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Propolis is a substance produced by bees from the collection of plant resins, with a chemical composition that varies according to the available flora and region, and it has several biological activities. Stingless bee propolis is often produced in reduced amounts, posing a challenge to the study of their volatile compounds, as traditional hydrodistillation extraction would demand more raw propolis than available. These bees collect resins from various sources, resulting in a variable composition, so a standardized reproducible method is fundamental for their analysis. Headspace solid-phase microextraction (HS-SPME), associated with gas chromatography, appears to be an efficient alternative for the analysis of these volatiles. In this study, the GC-MS results of three types of SPME fibers were compared to those of extracts obtained by hydrodistillation to evaluate their efficiency in representing the composition of essential oils from (geo)propolis of different species. The extraction time and temperature were also standardized. Among the fibers tested, PDMS/DVB extracted the volatiles in a similar manner to the essential oil obtained by hydrodistillation for all the samples tested, indicating this to be the best choice of fiber coating for propolis volatile extraction and analysis. Full article

This review summarizes the recent advances in the application of nanomaterial coatings in optical fiber sensors, with a particular focus on deposition techniques and the research progress over the past five years in humidity sensing, gas detection, and biosensing. Benefiting from the high specific surface area, abundant surface active sites, and quantum confinement effects of nanomaterials, advanced thin-film fabrication techniques—including spin coating, dip coating, self-assembly, physical/chemical vapor deposition, atomic layer deposition (ALD), electrochemical deposition (ECD), electron beam evaporation (E-beam evaporation), pulsed laser deposition (PLD) and electrospinning, and other techniques—have been widely employed in the construction of functional layers for optical fiber sensors, significantly enhancing their sensitivity, response speed, and environmental stability. Studies have demonstrated that nanocoatings can achieve high-sensitivity detection of targets such as humidity, volatile organic compounds (VOCs), and biomarkers by enhancing evanescent field coupling and enabling optical effects such as surface plasmon resonance (SPR), localized surface plasmon resonance (LSPR), and lossy mode resonance (LMR). This paper first analyzes the principles and optimization strategies of nanocoating fabrication techniques, then explores the mechanisms by which nanomaterials enhance sensor performance across various application domains, and finally presents future research directions in material performance optimization, cost control, and the development of novel nanocomposites. These insights provide a theoretical foundation for the functional design and practical implementation of nanomaterial-based optical fiber sensors. Full article

Climate change is having a significant impact on vine physiology and grape composition, leading to notable alterations in wine quality, such as reduced acidity, increased ethanol content, and higher pH levels. These effects are particularly problematic in arid and semi-arid regions, such as Mediterranean areas, where high summer temperatures and low rainfall accelerate the degradation of organic acids in grapes. As a result, wines produced under these conditions often lack the acidity required to preserve their freshness and enological quality. This study evaluated the effect of must acidification using cation-exchange resins on the composition and quality of red wines made from the Monastrell variety, comparing them with wines acidified using tartaric acid to reach the same target pH. The results showed that treating a portion of the must (20% and 30%) with cation-exchange resins significantly reduced wine pH values and increased total acidity compared to the control wine. A similar result was observed in wines acidified with tartaric acid. However, as an additional effect, the treatment with resin more markedly reduced the concentration of pro-oxidant metal cations such as iron, copper, and manganese, contributing to lower values of volatile acidity and a greater stability against oxidation of phenolic compounds. Must acidification with both methods improved wine color quality by increasing color intensity and decreasing hue values. Although no significant differences were found in the total concentration of phenolic compounds, variations were detected in their compositional profile. Furthermore, the acidification also affected the concentration and composition of aromatic compounds in the final wine. Sensory analysis revealed that the treated wines—particularly those made with must acidified using cation-exchange resins—exhibited greater aromatic intensity, more pronounced fruity notes, and reduced astringency, resulting in a fresher mouthfeel. In conclusion, must treatment with cation-exchange resins appears to be a low-cost good alternative compared tartaric acid addition for reducing pH and increasing acidity in Monastrell red wines, thereby enhancing their quality in winegrowing regions with arid or semi-arid climates. Full article

This study aims to screen out high-yield protease lactic acid bacteria (LAB) from cheese and analyze the flavor and functional characteristics of their fermentation of corn protein hydrolysate (CPH). Lacticaseibacillus rhamnosus ZYN-71 and Limosilactobacillus fermentum ZYN-76 were isolated and screened by traditional biological methods. Then, the two strains synergistically fermented CPH, and it was found that the scavenging rate of DPPH, ·OH, and O²⁻· and the chelating ability of Fe²⁺ of the fermented CPH increased by 22.85%, 3.82%, 63.37%, and 43.27%, respectively. Meanwhile, the solubility, water-holding capacity, oil-holding capacity, foaming property, foam stability, emulsification property, and emulsification stability had also been improved to varying degrees. The aroma of the CPH after fermentation mainly consisted of aldehydes (20.2%) and nitrogen heterocyclic compounds (19.4%), and the content of off-flavor components was reduced. LAB fermentation effectively improves the practical problems existing in the current application of corn proteolytic products. This research can provide a research basis for corn protein-related products. Full article

Zeolites are promising materials for volatile organic compound (VOC) adsorption and catalytic oxidation, where tuning their structure via defect engineering can enhance adsorption capacity and active metal dispersion. In this study, a concentration-sensitive chelation strategy using diethylenetriaminepentaacetic acid (DTPA) was developed to achieve moderate dealumination for Beta and Y zeolites. For Y zeolite, 0.1 M DTPA treatment increased the toluene adsorption capacity from 59 to 110 mg/g. After platinum (Pt) loading, both DTPA-modified Beta- and Y-based catalysts showed improved toluene oxidation efficiency compared to their unmodified counterparts. Remarkably, the Y-DTPA-0.01-Pt catalyst achieved 90% toluene conversion at 150 °C with CO₂ selectivity above 90%. DRIFTS and H₂-TPR results confirmed that moderate dealumination by DTPA generated silanol defects in zeolite Y that strongly anchored Pt²⁺ in a highly dispersed form and suppressed PtO formation. Severe dealumination using 0.1 M DTPA created larger defects that favored the aggregation of Pt⁰ clusters whilst causing significant loss in the micropores, thus reducing the Pt loading content and catalytic activity. This work demonstrates a simple and effective approach to optimize zeolite-based catalysts by controlling defect formation through controllable chelation, offering new insights into VOC abatement via tailored support design. Full article

The aim of the study was to use vacuum impregnation (VI) with onion and beetroot juices as a pre-treatment before drying to develop innovative dried kohlrabi products. Two modern drying techniques were used: freeze-drying (FD) and vacuum drying (VD). The physicochemical properties were determined, including color, water activity, dry matter, density, volumetric gel index, texture, antioxidant capacity, total phenolic content (TPC), and volatile organic compounds (VOCs). It was shown that vacuum impregnation reduced the color lightness and springiness of kohlrabi. In addition, vegetables after VI showed an increase in dry matter, water activity, bulk density, volume gel index, color attributes a* and b*, color difference, hardness, and chewiness. Furthermore, the pre-treatment allowed for the introduction of additional VOCs characteristic of onions (1-Heptene, 2-methyl-(19.81%), Pentyl formate (19.81%), and 4-(Methylthio)butyl isothiocyanate (18.22%) in kohlrabi with onion juice: dimethyl trisulfide, methyl prop(en)yl disulfide, and 3,5-diethyl-1,2,4-trithiolane) and beetroot (dimethyl trisulfide), myrcene. The vacuum impregnation process significantly increased antioxidant capacity and total polyphenol content compared to raw samples. The results of dry weight, water activity, density, TPC, antioxidant capacity and texture in the case of freeze-dried products confirm that FD is a more advantageous method. In addition, freeze-drying allowed for significant preservation of volatile compounds and the color of kohlrabi. The results indicate the potential of VI as a method for modifying the properties of kohlrabi and producing functional and innovative dried products. Full article

Pea protein isolate (PPI) is a plant protein with high nutritional value, but its application in food is limited by an unpleasant beany flavor. This study aimed to investigate the feasibility of improving the flavor of PPI through fermentation with Enterococcus faecalis 07. PPI was subjected to fermentation by E. faecalis 07 for different durations (0 H, 24 H, 48 H, and 72 H). After fermentation, pH, viable cell counts, free amino acid contents, electronic tongue analysis, and volatile organic compounds were determined. The results showed that fermentation significantly reduced the bitterness of PPI and enhanced its umami intensity. A total of 64 volatile organic compounds were identified in the fermented samples, 42 more than in the unfermented sample. Quantitative analysis revealed that hexanal (grass-like odor) decreased by 92% after 72 h of fermentation, 1-octen-3-ol (mushroom-like odor) decreased from 6.94 mg/kg to 1.73 mg/kg, and trans-2-octenal decreased to 0.59 mg/kg; meanwhile, aromatic compounds such as esters and ketones were produced. Along with changes in the physicochemical properties, organic acids, and free amino acid composition of PPI, correlation analysis between electronic tongue data and volatile compounds further indicated that changes in volatile components simultaneously affected the perception of five taste attributes of PPI (bitterness, sourness, sweetness, saltiness, and umami). In conclusion, this study demonstrated the feasibility of fermenting PPI with E. faecalis 07, which effectively improved its sensory attributes and physicochemical properties to a certain extent. Full article

This study investigates the chemical and sensory effects of UV-C disinfection on black, white, green, and pink peppercorns using a scalable mechanical drum reactor. While previous research has demonstrated the efficacy of UV-C radiation in microbial disinfection, there is a lack of deep, quality-focused research on food products. Nevertheless, for spices, this is just as important, if not more so, than food safety. Different analyses were conducted to assess changes in volatile compounds, organic acids, fatty acids, tocopherols, and colour following UV-C exposure. Additionally, sensory evaluations were performed using triangular tests to determine whether these chemical changes were perceptible to consumers. Results revealed that many of the measured chemical components were affected by the UV treatment, with some volatile compounds decreasing by up to 90%, while certain organic acids increased by more than 150%. Despite these changes, no significant differences in colour, aroma, or flavour were detected by the sensory panel across all pepper types. These findings suggest that UV-C irradiation, when applied under the tested conditions, preserves the sensory quality of peppercorns, supporting its potential as a non-thermal processing method for spice treatment. Full article

Odorous emissions from hot-mix asphalt (HMA) plants are a growing environmental concern, particularly due to airborne aldehydes and ketones, which have low odor thresholds and a strong sensory impact. This study presents a field-ready analytical method for monitoring odor-active volatile compounds. The system uses dynamic solid-phase microextraction (SPME and SPME Arrow) with on-fiber derivatization via O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and is coupled to gas chromatography–mass spectrometry (GC–MS) for direct detection. A flow-cell sampling unit enables the real-time capture of aliphatic aldehydes and ketones under transient emission conditions. Calibration using permeation tubes demonstrated sensitivity (limits of detection (LODs) below 0.13 μg/m³), recovery above 85% and consistent reproducibility. Compound identity was confirmed using retention indices and fragmentation patterns. Uncertainty assessment followed ISO GUM (Guide to the Expression of Uncertainty in Measurement) standards, thereby validating the method’s environmental applicability. Field deployment 200 m from an HMA facility identified measurable concentrations that aligned with CALPUFF model predictions. The method’s dual-isomer resolution and 10 min runtime make it ideal for responding to time-sensitive odor complaints. Overall, this approach supports regulatory efforts by enabling high-throughput on-site chemical monitoring and improving source attribution in cases of odor nuisance. Full article

Colon cancer ranks among the most prevalent and lethal cancers worldwide. Lifestyle and dietary factors—such as high consumption of processed foods, red meat, and alcohol, coupled with sedentary behavior—are key contributors to its development. Despite the availability of standard treatments like surgery, chemotherapy, and radiotherapy, colon cancer remains a significant cause of cancer-related deaths. These conventional approaches are often limited by severe side effects, toxicity, recurrence, and the emergence of drug resistance, highlighting the urgent need for alternative therapeutic strategies. Essential oils are a potential cancer-treatment candidate owing to their diverse composition and favorable safety profile. Numerous studies have revealed essential oils’ promising cytotoxic, antioxidant, and anti-inflammatory effects, supporting their potential role in cancer prevention and treatment. Nevertheless, applying volatile oils to the colon faces several limitations, mainly due to their low bioavailability. Furthermore, conditions within the gastrointestinal tract also contribute to the reduced therapeutic efficacy of essential oils. Novel and promising strategies have been developed to overcome the limitations associated with the application of essential oils. The utilization of targeted drug delivery systems has improved the stability of essential oils and enhanced their therapeutic potential in colon cancer treatment. Moreover, even though essential oils cannot replace conventional chemotherapy, they can mitigate some of its adverse effects and improve the efficacy of associated chemotherapy drugs. This review explores the potential of essential oils and their bioactive compounds in colon cancer therapy and highlights current advancements in micro- and nanoencapsulation techniques for their targeted delivery to the colon. Full article

Terpenes, the largest class of plant specialized products, are built from C5 building blocks via terpene synthases and oxidized by cytochrome P450 enzymes (CYPs) for structural diversity. In some cases, CYPs do not simply oxidize the terpene backbone, but induce backbone rearrangements, methyl group shifts, and carbon–carbon (C–C) scissions. Some of these reactions were characterized over 25 years ago, but most of them were reported in recent years, indicating a highly dynamic research area. These reactions are involved in mono-, sesqui-, di- and triterpene metabolism and provide key catalytic steps in the biosynthesis of plant hormones, volatiles, and defense compounds. Many commercially relevant terpenoids require such reaction steps in their biosynthesis such as triptonide (rodent pest management), secoiridoids (flavor determinants), as well as ginkgolides, cardenolides, and sesquiterpene lactones with pharmaceutical potential. Here, we provide a comprehensive overview of the underlying mechanisms. Full article

With CO₂ generation and emissions requirements, the cement industry faces huge pressure for reducing carbon emissions. Choosing alternative fuels instead of coal is a promising approach. However, the fuel properties of the alternative fuels have not been comprehensively studied. In this work, the fifty typical alternative fuels were selected based on the compositions for different classifications, and the basic fuel properties including proximate analysis, ultimate analysis, and low calorific values were analyzed. Most fuels from plastics and clothes have relatively low moisture; the values of as-received basis moisture (M_ar) and air-dry basis moisture (M_ad) of the others are all lower than 30 wt%. However, the alternative fuels of plastic and cloth all have relatively high contents of air-dry basis volatile compounds (V_ad) (>60 wt%), and they all have low contents of air-dry basis fixed carbon (FC_ad) (commonly <20 wt%) and air-dry basis ash (A_ad) (<30 wt%). The air-dry basis carbon contents (C_ad) of plastics are higher than 40 wt%, while the C_ad values of biomass are lower than 50 wt%. As for air-dry basis hydrogen (H_ad), the contents are all lower than 14 wt% and relatively stable for different kinds of alternative fuels. As for air-dry basis nitrogen (N_ad), the contents are all lower than 9 wt%, and most of them are lower than 3 wt%. In addition, the contents of air-dry basis sulfur (S_ad) of different alternative fuels are also lower than 3 wt%, while plastics, biomass, and clothes are all lower than 1 wt%. Also, the low calorific values (Q_net,ar) for the alternative fuels of plastic are commonly high, and the values for biomass are commonly between 500 and 1500 kJ/kg, while Q_net,ar values for the alternative fuels of cloth and others vary. The fuel properties of the fifty typical alternative fuels can guide fuel selection and optimization when they are mixed for combustion with coals in cement decomposition furnaces. Full article

Background/Objectives: Anaerobic gut fungi (Neocallimastigomycota) are biotechnologically relevant, lignocellulose-degrading microbes with under-explored biosynthetic potential for secondary metabolites. Untargeted metabolomic profiling with gas chromatography–mass spectrometry (GC-MS) was applied to two gut fungal strains, Anaeromyces robustus and Caecomyces churrovis, to establish a foundational metabolomic dataset to identify metabolites and provide insights into gut fungal metabolic capabilities. Methods: Gut fungi were cultured anaerobically in rumen-fluid-based media with a soluble substrate (cellobiose), and metabolites were extracted using the Metabolite, Protein, and Lipid Extraction (MPLEx) method, enabling metabolomic and proteomic analysis from the same cell samples. Samples were derivatized and analyzed via GC-MS, followed by compound identification by spectral matching to reference databases, molecular networking, and statistical analyses. Results: Distinct metabolites were identified between A. robustus and C. churrovis, including 2,3-dihydroxyisovaleric acid produced by A. robustus and maltotriitol, maltotriose, and melibiose produced by C. churrovis. C. churrovis may polymerize maltotriose to form an extracellular polysaccharide, like pullulan. GC-MS profiling potentially captured sufficiently volatile products of proteomically detected, putative non-ribosomal peptide synthetases and polyketide synthases of A. robustus and C. churrovis. The triterpene squalene and triterpenoid tetrahymanol were putatively identified in A. robustus and C. churrovis. Their conserved, predicted biosynthetic genes—squalene synthase and squalene tetrahymanol cyclase—were identified in A. robustus, C. churrovis, and other anaerobic gut fungal genera. Conclusions: This study provides a foundational, untargeted metabolomic dataset to unmask gut fungal metabolic pathways and biosynthetic potential and to prioritize future efforts for compound isolation and identification. Full article

Corn residues are an abundant and low-cost lignocellulosic feedstock that provides a renewable carbon platform for the production of biofuels, bioplastics, and high-value aromatic volatile compounds (AVCs). Isoamyl alcohol, an important AVC, has applications in the food, cosmetics, and biofuel industries. This study evaluated the bioconversion of corn cob acid hydrolysates by Meyerozyma guilliermondii into isoamyl alcohol and ethanol. Corn cob was selected as feedstock due to its high hemicellulose content. A Box–Behnken (BBD) design was used to optimize phosphoric acid hydrolysis. The optimal treatment (2.49% v/v H₃PO₄, 130 °C, 120 min, 1 mm particle size) generated 19.79 g L⁻¹ xylose with 2.74 g L⁻¹ acetic acid. Then, agitation speed and nitrogen concentration were optimized via a central composite design (CCD) in synthetic and hydrolysate-based media fermentations. Isoamyl alcohol specific yield after 48 h of fermentation was higher in hydrolysate medium (12.08 ± 0.67 mg·g⁻¹) than in synthetic medium (8.274 ± 0.83 mg·g⁻¹). Free amino nitrogen (FAN) and intracellular protein analyses revealed higher nitrogen consumption in synthetic media fermentation and greater biomass production in acid hydrolysate media. In addition to isoamyl alcohol (33 mg·L⁻¹), and ethanol (10.18 g·L⁻¹), 1-butanol (61.2 mg·L⁻¹), 1-propanol (13.25 mg·L⁻¹), and acetaldehyde (14.88 mg·L⁻¹) were produced. These results demonstrate the potential of M. guilliermondii to convert corn cob into value-added products. Full article

Oxygenated volatile organic compounds (OVOCs) are key precursors to atmospheric ozone (O₃) and secondary organic aerosols (SOA). However, research on the sources of OVOCs is still limited, particularly in terms of multi-point observations at urban sites. This study conducted a one month continuous enhanced observation at an urban site (BA) and a suburban site (DP) in December 2024. During the study period, the average total VOCs concentration at the BA site was 29.9 ± 6.5 ppbv, significantly higher than that at the DP site (6.4 ± 1.3 ppbv). To enhance the representation of the biogenic fraction in OVOCs, isoprene was employed as a biogenic tracer; prior to source apportionment, its anthropogenic components were subtracted based on local emission ratio coefficients, thereby providing a more representative basis for biogenic source attribution. The optimized source apportionment results show that the contribution ratio of biogenic sources had decreased significantly, with a particularly noticeable decline at the urban site. Among these, the contribution rates of acetaldehyde and acetone had decreased significantly: by 14.7% and 12.2%, respectively. Based on the improved source apportionment method, the source apportionment of OVOCs at the urban site showed that methanol, acetone, and MEK were primarily dominated by anthropogenic primary sources (accounting for 44.5% to 68.5%), while acetaldehyde was primarily dominated by secondary anthropogenic generation (37.1%), indicating its key role as a photochemical product. In contrast, at the suburban site, the biogenic source contribution to acetaldehyde (37.8%) was significant. This difference highlights the necessity of optimizing biogenic source tracers and conducting OVOC source apportionment studies at multiple locations. Full article