Low intramuscular fat (but high in PUFA) content in cooked cured pork ham decreased Maillard reaction volatiles and pleasing aroma attributes

Formation and retention of aroma compounds in pigeons roasted by circulating non-fried roast technique by means of UHPLC-HRMS and GC-O-MS

Lipids are key aroma contributors in meat products. However, the role of different lipids in the presence of aroma compounds in roasted pigeons has not been studied. The formation of aroma compounds and lipids during the circulating non-fried roasting of pigeons was investigated. The results presented that 18 aroma compounds, including 5-methy-2,3-diethylpyrazine, were identified as key aroma compounds. A total of 6324 lipids were classed into 47 categories, such as phosphatidylcholine (PC), phosphatidylethanolamine (PE), and triglyceride (TG). Nine lipids, containing PA(P-20:0/22:4(7Z,10Z,13Z,16Z)) and LPC 16:0-SN1, showed promise as potential biomarkers for discriminating differential pigeons using OPLS-DA. PC (13.76%), TG (13.58%), and their products were major lipids, among which TG 16:0 16:0 18:2, LPC 18:2-SN1, and PC 18:1_18:1 played a crucial role in the presence of aroma compounds. Interestingly, the linoleic acid, an important aroma contributor, was predominantly bonded to the sn-2 position of phospholipid and sn-3 position of neutral lipids.

Comparative analysis for nutrients, flavor compounds, and lipidome revealed the edible value of pond-cultured male Pelodiscus sinensis with different ages

Pelodiscus sinensis is an aquatic product with a long growth cycle in pond culture and high nutritional value meat. The flavor compounds, nutrients, and lipidome were investigated to explore the edible value changes of turtle meat aged 3 to 6 years (Y3 to Y6). Typically, P. sinensis meat is rich in high-quality protein (EAAI ≥81.22, AAS ≥86.47). Y6 has the highest level of Se, protein, amino acids, and high unsaturated fatty acids, including EPA + DHA. Y5 has the most delicious amino acids, polyunsaturated fatty acids, and key odorant content. The stronger flavor of Y5 may be mainly related to C18:2n6t and C18:2n6c. Further, triacylglycerols (TAG) and phosphatidylcholine (PC) were significant changes in Y5. Additionally, PI (16:0/18:1) was identified as the potential biomarker. These results provided available information on P. sinensis marketing age and revealed the potential impact of nutrients on the formation of VOCs.

Identification and selection of volatile compounds derived from lipid oxidation as indicators for quality deterioration of frozen white meat and red meat using HS-SPME-GC-MS combined with OPLS-DA

This work aimed to investigate the effects of frozen storage on volatile compounds of white meats (chicken and duck) and red meats (pork, beef, and mutton). The samples were stored at -18 °C for 0, 2, 4, 10, 18 weeks, and volatile compounds were analyzed by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. Results indicated that the total amounts of volatile compounds increased with frozen storage duration of meats. The correlations were observed between frozen storage duration and levels of 2-ethyl-1-hexanol, tetradecane, nonanal, decanal, octanal, tridecanal, benzaldehyde, pentadecane, propanoic acid,2-methyl-,3-hydroxy-2,2,4-trimethylpentyl ester, heptadecane, and hexanal (r = 0.7456-0.9873). Levels of octanal and propanoic acid,2-methyl-,3-hydroxy-2,2,4-trimethylpentyl ester in white meat and benzaldehyde in red meat versus frozen storage duration fitted very well with zero-order reactions. Therefore, it was concluded that changes in volatile compounds derived from lipid oxidation may be used as indicators of quality deterioration during frozen storage of meat.

Characterization of the flavor profile of Hulatang using GC-IMS coupled with sensory analysis

Background

Hulatang is a traditional specialty snack in Henan, China, and is well known for its unique flavor.

Methods

In this study, the volatile organic compounds (VOCs) in four kinds of Hulatang from two representative regions in Henan Province (Xiaoyaozhen and Beiwudu) were evaluated using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS).

Results

The results showed that Xiaoyaozhen Hulatang exhibited more ethers, fewer terpenes and ketones than Beiwudu Hulatang. Additionally, Hulatang from different regions were classified using the orthogonal partial least squares-discriminant analysis (OPLS-DA) based on GC-IMS data. Twenty aroma substances were selected as the potential markers using the variable importance in the projection (VIP) variable selection method. Additionally, fifteen aroma components significantly contributing to the aroma of Hulatang were screened using the relative odor activity value (ROAV) (ROAV > 1). Combined with the sensory score results, twelve key substances with significant correlation with odor perception were selected. The flavor characteristics of the key substances revealed that the flavor of Hulatang was mainly composed of volatile components with camphor, green, almond, fatty, spicy, herbal, vegetable, fruity, floral, musty, and solvent aromas.

Conclusion

Overall, the experimental results provide a theoretical basis for evaluating the flavor characteristics of Hulatang from different regions using GC-IMS.

Transcriptomic analysis of different intramuscular fat contents on the flavor of the longissimus dorsi tissues from Guangling donkey

BACKGROUND

In this study, researchers aimed to explore the impact of intramuscular fat (IMF) concentration on the flavor of donkey meat, specifically in the longissimus dorsi muscle of Guangling donkeys. The internal volatile organic compounds that cause the flavor differences between donkey muscles are not clear at present. Transcriptomic technologies were utilized to analyze gene expression and its relationship to donkey meat flavor.

METHOD

Thirty Guangling donkeys had their IMF content evaluated in the longissimus dorsi muscle. Based on IMF content, 16 donkeys of similar ages were divided into two groups: low-fat (L) and high-fat (H). Headspace solid-phase microextraction Gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace solid phase microextraction mass spectrometry were used to identify potential flavor components that differed between the two groups.

RESULTS

Five key volatile substances were identified, and WGCNA and KEGG analysis was conducted to analyze the genes associated with these substances. The results showed that pathways like PPAR signaling, nucleotide excision repair, glucagon signaling, arachidonic acid metabolism, and glycolysis/glycogenesis were involved in lipid deposition. Additionally, a gene-gene interaction network map was constructed, highlighting the importance of hub genes such as EEF2, DDX49, GAP43, SNAP25, NDUFS8, MRPS11, RNASEH2A, POLR2E, POLR2C and ALB in regulating key flavor substances.

CONCLUSION

This study provided valuable insights into the regulation of genes and protein expression related to flavor substances in donkey meat. It also deepened understanding of the influence of IMF on flavor and laid a foundation for future molecular breeding improvements in Guangling donkeys.

Analysis of carcass traits, meat quality, amino acid and fatty acid profiles between different duck lines

To investigate the effect of genetic selection on meat quality in ducks, twenty of each fast growth ducks (LCA) and slow growth ducks (LCC) selected from F6 generation of Cherry Valley ducks (♂) x Liancheng white ducks (♀) were analyzed for carcass characteristics, meat quality (physicochemical and textural characteristics), amino acid and fatty acid profiles at 7 wk. Results showed that live body weight, slaughter weight, eviscerated yield and abdominal fat percentage of LCA were significantly higher than those in LCC ducks (P < 0.01). Moreover, the average area and diameter of myofiber were larger in LCA than LCC ducks (P < 0.01). The breast and thigh muscles of LCA exhibited significantly lower water holding capacity and thermal loss compared with LCC ducks (P < 0.01). In addition, the content of nonessential amino acids (Glu, Asp, and Arg) in breast muscles and Asp, Ser, Thr, and Met in thigh muscles was higher in LCC than LCA ducks (P < 0.05). The proportion of polyunsaturated fatty acids (PUFA) in breast muscles of LCC was higher than LCA ducks (P < 0.05). However, the content of saturated fatty acids (SFA) in breast and thigh muscles of LCA was higher compared with LCC ducks (P < 0.05). The proportion of monounsaturated fatty acids (MUFA) in thigh muscles was significantly higher in LCC compared with LCA ducks (P < 0.01). Finally, multiple traits were evaluated by applying principal component analysis (PCA) and the results indicated that PUFA and SFA in breast muscles of LCA played important roles in meat quality, followed by Warner-Bratzler shear force (WBSF) and MUFA. However, water holding capacity (WHC) had a dominant effect in meat quality of thigh muscles in both LCA and LCC ducks.

Characterization and discrimination of lamb with different breeds and muscle types using precursors and volatile compounds

The unique aromas of mutton stem from the chemical reactions between the characteristic precursors during cooking. This study aimed to establish the relationship of volatile compounds and aroma precursors (protein, fat, free amino acids and fatty acids) in lamb from different breeds and muscle types. Hong lamb was characterized by greater tenderness and water holding capacity, higher polyunsaturated fatty acids and higher essential/non-essential amino acids in comparison with Hu lamb. Aldehydes, such as heptanal, hexanal, octanal and nonanal were higher in Hong-ST compared with Hu-ST. Principal component analysis (PCA) showed that aroma precursors were closely related to volatile components of cooked lamb. Discriminant analysis results showed that precursors and volatile compounds could be used to identify the breeds and muscle types of lamb. These findings revealed the contributors of lamb aroma and might help understand the regulatory mechanism of aroma in lamb from different breeds and muscle types.

Comparative transcriptome analysis of longissimus dorsi muscle reveal potential genes affecting meat trait in Chinese indigenous Xiang pig

In this study, we compared the transcriptome of longissimus dorsi muscle between Guizhou Xiang pigs (XP) and Western commercial Large White pigs (LW), which show diffirent meat quality between them. In terms of meat quality traits, the pH 45 min, color score, backfat thickness, and intramuscular fat (IMF) content were higher in Xiang pigs than in Large White pigs (P < 0.01), while the drip loss, lean meat percentage, shear force, and longissimus dorsi muscle area of Xiang pigs were lower than that of Large White pigs (P < 0.01). Nutrients such as monounsaturated fatty acid (MUFA), total amino acids (TAA), delicious amino acids (DAA) and essential amino acids (EAA) in Xiang pigs were higher than that in Large White pigs, and the proportion of polyunsaturated fatty acid (PUFA) of Xiang pigs was significantly lower than Large White pigs (P < 0.01). Transcriptome analysis identified 163 up-regulated genes and 88 genes down-regulated in Xiang pigs longissimus dorsi muscle. Combined with the correlation analysis and quantitative trait locis (QTLs) affecting meat quality, a total of 227 DEGs were screened to be significantly associated with meat quality values. Enrichment analysis indicated that numerous members of genes were gathered in muscle development, adipogenesis, amino acid metabolism, fatty acid metabolism and synthesis. Of those, 29 genes were identified to be hub genes that might be related with the meat quality of Xiang pig, such as MYOD1, ACTB, ASNS, FOXO1, ARG2, SLC2A4, PLIN2, and SCD. Thus, we screened and identified the potential functional genes for the formation of meat quality in Xiang pigs, which provides a corresponding theoretical basis for the study of the molecular regulatory mechanism of pork quality and the improvement of pork quality.

Generation of key aroma compounds in fat and lean portions of non-smoked bacon induced via lipid pyrolysis reaction

This study explored the evolution of key aroma compounds and their lipid precursors in the lean (LN) and fat (FT) portions of non-smoked bacon during hot air drying. The results showed that the LN portion contained most of the aroma compounds in the bacon (>88%). The volatile content of the FT portion increased as the drying time increased, whereas that of the LN portion reached a maximum within 24 h and then decreased. Based on the highest volatile contents (4889.48 ± 202.06 µg/kg) and sensory scores, 24 h was considered the optimal drying time. For key aroma compounds, hexanal and 2,3-octanedione were derived from free fatty acids and polar lipids. Notably, 1-octen-3-ol was generated only from polar lipids in the FT and LN portions. The 2-undecenal and (E, E)-2,4-decadienal were produced by the oxidation of neutral lipids in the FT portion. Dihydro-5-pentyl-2(3H)-furanone was derived from polar lipids in the LN portion. Altogether, these findings provide theoretical insights into improving the aroma of bacon by optimizing raw material selection and processing methods.

Staphylococcus inoculation enhances the sensorial attributes of Chinese bacon by coordinating the composition of flavor compounds through amino acid metabolism

In this study, we aimed to uncover the potential underlying mechanisms of the flavor modulation of Chinese bacon by Staphylococcus. To that end, taste-enhancing S. cohnii WX-M8 and S. saprophyticus MY-A10 screened from Chinese bacon were used to investigate the effects of their individual and mixed fermentations and their synergistic fermentation with Lactobacillus plantarum BL-1 on the sensorial attributes, physicochemical properties, microbial diversity, and volatile compounds (VOCs) of Chinese bacon. Our results revealed that S. cohnii WX-M8 and S. saprophyticus MY-A10 significantly increased a* (redness) and Aw and reduced thiobarbituric acid reactive substances (TBARS) when fermented in a mixture. Moreover, they promoted the formation of esters, aldehydes (especially straight-chain aldehydes), and phenolic compounds through pathways related to amino acid metabolism, enhancing sensorial attributes. While synergistic fermentation with L. plantarum BL-1 resulted in an improved a* (redness) of Chinese bacon, and the increased microbial metabolism of the carbohydrate and lipid metabolic pathways, the increase in TBARS and the higher content of acidic volatiles, led to a change in the composition of the flavor substances. The advantage of co-fermentation of Staphylococci in sensory attributes can be attributed to their capability to metabolize amino acids and associates. These findings provide insights into the role of Staphylococcus as a starter in regulating bacon flavor.

Mushroom alcohol(1-octen-3-ol)and other 7 aroma compounds selected from Chinese dry-cured hams can enhance saltiness perception

Reducing NaCl content in food while maintaining acceptability poses a significant challenge. Odor-induced saltiness enhancement (OISE) emerges as a promising solution. This study utilized gas chromatography-olfactory (GC-O) in conjunction with gas chromatography-mass spectrometry (GC-MS) to identify 37 key volatile compounds in three representative Chinese dry-cured hams. These compounds had an odor activity value (OAV) of ≥1 or a modification frequency (MF) of ≥30%. Subsequently, quantitative descriptive analysis (QDA) identified eight odorants associated with saltiness. These included 1-octen-3-ol, nonanal, heptanal, 2-methylbutanal, 3-methyl-butanal, benzaldehyde, octanal, and 2,6-dimethylpyrazine. Remarkably, these odorants significantly intensified saltiness (P < 0.05) when added to a low-concentration NaCl solution (0.3%), compared to zero or high concentrations (0.75% and 0.8%). As a result, traditional Chinese salty meat products offer a promising source of odorants for enhancing saltiness, compensating for reduced NaCl content through OISE.

Production and meat quality traits of genetically lean immunocastrated pigs naturally divergent for loin tenderness

Warner-Bratzler Shear Force (WBSF) is a quantitative measurement of meat toughness that has great impact on the consumer acceptability of meat. This study was conducted to evaluate growth performance, carcass and meat quality characteristics, and fatty acids profile of longissimus lumborum (LL) intramuscular fat (IMF) of pigs that are genetically divergent for WBSF. Based on WBSF values of the LL from a previous study, 12 immunocastrated male pigs selected from 96 pigs were divided into two groups with high WBSF (53.28 to 42.50 N) and low WBSF (37.27 to 27.79 N). Although high-WBSF pigs tended to have improved (P = 0.08) gain-to-feed ratio, overall performance was similar between WBSF groups. High-WBSF pigs also tended to have higher (P = 0.09) cooling loss and lean percentage as well as decreased (P = 0.08) 10th-rib backfat depth than low-WBSF pigs. Loins from high-WBSF pigs tended to have lower (P = 0.07) IMF content and higher (P = 0.09) cooking loss than low-WBSF pigs. Compared to low-WBSF pigs, IMF of the LL from high-WBSF pigs had lower (P = 0.05) percentage of oleic acid and tended to have a decreased (P = 0.07) percentage of total monounsaturated fatty acids. Loins from pigs with high WBSF tended to have increased (P = 0.09) total polyunsaturated fatty acids (PUFA) content and had higher (P = 0.03) PUFA: saturated fatty acid ratio than low-WBSF pigs. Selecting pigs for pork tenderness could potentially conflict with lean growth efficiency and a healthier fatty acids profile for human consumption.

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.

Characteristic fingerprints and comparison of volatile flavor compounds in Morchella sextelata under different drying methods

Morchella sextelata is a precious and popular commercial edible fungus that was developed recently in China. This research aimed to characterize the volatile profiles of M. sextelata under three dehydration methods (freeze, hot air, and natural air drying). Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-ToF-MS) was shown to the best choice to discriminate the volatile profiles of M. sextelata Characteristic flavor substances of M. sextelata were eight-carbon-containing (C8) compounds, hexanal, 2(5 h)-furanone, and benzaldehyde. Drying methods had significant influences on the volatile flavor profiles of M. sextelata, and 104 differential compounds were screened by multivariate statistical analysis. Freeze-dried samples had the most abundant volatile compounds and maintained more alcohols, ketones, aldehydes, and esters described as mushroom, sweet, and green flavor, like 1-octen-3-ol, 1-octen-3-one, nonanal, 2,3-butanedione, and so on. Hot air-drying promoted the production of heterocycles and ketones with roasted flavor due to the thermalreaction, such as 2-cyclohexen-1-one, furan, 3-phenyl-, etc. Natural air-drying resulted in acids releasing an unpleasant flavor, e.g., acetic acid, 2-methylbutanoic acid, etc. Overall, thermal reaction combined with vacuum conditions might be suitable for maintaining and enriching the aroma flavor of dried true morels.

Comparison of Lipids and Volatile Compounds in Dezhou Donkey Meat with High and Low Intramuscular Fat Content

The intramuscular fat (IMF) content is considered an important factor for assessing meat quality, and is highly related to meat flavor. However, in donkey meat, the influences of IMF content on lipid and volatile profiles remain unclear. Thus, we conducted lipidomic and volatilomic investigations on high- and low-IMF samples from donkey longissimus dorsi muscle. When the IMF level increased, the monounsaturated fatty acid (especially oleic acid) content significantly increased but the saturated fatty acid content decreased (p < 0.05). Twenty-nine of 876 lipids showed significant differences between the two groups. Volatile profiles from differential IMF content samples were also distinct. Five differential volatile odorants were identified in the two groups: 2-acetyl-2-thiazoline, octanal, 2-pentylfuran, pentanal, and 1-(2-pyridinyl) ethanone. Additionally, strong correlations were found between differential fatty acids and lipids with differential odorants. Thus, the difference in volatile odorants may result from the change in the fatty acid composition and lipid profiles induced by different IMF contents, highlighting the urgent need to increase IMF levels in donkey meat.

Effect of feeding olive pomace acid oil on pork lipid composition, oxidative stability, colour, and sensory acceptance

One of the targets of the meat industry is to reduce production costs and to increase the sustainability of the food chain, which has driven the attention towards the use of by-products as feed ingredients. Acid oils are fat by-products coming from the chemical refining process of edible oils, with a high energy value and that are approved as feed ingredients in the European Union. However, meat producers are hesitant to utilise them due to their varying composition and the limited understanding of their impact on animal performance and meat quality. The objective of this study was to evaluate the effects of using olive pomace acid oil (OPAO) instead of its corresponding crude olive pomace oil (OPO) or crude palm oil (PO) in pig diets on lipid composition, lipid oxidation and quality of pork loin (longissimus dorsi), fresh and after commercial refrigerated storage for 8 days. The experimental design consisted of feeding pigs with four diets supplemented with a 5% of PO, OPO, OPAO or a blend (B) of PO and OPAO (50:50, w/w). Fresh and refrigerated pork loin samples were assessed for fatty acid profile; tocopherol (T) and tocotrienol (T3) composition; lipid oxidative stability with the ferrous oxidation-xylenol orange method; 2-thiobarbituric acid (TBA) value; volatile compounds; colour; and sensory acceptance. Results showed that refrigeration reduced the total T + T3 levels and increased the TBA values and the volatile compound concentrations. The refrigerated storage also affected the instrumental colour parameters (L*, a* and b*) but not the overall acceptance of pork. Regarding the diet, pork from OPAO diet showed a higher unsaturated-to-saturated fatty acid ratio than pork from PO and B diets. The lowest T + T3 concentration was found in OPO and OPAO fresh pork and in OPAO refrigerated pork. The oxidative stability of fresh pork was lower for OPAO than for PO diet, but no significant effect of the diet was observed for this parameter in refrigerated pork. The TBA values and volatile compound concentrations of fresh pork were not affected by the diet. After refrigeration, OPAO pork had the highest TBA value and volatile compound concentrations. In any case, colour and consumer acceptance of pork were not affected by diet. In conclusion, in order to upcycle acid oils in pig diets, and considering results on the lipid oxidative stability of pork, it would be preferable to add the OPAO used in this study blended with PO.

Lipid oxidation and flavor changes in saturated and unsaturated fat fractions from chicken fat during a thermal process

Chicken fat, due to its rich fatty acids (FAs), is more prone to lipid oxidation and the production of volatile compounds. The aim of the present study was to investigate the oxidative characteristics and flavor changes of saturated (SFF) and unsaturated fat fractions (USFF) from chicken fat induced by heating (140 °C at 70 rpm min-1 for 1 h and 2 h: SFF1, USFF1, SFF2 and USFF2). The FAs and volatile compounds were analyzed by gas chromatography-mass spectrometry (GC-MS) and two-dimensional gas chromatography time of flight mass spectrometry (GC × GC-ToFMS), respectively. The results showed that higher contents of unsaturated fatty acids (UFAs) were found in USFF compared to that in SFF, whereas USFF showed lower levels of saturated fatty acids (SFAs). With the extension of heating time, the SFA/UFA ratio in USFF and SFF significantly increased (p < 0.05), and more aldehydes, alcohols, ketones, and lactones were formed. Moreover, the odor activity values of 23 important compounds in USFF1-2 were significantly higher (p < 0.05) than those in SFF1-2. As revealed by principal component analysis (PCA) and cluster analysis (CA), it was obviously observed that all samples were divided into four clusters (USFF-SFF, USFF1-SFF1, USFF2, and SFF2). According to correlation analysis between FAs and volatile compounds, C18:2 ω6, C18:3 ω6 and C18:3 ω3 were significantly associated with dodecanal, (Z)-3-hexenal, (E)-2-decenal, 2-undecenal, (E)-2-dodecenal, (E,E)-2,4-nonadienal, (E,E)-2,4-decadienal, 2-decanone, γ-octalactone and γ-nonalactone. Our data elucidated that fat fractions from chicken fat with varying degrees of saturation could impart different flavor characteristics during a thermal process.

Physicochemical property, volatile flavor quality, and microbial community composition of Jinhua fatty ham and lean ham: A comparative study

The physicochemical property, volatile flavor compounds, and microbial community structure of Jinhua fatty ham (FH) and lean ham (LH) were investigated and compared by high-throughput sequencing and HS-GC-IMS. Results showed that FH had higher pH and slightly lighter and yellower color than LH. Meanwhile, 33 volatile flavor compounds were identified from FH and LH, among which LH showed higher abundance of total alcohols and acids, but FH had generally richer aldehydes, ketones, esters, heterocyclic, and sulfur-containing compounds. Moreover, FH and LH did not have significant difference in α-diversity of bacterial community, but LH presented a much lower α-diversity of fungal community than FH. Besides, the dominant microorganisms (relative abundance >2%) in FH were Ruminococcaceae UCG-005, Staphylococcus, Ruminococcaceae UCG-014, Meyerozyma, and Aspergillus at the genus level, while in LH were Staphylococcus, Psychrobacter, Halomonas, Propionicicella, Ruminococcaceae UCG-005, Meyerozyma, Yamadazyma, and Aspergillus. Furthermore, the analysis of Pearson's correlation and metabolic network confirmed that the discriminative flavor compounds of FH were mainly β-oxidation and degradation products of fatty acids, while those of LH were mostly derived from the Strecker reaction or microbial metabolism of amino acids. The present study could help understand the potential pathway of characteristic microorganisms affecting flavor formation of fat-deficient dry-cured hams and provide theoretical supports for developing healthier fermented meat products.

Perilla frutescens seed meal as a fat substitute mitigates heterocyclic amine formation and protein oxidation and improves fatty acid profile of pan-fried chicken patties

Fatty acid profile, protein and fatty acid oxidation and flavor profile of pan-fried chicken patties formulated with various levels of Perilla frutescens seed meal (PSM) as a fat substitute was investigated in this study. The formation of heterocyclic amines (HCAs) in the chicken patties was also evaluated. The results showed that pan-fried patties formulated with 20% PSM (PSM4) had the highest ranges of oleic acid and ΣMUFA content and ΣPUFA/ΣSFA ratio. Low to medium levels of PSM (PSM1, 2, and 3 corresponding to 5, 10, and 15% of PSM, respectively) reduced the content of lipid peroxidation products, while high level (PSM4) increased it. All levels of PSM were also found to be effective against elevation in carbonyl content relative to the control. Moreover, the PSM effectively inhibited HCA formation in the chicken patties. The total contents of HCAs in PSM1, PSM2, PSM3, and PSM4 samples were significantly (P < 0.05) lower than that of the control sample, corresponding to 31.9, 46.1, 57.2, and 44.8% inhibition, respectively. PSM4, however, had no or very little effect on the formation of PhIP, 4,8-DiMeIQx and AαC, despite a strong inhibitory effect on MeIQx formation. These findings not only support the promising potential of PSM for application as a fat substitute to improve the fatty acid profile and reduce the content of harmful by-products in heat-processed chicken, but also highlight that appropriate addition level is a critical factor in optimizing the functional capacity of this natural agent.

Changes in lipids and aroma compounds in intramuscular fat from Hu sheep

Intramuscular fat (IMF) content is associated with lamb flavor and largely varies between individuals of the same breed. However, studies investigating the effects of IMF variations on lipid profiles and aroma compounds are limited. Here, we performed lipidomic and volatilomic profiling of high-IMF and low-IMF Hu lambs. Triglycerides and diglycerides in the high-IMF group were significantly higher than those in the low-IMF group (p < 0.05). Seventy-nine of 842 lipids identified were significantly different between the groups under positive and negative ion modes (variable importance in projection > 1, p < 0.05). Volatilomic analyses revealed that the aroma profiles also differed between the groups. Fifteen aroma compounds, mainly originating from lipid oxidation, could be responsible for this difference. Thus, our findings provide a comprehensive understanding of the increases in IMF content that drive consumers' satisfaction and also provide a basis for underpinning breeding value for IMF.

Impact of Chilling Rate on the Evolution of Volatile and Non-Volatile Compounds in Raw Lamb Meat during Refrigeration

The aim of this study was to investigate the effect of chilling rate (1.44, 22.2, and 32.4 °C/h) on the evolution of volatile and non-volatile compounds in raw lamb meat during refrigeration (1, 24, 72, and 120 h). Through orthogonal projection to latent structure-discriminant analysis, the calculation of odor activity values (OAV > 1) and taste activity values (TAV > 1) analysis, 1-octen-3-ol, (E, E)-2,4-decadienal, nonanal, hexanal, nona-3,5-dien-2-one, 2,3-octanedione, hexanoic acid, 1-nonen-4-ol, aspartate (Asp), Glutamic Acid (Glu), 5′-GMP, 5′-IMP, and 5′-AMP were regarded as differential flavor or taste compounds for raw meat undergone different chilling rates. With a rapid chilling rate at 24 h after slaughter, the contribution of 1-octen-3-ol decreased, but (E, E)-2,4-decadienal increased. Moreover, at 24 h post-mortem, the equivalent umami concentration of Asp, Glu, 5′-GMP, 5′-IMP and 5′-AMP in raw meat were significantly lower at a chilling rate of 1.44 °C/h than 32.4 °C/h (p < 0.05). Conclusively, under the rapid chilling rate, more fatty odor and umami compounds accumulated in 24 h aged meat.

Analysis of Volatile Organic Compounds by HS-GC-IMS in Powdered Yak Milk Processed under Different Sterilization Conditions

Headspace-gas chromatography-ion mobility spectroscopy (HS-GC-IMS) was used to detect the volatile organic compounds (VOCs) of yak milk powders (YMPs) under ultra-high-pressure sterilization (UHPS) and thermization (TH) methods. The analyses led to the identification of several characteristic of compounds, therefore, exploitation and comparison of the different flavors. A total of 46 peaks were detected, and 17 compounds were identified, including 7 aldehydes, 5 ketones, 3 acids, 1 terpene, and 1 ester. Furthermore, principal component analysis (PCA) and fingerprint similarity analysis based on Euclidean distance compared the YMPs and found that the YMPs had certain differences, which can distinguish the YMPs with different sterilization methods. In conclusion, different sterilization methods possibly affect the flavor of YMPs, and UHPS is bettedslfr than TH. Also, aldehydes were mainly be detected in UHPS groups, whereas the ketones and acids mostly appeared in TH groups. Most importantly, UHPS can retain the original flavor of yak milk to a greater extent.

Volatile composition analysis of tree peony (Paeonia section Moutan DC.) seed oil and the effect of oxidation during storage

Peony (Paeonia section Moutan DC.) seed oil is a novel vegetable oil with unique aromatic profile. The objectives of this study were to characterize the volatile compounds with optimized analysis conditions, and to study the effects of oxidation during storage. The Headspace Solid-phase Micro-extraction (HS-SPME) conditions were optimized with factors including extraction fiber, extraction time and temperature, as well as sample amount and desorption time. Then, the aromatic compounds extracted from peony seed oil were determined using the odor activity value (OAV) method coupled with the GC-olfactometry. Results found that the best HS-SPME conditions were DVB/CAR/PDMS fibers with magnetic stirring for 50 min of extraction at 60°C. The optimal sample amount was 4 g with 6 min of desorption. Forty-one volatile components were found, and 19 aromatic components were identified using GC-MS and GC-olfactometry. This is the first study to describe 4,7-dimethylbenzofuran in peony seed oil with a unique aroma of grass, light bitter, and fragrance. The stability of alcohol and terpenoids decreased as accelerated oxidation progresses. This study provides the theoretical basis for the sensory attributes, and shelf-life of peony seeds oil products for industry production and marketing.

Feeding a high oleic acid (C18:1) diet improves pleasing flavor attributes in pork

One of the main drivers in consumer meat choice is flavor with some pleasing flavor attributes associated with high oleic acid (C18:1) content in the intramuscular fat. This project aimed to produce pork with a distinctively pleasant bouquet by feeding C18:1 rich macadamia oil compared to corn oil. The project also tested three feed formulations based on cereals and pulses representing different pork producing areas: corn/soy (CS), sorghum-lupins (SL), or wheat/canola (WC). Compared to corn oil, feeding macadamia oil resulted in a significant increase in the C18:1 content in pork loin (longissimus dorsi) with the CS showing a higher impact than the WC diets. Pork loins from the two CS-based groups (CS-Corn and CS-Macadamia) were selected for a consumer sensory study involving 82 panelists (39 of Chinese background). Across ethnic backgrounds the taste of high C18:1 pork resulted in the highest hedonic values.

Free fatty acids responsible for characteristic aroma in various sauced-ducks

To investigate the effects of various duck sources on the lipid oxidation and aroma flavor of sauced-ducks, Mallard (ML), Sheldrake (SD), Muscovy (MC), and Cherry-Valley (CV) ducks were used in sauced-duck processing. The results showed significantly different thiobarbituric acid reactive substances (TBARS) values of the four samples (SD > CV > ML > MC, p < 0.05), while the contents of unsaturated fatty acids (UFAs) were ML > SD/CV > MC (p < 0.05). Altogether, 105 volatile flavor compounds were detected in sauced-ducks, including acids, alcohols, aldehydes, ketones, esters, hydrocarbons, furans, nitrogen compounds, and others. The volatile compounds were observed differentially composed in the four products, and nineteen potential characteristic biomarkers were explored. The correlation analysis indicated that the characteristic aroma flavor of sauced-ducks were significantly associated with specific free fatty acids. These information are useful for learning aroma formation and meat selection and identification in duck products.

Effects of replacing fat with Perilla seed on the characteristics of meatballs

A portion of the fat used in the preparation of meatballs was replaced with different amounts of Perilla seeds rich in unsaturated fatty acids. Five treatments with mass percentages of 0%, 5%, 10%, 15%, and 20%, including a set of blank treatment and four groups treated with different Perilla seed contents, were performed. The effects of Perilla seed content on the proximate composition, pH, color, cooking yield, emulsion stability, texture, fatty acid composition, and sensory properties of meatballs were analyzed. The meatballs with Perilla seeds showed remarkably better properties than those without seeds. The addition of 10% (w/w) Perilla seeds significantly (P < 0.05) improved the texture, composition, and content of polyunsaturated fatty acids (PUFAs), dietary fiber, and protein in meatballs. Moreover, the characteristic flavor components were rich and varied, which enhanced the taste, flavor, and satiety of the meatballs. This work provided theoretical and data support for the preparation of Perilla meatballs rich in PUFAs and dietary fiber.

Mechanism of aroma compounds changes from sea cucumber peptide powders (SCPPs) under different storage conditions

A rapid and sensitive measurement technique was used to investigate the mechanism of aroma compounds changes in SCPPs under the storage conditions with hygroscopicity and no-microorganism (HNM), nonhygroscopicity and no-microorganism (NHNM) and hygroscopicity and microorganism (HM) by HS-GC-IMS. The types and signal of aroma compounds increased obviously at the 5th day under the storage condition (HNM and HM). The signal of majority of aroma compounds decreased gradually since the 5th day. However, during the storage of SCPPs for 15 days, the total signals of aldehydes, ketones and alcohols gradually increased and reached a maximum. Thereinto, the saturated aldehydes such as hexanal had been produced as an off-flavor. These off-flavor compounds principally including aldehydes and ketones could be generated through Maillard reaction, while alcohols could be generated by microbial fermentation. The study discovered moisture adsorption and microorganism during storage could affect aroma compounds of SCPPs and the effect of moisture absorption was greater than microorganisms.

Monitoring oxidation during the storage of pressure-treated cooked ham and impact on technological attributes

High-pressure processing is a post-processing preservation method commonly used on meat products. However, it can affect the structural properties and the physico-chemical properties of the meat. The aim of this study was to compare the physical properties, lipid and protein oxidation of control and treated (500 MPa, 20 °C, 5 min) cooked ham during subsequent storage (21 days at 4 °C). High pressure processing induced increase of hardness and syneresis after 7 days of storage. The redness (a*) was slightly affected by the high pressure treatment but not the lightness (L*) and the yellowness (b*). However, the fluctuation of color was not clearly visible. Evaluation of primary (conjugated dienes) and secondary (malondialdehyde MDA and thiobarbituric reactive substances TBA-RS) lipid oxidation products showed that pressure increases oxidation of lipids. Whereas, high pressure processing had no immediate effect on MDA and TBA-RS content, higher amount compared to control were observed during the refrigerated storage. This lipid oxidation could be due to the release of prooxidant iron from hemoproteins after the high pressure treatment. Finally, the determination of free and accessible thiols showed that the high pressure treatment leads to a protein oxidation.

Characterization and Discrimination of Chinese Marinated Pork Hocks by Volatile Compound Profiling Using Solid Phase Microextraction Gas Chromatography-Mass Spectrometry/Olfactometry, Electronic Nose and Chemometrics

The primary aim of this study was to investigate volatile constituents for the differentiation of Chinese marinated pork hocks from four local brands, Dahongmen (DHM), Daoxiangcun (DXC), Henghuitong (HHT) and Tianfuhao (TFH). To this end the volatile constituents were evaluated by gas chromatography-mass spectrometry/olfactometry (GC-MS/O), electronic nose (E-nose) and chemometrics. A total of 62 volatile compounds were identified and quantified in all pork hocks, and 24 of them were considered as odour-active compounds because their odour activity values (OAVs) were greater than 1. Hexanal (OAV at 3.6⁻20.3), octanal (OAV at 30.3⁻47.5), nonanal (OAV at 68.6⁻166.3), 1,8-cineole (OAV at 36.4⁻133.3), anethole (OAV at 5.9⁻28.3) and 2-pentylfuran (OAV at 3.5⁻29.7) were the key odour-active compounds contributing to the integral flavour of the marinated pork hocks. According to principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) of GC-MS/O and E-nose data, the results showed that the marinated pork hocks were clearly separated into three groups: DHM, HHT, and DXC-TFH. Nine odour-active compounds, heptanal, nonanal, 3-carene, d-limonene, β-phellandrene, p-cymene, eugenol, 2-ethylfuran and 2-pentylfuran, were determined to represent potential flavour markers for the discrimination of marinated pork hocks. This study indicated the feasibility of using GC-MS/O coupled with the E-nose method for the differentiation of the volatile profile in different brands of marinated pork hocks.

Effects of slaughter weight and growth rate on the longissimus muscle metabolic characteristics, and pork sensory quality in pigs of two sexes

A total of 119 pigs were used to investigate the effect of slaughter weight (107, 115, and 125 kg), growth rate (fast vs. slow), and sex (barrows vs. gilts) on the longissimus muscle biochemical and sensory traits. Increasing slaughter weight to 125 kg resulted in greater postmortem activity of calpastatin (P = 0.01), lactate dehydrogenase (P = 0.01), and citrate synthase (P = 0.02). Pork toughness and juiciness at 6 d were affected by the interaction slaughter weight × growth rate × sex, with pork being tougher (P = 0.04) and juicer (P = 0.03) in slow-growing gilts slaughtered at 125 and 115 kg, respectively. Flavour was scored higher (P = 0.03) in pork from gilts than from barrows. Overall, based on the slight and likely undetectable differences by the average consumer in the meat sensory traits, it can be concluded that slaughter weight can be increased to 125 kg without appreciable effect on the sensory properties.

Understanding the implications of current health trends on the aroma of wet and dry cured meat products

Meat product aroma is affected by various meat processing factors. In this review the main biochemical reactions involved in the development of meat product aroma (wet, dry cured and fermented) are fully described. Moreover, the different techniques used for key aroma elucidation in meat products are defined. The aroma compounds present in wet, dry cured and fermented meat products (sausage and whole piece) have been summarized. The mechanisms of aroma formation during the manufacture of cooked and dry/fermented meat products are described. In wet meat products the main reactions described are lipid degradation (oxidative reactions), Maillard reactions, Strecker degradation, and thiamine degradation while in dry meat products are; lipid degradation (oxidative reactions), thiamine degradation, microbial carbohydrate fermentation and microbial metabolism including complex interactions among them such as the amino acid degradation produced by lipid oxidation products. Finally, the effect of current health trends such as salt, fat and nitrifying content reduction on the development of meat product aroma is explained.