE, PE (P) and PE (O)), phosphatidylglycerols (PG) and phosphatidylinositol (PI), while the up-reglated DLMs in AF were mainly glycerolipids (GLs), including most of triacylglycerols (TG) and diacylglycerols (DG). We further identified 28 main DLMs contributing to the heterogeneous deposition of IMF and AF, including 11 TGs common to IMF and AF, 12 PCs/PC (P)s specific to IMF and 5 DGs specific to AF. Further integration of transcriptome with the main DLMs by weighted gene co-expression network analysis (WGCNA), we found five key gene sets that included 386 unique genes promoting IMF deposition in pectoralis, 213 unique genes promoting AF deposition, 6 unique genes detrimental to AF deposition, 7 common genes that promote IMF deposition in pectoralis while adversely affect AF deposition, and 28 genes that only promoted IMF deposition in pectoralis but had no effect on AF deposition. In addition, we also observed the expression characteristics of key genes in vivo and in vitro, and found that transmembrane protein family gene TMEM164 might be mainly involved in the positive regulation of intramuscular fat deposition in pectoralis and zinc finger protein family gene ZNF488 had a potential unique positive regulatory function on abdominal fat deposition. These findings provide new perspectives for understanding IMF and AF heterodeposition and will serve as a valuable information resource for improving meat quality via breeding selection in chicken.

Analysis of Volatile Markers and Their Biotransformation in Raw Chicken during Staphylococcus aureus Early Contamination

To address the potential risks to food safety, headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) were used to analyze the volatile organic compounds (VOCs) generated from chilled chicken contaminated with Staphylococcus aureus during early storage. Together with the KEGG database, we analyzed differential metabolites and their possible biotransformation pathways. Orthogonal partial least squares discriminant analysis (OPLS-DA) was applied to characterize VOCs and identify biomarkers associated with the early stage of chicken meat contamination with S. aureus. The results showed 2,6,10,15-tetramethylheptadecane, ethyl acetate, hexanal, 2-methylbutanal, butan-2-one, 3-hydroxy-2-butanone, 3-methylbutanal, and cyclohexanone as characteristic biomarkers, and 1-octen-3-ol, tetradecane, 2-hexanol, 3-methyl-1-butanol, and ethyl 2-methylpropanoate as potential characteristic biomarkers. This provides a theoretical basis for the study of biomarkers of Staphylococcus aureus in poultry meat.

Dietary Grape Pomace Supplementation in Lambs Affects the Meat Fatty Acid Composition, Volatile Profiles and Oxidative Stability

The aim of this study was to evaluate the effects of supplementing grape pomace (GP) in lambs’ diets. A total of 30 lambs homogeneous for body weight (13.1 ± 2.1 kg) and age (25–30 days) were randomly allocated into two groups. The control group (CTR) received a standard diet for 45 days, while in the same period the experimental group (GP+) was fed with a diet containing 10% GP on a dry matter (DM) basis. The meat samples from the two groups showed no significant differences in drip loss, cooking loss, meat color and total lipid amount. However, the experimental feeding strategy influenced the meat fatty acid composition, with an increase in the relative percentages of stearic, vaccenic and rumenic acids. In particular, the increase in rumenic acids is associated with several health benefits attributed to its high bioactive properties. In cooked meat samples stored for 5 days at 4 °C, the dietary GP supplementation induced an increase in nonanal and 1-octen-3-ol and a significant reduction of hexanal, an indicator of oxidation; this improved resistance to oxidation in the GP+ samples and was also confirmed by the thiobarbituric acid reactive species (TBARS) test. In summary, the present study showed that the dietary GP supplementation was effective in improving the fatty acid composition and the oxidative stability of lamb meat. The use and valorization of the GP as a matrix of interest for zootechnical nutrition can, therefore, represent a suitable strategy for improving the qualitative aspects of animal production.

Comparative Characterization of Volatile Compounds of Ningxiang Pig, Duroc and Their Crosses (Duroc × Ningxiang) by Using SPME-GC-MS

With the aim to study the flavor characteristics of Ningxiang pigs (NX), Duroc (DC) pigs, and their crosses (Duroc × Ningxiang, DN), electronic nose and gas chromatography-mass spectrometry analysis were used to detect the volatile flavor substances in NX, DC, and DN (n = 34 pigs per population). A total of 120 volatile substances were detected in the three populations, of which 18 substances were common. Aldehydes were the main volatile substances in the three populations. Further analysis revealed that tetradecanal, 2-undecenal, and nonanal were the main aldehyde substances in the three kinds of pork, and the relative content of benzaldehyde in the three populations had significant differences. The flavor substances of DN were similar to that of NX and showed certain heterosis in flavor substances. These results provide a theoretical basis for the study of flavor substances of China local pig breeds and new ideas for pig breeding.

Integrated metabolomics and lipidomics evaluate the alterations of flavor precursors in chicken breast muscle with white striping symptom

White striping (WS) is the most common myopathy in the broiler chicken industry. To reveal flavor changes of WS meat objectively, flavor precursors of WS breast muscle were evaluated systematically with integrated metabolomics and lipidomics. The results showed that WS could be distinguished from normal controls by E-nose, and four volatile compounds (o-xylene, benzene, 1,3-dimethyl, 2-heptanone and 6-methyl and Acetic acid and ethyl ester) were detected as decreased compounds by gas chromatography-mass spectrometry. Lipidomic analysis showed that WS breast fillets featured increased neutral lipid (83.8%) and decreased phospholipid molecules (33.2%). Targeted metabolomic analysis indicated that 16 hydrophilic metabolites were altered. Thereinto, some water-soluble flavor precursors, such as adenosine monophosphate, GDP-fucose and L-arginine increased significantly, but fructose 1,6-bisphosphate and L-histidine significantly decreased in the WS group. These results provided a systematic evaluation of the flavor precursors profile in the WS meat of broiler chickens.

Dietary Effect of Brevibacillus laterosporus S62-9 on Chicken Meat Quality, Amino Acid Profile, and Volatile Compounds

Probiotics are being used in diets to improve the quality of chicken meat. The aim of the study was to investigate the effects of dietary supplementation with Brevibacillus laterosporus S62-9 microbial agent on the meat quality, amino acids, and volatile compounds of chicken. The experiment was carried out with 160 1-day-old Arbor Acres male broiler chickens, rearing for 42 d. The chickens were randomly divided into two groups of 8 replicates each, with 10 chickens in each group. No supplement was added to the basal diet in the control group and Brevibacillus laterosporus S62-9 microbial agent was added to the diet of the experimental group. At the end of the experiment, the meat quality, meat chemical composition, amino acid composition, and volatile compounds of chicken were determined. The results showed that pH (p < 0.05), pressing loss (p < 0.05), cooking loss (p < 0.05), and shear force (p < 0.01) were notably decreased, the percentage of breast meat (p < 0.01), protein content (p < 0.05) were visibly increased, and remarkable changes were observed in the amino acid composition (change in seven amino acids) and volatile compounds profile (an increase of about 20-fold in the contents of 1-octen-3-ol and hexanal). In summary, it was found that Brevibacillus laterosporus S62-9 microbial agent can be used as a novel and effective feed supplement to improve the nutritional quality and flavor characteristics of broilers.

Evaluation of dietary metabolizable energy concentrations on meat quality and lipid metabolism-related gene expression in yellow-feathered chickens

This study evaluated the effects of different dietary metabolizable energy (ME) concentrations on the meat quality, carcass traits, volatile flavour and lipid metabolism-related gene expression levels in yellow-feathered chickens. In total, 600 Huxu female chickens aged 90 days were randomly assigned to six dietary treatments, each with 10 replicates of 10 birds. During the finisher phase, the birds were fed diets containing 2880 (low), 2940, 3000, 3060, 3120 and 3180 (high) kcal ME/kg. The results showed that the average daily gain of chickens increased as the dietary ME concentration increased, while the feed to gain improved (p < 0.05), and the intramuscular fat content of breast muscle increased (p < 0.05). The energy concentration had no effect on the breast muscle pH (45 min and 24 h), colour parameter (L*) or percentage of drip loss (p > 0.05), but the shear force values decreased significantly (p < 0.05). The diameter and area of the breast muscle fiber decreased and the muscle fibre density increased as the dietary ME concentration increased (p < 0.05). The highest ME concentration (3180 kcal) increased the percentages of aldehydes (hexanal, heptanal, 2,4-nonadienal, octanal, nonanal and 2-decenal), alcohols (2-nonen-1-ol, trans-2-undecen-1-ol, 7-hexadecenal, 2-hexyl-1-decanoal and n-nonadecanol-1,3,7,11-trimethyl-1-dodecanol), alkanes (2,6-dimethyl-heptadecane) and carboxylic acids (9-hexadecenoic acid), but reduced the percentages of octadecanal, octadecane, heneicosane and tetradecanal (p < 0.05). In addition, the mRNA gene expression levels of fatty acid-binding protein 3 and apolipoprotein B were significantly upregulated in the liver, whereas that of cholesteryl ester transfer protein was significantly downregulated. In conclusion, increasing the ME diet to 3180 kcal/kg significantly improved the quality and flavour of the meat from yellow-feathered broilers. our finding may help poultry producers to improve the taste of meat by regulating genes related to lipid metabolism, thereby achieving the flavour and taste characteristics preferred by consumers.

A Comparison between the Egg Yolk Flavor of Indigenous 2 Breeds and Commercial Laying Hens Based on Sensory Evaluation, Artificial Sensors, and GC-MS

The focus of this study was to compare the yolk flavor of eggs from laying hens of Chinese indigenous and commercial, based on detection of volatile compounds, fatty acids, and texture characteristics determination, using sensory evaluation, artificial sensors (electronic nose (E-nose), electronic tongue (E-tongue)), and gas chromatography-mass spectrometry (GC-MS). A total of 405 laying hens (Hy-Line Brown (n = 135), Xueyu White (n = 135), and Xinyang Blue (n = 135)) were used for the study, and 540 eggs (180 per breed) were collected within 48 h of being laid and used for sensory evaluation and the instrument detection of yolk flavor. Our research findings demonstrated significant breed differences for sensory attributes of egg yolk, based on sensory evaluation and instrument detection. The milky flavor, moisture, and compactness scores (p < 0.05) of egg yolk from Xueyu White and Xinyang Blue were significantly higher than that of Hy-Line Brown. The aroma preference scores of Xinyang Blue (p < 0.05) were significantly higher, compared to Hy-Line Brown and Xueyu White. The sensor responses of WIW and W2W from E-nose and STS from E-tongue analysis were significantly higher foe egg yolks of Hy-Line Brown (p < 0.05), compared to that of Xueyu White and Xinyang Blue. Additionally, the sensor responses of umami from E-tongue analysis, was significantly higher for egg yolks of Xueyu White (p < 0.05), compared to that of Hy-Line Brown and Xinyang Blue. Besides, the contents of alcohol and fatty acids, such as palmitic acid, oleic acid, and arachidonic acid, in egg yolk were positively correlated with egg flavor. The texture analyzer showed that springiness, gumminess, and hardness of Hy-Line Brown and Xueyu White (p < 0.05) were significantly higher, compared to Xinyang Blue. The above findings demonstrate that the egg yolk from Chinese indigenous strain had better milky flavor, moisture, and compactness, as well as better texture. The egg yolk flavors were mainly due to presence of alcohol and fatty acids, such as palmitic acid, oleic acid, and arachidonic acid, which would provide research direction on improvement in egg yolk flavor by nutrition. The current findings validate the strong correlation between the results of egg yolk flavor and texture, based on sensory evaluation, artificial sensors, and GC-MS. All these indicators would be beneficial for increased preference for egg yolk flavor by consumers and utilization by food processing industry, as well as a basis for the discrimination of eggs from different breeds of laying hens.

Comparative Characterization of Key Volatile Compounds in Slow- and Fast-Growing Duck Raw Meat Based on Widely Targeted Metabolomics

The volatile aroma compounds in raw duck meat strongly affect consumers' purchase decisions and they vary among breeds with different growth rates. In this study, slow-growing (SG) Liancheng White and fast-growing (FG) Cherry Valley ducks were selected, and their volatile compounds were characterized using electric nose and gas chromatography-mass spectrometry. Furthermore, a widely targeted metabolomics approach was used to investigate the metabolites associated with volatile compounds. The results showed that hexanal, nonanal, octanal, heptanal, and 2-pentylfuran were abundantly present in duck meat, regardless of the breed. The higher nonanal and octanal rates contributed to the fatty and fruity aroma in SG meat than FG meat, while FG meat had a mushroom note resulting from higher octenol. Furthermore, widely targeted metabolomics showed a lower carnitine content in SG meat, which might promote lipid deposition to produce more octanal and nonanal. Higher sugar and amino acid contents led to a meaty aroma, whereas more trimethylamine N-oxide may generate a fishy note in SG meat. Taken together, this study characterized the raw duck meat aroma and provided the basic mechanism of the formation of the key volatile compound.

Identification and Characterization of Transcription Factors Involved in Geraniol Biosynthesis in Rosa chinensis

Fragrance is an important characteristic of rose flowers and is largely determined by the terpenes. Rose has a unique NUDX1 (NUDIX HYDROLASES 1)-dependent monoterpene geraniol biosynthesis pathway, but little is known about its transcriptional regulation. In this study, we characterized two China rose (Rosa chinensis) materials from the 'Old Blush' variety with contrasting aromas. We profiled the volatile metabolome of both materials, and the results revealed that geraniol was the main component that distinguishes the aroma of these two materials. We performed a comparative transcriptome analysis of the two rose materials, from which we identified the hydrolase RcNUDX1 as a key factor affecting geraniol content, as well as 17 transcription factor genes co-expressed with RcNUDX1. We also determined that the transcription factor RcWRKY70 binds to four W-box motifs in the promoter of RcNUDX1, repressing RcNUDX1 expression, based on yeast one-hybrid and transient dual-luciferase assays. These results provide important information concerning the transcriptional regulatory framework underlying the control of geraniol production in rose.

Effect of cooking modes on quality and flavor characteristic in Clitocybe squamulose chicken soup

The effects of cooking modes [cooking in stainless-steel pot (SS), ceramic pot (CP), and electrical ceramic stewpot (EC) with different stewing time] on chemical compositions, whiteness, 5'-nucleotides, fatty acids (FAs), sensory quality and flavor substances in chicken soup added Clitocybe squamulose (Pers.) Kumm (a natural edible fungus) were investigated. The results showed that CP chicken soup had higher soluble solid matter (5.83 g/100 mL), total sugar (2.38 mg/mL), crude protein (7.58 g/100 g), and 5'-nucleotides (325.53 mg/mL) than EC and SS chicken soups. 48 volatile flavor compounds, mainly aldehydes and alkanes, were found by gas chromatography-mass spectrometry (GC-MS), and the characteristic flavor substances were identified by Principal component analysis (PCA) and orthogonal partial least squares discrimination analysis (OPLS-DA). Hexanal, (E,E)-2,4-decadienal and 3-methyl-hexadecane were the most abundant differential volatile compounds in the CP chicken soup. Additionally, the results of sensory evaluation showed that the chicken soup cooked in CP had the higher values of aroma, taste, and overall acceptability. Our results indicate that CP mode might be the best option for cooking chicken soup. This study provides a new perspective in the improvement of the quality and flavor of chicken soup by using an appropriate cooking mode. Theoretical support for the use of various cooking modes is also discussed to improve the quality of chicken soup at home and in the industry.

Data Mining as a Tool to Infer Chicken Carcass and Meat Cut Quality from Autochthonous Genotypes

The present research aims to develop a carcass quality characterization methodology for minority chicken populations. The clustering patterns described across local chicken genotypes by the meat cuts from the carcass were evaluated via a comprehensive meta-analysis of ninety-one research documents published over the last 20 years. These documents characterized the meat quality of native chicken breeds. After the evaluation of their contents, thirty-nine variables were identified. Variables were sorted into eight clusters as follows; weight-related traits, water-holding capacity, colour-related traits, histological properties, texture-related traits, pH, content of flavour-related nucleotides, and gross nutrients. Multicollinearity analyses (VIF ≤ 5) were run to discard redundancies. Chicken sex, firmness, chewiness, L* meat 72 h post-mortem, a* meat 72 h post-mortem, b* meat 72 h post-mortem, and pH 72 h post-mortem were deemed redundant and discarded from the study. Data-mining chi-squared automatic interaction detection (CHAID)-based algorithms were used to develop a decision-tree-validated tool. Certain variables such as carcass/cut weight, pH, carcass yield, slaughter age, protein, cold weight, and L* meat reported a high explanatory potential. These outcomes act as a reference guide to be followed when designing studies of carcass quality-related traits in local native breeds and market commercialization strategies.

Formation and Analysis of Volatile and Odor Compounds in Meat-A Review

The volatile composition and odor of meat and meat products is based on the precursors present in the raw meat. These are influenced by various pre-slaughter factors (species, breed, sex, age, feed, muscle type). Furthermore, post-mortem conditions (chiller aging, cooking conditions, curing, fermentation, etc.) determine the development of meat volatile organic compounds (VOCs). In this review, the main reactions leading to the development of meat VOCs such as the Maillard reaction; Strecker degradation; lipid oxidation; and thiamine, carbohydrate, and nucleotide degradation are described. The important pre-slaughter factors and post-mortem conditions influencing meat VOCs are discussed. Finally, the pros, cons, and future perspectives of the most commonly used sample preparation techniques (solid-phase microextraction, stir bar sorptive extraction, dynamic headspace extraction) and analytical methods (gas chromatography mass spectrometry and olfactometry, as well as electronic noses) for the analysis of meat VOCs are discussed, and the continued importance of sensorial analysis is pinpointed.

Fatty acid metabolism-related genes are associated with flavor-presenting aldehydes in Chinese local chicken

Aldehydes are primary volatile organic compounds (VOCs) in local Chinese chicken meat and contribute green grass, fatty, citrus, and bitter almond aromas to chicken meat. To understand the genetic basis of these aldehyde VOC aromas, we used approximately 500 Chinese Jingxing Yellow (JXY) chickens to conduct genome-wide association studies (GWAS) on the flavor traits with the data of single nucleotide polymorphisms (SNPs) and insertions and deletions (INDELs). In total, 501 association variants (253 SNPs and 248 INDELs) were found to be suggestively (SNPs: p-value < 2.77e-06 and INDELs: p-value < 3.78e-05) associated with total aldehydes (the sum of nine aldehydes), hexanal, heptanal, benzaldehyde, (E,E)-2,4-nonadienal, octanal, (E)-2-decenal, nonanal, decanal, and octadecanal. Of them, six SNPs and 23 INDELs reached a genome-wide significance level (SNPs: p-value < 1.38e-07 and INDELs: p-value < 1.89e-06). Potential candidate aldehyde genes were functionally annotated for lipid metabolism, especially fatty acid-related pathways and phospholipid-related gene ontology (GO) terms. Moreover, the GWAS analysis of total aldehydes, hexanal, and nonanal generated the most significant signals, and phenotypic content differed between different genotypes at candidate gene-related loci. For total aldehydes and hexanal traits, candidate genes were annotated based on the significant and suggestive variants on chromosomes 3 and 8 with highly polymorphic linkage blocks. The following candidate genes were also identified: GALM, MAP4K3, GPCPD1, RPS6KA2, CRLS1, ASAP1, TRMT6, SDC1, PUM2, ALDH9A1, MGST3, GMEB1, MECR, LDLRAP1, GPAM and ACSL5. We also found that polyunsaturated fatty acids (PUFAs) (C18:2n6c linoleic acid and C18:3n3 linolenic acid) were significantly correlated with total aldehydes and hexanal contents. PUFAs are important aldehyde precursors, and consistently, our results suggested that candidate genes involved in fatty acid pathways and phospholipid GO terms were identified in association loci. This work provides an understanding of the genetic basis of aldehyde formation, which is a key flavor-forming compound.

Physicochemical, Nutritional Properties and Metabolomics Analysis Fat Deposition Mechanism of Chahua Chicken No. 2 and Yao Chicken

Poultry is an important dietary source of animal protein, accounting for approximately 30% of global meat consumption. Because of its low price, low fat and cholesterol content, and no religious restrictions, chicken is considered a widely available healthy meat. Chahua chicken No. 2 is a synthetic breed of Chahua chicken derived from five generations of specialized strain breeding. In this study, Chahua chicken No. 2 (CH) and Yao chicken (Y) were used as the research objects to compare the differences in physicochemical and nutritional indicators of meat quality between the two chicken breeds, and metabolomics was used to analyze the differences in metabolites and lipid metabolism pathways and to explore the expression of genes involved in adipogenesis. The physical index and nutritional value of CH are better than that of Y, and the chemical index of Y is better than that of CH. However, the chemical index results of CH are also within the normal theoretical value range. Comprehensive comparison shows that the meat quality of CH is relatively good. Metabolomics analysis showed that CH and Y had 85 different metabolites, and the differential metabolites were mainly classified into eight categories. KEGG pathway enrichment analysis revealed 13 different metabolic pathways. The screened PPARG, FABP3, ACSL5, FASN, UCP3 and SC5D were negatively correlated with muscle fat deposition, while PPARα, ACACA and ACOX1 were positively correlated with muscle fat deposition. The meat quality of CH was better than Y. The metabolites and metabolic pathways obtained by metabonomics analysis mainly involved the metabolism of amino acids and fatty acids, which were consistent with the differences in meat quality between the two breeds and the contents of precursors affecting flavor. The screened genes were associated with fatty deposition in poultry.

A Comparison of Different Tissues Identifies the Main Precursors of Volatile Substances in Chicken Meat

Amino acids and fatty acids are the main precursors of volatile organic compounds (VOCs) in meat. The purpose of this study was to determine the main VOC components in chicken breast muscle (BM) and abdominal fat (AF) tissue, as well as the source of VOCs, to provide a basis for quality improvement of broilers. BM and AF served as experimental and control groups, and gas chromatography-mass spectrometry (GC-MS) and untargeted metabolomics were employed to identify the source of VOCs. The results revealed nine VOCs in BM and AF tissues, including hexanal, octanal, and nonanal. VOCs including 1-octen-3-ol, (E,E)-2, 4-nonadienal, and benzaldehyde were significantly elevated in BM compared with AF (p < 0.05), while heptane and diethyl disulphide showed the opposite trend (p < 0.05). Levels of hexanal, heptanal, and octanal were similar in the two tissues. Metabolites of VOCs in chicken BM were investigated by weighted co-expression network analysis. However, only blue module in BM tissue was positively correlated with hexanal (r = 0.66, p = 0.01), heptanal (r = 0.67, p = 0.008), and (E,E)-2,4-nonadienal (r = 0.88, p = 3E-05). L-tyrosine, L-asparagine, adenosine, and valine were the main precursors of (E,E)-2,4-nonadienal and heptanal in BM tissue. Amino acids are the main precursors of 1-octen-3-ol, (E,E)-2, 4-nonadienal, and heptanal in chicken meat, while fatty acids are the main precursors of diethyl disulfide. However, hexanal can be synthesized from amino acids and small amounts of fatty acids as precursors. These findings expand our understanding of VOCs in chicken.

Characterization of Volatile Profiles and Correlated Contributing Compounds in Pan-Fried Steaks from Different Chinese Yellow Cattle Breeds through GC-Q-Orbitrap, E-Nose, and Sensory Evaluation

This study focused on characterizing the volatile profiles and contributing compounds in pan-fried steaks from different Chinese yellow cattle breeds. The volatile organic compounds (VOCs) of six Chinese yellow cattle breeds (bohai, jiaxian, yiling, wenshan, xinjiang, and pingliang) were analyzed by GC-Q-Orbitrap spectrometry and electronic nose (E-nose). Multivariate statistical analysis was performed to identify the differences in VOCs profiles among breeds. The relationship between odor-active volatiles and sensory evaluation was analyzed by partial least square regression (PLSR) to identify contributing volatiles in pan-fried steaks of Chinese yellow cattle. The results showed that samples were divided into two groups, and 18 VOCs were selected as potential markers for the differentiation of the two groups by GC-Q-Orbitrap combined multivariate statistical analysis. YL and WS were in one group comprising mainly aliphatic compounds, while the rest were in the other group with more cyclic compounds. Steaks from different breeds were better differentiated by GC-Q-Orbitrap in combination with chemometrics than by E-nose. Six highly predictive compounds were selected, including 3-methyl-butanal, benzeneacetaldehyde, 2-ethyl-6-methyl-pyrazine, 2-acetylpyrrole, 2-acetylthiazole, and 2-acetyl-2-thiazoline. Sensory recombination difference and preference testing revealed that the addition of highly predictive compounds induced a perceptible difference to panelists. This study provides valuable data to characterize and discriminate the flavor profiles in pan-fried steaks of Chinese yellow cattle.

A selected population study reveals the biochemical mechanism of intramuscular fat deposition in chicken meat

BACKGROUND

Increasing intramuscular fat (IMF) is an important strategy to improve meat quality, but the regulation mechanism of IMF deposition needs to be systematically clarified.

RESULTS

A total of 520 chickens from a selected line with improved IMF content and a control line were used to investigate the biochemical mechanism of IMF deposition in chickens. The results showed that the increased IMF would improve the flavor and tenderness quality of chicken meat. IMF content was mainly determined both by measuring triglyceride (TG) and phospholipid (PLIP) in muscle tissue, but only TG content was found to be decisive for IMF deposition. Furthermore, the increase in major fatty acid (FA) components in IMF is mainly derived from TGs (including C16:0, C16:1, C18:1n9c, and C18:2n6c, etc.), and the inhibition of certain very-long-chain FAs would help to IMF/TG deposition.

CONCLUSIONS

Our study elucidated the underlying biochemical mechanism of IMF deposition in chicken: Prevalent accumulation of long-chain FAs and inhibitions of medium-chain FAs and very long chain FA would jointly result in the increase of TGs with the FA biosynthesis and cellular uptake ways. Our findings will guide the production of high-quality chicken meat.

The Use of Electronic Nose in the Quality Evaluation and Adulteration Identification of Beijing-You Chicken

The objective of this study was to reveal the secrets of the unique meat characteristics of Beijing-you chicken (BJY) and to compare the difference of quality and flavor with Luhua chicken (LH) and Arbor Acres broiler (AA) at their typical market ages. The results showed the meat of BJY was richer in essential amino acids, arachidonic acid contents, inosine monophosphate (IMP), and guanosine monophosphate (GMP). The total fatty acid and unsaturated fatty acid contents of BJY chicken and LH chicken were lower than that of AA broilers, whereas the ratios of unsaturated fatty acids/saturated fatty acids (2.31) and polyunsaturated fatty acids/monounsaturated fatty acids (1.52) of BJY chicken were the highest. The electronic nose and SPME-GC/MS analysis confirmed the significant differences among these three chickens, and the variety and relative content of aldehydes might contribute to a richer flavor of BJY chicken. The meat characteristics of BJY were fully investigated and showed that BJY chicken might be favored among these three chicken breeds with the best flavor properties and the highest nutritional value. This study also provides an alternative way to identify BJY chicken from other chickens.

UHPLC-QTOF/MS-based comparative metabolomics in pectoralis major of fast- and slow-growing chickens at market ages

The molecular regulatory mechanism underlying meat quality between different chicken genotypes remains elusive. This study aimed to identify the differences in metabolites and pathways in pectoralis major (breast muscle) between a commercial fast-growing chicken genotype (Cobb500) and a slow-growing Chinese native chicken genotype (Beijing-You chickens, BYC) at market ages respectively based on ultra-high-performance liquid chromatography-quadrupole/time of flight mass spectrometry (UHPLC-QTOF/MS). Eighteen metabolites were identified as potential biomarkers between BYC and Cobb500 at market ages. Among them, L-cysteine exhibited a higher relative intensity in BYC compared with Cobb500 and was enriched into 10 potential flavor-associated KEGG pathways. In addition, the glycerophospholipid metabolism pathway was found to be associated with chicken meat flavor and the accumulation of sn-glycerol 3-phosphate and acetylcholine was more predominant in BYC than that in Cobb500, which were catalyzed by glycerophosphocholine phosphodiesterase (GPCPD1, EC:3.1.4.2), choline O-acetyltransferase (CHAT, EC:2.3.1.6), and acetylcholinesterase (ACHE, EC:3.1.1.7). Overall, the present study provided some metabolites and pathways for further investigating the roles of the differences in meat flavor quality in breast muscle between Cobb500 and BYC at market ages.

The SLC27A1 Gene and Its Enriched PPAR Pathway Are Involved in the Regulation of Flavor Compound Hexanal Content in Chinese Native Chickens

The role of hexanal in flavor as an indicator of the degree of oxidation of meat products is undeniable. However, the genes and pathways of hexanal formation have not been characterized in detail. In this study, we performed differential gene expression analysis and weighted gene co-expression network analysis (WGCNA) on groups of Tiannong partridge chickens with different relative hexanal content in order to find the genes involved in the formation of hexanal and the specific pathways of hexanal formation. Then we confirmed the relationship of these candidate genes with hexanal using Jingxing Yellow chicken and Wenchang chicken. In this study, WGCNA revealed a module of co-expressed genes that were highly associated with the volatile organic compound hexanal. We also compared transcriptome gene expression data of samples from chicken groups with high and low relative contents of hexanal and identified a total of 651 differentially expressed genes (DEGs). Among them, 356 genes were up regulated, and 295 genes were downregulated. The different biological functions associated with the DEGs, hub genes and hexanal were identified by functional analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations. Among all the hub genes in the significant module identified by WGCNA, more were enriched in the PPAR signaling pathway, the proteasome pathway, etc. Additionally, we found that DEGs and hub genes, including SLC27A1, ACOX3, NR4A1, VEGFA, JUN, EGR1, CACNB1, GADD45A and DUSP1, were co-enriched in the peroxisome proliferator-activated receptor (PPAR) signaling pathway, p53 signaling pathway and mitogen-activated protein kinases (MAPK) signaling pathway, etc. Transcriptome results of the Jingxing Yellow chicken population showed that the SLC27A1 gene was significantly associated with hexanal and enriched in the PPAR pathway. Our study provides a comprehensive insight into the key genes related to hexanal content, and can be further explored by functional and molecular studies.

Analysis of the volatile compounds in Fuliji roast chicken during processing and storage based on GC-IMS

To investigate the flavor changes of Fuliji roast chicken during processing and storage, the volatile organic compounds (VOCs) during processing (fresh, fried, stewed and sterilized) and storage (1 month, 2 months and 4 months) were determined by gas chromatography ion mobility spectrometry (GC-IMS). A total of 47 kinds of VOCs were identified across seven sampling stages, including aldehydes, hydrocarbons, alcohols, ketones, esters, ethers and heterocyclic compounds. More diverse range of aldehydes, alcohols, ketones and esters have been detected compared to acids, ethers and heterocyclic substances. Fingerprints directly reflect the pattern of VOCs at different stages of growth and decay, revealing that frying and stewing are key processes in flavor formation, and that sterilization and storage processes lead to flavor loss in Fuliji roast chicken. Hexanal, nonanal, octanal, 2-heptanone, 3-octanol, 1-octene-3-alcohol, 1-pentanol and ethyl acetate were mainly generated during the frying process. Benzaldehyde, nonanal, octanal, methyl-5-hepten-2-one, 2-methyl-3-heptanone, 1,8-Cineole, linalool, butyl acetate, ethyl propionate, ethyl acetate, coumarin, 2-furfuryl methyl disulfide and 2-pentyl furan were mainly generated during the stewing process. After sterilization, the content of octanal-D, 2-heptanone-D, 2-Methyl-3-heptanone, pentan-1-ol-D decreased, resulting in the reduction of aroma, lemon flavor and oil flavor of Fuliji roast chicken. Seven flavor markers, including hexanal-D, nonanal-M, octanal-M, heptanal-D, acetone, 3-octanol and ethyl acetate-D, were identified in the evolution of the aroma profile of Fuliji roast chicken.

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GC-IMS profiles of flavor components in poultry product processing line.

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47 kinds of volatile substances were identified by GC-IMS.

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Frying and stewing were the key processes of flavor formation.

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Flavor markers in the evolution of aroma characteristics of Fuliji roast chicken were determined.

Large-Scale Whole Genome Sequencing Study Reveals Genetic Architecture and Key Variants for Breast Muscle Weight in Native Chickens

Breast muscle weight (BrW) is one of the most important economic traits in chicken, and directional breeding for that results in both phenotypic and genetic changes. The Jingxing yellow chicken, including an original (without human-driven selection) line and a selected line (based on selection for increased intramuscular fat content), were used to dissect the genetic architecture and key variants associated with BrW. We detected 1069 high-impact single nucleotide polymorphisms (SNPs) with high conserved score and significant frequency difference between two lines. Based on the annotation result, the ECM-receptor interaction and fatty acid biosynthesis were enriched, and muscle-related genes, including MYOD1, were detected. By performing genome-wide association study for the BrW trait, we defined a major haplotype and two conserved SNPs that affected BrW. By integrated genomic and transcriptomic analysis, IGF2BP1 was identified as the crucial gene associated with BrW. In conclusion, these results offer a new insight into chicken directional selection and provide target genetic markers by which to improve chicken BrW.