Search Results (46)

The significant demand for medicinal plants with special efficacy has prompted us to adopt appropriate processing methods to enhance the nutritional quality and flavor of raw materials. This study evaluated the impacts of freeze-drying (FD), hot-air drying (HAD), and spray drying (SD) on the bioactive compounds, flavor characteristics, and inhibition of starch digestion in mulberry leaf ethanol extract (MLE). Results indicated that FDMLE exhibited the highest total alkaloids content (TAC: 0.14 ± 0.02 mg/g) and total flavonoid content (TFC: 19.32 ± 0.58 mg/g), along with significant inhibitory effects on starch hydrolysis at 180 min (starch hydrolysis rate <50%). The microstructure of HADMLE was closest to that of the mulberry leaf powder (ML), but SD better preserved the color of ML (ΔE = 1.55 ± 0.04). Combined with the electronic nose and gas chromatography-ion mobility spectrometry (GC-IMS) found HAD processing facilitated the conversion of flavor precursors in ML into Ethyl formate, rose oxide, and (Z)-3-hexenol (M). SDMLE contained higher levels of pentanal, (E)-2-hexenal (D), (E)-2-pentanone, 3-Methyl-2-butenal (D), ethyl butyrate, and 1-penten-3-one (D). FDMLE exhibited the highest diversity of novel volatile compounds (VOCs), with 18 newly identified species. In conclusion, FD is a potential method to effectively reduce the degradation of quality and efficacy of MLE during the drying process. Full article

The change in the surface properties of polymer materials used in an extracorporeal membrane oxygenation (ECMO) device due to nitric oxide (NO) treatment was characterized by zeta-potential and dynamic contact-angle measurements. FTIR-ATR was used to determine the stability of these effects during liquid contact. Polymethyl pentene (PMP), methyl methacrylate acrylonitrile butadiene styrene (MABS), and polyurethane (PU) were investigated. The polymer materials were treated with NO (1000 ppm) for 17 h. The samples for FTIR-ATR measurements were submerged in water or physiological sodium chloride solution for 120 and 240 h after the end of the gas treatment. PMP showed no changes at all. MABS showed decreased contact-angles and increased contact-angle hysteresis. In contrast, PU showed decreased contact-angles and a shift in its zeta-potential curve, indicating a more hydrophilic and acidic surface. The FTIR-ATR measurements showed a slight decrease in the signal intensities after liquid contact. The results indicated an improvement in the liquid contact properties of MABS and the PU due to increased surface hydrophilicity caused mainly by the adsorbed nitric acid (HNO₃) molecules formed by the NO treatment. The results presented in this paper point towards a simple and complication-free method of introducing NO into an ECMO circuit. Full article

The flavour of foxtail millet (Setaria italica (L.) P. Beauv.) is an important indicator for evaluating the quality of the millet. The volatile components in steamed millet porridge samples were analysed using electronic nose (E-Nose) and gas chromatography–ion mobility spectrometry (GC-IMS) techniques, and characteristic volatile fingerprints were constructed to clarify the differences in the main flavour substances in different foxtail millet varieties (two hybrids and two conventional foxtail millets). After sensory evaluation by judges, Jingu 21 (JG) scored significantly higher than the other varieties, and the others were, in order, Jinmiao K1 (JM), Changzagu 466 (CZ) and Zhangzagu 3 (ZZ). E-Nose analysis showed differences in sulphides and terpenoids, nitrogen oxides, organosulphides and aromatic compounds in different varieties of millet porridge. A total of 59 volatile components were determined by GC-IMS in the four varieties of millet porridge, including 23 aldehydes, 17 alcohols, 9 ketones, 4 esters, 2 acids, 3 furans and 1 pyrazine. Comparative analyses of the volatile components in JG, JM, ZZ and CZ revealed that the contents of octanal, nonanal and 3-methyl-2-butenal were higher in JG; the contents of trans-2-butenal, 2-methyl-1-propanol, trans-2-heptenal and trans-2-pentenal were higher in JM; and the contents of 2-octanone, hexanol, 1-octen-3-ol, 2-pentanone and butyraldehyde were higher in ZZ. The contents of 2-butanol, propionic acid and acetic acid were higher in CZ. A prediction model with good stability was established by orthogonal partial least squares discriminant analysis (OPLS-DA), and 25 potential characteristic markers (VIP > 1) were screened out from 59 volatile organic compounds (VOCs). These volatile components can be used to distinguish the different varieties of millet porridge samples. Moreover, we found conventional foxtail millet contained more aldehydes than the hybridised foxtail millet; especially decanal, 1-nonanal-D, heptanal-D, 1-octanal-M, 1-octanal-D and 1-nonanal-M were significantly higher in JG than in the other varieties. These results indicate that the E-Nose combined with GC-IMS can be used to characterise the flavour volatiles of different foxtail millet, and the results of this study may provide some information for future understanding of the aroma characteristics of foxtail millet and the genetic improvement of hybrid grains. Full article

As a kind of high-performance thermoplastic crystalline resin, poly(4-methyl-1-pentene) (PMP) is characterized by its low density, low dielectric constant, exceptional mechanical and chemical properties, high transparency, and gas permeability. PMP has recently received more attention since COVID-19, because it is used as a hollow-fiber membrane for extracorporeal membrane oxygenation (ECMO) based on its high permeability and excellent biocompatibility. This review summarizes the chemical structure, synthesis, properties, and application of PMP. The advancements in catalyst systems for the catalytic synthesis of PMP, including Ziegler–Natta, metallocene, post-metallocene, and late-transition metal catalysts are emphasized. Furthermore, the molecular chain structure, helical conformation, and crystallization morphology of PMP, as well as its properties and applications, are also introduced in detail. Additionally, PMP composites and functional PMP materials are also described as promising and high-performance materials. Full article

Branched fluorinated surfactants with creatively introduced acrylate in the hydrophilic group were designed and prepared by adopting perfluoro-2-methyl-2-pentene as the raw substrate. These new compounds showed excellent surface properties, and the surface tension of their aqueous solution at 25 °C could be below 20.00 mN/m at the critical micelle concentration. Compared with similar structures we have synthesized previously, these synthesized compounds exhibit a great improvement with regard to their molecular arrangement at the gas–liquid interface, their polymerizability, and the antibacterial properties of their polymer form, which can provide new ideas in the work to replace perfluorooctane sulfonate/perfluorooctanoic acid. Full article

This study investigates the effect of variable-temperature roasting on the flavor compounds of Xinjiang tannur-roasted mutton. Gas chromatography coupled with ion mobility spectroscopy (GC-IMS) was used to compare and analyze the volatile components and flavor fingerprints of Xinjiang tannur-roasted mutton using variable-temperature electrically heated air roasting (VTR), constant-temperature electrically heated air roasting (EHAR), and constant-burning charcoal roasting (BCR) techniques. The changes in fatty acids and free amino acids in Xinjiang tannur-roasted mutton under different roasting conditions were compared. By using GC-IMS analysis, 11 flavor compounds, including 4-methyl-3-penten-2-one, isoamyl propionate, trans-2-heptenal, trans-2-heptenal, 2-hexanone, n-hexanol, 2-hexenal, 2-ethylfuran, and ethyl 2-methylbutanoate, were identified as characteristic volatile compounds in the temperature-controlled electrothermal roasting of Xinjiang tannur-roasted mutton using the following conditions: 0–4 min, 300 °C; 5–10 min, 220 °C; and 11–17 min, 130 °C (VTR₃). Through principal component analysis, it was found that the substances with the highest positive correlation with PC1 and PC2 were n-hexanol and 3-methylbutanol. The sensory evaluation showed that VTR₃ had high acceptability (p < 0.05) and a fat flavor (p < 0.05). There was no significant difference in the total fatty acid (TFA) content between the VTR₃ and burning charcoal roast for 1–17 min at 300 °C (BCR₃) (p > 0.05), but it was lower than that in the other experimental groups (p < 0.05). The lowest proportion of glutamic acid content in VTR₃ was 22.44%, and the total free amino acid content in the electric thermostatic roasting for the 1–17 min, 300 °C (EHAR₃) group (347.05 mg/100 g) was significantly higher than that in the other experimental groups (p < 0.05). By using Spearman correlation analysis, the roasting loss rate showed a highly significant negative correlation with essential amino acids (EAAs), non-essential amino acids (NEAAs), and total free amino acids (TAAs) (the correlation coefficients (r) were 0.82, 0.87, and 0.87, respectively) with p < 0.01. There was no correlation between changes in the free amino acid content and fatty acid content (p > 0.05). By using Differential scanning calorimetry (DSC) analysis, we also found that there was no significant difference in peak temperature (Tp) between the VTR₃ and EHAR experimental groups (p > 0.05). Variable temperature electric heating can affect the flavor of lamb, and there are significant differences in the content of flavor precursors such as fatty acids and amino acids in Xinjiang tannur-roasted mutton. Full article

Hydrotalcite-derived materials are eco-friendly, cheap, and efficient catalysts of different reactions. However, their application in liquid-phase hydrogenation could be more extensive. Hence, this work concerns the application of three hydrotalcite-derived materials with different CuZnAl molar ratios in the liquid-phase continuous-flow hydrogenation of 2-methyl-2-pentenal (MPEA) at a wide range of temperature (298–378 K) and pressure (1 × 10⁶–6 × 10⁶ Pa). The catalytic investigations were supported by catalysts characterization by ICP-OES, TPR, in situ XRD, XPS, NH₃-TPD, CO₂-TPD, and TEM measurements on different stages of their biography. It was shown that the catalytic activity of these samples is related to the Cu⁰/Cu⁺ ratio. Depending on the reaction conditions, selectivity control is possible. All catalysts were 100% selective to 2-methylpentanal (MPAA)—sedative drug precursor, with low conversion, at temperatures ≤ 338 K at every pressure. However, the selectivity of the second desired product, fragrance intermediate, 2-methyl-2-penten-1-ol (MPEO), increased significantly at higher temperatures and pressures. It reached the unique value of 54% with 60% substrate conversion at 378 K and 6 × 10⁶ Pa for the catalyst with the highest Cu loading. It was revealed that the production of significant amounts of MPEO is related to the reaction conditions, the Cu⁺ predominance on the surface, the hydrogen spillover effect, and the acid–base properties of these systems. Full article

In this study, three different brands of commercially available marinated tofu were analyzed and compared with homemade products to explore the effect of key flavor substances on their sensory quality, sensory properties, texture characteristics, and volatile components. The texture characteristics and flavor substances of the three brands of commercially available marinated tofu were significantly different from those of homemade products. A total of 64 volatile components were identified by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), mainly including 11 hydrocarbons, 11 alcohols, 10 ketones, 15 aldehydes, 4 esters, 1 acid, and 12 other volatile substances. Among these, nine key flavor compounds (ROAV > 1, VIP > 1) were identified using the relative odor activity value (ROAV) combined with a partial least squares discriminant analysis (PLS-DA) and variable importance in projection, including α-Pinene, β-Myrcene, α-Phellandrene, 1-Penten-3-one, Butanal, 3-Methyl butanal, acetic acid ethyl ester, 1,8-Cineol, and 2-Pentyl furan. The correlation heatmap showed that sensory evaluation was positively correlated with hardness, gumminess, chewiness, and springiness while negatively correlated with 2-Pentyl furan, α-Pinene, resilience, α-Phellandrene, 1-Penten-3-one, acetic acid ethyl ester, and 1,8-Cineol. Overall, this study provides a theoretical reference for developing new instant marinated tofu snacks. Full article

The application of organic fertilizers is one of the most important agricultural measures aimed at improving the flavor and productivity of Lycopersicon esculentum, with the granulation and coating of organic fertilizers, which can reduce seepage losses of great significance to the ecosystem. In this study, Jingcai 8 tomato was selected as the test material. Headspace solid-phase microextraction and gas chromatography–mass spectrometry (HS-SPME-GC-MS) methods were used to investigate the effects of different pelletized organic fertilizers and various coating materials on the flavor profile of the tomatoes. The results indicated that 67 volatile organic compounds (VOCs) were identified in the tomato fruits and 62 volatile compounds were identified in the leaves under different fertilizer treatments. The volatile compound content of the fruits in the BP treatment group was 35.38 μg/g, which was higher than that in other treatment groups, and the volatile compound content of the leaves was lower. A differential compound analysis with log₂|fold change| ≥ 1 and variable important in projection (VIP) > 1 highlighted styrene, 3-methyl-1-butanol, and (E, E)-2,4-hexadienal as the major up-regulated compounds and methyl salicylate as the major down-regulated compound in the tomato fruit BCK (control) vs. BP. Moreover, the α-phellandrene content decreased in the tomato leaves. In addition, an analysis of the tomato fruit differential compounds and compounds with odor activity values (OAV) of ≥ 1, considering the OAV values of characteristic aroma compounds, identified key compounds affecting the flavor of the tomato fruits under the BP treatment. These included 2-nonenal, (E)-2-pentylfuran, trans-β-ionone, 1-penten-3-one, (E, E)-2,4-hexadienal, and 3-hexenol (fruity, floral, and herbaceous odors), (E, E)-2,4-heptadienal (fatty odor), and hexanal (green odor). The combined results analysis of the volatile compound content, differential compounds, and OAV values of characteristic aroma compounds aimed to clarify that the BP treatment group, which applied pelletized, large-grain organic fertilizer with polyurethane (pozzolanic + small-grain oil-coated + 2% paraffinic + 4% polyurethane) as a coating material, proved to be most effective in influencing the flavor of the tomato fruits. This finding lays the foundation for its potential commercial application in artificial orchards. Full article

Longjing tea is favored by consumers due to its refreshing and delicate aroma, as well as its fresh and sweet flavor. In order to study the processing technology of Longjing tea with ‘Baiye 1’ tea varieties, solid phase microextraction and gas chromatography–mass spectrometry were used to analyze the volatile components of Longjing tea in different process stages. The results revealed the identification of 275 aroma metabolites in the processing samples of Longjing tea. The sensory evaluation and principal component analysis revealed that the leaves of fresh (XY) and spreading (TF) were different from the leaves of first panning (YQ), second panning (EQ), final panning (HG), and fragrance enhancing (TX). The relative contents of geraniol (1199.95 and 1134.51), linalool (745.93 and 793.98), methyl salicylate (485.22 and 314.67), phenylethyl alcohol (280.14 and 393.98), 2-methylfuran (872.28 and 517.96), 2-butenal (56.01 and 154.60), and 2-hexenal (46.22 and 42.24), refreshing and floral substances in the XY and TF stages, were higher than other stages. The aroma contents of 2-methylfuran, furfural, 2-methyl-1-penten-3-one, 3-hexen-2-one, dodecane, hexanoyl hexanoate, 2,5-dimethyl-pyrazine, and methyl-pyrazine were found to be significantly positively correlated with the intensity of chestnut aroma. In conclusion, this study contributes to a better understanding of the composition and formation mechanism of chestnut-like aroma and provides new insights into the processing technology to improve the quality of albino green tea. Full article

Capsaicin stress, along with salt stress, could be considered the main stressors for lactic acid bacteria in traditional fermented pepper products. Until now, insufficient attention has been paid to salt stress, while the effect of capsaicin on the aroma-producing properties of Lactobacillus plantarum (L. plantarum) is unclear. The present study attempted to illustrate the effect of capsaicin stress on the aroma-producing properties of L. plantarum CL-01 isolated from traditionally fermented peppers based on E-nose and GC–IMS. The results showed that E-nose could clearly distinguish the overall flavor differences of L. plantarum CL-01 under capsaicin stress. A total of 48 volatile compounds (VOCs) were characterized by means of GC–IMS, and the main VOCs belonged to acids and alcohols. Capsaicin stress significantly promoted L. plantarum CL-01 to produce alpha-pinene, ethyl crotonate, isobutyric acid, trans-2-pentenal, 2-methyl-1-butanol, 3-methyl-3-buten-1-ol, 1-penten-3-one, 2-pentanone, 3-methyl-1-butanol-D, and 2-heptanone (p < 0.05). In addition, under capsaicin stress, the contents of 1-penten-3-one, 3-methyl-3-buten-1-ol, 5-methylfurfuryl alcohol, isobutanol, 2-furanmethanethiol, 2,2,4,6,6-pentamethylheptane, 1-propanethiol, diethyl malonate, acetic acid, beta-myrcene, 2-pentanone, ethyl acetate, trans-2-pentenal, 2-methylbutyl acetate, and 2-heptanone produced by L. plantarum CL-01 were significantly increased along with the fermentation time (p < 0.05). Furthermore, some significant correlations were observed between the response values of specific E-nose sensors and effective VOCs. Full article

To improve the palatability of Artemisia argyi, fermented A. argyi (AAF) were prepared by Lactobacillus plantarum and Saccharomyces cerevisiae, which were used in the hen industry subsequently. Six hundred hens were randomly divided into three groups: control (A), dietary supplementation AAF at a low level (B), and dietary supplementation AAF at a high level (C). After feeding for four months, egg production, egg quality, egg nutrition, egg flavor, plasma biochemical parameters, intestinal histology, and microbiome of the gut contents were analyzed among the three tested groups. Interestingly, 5–6 percentage points elevation in the laying rates were observed in the AAF-supplemented groups in comparison to the control, accompanied with a 5 g increase in daily feed consumption. Since no alteration in egg/body weights was detected, laying performance enhancement was the main effect of dietary supplementation AAF. Meanwhile, the compositions of the egg amino acids and fatty acids changed as the feed inclusion AAF changed, e.g., His and linoleic acid decreased almost 0.1 and 0.5 g/100 g, respectively, while oleic acid increased almost 0.4 g/100 g. In addition, although no significant difference was detected (p > 0.05), the β-diversity of the gut microbiota decreased as the diet addition of AAF decreased, and probiotics (Faecalibacterium, Prevotellaceae, Intestinimonas, and Lachnospiraceae) were the dominant keystone species under AAF treatments. These probiotics were well associated with the egg nutrition component variations based on the correlation analysis, as the Sankey plot showed. Furthermore, the results of headspace-gas chromatography-ion mobility spectrometry manifested that the egg volatile components varied (e.g., the contents of acetone, 4-methyl-3-penten-2-one, 1-hydroxy-2-propanone, ethyl acetate, ethyl octanoate, ethanol, and 2-butanol in the B and C groups were higher than in the A group) and separated clearly as daily supplementation AAF, indicating AAF hugely contributed to the egg flavor variation. Due to no significant differences noticed between the B and C groups, dietary supplementation AAF at a relative low level was enough to serve as a feed attractant in the hen industry for real feeding. Full article

Actinidia arguta is a fruit crop with high nutritional and economic value. However, its flavor quality depends on various factors, such as variety, environment, and post-harvest handling. We analyzed the composition of total soluble sugars, titratable acids, organic acids, and flavor substances in the fruits of ten A. arguta varieties. The total soluble sugar content ranged from 4.22 g/L to 12.99 g/L, the titratable acid content ranged from 52.55 g/L to 89.9 g/L, and the sugar–acid ratio ranged from 5.39 to 14.17 at the soft ripe stage. High-performance liquid chromatography (HPLC) showed that citric, quinic, and malic acids were the main organic acids in the A. arguta fruits. Headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS) detected 81 volatile compounds in 10 A. arguta varieties, including 24 esters, 17 alcohols, 23 aldehydes, 7 ketones, 5 terpenes, 2 acids, 1 Pyrazine, 1 furan, and 1 benzene. Esters and aldehydes had the highest relative content of total volatile compounds. An orthogonal partial least squares discriminant analysis (OPLS-DA) based on the odor activity value (OAV) revealed that myrcene, benzaldehyde, methyl isobutyrate, α-phellandrene, 3-methyl butanal, valeraldehyde, ethyl butyrate, acetoin, (E)-2-octenal, hexyl propanoate, terpinolene, 1-penten-3-one, and methyl butyrate were the main contributors to the differences in the aroma profiles of the fruits of different A. arguta varieties. Ten A. arguta varieties have different flavors. This study can clarify the differences between varieties and provide a reference for the evaluation of A. arguta fruit flavor, variety improvement and new variety selection. Full article

In this study, GC-IMS was used to analyze the volatile component and flavor profiles of Crassostrea gigas individuals of different ploidy and gender. Principal component analysis was used to explore overall differences in flavor profiles, and a total of 54 volatile compounds were identified. The total volatile flavor contents in the edible parts of tetraploid oysters were significantly higher than in diploid and triploid oysters. The concentrations of ethyl (E)-2-butenoate and 1-penten-3-ol were significantly higher in triploid oysters than in diploid and tetraploid oysters. In addition, the volatile compounds propanoic acid, ethyl propanoate, 1-butanol, butanal, and 2-ethyl furan were significantly higher in females than in males. The volatile compounds p-methyl anisole, 3-octanone, 3-octanone, and (E)-2-heptenal were present in higher levels in male than in female oysters. Overall, different ploidy and gender of oysters are connected with different sensory characteristics, providing new insights for understanding the flavor characteristics of oysters. Full article

Sour meat is a highly appreciated traditional fermented product, mainly from the Guizhou, Yunnan, and Hunan provinces. The flavor profiles of sour meat from goose and pork were evaluated using gas chromatography–ion mobility spectrometry (GC–IMS) combined with an electronic nose (E-nose) and tongue (E-tongue). A total of 94 volatile compounds were characterized in fermented sour meat from both pork and goose using GC–IMS. A data-mining protocol based on univariate and multivariate analyses revealed that the source of the raw meat plays a crucial role in the formation of flavor compounds during the fermentation process. In detail, sour meat from pork contained higher levels of hexyl acetate, sotolon, heptyl acetate, butyl propanoate, hexanal, and 2-acetylpyrrole than sour goose meat. In parallel, sour meat from goose showed higher levels of 4-methyl-3-penten-2-one, n-butyl lactate, 2-butanol, (E)-2-nonenal, and decalin than sour pork. In terms of the odor and taste response values obtained by the E-nose and E-tongue, a robust principal component model (RPCA) could effectively differentiate sour meat from the two sources. The present work could provide references to investigate the flavor profiles of traditional sour meat products fermented from different raw meats and offer opportunities for a rapid identification method based on flavor profiles. Full article