Search Results (963)

Rolling is a critical step in the processing of black tea, marking the beginning of fermentation. At this stage, the formation of tea pigments causes significant changes in the color of the processed leaves, laying the essential groundwork for the development of color and flavor quality components in subsequent fermentation processes. However, the rapid and non-destructive sensing of tea pigments during black tea rolling remains challenging. This study focused on black tea products undergoing rolling as its research subject, utilizing electrical characteristic detection technology to collect time-series electrical parameters of rolling leaves at various testing frequencies. The original electrical parameters were preprocessed using multiplicative scatter correction (MSC), min-max normalization (Min-Max), and smoothing (Smooth). Various selection methods, including the competitive adaptive reweighting algorithm (CARS), uninformative variable elimination (UVE), and the variable combination population analysis and iterative retained information variable algorithm (VCPA-IRIV), were employed to identify electrical parameters relevant to the targeted attributes. Quantitative prediction models for the content of tea pigments were established using partial least squares regression (PLSR) and support vector machine regression (SVR). The results demonstrated that the Smooth-VCPA-IRIV-SVR model exhibited superior performance in predicting the contents of theaflavins (TFs), thearubigins (TRs), and theabrownins (TBs). Correlation coefficients of prediction (R_p) all exceeded 0.99, and Relative prediction deviation (RPD) values were all above 6.5, indicating that the model enables rapid and non-destructive detection of tea pigment content during black tea rolling. These findings provide preliminary technical support and reference for the digital production of black tea. Full article

Background: Dietary supplements and functional foods derived from mushrooms have gained increasing popularity. Among these, Coprinus comatus stands out due to its excellent flavor and high nutritional value. However, its susceptibility to autolysis and short shelf life significantly limits its utilization. Although a few studies have attempted to elucidate the autolysis mechanism of C. comatus, only few research has been conducted on the detailed metabolic changes occurring during its growth cycle. Objectives: By conducting a dynamic metabolic profiling analysis of C. comatus metabolites across different developmental stages and tissue parts, this study aims to elucidate the variations in its metabolic composition. Methods: In this study, fruiting bodies of C. comatus were cultivated and collected at four distinct developmental stages. These samples were further divided into cap and gills (CG) and stipe (ST) tissues. Subsequently, UHPLC-Q-Orbitrap was employed for non-targeted dynamic metabolomics analysis of C. comatus samples. The identification of analytes was performed using Compound Discovery 3.3. Then, differential accumulated metabolites (DAMs) between CG and ST at the same stage and CG or ST between adjacent stages were identified. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was conducted to identify potential contributors to the observed metabolic changes. In addition, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity of samples was determined. Results: A total of 490 metabolites were annotated, and the most abundant metabolite groups were lipids, alkaloids, amino acids and their derivatives. It revealed that the metabolites of the ST remained relatively stable across the four growth stages, whereas autolysis induced significant alterations in the metabolites of the CG. KEGG pathway analysis indicated that these changes were primarily linked to lipid and amino acid biosynthesis and metabolic pathways. Furthermore, DPPH assays demonstrated a significant increase in the free radical scavenging activity of CG following autolysis. Conclusions: The metabolites of C. comatus exhibit dynamic variations across different growth stages and tissue locations. The significant morphological changes in CG induced by autolysis are mirrored by corresponding alterations in its metabolic profile. The enhanced DPPH free radical scavenging activity observed in the autolyzed samples, along with the distribution patterns of bioactive components, provides valuable insights for the efficient utilization of C. comatus. Full article

Interpreting multi-component ¹H NMR spectra is difficult due to peak overlap, concentration variability, and low-abundance signals. We cast mixture identification as a single-pass multi-label task. A compact CNN–Transformer (“Hybrid”) model was trained end-to-end on domain-informed and realistically simulated spectra derived from a 13-component flavor library; the model requires no real mixtures for training. On 16 real formulations, the Hybrid attains micro-F1 = 0.990 and exact-match (subset) accuracy = 0.875, outperforming CNN-only and Transformer-only ablations, while remaining efficient (~0.47 M parameters; ~0.68 ms on GPU, V100). The approach supports abstention and shows robustness to simulated outsiders. Although the evaluation set was small, and the macro-ECE (per-class, 15 bins) was inflated by sparse classes (≈0.70), the micro-averaged Brier is low (0.0179), and temperature scaling had negligible effect (T ≈ 1.0), indicating the good overall probability quality. The pipeline is readily extensible to larger libraries and adjacent applications in food authenticity and targeted metabolomics. Classical chemometric baselines trained on simulation failed to transfer to real measurements (subset accuracy 0.00), while the Hybrid model maintained strong performance. Full article

In order to understand the dynamic interaction process among species, enzymes, and metabolites during the fermentation process of Baobaoqu, which is a representative Daqu starter for Chinese baijiu, the intimate connection between the progression of microbial communities and the diversities and activities of enzymes was examined by metagenomics, metatranscriptomics and metaproteomics. It was found that while 5211 species of microorganisms were detected by metagenomics, only 1774 active species were detected by metatranscriptomics, which indicated that only a small proportion (34.04%) were active. The metabolic routes associated with the breakdown of substrates and synthesis of metabolites were redesigned, and the special functional microorganisms for lactate, pyrazines and phenylethyl alcohol production were isolated. It was found that the progression of the microbial community was highly coupled with the components of enzymes and flavor substrates, precisely corresponding to the three stages of the Baobaoqu fermentation process, and were regulated by multiple physical factors. During the Baobaoqu-making process of the fermentation, microorganisms with different functions work together to complete metabolism in different stages. These findings will aid us in gaining a deeper and clearer understanding of the “species–enzyme–metabolite” system within the Daqu starter culture, thus offering valuable perspectives for developing artificial synthetic communities and the production of high-quality Baobaoqu. Full article

Brick tea is a type of post-fermented food that involves microorganisms. Long-term consumption of brick tea exposes consumers to high fluoride levels, which can adversely affect their health. This study explored the feasibility of selective defluorination of Qingzhuan brick tea through membrane separation technology, and pilot production was conducted to produce defluorinated instant brick tea. The concentration of tea polyphenols increased by more than 10 times after nanofiltration, demonstrating the high selectivity of nanofiltration membranes toward fluoride. Defluorination trends were studied at different initial material concentrations (0.5–4%) and operating pressures (0.1–0.5 MPa) under cyclic defluorination. Defluorinated instant brick tea products were also industrially prepared using 300- (DF-300) and 1000-Da (DF-1000) membranes, followed by vacuum freeze-drying. The DF-1000 and DF-300 products exhibited a defluorination rate of 51.46% and 67.96%, respectively. The products have excellent characteristics in terms of color, aroma, and flavor quality, as well as solubility. Gas chromatography–mass spectrometry indicated that the volatile components in the defluorinated instant brick tea were slightly different from those in the original tea, but the key aroma and flavor characteristics of the defluorinated brick tea remained unchanged. Membrane separation provides technical support for the large-scale production of low-fluoride post-fermented tea. Full article

Wheat serves as the primary raw material for medium- and high-temperature Daqu, a key saccharification, fermentation, and flavoring agent in Chinese Baijiu production. To investigate the influence of wheat’s main components on the quality and volatile profile of Daqu, this study comparatively analyzed the main components of three distinct wheat varieties and the physicochemical indices and volatile characteristics of the Daqu produced from them. Results indicated significant differences (p < 0.05) in the main components of the wheats and in the physicochemical indices and sensory scores of their corresponding Daqu samples. CM605 Daqu exhibited the highest acidity, NM660 Daqu showed the highest saccharification power, and MM907 Daqu had the highest liquefaction power. A total of 66 volatile compounds were identified across the three Daqu types, encompassing esters, alcohols, aldehydes, acids, phenols, ketones, pyrazines, etc. The contents of volatile compounds varied significantly among the Daqu samples made from different wheats; notably, the total contents of esters, alcohols, and aldehydes showed significant differences (p < 0.05). The Spearman correlation analysis revealed highly significant correlations (p < 0.01) between several wheat quality characteristics and Daqu quality indices, identifying wheat starch and protein as key factors affecting Daqu quality. The PLS-DA analysis revealed 34 differential volatile compounds. Mantel test correlation analysis further confirmed that wheat components including starch, albumin, globulin, gliadin, glutenin, and fat could influence the differential volatiles in Daqu. For instance, amylopectin content showed a significant positive correlation with n-pentanol, isovaleric acid, and propyl acetate (p < 0.05). This study provides a solid foundation for a deeper understanding of the relationship between wheat composition and Daqu quality, facilitating the more precise selection of wheat varieties to improve Daqu quality during production. Full article

Free amino acids play a key role as flavor components and metabolic precursors in fresh corn, with umami taste largely attributing to their concentration, particularly the umami amino acid glutamate and aspartate. While several genes involved in the biosynthesis of these amino acids have been identified, their regulatory pathways remain poorly understood. Sweet waxy corn ‘Qianjiangnuo No.3’ (Q3) and waxy corn ‘Huayunhuanuo 402’ (H402), with contrasting umami taste, were used in this study. Transcriptomic, metabolomic, and targeted metabolite profiling were conducted at kernel-filling stage. Our analysis showed that Q3 ears possessed significantly higher levels of free amino acids than H402, and its umami amino acids were highly enriched. Diverse enrichment of amino acids was observed across the isolated kernels distribution in ears. The O2 (bZIP1), Naked endosperm1 (NKD1), and bZIP genes were found significantly downregulated in Q3 compared to H402. Conversely, genes involved in glutamate and aspartate biosynthesis showed higher expression in Q3 than H402 while translation-associated genes snoRNA U3-2 and rRNA28S exhibited lower expression in Q3 than H402, correlating with a notable enrichment of free umami amino acids. Genes promoter analysis revealed an abundance of bZIPs binding motifs. These findings suggest that bZIP members may act as central regulators modulating free amino acid synthesis and accumulation in fresh kernels. Full article

The pollen morphological characteristics of 16 pummelos and 4 other citrus germplasms from Vietnam, Thailand, and China were observed using scanning electron microscopy (SEM). Observations included equatorial view, polar view, and exine ornamentation. The results showed that the pollen of all tested materials was monads, prolate, or subprolate. The average polar axis length of the pollen ranged from 29.121 to 37.043 µm, and that of the equatorial axis ranged from 19.861 to 25.911 µm. A t-test revealed that the polar axis of pollen from Chinese pummelo germplasms was significantly longer than that of varieties from Southeast Asia, indicating certain geographical differentiation. The apertures were all colporate type, predominantly with four to five colpi (75% of grains); only four colpi were observed in the remainder (25%). The pollen exine ornamentation of pummelo germplasms was perforated, whereas that of other citrus types was reticulate. Pummelos exhibited a smaller pori diameter (0.264–0.673 µm) and wider distance between pori (0.581–1.118 µm), while other citrus species had larger lumina (1.253–1.684 µm) and narrower muri (0.443–0.664 µm). Principal component analysis (PCA) and cluster analysis were performed based on pollen traits, and two principal component factors were extracted. The pummelo germplasms were divided into two subgroups: sweet pummelo and red pummelo, which demonstrated a correlation among their pollen morphology, flesh color, and flesh flavor. The phenotypic diversity of pollen among different pummelo germplasms may provide a valuable auxiliary reference for the identification and systematic classification of pummelos. Full article

In this study, six club raspberry varieties were examined for their aromatic profiles and sensory qualities, and statistical approaches were used to determine how aroma components affect consumer impressions. Analysis of the aroma’s chemical composition was performed utilizing headspace SPME and GC-MS. MS-DIAL -v5.5.250627 software was used to identify components from commercial libraries, after 10 repetitions for each variety, followed by manual verification. A sensory evaluation of fresh fruits, with 55 volunteers, was statistically analyzed and linked to chemical composition using multivariate analysis and the OPLS-HDA classification method, which was employed for the first time. Tula Magic was scored the highest in the sensory evaluation compared to Adelita, Himbo Top, Glen Dee, San Rafael, and Cascade Harvest. 2-Heptanol (fresh, lemongrass-like, herbal, floral, fruity, green), heptanal (fresh, aldehydic, fatty, green, herbal), and 2-methyl-6-hepten-1-ol (oily-green, herbaceous-citrusy) separated Tula Magic from the other varieties assessed. The same components were recognized in OPLS as positive contributors to the flavor score, while terpenoids like trans-β-ionone, α-ionone, and α,β-dihydro-β-ionone, as well as 2-heptanone, scored slightly lower. This suggests that a fine balance between the individual components is key to the overall aroma sensation. Full article

The volatile organic compounds (VOCs) are the main flavor constituents of different pig breeds, which have positive effects on the quality evaluation of pork. This study aimed to clarify the effects of lipid oxidation on characteristic VOCs in different breeds of pigs. The fatty acid composition and antioxidant characteristics of the Ningxiang (NX) pig, Rongchang (RC) pig, Duroc × Wujin (DW) pig, and Duroc × Landrace × Yorkshire (DLY) pig were determined. The VOCs from these four pig breeds were analyzed by gas chromatography–ion migration spectrometry (GC-IMS) and solid-phase micro-extraction–gas chromatography–olfactory mass spectrometry (SPME-GC-O-MS). A total of 49 volatile compounds were identified by GC-IMS, whereas GC-O-MS detected 97 volatile components, including aldehydes, alcohols, ketones, acids, and esters. Among these, aldehydes and alcohols were the predominant categories. The results showed that RC breed pork had the highest fatty acid content, whereas NX breed pork exhibited the highest antioxidant activity. Among the VOCs from these four pig breeds, tridecanal showed a strong positive correlation with antioxidant capacity (T-AOC) and vitamin E, which was mainly reflected in NX. Furthermore, the key VOCs across the different pig breeds were mainly related to unsaturated fatty acids, such as C20:3n6, C18:1n9c, and C18:2n6c. In conclusion, the antioxidant characteristics of NX pigs are closely associated with their unique volatile flavor profile, while the characteristic flavor compounds across different pig breeds are primarily influenced by the composition and oxidation of unsaturated fatty acids. Full article

Ocimum, commonly known as basil, is a group of aromatic plants extensively cultivated for their aromatic leaves, flavorful seeds, and essential oils, finding applications in food and herbal medicine. Drought stress is a crucial environmental factor that has a considerable impact on basil growth and the accumulation of bioactive compounds. This study aims to evaluate how drought stress affects biomass production and volatile oil accumulation in selected Ocimum species over two consecutive years in an open-field cultivation setting. Five distinct basil genotypes, O. basilicum L. ‘Ohře,’ O. basilicum L. ‘Genovese,’ O. × africanum Lour., O. americanum L., and O. sanctum L., were evaluated under two levels of water supply, with one group receiving irrigation as a control and the other exposed to non-irrigated conditions to induce drought stress. Consistent negative impacts of drought stress on biomass production were observed in both years. The reduction in fresh herb yield varied from 16.5 g plant⁻¹ (10.3%) for O. sanctum to 118 g plant⁻¹ (41.7%) for O. basilicum ‘Ohre.’ Across the study years, drought stress slightly increased the essential oil content of O. × africanum and O. basilicum ‘Genovese’ by 9.8% and 26%, respectively. The essential oil composition varied considerably among the different Ocimum species and cultivars. Cultivars Ohře and Genovese had linalool as a major component, exceeding 40%. O. americanum was rich in citral compounds—neral and geranial—accounting for 26–37%, which contribute to its strong lemon-like fragrance. The hybrid O. × africanum contained high proportions of 1,8-cineole (32–38%) and limonene (14–16%), while O. sanctum was characterized by its elevated levels of eugenol (36.4–50.3%) and β-caryophyllene (26.4–38.5%). The influence of water availability on essential oil content and composition was inconsistent across species. Similarly, variations were observed in total phenolic content (TPC) and antioxidant capacity (AOC) depending on both species and growing year. Notably, the highest TPC (341.4 mg GAE g⁻¹ DM) and AOC (122.9 mg AAE g⁻¹ DM) were recorded for O. sanctum grown under drought stress during the first experimental year. In conclusion, it is recommended to irrigate the studied basil species at least twice a week under open-field conditions to minimize the negative effects of drought stress. Full article

Tea-flavor baijiu, in which the aroma combines the tea note and the typical profile of baijiu, has brought a fresh flavor to the market. Yet its flavor evolution during the storage period and the associated changes in volatile compounds remain poorly characterized. To systematically address the flavor profile dynamics during storage, the study evaluated tea-flavor baijiu of varying ages using integrated sensory and instrumental analyses. Through napping with ultra-flash profiling (Napping-UFP) and check-all-that-apply (CATA), the sensory attributes from aroma, flavor, and mouthfeel profiles of tea-flavor baijiu were established, and quantitative descriptive analysis (QDA) was employed to distinguish the distinct sensory profiles among samples with different aging durations. The overall aroma patterns were examined using an electronic nose (E-nose), and the distinction of sample A401 with the longest storage period was notable. Headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) were used to identify and quantify the volatile compounds, while aging notably altered volatile composition with increased ester levels and reduced alcohol content; hence, the short-aged (one to three years), mid-aged (four to six years), and long-aged (seven and eight years) samples could be easily differentiated. Through the analysis of the data, 12 key odor-active compounds, namely (E)-2-methyl-2-butenal, ethyl caproate, 3-methylbutanal, 2-pentanone, ethyl acetate, ethyl heptanoate, ethyl 2-methylbutanoate, ethyl pentanoate, ethyl butyrate, ethyl hexanoate, ethyl octanoate, and 2,4-di-tert-butylphenol, were identified as major contributors to shifts. Furthermore, Pearson correlation analysis revealed a strong negative association between the accumulation of esters and the intensity of tea aroma in long-aged samples, clarifying the chemical mechanism underlying the diminished tea note in aged tea-flavor baijiu. This study provides new insights into the impact of aging on the flavor profile of tea-flavor baijiu and offers a scientific foundation for improving its production, storage, and quality management. Full article

Pomegranate (Punica granatum L.), valued for its health benefits and distinctive flavor, derives its characteristic aroma from volatile organic compounds (VOCs) that vary significantly with geographical origin. In this study, VOCs in pomegranates from six Chinese geographical regions were characterized using an electronic nose (E-nose), an electronic tongue (E-tongue), headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS), and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS). To elucidate geographical variations in odor, taste, and volatile profiles, a comprehensive multivariate statistical analysis integrating principal component analysis (PCA), hierarchical cluster analysis, orthogonal partial least squares-discriminant analysis (OPLS-DA), and variable importance in projection (VIP) was employed. The results demonstrated that the E-nose and E-tongue effectively distinguished pomegranate by geographical origin, with aroma contributing more significantly than taste to regional differentiation. A total of 46 and 58 VOCs were identified using HS-GC-IMS and HS-SPME-GC-MS, respectively, with different characteristic volatile compounds in pomegranate from various origins, and alkenes, esters, and alcohols were the primary contributors to regional variations. Notably, OPLS-DA revealed that HS-GC-IMS exhibited superior discriminatory power in separating pomegranates of different geographical origins, with HY and HL displaying closely related odor profiles while the other samples showed the most pronounced odor differences, but these findings contrasted with HS-SPME-GC-MS results. Additionally, the VIP method and the relative odor activity value (ROAV) further identified six and eight key aroma compounds based on HS-GC-IMS and HS-SPME-GC-MS data; in particular, hexanal, nonanal, β-pinene, 3-hydroxybutan-2-one, and β-ocimene were identified as key aroma compounds in pomegranate as potential regional markers. These findings highlight VOC profiles as potential geographical origin markers, supporting origin traceability and quality control in the pomegranate industry. Full article

The Australian pork industry has been seeking a rapid and non-destructive way to predict pork chemical components and eating quality. In this study, near-infrared spectroscopy (NIRS) and nuclear magnetic resonance (NMR) were applied to fresh pork Longissimus thoracis et lumborum (LTL) and Semimembranosus (SM) with the aim to build prediction models for intramuscular fat (IMF) content, collagen content and solubility, pH, and sensory attributes, namely tenderness, juiciness, liking of flavor and overall liking as well as investigate the effects of chemical components on pork eating quality. Results showed that the NIRS output, which was a predicted IMF content calibrated for the IMF of lamb, correlated with the chemically analyzed IMF content across both muscles. In LTL, NMR parameter p_2f was weakly correlated with IMF and pH. For the LTL, NMR parameters p₂₁ and p₂₂ were related to sensory tenderness, while T₂₂ was correlated with the liking of flavor. In both muscles, the collagen content and pH were related to all sensory attributes, and IMF was related to the liking of flavor. The chemical properties of SM were weakly correlated with those of LTL. The NIRS and NMR weakly predicted the pork chemical components and sensory properties, but more studies are required to improve the accuracy. Full article

Laying hens in the late laying period often experience reduced productivity and declining egg and meat quality, which limits breeding efficiency and resource utilization. This study aimed to evaluate the effects of multi-component Botanical Crude Extracts (BCEs) on egg and meat quality, metabolic health, and gut microbiota in aged laying hens. A total of 4320 hens were supplemented with 0.3% BCEs for 100 days, with evaluations at 60 and 100 days. BCE supplementation significantly enhanced egg flavor by promoting aromatic and fat-soluble volatiles and reducing odorous compounds (p < 0.05). BCEs improved yolk nutrition by enriching n-3 polyunsaturated fatty acids, especially docosahexaenoic acid (DHA), and optimizing the n-6/n-3 ratio (p < 0.05). A moderate reduction in amino acids was observed, which may reduce bitterness and ammonia burden (0.05 ≤ p < 0.10, trend). In muscle, BCEs improved protein–fat distribution, increased intramuscular fat, and enhanced flavor-related metabolites, significantly improving meat quality of culled hens (p < 0.05). BCEs also reshaped gut microbiota, reducing harmful taxa and promoting short-chain fatty acid and aromatic metabolite biosynthesis (p < 0.05). Serum metabolomics revealed modulation of AMPK, calcium, and cholesterol pathways, improving antioxidant capacity and lipid regulation (p < 0.05). Correlation analyses linked beneficial bacteria and metabolites with yolk DHA levels and flavor (p < 0.05). Overall, BCEs enhanced egg and meat quality and physiological health, providing guidance for functional feed strategies in aged laying hens. Full article