Characteristic volatile compounds in different parts of grass carp by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry

Characterization of the flavor profile of four major Chinese carps using HS-SPME-GC-MS combined with ultra-fasted gas chromatography-electronic nose

The four major Chinese carps are highly popular for their distinctive nutritional benefits. However, the differences in flavor among these carps remain unclear. This study investigated the flavor profiles of these carps using headspace solid-phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) combined with ultra-fasted gas chromatography electronic nose (GC E-nose). The four major Chinese carps had high protein content (16.68-18.61 %) and low fat levels (0.42-1.29 %). A total of 45 volatile compounds were identified in these carps. Both the GC E-nose and HS-SPME-GC-MS results consistently showed significant flavor profiles differences among these carps, with Ctenopharyngodon Idella (CI) exhibiting the most pronounced distinctions compared to the other three species. Based on VIP >1 and p < 0.05, 10 key compounds including 2-Nonanone, Cyclodecanol, Eugenol, 1,3-Cyclooctadiene, etc., largely contributed to the distinctive overall flavor profile of four major Chinese carps derived mainly from amino acid and fatty acid metabolism.

Effects of Broth pH and Chilling Storage on the Changes in Volatile Profiles of Boiled Chicken Flesh

This study investigated the changes in volatile compounds in chicken flesh after boiling at various pHs (6.0-9.0) and after chilling storage (4.0±1.0°C) for 7 d. The volatile compounds were assessed qualitatively and quantitatively by using a headspace gas chromatography-mass spectrometry analysis. Twenty-one volatile compounds were discovered and categorized as amine, aldehyde, alcohol, ketone, acid, and furan. One type of amine, (2-aziridinylethyl) amine, was the most prevalent volatile component, followed by aldehyde, ketone, aldehyde, acid, ester, and furan. The results showed that the quantity and quality of the volatile compounds were influenced by a pH of the boiling medium. Additionally, the types and volatile profiles of the chicken were altered during chilling. In particular, in the chicken that was boiled at a pH of 8.0, the hexanal (an aldehyde) content increased the most after 7 d of chilling. Moreover, various alcohols formed after the 7 d of chilling of the chicken that was boiled at pHs of 8.0 and 9.0. Because of the oxidation and degradation of fat and proteins, the most altering volatile compounds were the reducing amines and the increasing aldehydes.

Influence of Liquid Nitrogen Pre-Freezing and Drying Methods on the Collagen Content, Physical Properties, and Flavor of Fish Swim Bladder

Fish swim bladder (FSB) is a type of traditional nutraceutical, but the lack of high-quality drying methods limits its premium market development. In order to obtain optimal-quality dried FSBs from Chinese longsnout catfish, the effects of liquid nitrogen pre-freezing (LNF) and drying on the physical properties and flavor of FSB were evaluated. Four methods were used for FSB drying, including natural air-drying (ND), hot-air-drying (HD), LNF combined with freeze-drying (LN-FD), and LNF combined with HD (LN-HD). Color, collagen content, rehydration ratio, textural properties, and flavor characteristics (by GC-IMS, E-nose, and E-tongue) were measured to clarify the differences among four dried FSBs. The results showed that ND cannot effectively remove moisture from FSB as the final product showed a stronger sourness in taste. HD led to a decrease in the collagen content and the collapse of the fiber structure in FSB. Compared to HD, LN-HD showed a higher collagen content (0.56 g/g) and a different flavor fingerprint. FSB treated by LN-FD had better physical qualities in terms of an attractive color, a high collagen content (0.79 g/g), low shrinkage, a higher rehydration ratio (2.85), and a soft texture, while also possessing richer characteristic flavors. The application of LN-FD may help the optimization of the nutrition level, rehydration ability, mouthfeel, and flavor of dried FSB.

Detection and Analysis of VOCs in Cherry Tomato Based on GC-MS and GC×GC-TOF MS Techniques

Volatile organic compounds (VOCs) play a significant role in influencing the flavor quality of cherry tomatoes (Solanum lycopersicum var. cerasiforme). The scarcity of systematic analysis of VOCs in cherry tomatoes can be attributed to the constraints imposed by detection technology and other contributing factors. In this study, the cherry tomato cultivar var. 'Zheyingfen1' was chosen due to its abundant fruit flavor. Two detection technology platforms, namely the commonly employed headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and the most advanced headspace solid-phase microextraction-full two-dimensional gas chromatography-time-of-flight mass spectrometry (HS-SPME-GC×GC-TOFMS), were employed in the analysis. The VOCs of cherry tomato cultivar var. 'Zheyingfen1' fruits at red ripening stage were detected. A combined total of 1544 VOCs were detected using the two aforementioned techniques. Specifically, 663 VOCs were identified by through the HS-SPME-GC-MS method, 1026 VOCs were identified by through the HS-SPME-GC×GC-TOFMS, and 145 VOCs were identified by both techniques. The identification of β-ionone and (E)-2-nonenal as the principal VOCs was substantiated through the application of the relative odor activity value (rOAV) calculation and subsequent analysis. Based on the varying contribution rates of rOAV, the analysis of sensory flavor characteristics revealed that cherry tomato cultivar var. 'Zheyingfen1' predominantly exhibited green and fatty attributes, accompanied by elements of fresh and floral flavor characteristics. In conclusion, our study conducted a comprehensive comparison of the disparities between these two methodologies in detecting VOCs in cherry tomato fruits. Additionally, we systematically analyzed the VOC composition and sensory flavor attributes of the cherry tomato cultivar var. 'Zheyingfen1'. This research serves as a significant point of reference for investigating the regulatory mechanisms underlying the development of volatile flavor quality in cherry tomatoes.

Changes in volatile compounds and lipid oxidation in various tissues of Nile tilapia (Oreochromis niloticus) during ice storage

Changes in the lipid oxidation and volatile compounds of a variety of tilapia tissues (Oreochromis niloticus) including the muscle, gills, and skin during ice storage were investigated by evaluating peroxide values (PVs), lipoxygenase (LOX) activity, fatty acid (FA) composition, and volatile substances. LOX activity and PV were determined in the gills, skin, and muscles throughout 9 days of storage in ascending order to the extended storage time. The highest level of LOX activity was found in the gills, whereas the highest PV was determined in the skin. FA content of all tissues decreased during the storage period. Oleic acid was the predominant monounsaturated fatty acid, whereas linoleic acid and docosahexaenoic acid were the main polyunsaturated fatty acids and omega-3 in all tissues. The fish gills were shown to have the highest level of volatile compounds followed by the skin and muscle, based on headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. Principal component analysis indicated gradual changes in the volatile compound composition with increasing storage time. 2-Butanone and nonanal in the muscle, 6-methyl-2-heptanone and 2-nonenal in the gills, and 1-heptanol, and 1-nonanol in the skin were found to be the potential freshness indicators. In addition, hexanal could be a general potential marker for measuring the degree of lipid oxidation in all tissues. PRACTICAL APPLICATION: Understanding the volatile compound formation related to lipid oxidation within storage time at various tissues of tilapia could be critical to the side-stream processing to yield the desired quality.

Comprehensive mRNA and microRNA analysis revealed the effect and response strategy of freshwater fish, grass carp (Ctenopharyngodon idella) under geosmin exposure

Geosmin is an environmental pollutant that causes off-flavor in water and aquatic products. The high occurrence of geosmin contamination in aquatic systems and aquaculture raises public awareness, however, few studies have investigated the response pathways of geosmin stress on freshwater fish. In this research, grass carp were exposed to 50 μg/L geosmin for 96 h, liver tissue was sequenced and validated using real-time qPCR. In total of 528 up-regulated genes and 488 down-regulated genes were observed, includes cytochrome P450 and uridine diphosphate (UDP)-glucuronosyltransferase related genes. KEGG analysis showed that chemical carcinogenesis-DNA adducts, metabolism of xenobiotics by cytochrome P450, drug metabolism-cytochrome P450 pathway was enriched. Common genes from the target genes of microRNAs and differential expression genes are enriched in metabolism of xenobiotics cytochrome P450 pathway. Two miRNAs (dre-miR-146a and miR-212-3p) down regulated their target genes (LOC127510138 and adh5, respectively) which are enriched cytochrome P450 related pathway. The results present that geosmin is genetoxic to grass carp and indicate that cytochrome P450 system and UDP-glucuronosyltransferase play essential roles in biotransformation of geosmin. MicroRNAs regulate the biotransformation of geosmin by targeting specific genes, which contributes to the development of strategies to manage its negative impacts in both natural and artificial environments.

Effects of Different Freezing Rate and Frozen Storage Temperature on the Quality of Large-Mouth Bass (Micropterus salmoides)

In order to clarify the individual role of freezing and frozen storage on the quality of fish, fillets of large-mouth bass (Micropterus salmoides) were subjected to different freezing rates (freezing with -18 °C (A), -60 °C (B), and -60 °C with forced air circulation at 2 m/s (C), respectively) followed by frozen storage at -18 °C for 30 and 90 days. Another two groups were frozen at -60 °C, followed by storage at -40 °C (D) and -60 °C (E), respectively. Results showed that water-holding and TVBN were mainly affected by storage time. No significant changes were found in free thiol content among treatments. A greater freezing rate and lower storage temperature generally led to lower TBARS. GC × GC-TOFMS revealed a total of 66 volatile compounds, which were related to lipid oxidation. PLS-DA showed that fresh samples were separated from the frozen-thawed ones, and fillets in groups D and E were relatively close to fresh fillets in the composition of oxidation-related volatiles. In conclusion, freezing rate and storage temperature had a significant impact on lipid oxidation and protein denaturation in the fillets of large-mouth bass, while protein oxidation was more affected by freezing rate.

Identification of off-flavor compounds and deodorizing of cattle by-products

An unnatural flavor in a food or drink product caused by the presence of undesirable compounds due to contamination or deterioration is called off-flavor. This study determined the characteristics of cattle by-products off-flavor (heart, liver, lung, rumen, and intestine). We identified 25, 34, 26, 22, and 26 volatile compounds from the heart, liver, lung, rumen, and intestine, respectively, in the bovine via headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS). Based on the relative odor activity value (ROAV ≥ 1), 16 volatile compounds were labeled as characteristic off-flavor by principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). The compounds involved in the characteristic off-flavor in bovine heart were E,E-2,4-nonadienal, E,E-2,4-decadien-1-al, hexanal, (E)-2-octenal, and decyl aldehyde. In the bovine liver, the off-flavor compounds were 1-nonanol, ethyl hexanoate, 2-octanone, and dodecyl aldehyde and in bovine lung 3-heptylacrolein was the off-flavor compound. In bovine rumen, heptaldehyde, octanal, p-cresol, and 1-nonanal were off-flavor compounds, and lastly, 1-octen-3-ol and E-2-nonenal were off-flavor compounds with bovine intestine. The cattle by-products were deodorized by shallot-ginger extract masking, baker's yeast fermentation, active dry yeast + β-cyclodextrin (β-CD) composite, and ultrasound + chitosan composite. The above 16 labeled characteristic compounds decreased in concentration. The ultrasound + chitosan composite method showed a significantly better effect than the other methods (p < .05). The aim of this study was to determine the characteristic flavor information of cattle by-products and provide idea on how to improve the flavor by various deodorization methods. PRACTICAL APPLICATIONS: This study investigated the volatile flavor compounds of cattle by-products from five organs (heart, liver, lung, rumen, and intestine) by headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS). The 16 volatile compounds were labeled as the major characteristic off-flavor compounds by relative odor activity values and principal component analysis. Four different deodorization methods were adopted, and among them, ultrasound + chitosan composite method showed best results. This study has provided useful information about the characteristic off-flavor compounds and suggests how to improve the flavor of cattle by-products through various deodorization methods.

Large volume headspace GC/MS analysis for the identification of volatile compounds relating to seafood decomposition

Decomposition in seafood products in the United States is monitored by the Food and Drug Administration (FDA) laboratories using sensory testing, which requires highly trained analysts. A large‐volume headspace (LVHS) gas chromatography/mass spectrometry (GC/MS) method was developed to generate analytical results that can be directly compared to sensory evaluation. Headspace vapor was withdrawn from a 1‐L vial containing 50 g seafood sample using a large volume headspace autosampler. Various volatile compounds were collected simultaneously. Analytes were preconcentrated by a capillary column trapping system and then sent through a cryo‐focuser mounted onto the GC injector. A selected ion monitoring (SIM) MS acquisition method was used to selectively monitor 38 compounds of interest. Samples of red snapper, croaker, weakfish, mahi‐mahi, black tiger shrimp, yellowfin tuna, and sockeye salmon that have been assessed and scored by an FDA National Seafood Sensory Expert (NSSE) were used for method performance evaluation. Characteristic compounds potentially associated with seafood quality deterioration for each seafood species were identified by quantitative analysis using pooled matrix‐matched calibrations and two‐sample t‐test statistical analysis. Classification of fresh and decomposed samples was visualized on the analysis of variance (ANOVA)–principal component analysis (PCA) score plots. The results determined that the LVHS‐GC/MS technique appeared promising as a screening tool to identify compounds representative of sensory analysis.

Comparison of different edible parts of bighead carp (Aristichthys nobilis) flavor

The study aims to obtain the information on taste and odor among different edible parts (white dorsal meat, white abdomen meat, white tail meat, and dark meat) of bighead carp. The results showed that the white dorsal meat and white abdomen meat had the higher content of total amino acids among all edible parts of bighead carp samples. The highest inosine monophosphate and adenosine monophosphate content presented in white abdomen meat, and the highest equivalent umami concentration value presented in dark meat. The principal component analysis result of electronic tongue and electronic nose showed significant differences in the overall taste and odor characteristics among four group samples. Additionally, 41, 30, 42, and 29 volatile compounds were identified by headspace solid-phase microextraction/gas chromatography-mass spectrometry among white dorsal meat, white abdomen meat, white tail meat, and dark meat of bighead carp, respectively. Based on the data of relative olfactory activity value (ROAV ≥ 1), 12 relative olfactory activity compounds may mainly contribute to the overall odor of bighead carp, including 2-methylbutanal, hexanal, heptanal, (E)-2-octenal, nonanal, dodecanal, undecanal, decanal, 3-methyl-1-pentanol, 1-octen-3-ol, (Z)-2-octen-1-ol, and eucalyptol. Furthermore, according to the Partial Least Squares Discriminant Analysis profile derived from the ROAV of 12 characteristic volatile compounds, significant variations in the odor of different edible parts of bighead carp. Overall, there was a significant difference in taste and odor among different edible parts of bighead carp, and this study may provide useful information for unraveling the flavor characteristics of each edible part of raw bighead carp. PRACTICAL APPLICATIONS: The comprehensive information on taste and odor among different edible parts (white dorsal meat, white abdomen meat, white tail meat, and dark meat) of bighead carp were obtained using liquid chromatography-mass spectrometry, automatic amino acid analyzer, electronic tongue (E-tongue), headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS), and electronic nose (E-tongue), respectively. This study may provide useful information for unraveling the flavor characteristics of each edible part of raw bighead carp and improving the flavor of bighead carp products.