Search Results (87)

The electrochemical oxidation mechanism of biopolymer lignin is challenging to characterize due to its complex structure. Controlling the oxidation process is crucial for ensuring the economic feasibility of electrochemical depolymerization of lignin, as it often generates numerous undesirable compounds. Regulating the depolymerization process can lead to the production of high-yield aromatic compounds, such as phenols and carboxylic acids. In addition to the depolymerization of lignin by the electrocatalyst, hydroxyl radicals (^•OH) during the electrochemical oxidation could also depolymerize lignin. Previous studies have reported that ^•OH forms during electrochemical oxidation; however, it is still uncertain whether these radicals or electrocatalysts are responsible for depolymerizing lignin. This study investigates the pivotal issue of whether the depolymerization process is driven by ^•OH or by a direct electrochemical route. In this study, lignin compounds were electrochemically oxidized using a nickel-cobalt (Ni-Co) electrocatalyst at several electrode potentials, and the oxidized products were analyzed using headspace solid-phase micro-extraction gas chromatography–mass spectrometry (SPME-GC-MS) and factor analysis (FA). Electrochemical depolymerization of lignin yielded mainly phenolic compounds (e.g., tert-butyl phenols), phthalate esters (e.g., dibutyl phthalate, bis(2-methylpropyl) phthalate), furan derivatives (e.g., 2-butyltetrahydrofuran), and short-chain carboxylic acid esters. This work has successfully predicted that both electrocatalyst and ^•OH radicals contribute to the electrochemical depolymerization of lignin. Radical-mediated depolymerization yielded a broader range of products. 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

Food irradiation is a clean, safe and non-thermal technology applied to destroy pathogenic microorganisms, i.e., Salmonella spp., in hen eggs. Currently, in Europe only the egg white can be irradiated up to 3 kGy, so different control methods are crucial for official inspections to identify illicit treatments. In this work, an analytical method was proposed to determine the radiolytic markers, namely 2–dodecylcyclobutanone (2–DCB) and 2–tetradecylcyclobutanone (2–TCB) in hen egg samples. This method is based on headspace solid phase micro-extraction coupled with gas chromatography/mass spectrometry (HS–SPME/GC–MS). The eggs were treated by an X-ray irradiator at dose levels of 0.5, 1.0 and 3.0 kGy. The preliminary validation showed good selectivity, without matrix interferences in non-irradiated samples. Spiked samples showed linear responses in the range 2.5–25.0 µg kg⁻¹, where 2.5 µg kg⁻¹ was the limit of detection for both analytes. Irradiated samples showed a dose-dependent increase in signal intensity and a constant 2–DCB/2–TCB ratio. The minimum dose level detected was 0.5 kGy for all samples, and the 2–DCB and 2–TCB signals remained stable over one month after irradiation. Not least, white analytical chemistry was used to evaluate the HS–SPME/GC–MS method validation effectiveness, greenness power and economic efficiency, compared to the EN 1785:2003 standard method. The results of this study prove that the HS–SPME/GC–MS method is a reliable green alternative to the official method, which is suitable in food safety control programs. Full article

In this study, we analysed cocoa (a dried and fully fermented seed of Theobroma cacao L.) from two Amazonian cultivars and a commercial sample of the Amazonian variety EETP801, grown under sustainable organic conditions, in comparison to CCN51 cocoa grown on a neighbouring commercial farm using standard practises and a European commercial cacao powdered beverage. The overall metabolite profile of the 70% aq acetone sample cocoa extracts was analysed using high-performance TLC analyses (HPTLC), and the xanthine alkaloids were analysed using quantitative liquid chromatography–UV photodiode array (HPLC-DAD) analyses. The volatile fraction in the headspace of the freshly ground cocoa was subjected to solid phase micro-extraction and analysed by gas chromatography–mass spectrometry (HS-SPME/GC-MS). Total polyphenol content was determined by the Folin–Ciocalteu method. Despite the reduced production of cocoa by the EETP801 cultivar in comparison with the CCN51 cultivar, the obtained produce is significantly richer in theobromine (130 mg vs. 170 mg per g of cacao), with CCN51 having a double concentration of theophylline (12.6 vs. 6.5 mg per g of cacao). Qualitatively, the two Amazonian cocoa samples had a similar polyphenolic composition (per the HPTLC fingerprint). HS-SPME/GC-MS analyses revealed that all the samples show a spontaneous emission profile mainly rich in non-terpene derivatives, of which hydrocarbons and pyrazines are the most abundant groups. The most represented volatile organic compound is n-tridecane for both EETP801 and CCN51. The variability in the artisan fermentation and roasting processes influenced certain aspects of the volatile composition as reflected by the trimethyl pyrazine/tetramethyl pyrazine ratio, which was zero in EETP-801 and lower than 1 in CCN51. Acetic acid was absent in CCN51 but significant (c.a. 5.5.%) in EETP801 and the commercial samples. The cultivar EETP801 is a viable option for a more ecologically conscious sector of the cocoa beverages consumer group. Full article

Embryo rice, as a product of processing rice, improves palatability and retains the nutritional characteristics of brown rice. However, the storage period of embryo rice is only 30 d at room temperature. To delay the deterioration in the quality of embryo rice during storage, this study used polyethylene terephthalate/aluminum foil/polyethylene (PET/AL/PE) to vacuum-package embryo rice, and analyzed the quality changes under 25 or 4 °C storage conditions. At the same time, volatile compound analysis and transcriptomic analysis were integrated to explore the quality deterioration mechanism of embryo rice during storage. The electronic nose results showed that the odor of embryo rice changed significantly during different storage periods (p < 0.05). A total of 72 volatile compounds were identified by Headspace–Solid-Phase Micro-Extraction–Gas Chromatography–Mass Spectrometry (HS-SPME-GC-MS), with 2-pentylfuran, naphthalene, and styrene contributing the most in the early stage, and 2-hexenal, nonanal, trans-2-nonenal, and ethanol contributing more in the later stage. Correlation analysis showed that fatty acids, malondialdehyde (MDA), lipase, and ferric-reducing antioxidant power (FRAP) were positively correlated with aldehydes and acids (p < 0.05), while catalase (CAT) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) were negatively correlated (p < 0.05). This was mainly because the oxidative decomposition of lipids and the weakening of antioxidant capacity would lead to the accumulation of aldehydes. In the Mantel test analysis, color had the strongest correlation with volatile compounds, followed by taste value, and finally texture. In transcriptomic analysis, lipid synthesis and metabolism were key pathways for the storage deterioration of embryo rice, and the LOX gene played an important regulatory role. These results can provide a theoretical basis for the evaluation of quality and selection of storage method of embryo rice. Full article

Spices and aromatic herbs are important components of everyday nutrition in several countries and cultures, thanks to their capability to enhance the flavor of many dishes and convey significant emotional contributions by themselves. Indeed, spices as well as aromatic herbs are to be considered not only for their important values of antimicrobial agents or flavor enhancers everybody knows, but also, thanks to their olfactory and gustatory spectrum, as drivers to stimulate the consumers’ memories and, in a stronger way, emotions. Considering these unique characteristics, spices and aromatic herbs have caught the attention of consumer scientists and experts in sensory analysis for their evaluation using semi-quantitative approaches, with interesting evidence. In this pilot study as a first step, each studied botanical, belonging to Piperaceae or aromatic herbs, has been subjected to headspace solid phase micro-extraction (HS-SPME) coupled with gas-chromatography mass spectrometry (GC-MS) analysis to assess their spontaneous volatile emission, representing the complex chemical pattern, which encounters the consumers’ olfactory perception. Furthermore, the present investigation, performed on 12 individuals, outlines the administration of a pilot study, merging the typical sensory analysis with emotional data collection and the innovative contribution related to the study around the Autonomic and Central Nervous System activation in consumers, performed using wearable technologies and related signal processing. The results obtained by our study, beyond demonstrating the feasibility of the approach, confirmed, both in terms of emotional responses and biomedical signals, the significant emotional potential of spices and aromatic herbs, most of which featuring an overall positive valence, yet with inter-subjects’ variations. Future investigations should aim to increase the number of volunteers evaluated with such an approach to draw more stable conclusions and attempting a customization of product preferences based on both implicit and explicit sensory responses. Full article

Paratuberculosis is a debilitating disease of ruminants that causes significant economic loss in both cattle and sheep. Early detection of the disease is crucial to controlling the disease; however, current diagnostic tests lack sensitivity. This study evaluated the potential for volatile organic compounds (VOCs) detected by gas chromatography and an electronic nose (eNose) for use as diagnostic tools to differentiate between Map-infected and non-infected cattle and sheep. Solid-phase micro-extraction gas chromatography–mass spectrometry (SPME GC-MS) was used to quantify VOCs from the headspace of faecal samples (cattle and sheep), and partial least squares–discriminant analysis (PLS-DA) was used to determine the suitability as a diagnostic tool. Both the cattle and sheep models had high specificity and sensitivity, 98.1% and 92.3%, respectively, in cattle, and both were 100% in sheep. The eNose was also able to discriminate between Map-infected and non-infected sheep and cattle with 88.9% specificity and 100% sensitivity in sheep and 100% specificity and sensitivity in cattle. This is the first time that VOC analysis by eNose and GCMS has been used for identification of Map in cattle and sheep faeces. GCMS also allowed the identification of putative disease biomarkers, and the eNose diagnostic capability suggests it is a promising tool for point-of-care diagnosis for Map detection on farms. Full article

Aroma plays a pivotal role in defining tea quality and distinctiveness, and tea producers have often observed that specific drought conditions are closely associated with the formation and accumulation of characteristic aroma compounds in tea leaves. However, there is still limited understanding of the differential strategies employed by various tea cultivars in response to drought stress for the accumulation of key volatile aroma compounds in fresh tea leaves, as well as the associated metabolic pathways involved in aroma formation. In this study, two widely cultivated tea cultivars in China, Fuding Dabai (FD) and Wuniuzao (WNZ), were examined to assess the impact of mild field drought stress on the composition and accumulation of key volatile aroma compounds in fresh leaves using headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS) and headspace solid phase micro-extraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) technologies. Results revealed that drought stress led to a substantial increase in the diversity of volatile compounds (VOCs) in FD, while WNZ exhibited a notable rise in low-threshold VOC concentrations, amplifying sweet, floral, fruity, and earthy aroma profiles in post-drought fresh leaves. Through partial least squares discriminant analysis (PLS-DA) of HS-GC-IMS and HS-SPME-GC-MS data, integrating variable importance projection (VIP) scores and odor activity values (OAVs) above 1, 9, and 13, key odor-active compounds were identified as potential markers distinguishing the drought responses in the two cultivars. These compounds serve as crucial indicators of the aromatic profile shifts induced by drought, providing insights into the differential metabolic strategies of the cultivars. Additionally, KEGG enrichment analysis revealed 12 metabolic pathways, such as terpenoid biosynthesis, fatty acid synthesis, cutin, suberine, and wax biosynthesis, and phenylalanine metabolism, which may play crucial roles in the formation and accumulation of VOCs in tea leaves under drought stress. These findings provide a comprehensive framework for understanding the cultivar-specific mechanisms of aroma formation and accumulation in tea leaves under mild drought conditions. Full article

Fusarium graminearum (F. graminearum) in maize poses a threat to grain security. Current non-destructive detection methods face limited practical applications in grain quality detection. This study aims to understand the optical properties and volatileomics of F. graminearum-contaminated maize. Specifically, the transmission and reflection spectra (wavelength range of 200–1100 nm) were used to explore the optical properties of F. graminearum-contaminated maize. Volatile organic compounds (VOCs) of F. graminearum-contaminated maize were determined by headspace solid phase micro-extraction with gas chromatography-tandem mass spectrometry. The VOCs of normal maize were mainly alcohols and ketones, while the VOCs of severely contaminated maize became organic acids and alcohols. The ultraviolet excitation spectrum of maize showed a peak redshift as fungi grew, and the intensity decreased in the 400–600 nm band. Peak redshift and intensity changes were observed in the visible/near-infrared reflectance and transmission spectra of F. graminearum-contaminated maize. Remarkably, optical imaging platforms based on optical properties were developed to ensure high-throughput detection for single-kernel maize. The developed imaging platform could achieve more than 80% classification accuracy, whereas asymmetric polarization imaging achieved more than 93% prediction accuracy. Overall, these results can provide theoretical support for the cost-effective preparation of low-cost gas sensors and high-prediction sorting equipment for maize quality detection. Full article

Volatile organic compounds (VOCs) produced by Bacillus species exhibit biocontrol activity against fungal pathogens of fruits and vegetables. However, research on the effect of VOCs on Aspergillus flavus in stored grains is limited. This study aimed to investigate the effects of VOCs extracted from the strain R2, which was isolated from unhulled rice and identified as Bacillus paramycoides on A. flavus in vitro and unhulled rice. R2 VOCs effectively inhibited conidial germination and the hyphal growth of A. flavus in vitro. Moreover, R2 VOCs reduced the fungal population, aflatoxin B₁ (AFB₁) levels, and free fatty acid (FFA) value by 90.8%, 67%, and 38.7%, respectively, in unhulled rice. Eighteen R2 VOCs were identified using headspace solid-phase micro-extraction gas chromatography–mass spectrometry, and the individual activity of the VOCs against A. flavus was tested in vitro. Benzaldehyde (Ben) and 3,7-dimethyl-1-octanol (Dmo) showed strong inhibitory activities against A. flavus on PDA plates, with inhibition rates of 100% and 91.2%, respectively, at a concentration of 20 μL/dish. Ben at the concentration of 0.09 mg/mL, Dmo at the concentration of 0.07 mg/mL, or a mixture of both at halved concentrations could reduce the fungal population, AFB₁ levels, and FFA content in unhulled rice. Our findings suggest that R2 VOCs are good alternatives to traditional chemical fumigants for suppressing A. flavus in stored grains. However, further research is necessary to establish the optimal fumigation concentration of these two components in unhulled rice. The impact of their residues on grain quality should be explored through sensory evaluation and nutritional analysis, and their safety to the environment and human body should be evaluated through safety assessment. Full article

Autochthonous Italian pomegranate accessions are still underexplored, although they could be an important resource for fresh consumption, processing, and nutraceutical uses. Therefore, it is necessary to characterize the local germplasm to identify genotypes with desirable traits. In this study, six old Italian pomegranate landraces and a commercial cultivar (Dente di Cavallo) were investigated, evaluating their fruit pomological parameters, physicochemical (TSS, pH, TA, and color) characteristics, sugar content, and aromatic profiles (HeadSpace Solid-Phase MicroExtraction (HS-SPME)) coupled with Gas Chromatographyass Spectrometry (GC–MS) of pomegranate juices. Significant differences were observed in the size and weight of the seed and fruits (127.50–525.1 g), as well as the sugar content (100–133.6 gL⁻¹), the sweetness (12.9–17.6 °Brix), and the aroma profiles. Over 56 volatile compounds, predominantly alcohols (56%), aldehydes (24%), and terpenes (9%), were simultaneously quantified. Large variability among the genotypes was also statistically confirmed. The results indicate a strong potential for commercial exploitation of this germplasm, both as fresh and processed fruit, and highlight its versatility for diverse applications. The genetic diversity of the autochthonous pomegranate accessions represents a precious heritage to be preserved and enhanced. This work represents a preliminary step toward a more comprehensive characterization and qualitative valorization of the Italian pomegranate germplasm. Full article

Leaf spreading is a key processing step that affects the aroma formation of green tea. The effects of a single-light wavelength on the aroma and taste of tea have been extensively studied. Less attention has been paid to the effect of different complex light intensities on the formation of green tea’s volatile aroma during leaf spreading. The current study was designed to evaluate how leaf spreading under different complex light intensities relates to the quality of green tea. Using headspace solid-phase micro-extraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS), volatile flavor compounds in green tea were analyzed during leaf spreading in five different light conditions. Multivariate statistical analysis and odor activity values (OAVs) were used to classify these samples and identify key odors. Eight distinct groups, including ninety volatile compounds, were detected. The most prevalent volatile compounds found in green tea samples were hydrocarbons and alcohols, which accounted for 29% and 22% of the total volatile compounds, respectively. Fourteen volatile compounds (OAV > 1) were identified as key active differential odorants. The chestnut-like aroma in green tea was mostly derived from 3-methyl-butanal and linalool, which were significantly accumulated in medium-intensity light (ML). Full article

Monoterpenes are a class of volatile organic compounds that play crucial roles in imparting floral and fruity aromas to Muscat-type grapes. However, our understanding of the regulatory mechanisms underpinning monoterpene biosynthesis in grapes, particularly following abscisic acid (ABA) treatment, remains elusive. This study aimed to explore the impact of exogenous ABA on monoterpene biosynthesis in Ruiduhongyu grape berries by employing Headspace Solid-Phase Micro-Extraction Gas Chromatography–Mass Spectrometry (HS-SPME/GC–MS) analysis and transcriptome sequencing. The results suggested significant differences in total soluble solids (TSS), pH, and total acid content. ABA treatment resulted in a remarkable increase in endogenous ABA levels, with concentrations declining from veraison to ripening stages. ABA treatment notably enhanced monoterpene concentrations, particularly at the E_L37 and E_L38 stages, elevating the overall floral aroma of grape berries. According to the variable gene expression patterns across four developmental stages in response to ABA treatment, the E_L37 stage had the largest number of differential expressed genes (DEGs), which was correlated with a considerable change in free monoterpenes. Furthermore, functional annotation indicated that the DEGs were significantly enriched in primary and secondary metabolic pathways, underlining the relationship between ABA, sugar accumulation, and monoterpene biosynthesis. ABA treatment upregulated key genes involved in the methylerythritol phosphate (MEP) pathway, enhancing carbon allocation and subsequently impacting terpene synthesis. This study also identified transcription factors, including MYB and AP2/ERF families, potentially modulating monoterpene and aroma-related genes. Weighted gene co-expression network analysis (WGCNA) linked ABA-induced gene expression to monoterpene accumulation, highlighting specific modules enriched with genes associated with monoterpene biosynthesis; one of these modules (darkgreen) contained genes highly correlated with most monoterpenes, emphasizing the role of ABA in enhancing grape quality during berry maturation. Together, these findings provide valuable insights into the multifaceted effects of exogenous ABA on monoterpene compounds and grape berry flavor development, offering potential applications in viticulture and enology. Full article

The production of peanut oil in the industrial sector necessitates the utilization of diverse raw materials to generate consistent batches with stable flavor profiles, thereby leading to an increased focus on understanding the correlation between raw materials and flavor characteristics. In this study, sensory evaluations, headspace solid-phase micro-extraction gas chromatography mass spectrometry (HS-SPME-GC-MS), odor activity value (OAV) calculations, and correlation analysis were employed to investigate the flavors and main contributing amino acids of hot-pressed oils derived from different peanut varieties. The results confirmed that the levels of alcohols, aldehydes, and heterocyclic compounds in peanut oil varied among nine different peanut varieties under identical processing conditions. The OAVs of 25 key aroma compounds, such as methylthiol, 3-ethyl-2,5-dimethylpyrazine, and 2,3-glutarone, exceeded a value of 1. The sensory evaluations and flavor content analysis demonstrated that pyrazines significantly influenced the flavor profile of the peanut oil. The concentrations of 11 amino acids showed a strong correlation with the levels of pyrazines. Notably, phenylalanine, lysine, glutamic acid, arginine, and isoleucine demonstrated significant associations with both pyrazine and nut flavors. These findings will provide valuable insights for enhancing the sensory attributes of peanut oil and selecting optimal raw peanuts for its production. Full article

Data processing and data extraction are the first, and most often crucial, steps in metabolomics and multivariate data analysis in general. There are several software solutions for these purposes in GC-MS metabolomics. It becomes unclear which platform offers what kind of data and how that information influences the analysis’s conclusions. In this study, selected analytical platforms for GC-MS metabolomics profiling, SpectConnect and XCMS as well as MestReNova software, were used to process the results of the HS-SPME/GC-MS aroma analyses of several blackberry varieties. In addition, a detailed analysis of the identification of the individual components of the blackberry aroma club varieties was performed. In total, 72 components were detected in the XCMS platform, 119 in SpectConnect, and 87 and 167 in MestReNova, with automatic integral and manual correction, respectively, as well as 219 aroma components after manual analysis of GC-MS chromatograms. The obtained datasets were fed, for multivariate data analysis, to SIMCA software, and underwent the creation of PCA, OPLS, and OPLS-DA models. The results of the validation tests and VIP-pred. scores were analyzed in detail. Full article