Search Results (932)

Due to their diverse phytochemical composition, medicinal plants belonging to the families Amaryllidaceae, Lamiaceae, and Myrtaceae possess antimicrobial and antioxidant properties. In this study, six ethanolic extracts of Allium ursinum, Allium sativum, Allium cepa, Salvia rosmarinus, Ocimum basilicum, and Syzygium aromaticum were analyzed by HS-SPME GC-MS and HPLC. Their chemical composition was evaluated and compared by chemometrics and their biological activity determined by an antimicrobial assay. A total of 72 compounds was detected (terpenoids, phenolic derivatives, fatty acids, and phytosterols). In Allium species, phytosterols were mainly abundant, whereas O. basilicum extracts were characterized by high contents of linalool and S. rosmarinus by 2-hydroxychalcone and 4-hydroxybutanoic acid lactone. Principal component analysis distinguished chemically species-specific chemical profiles, whilst the HPLC evaluation resulted in the highest quercetin content in S. rosmarinus extracts, which also displayed the best antibacterial effect against Staphylococcus aureus. Despite the observed correlation between the quercetin content and antibacterial activity, no definitive relation could be established without biological replicates, MIC evaluation, and tests with isolated compounds. Full article

Sauce-aroma Baijiu is produced through a one-year cyclic process involving multiple fermentations and distillations. However, the dynamic changes and correlations among fermented grains (FG), distilled fermented grains (DG), heart liquor (HL) and tail liquor (TL) remain unclear. In this study, the physicochemical indicators and volatile compounds (VCs) from the 3rd to 6th distillation rounds were systematically analyzed. Across successive rounds, FG and DG exhibited similar trends in key physicochemical indicators, as did HL and TL. Headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME/GC-MS) identified 76, 73, 80 and 93 VCs in FG, DG, HL and TL, respectively. Multivariate statistical analyses revealed significant inter-round differences in volatile profiles, and further indicated that total acids and water contents in FG were positively correlated with the majority of VCs in liquor. These results clarify the dynamic change of physicochemical and flavor components during Baijiu production and provide a basis for quality evaluation. Full article

Polishing enhances the appearance and market competitiveness of rice. To better understand the effect of polishing on rice flavor, volatile flavor compounds in polished rice (PR), unpolished rice (UR), cooked polished rice (CPR), and cooked unpolished rice (CUR) were examined using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS). The results revealed fourteen volatile flavor compounds displayed significant differences in abundance, with eight of these compounds potentially contributing to the overall flavor profile based on their volatility and reported odor characteristics. Among these compounds, only eicosane and hexanal were detected in uncooked rice, whereas acetophenone, hexadecanol, dodecane, and octadecane were unique to CUR. Four compounds were associated with aroma notes reminiscent of flowers, wax, and almond, among others. However, nonanal and nerol were common in both cooked rice samples, and they may contribute to a sweet-like aroma in cooked rice. These findings illuminate the changes in volatile composition, offer insights to prevent over-polishing, and inspire further research toward producing rice with potentially improved aroma profiles. Full article

This study investigates the breeding of the German wine yeast Oppenheimer Kreuz 1894, which carries a FOT1 allele of a fungal oligopeptide transporter, with Freya, a Kveik ale yeast, to enhance fermentation performance and aroma in beer and wine. By combining Kveik traits (osmotolerance, thermotolerance, and rapid fermentation kinetics) with those of a German wine yeast (ethanol tolerance, broadened nitrogen utilization, and aroma production) and introducing FOT1 into an ale background via classical breeding, we aimed to leverage the Saccharomyces biodiversity to improve fermentation activity and expand aromatic complexity. Fermentation products and volatile aroma compounds were quantified by HPLC and HS-SPME-GC-MS. Spore clone derivatives of initial hybrid strains (F₂-generation) showed improved fermentation profiles with increased CO₂ production. In wine fermentations, the best-performing spore clone, GYBC 901, yielded a rich aromatic profile with elevated fruity and floral notes. In beer fermentations, GYBC 899 produced the most diverse and complex aroma. FOT1 was of minor relevance to the breeding outcome, whereas meiotic recombination generated a set of diverse spore clones. These results highlight the potential of strategic yeast breeding to optimize fermentation processes and tailor flavor profiles to diverse product targets. Future work will elucidate metabolic pathways underlying these phenotypes and advance the development of application-specific strains, offering avenues to enhance beverage quality and product differentiation in the fermentation industry. Full article

Phenolic compounds in Muscat grape juice contribute to antioxidant capacity, functional properties, and sensory quality; however, conventional enzymatic maceration is often limited in efficiency and typically requires elevated temperatures. This study systematically compared pectinase-assisted heat maceration (P45-HM), low-temperature pectinase maceration (P-CM), and low-temperature maceration mediated by the psychrotolerant yeast Metschnikowia pulcherrima (Mp-CM) in Muscat grape juice. Mp-CM significantly enhanced the extraction and transformation of phenolic compounds, with total phenolic and flavonoid contents increasing by 8.01% and 13.14%, respectively, compared with P-CM, and by 27.06% and 55.28%, respectively, compared with P45-HM. Moreover, Mp-CM exhibited higher antioxidant activities, as determined by DPPH, ABTS, and FRAP assays, as well as greater sodium glycocholate-binding capacity than P-CM (p < 0.05). Correlation analysis revealed strong positive correlations between phenolic composition and biological activities. Volatile compounds were analyzed by HS-SPME-GC-MS combined with principal component analysis (PCA), demonstrating distinct aroma profiles. Mp-CM was enriched in terpenes (14.63% higher than P-CM), whereas P-CM was dominated by esters, suggesting that M. pulcherrima possesses a distinct biotransformation capacity that modulates volatile compounds potentially contributing to the characteristic Muscat aroma. These findings indicate that Mp-assisted cold maceration represents an efficient and promising biological maceration strategy for enhancing the quality of grape juice. Full article

Crackers and cookies have become the most widely consumed snacks due to their low production costs, long shelf life, and ability to deliver essential nutrients. Increasing consumer health consciousness has shifted preferences toward foods perceived as natural and beneficial. This shift elevates demand for cracker formulations with novel, health-promoting natural ingredients. This study examined the effects of incorporating freeze-dried olive leaf powder (FDOLP) into crackers on their physicochemical properties, phenolic and volatile compound profiles, antioxidant capacity, and sensory acceptability. Total polyphenol content of crackers was determined using the Folin–Ciocalteu method, while antioxidant capacity was evaluated by FRAP and DPPH assays. The UHPLC-ESI-HRMS analysis evaluated olive-derived compounds, including tyrosol, oleuropein derivatives, and pinoresinol 4-O-glucoside, present in olive leaf-enriched crackers. The characterisation of volatile compounds in crackers was performed using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME/GC-MS). A darker colour was observed in the enriched crackers compared to the control samples. Results demonstrated that increasing the proportion of FDOLP led to enhanced phenolic composition and antioxidant activity, as well as changes in the volatile profile of the crackers. Sensory analyses indicated that crackers enriched with moderate levels of FDOLP maintained acceptable overall sensory scores, suggesting a potential for the development of functional snacks. These findings demonstrate that olive leaves can be effectively utilised as a natural functional ingredient in cracker formulations to enhance their nutritional value and bioactive properties. Full article

Seasonal variation in aroma quality is critical for commercial grading of Xinyang Maojian (XYMJ) green tea, and how seasonal changes shape its volatile composition and aroma profile remains unclear. This study investigated the volatile profiles of XYMJ harvested in spring, summer, and autumn using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and odor activity value (OAV) analysis. A total of 93 volatile compounds were identified, with alkenes, alcohols, and esters being the most numerous chemical classes. Total volatile content decreased significantly seasonally (p < 0.05), being highest in spring (1716.68 μg/kg), followed by summer (1566.72 μg/kg) and autumn (1378.21 μg/kg). PCA and PLS-DA clearly distinguished seasons. Using a dual-filtering strategy (variable importance in the projection > 1.0 and p < 0.01), 14 differential volatile metabolites were identified as core seasonal markers. Geraniol, cis-jasmone, and indole were identified as key drivers of the premium floral fragrance in spring XYMJ, while cis-3-hexenyl hexanoate and linalool peaked in the summer harvest. OAV results and cross-modal sensory interaction principles suggest that the superior flavor of spring XYMJ arises from both higher aromatic intensity and an optimized aroma-taste balance. These findings provide useful insights into the seasonal variations in the metabolic and chemical profiles of XYMJ, enhancing our understanding of the biochemical markers associated with its production timeline. Full article

While withering is a critical processing step influencing the flavor profile of white teas, the effects of temperature-changing withering remain elusive. This study systematically investigated the variations in two withering methods (natural withering, temperature-changing withering) in volatile compounds of white teas made from four cultivars. The quality of white teas produced from ‘Mingshan No. 131’ (MS131), ‘Fuxuan No. 9’ (FX9), ‘Ziyan’ (ZY), and ‘Fudingdabai’ (FDDB) was evaluated using quantitative descriptive analysis (QDA), headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS), and odor activity value (OAV) analysis. The sensory evaluation results indicated that temperature-changing withering enhanced the development of sweet and fruity aromas while suppressing grassy notes. A total of 176 volatile compounds were identified, and temperature-changing withering induced significant alterations in the aroma profile, notably increasing the levels of ketones, esters, and alkenes (p < 0.05). Based on the criteria of OAV > 1, p < 0.05, and a fold change ≥ 1.5 (for upregulated compounds) or ≤0.67 (for down-regulated compounds), key volatile compounds in white teas from the four cultivars were identified. The common upregulated volatile compounds, namely 1-octen-3-one, cedrol, (E,E)-2,4-heptadienal, and (E)-2-hexenal, promoted the fresh flavor profile of white teas. These findings demonstrate that temperature-changing withering optimizes flavor-related metabolites, thereby providing a theoretical foundation for improving white tea processing. Full article

Musalais is a traditional fermented beverage of the Uyghur people in Xinjiang, China. Its production involves boiling grape juice at high temperatures to concentrate it and enhance its sugar content, followed by natural fermentation. However, this high-temperature concentration process leads to a significant loss of bioactive and flavor compounds, adversely affecting the quality of the final product. Adding composite ingredients may help mitigate this quality decline. This study compares Musalais new product with traditional Musalais. Phenolic analysis showed that total monomeric phenols were 182.36 mg·L⁻¹ in the new product versus 14.76 mg·L⁻¹ in traditional Musalais. Headspace solid-phase microextraction/gas chromatography–mass spectrometry (HS-SPME/GC-MS) identified 72 volatile compounds in the new product (total content of 569,848.88 μg·L⁻¹) compared to 58 compounds (total content of 362,774.17 μg·L⁻¹) in traditional Musalais. Compared to traditional Musalais, the new product exhibits a 24.14% increase in volatile compound variety and a 57.09% increase in total concentration, with more pronounced floral, fruity, and vinous aromas, as well as higher sensory scores. Non-targeted metabolomics suggests that the new product may have superior phenolic and volatile profiles. Full article

To investigate how spreading conditions affect green tea taste and aroma and to develop a generalizable prediction model from small data for process optimization, this study integrated SEM, non-targeted dual-omics, and TabPFN to systematically analyze Echa No. 10 spreading. A central composite design was used. Dehydration-induced mechanical stress altered cell membrane permeability, driving non-volatile taste compound transformation and volatile aroma release. Two chemical-sensory proxies, relative polyphenol-to-amino acid ratio (R-PAR) and floral intensity index (FII), were established using ultra-high performance liquid chromatography–high-resolution mass spectrometry (UHPLC-HRMS) and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS). A prediction model was built with these indicators and TabPFN. Multi-objective optimization yielded optimum conditions: initial moisture 76.8%, temperature 26.2 °C, relative humidity 61.5%, air speed 0.85 m/s, achieving R-PAR 0.465 and FII 125.70. Compared with response surface methodology (RSM), partial least squares regression (PLSR), and support vector regression (SVR), TabPFN showed prediction R² of 0.81 and 0.77, showing favorable applicability and predictive capability on small-sample data. This study validates TabPFN’s suitability for small-sample tea processing modeling, quantifies the mapping between spreading and key taste/aroma metabolism, and provides a methodological foundation for digital precision and intelligent optimization in green tea production. Full article

Silicon (Si) amendment can enhance plant resistance to biotic stress, yet its role in tri-trophic interactions under multiple herbivore attack remains unclear. This study examined how Si influences herbivore-induced plant volatiles (HIPVs) and the foraging behavior of the predatory mirid Cyrtorhinus lividipennis that preys on eggs of the white-backed planthopper (WBPH; Sogatella furcifera). A 2 × 2 factorial design was employed to test the effects of Si amendment (+Si vs. −Si) and the striped stem borer (SSB; Chilo suppressalis) infestation (+SSB vs. −SSB) on plant volatile emissions and predator behaviors, with WBPH infestation present in all treatments. Cage and Y-tube experiments showed higher predator attraction and increased WBPH egg predation in +Si+SSB treatment relative to −Si+SSB treatment. HS-SPME-GC/MS analysis revealed that, regardless of Si amendment, SSB infestation massively altered the overall volatile profile, while Si amendment reduced emission of many volatiles in SSB infested plants. Single compound bioassays further identified that, regardless of Si amendment, SSB infestation significantly up-regulated four repellents for C. lividipennis. Compared with the −Si+SSB treatment, the +Si+SSB treatment down-regulated one repellent volatile and up-regulated three attractant volatiles. These findings indicate that Si amendment potentially enhances biocontrol of the subsequent herbivore under dual herbivory through altering HIPV emissions induced by the prior herbivory. Full article

This study presents a novel analytical approach combining headspace solid-phase microextraction (HS-SPME) with gas chromatography–mass spectrometry (GC–MS) and advanced chemometric techniques to detect adulteration in coriander honey. A total of 34 volatile compounds were identified and quantified, revealing a progressive decrease in both profile complexity and compound abundance with increasing levels of invert sugar and high-fructose corn syrup (HFCS) adulteration. Chromatographic and chemometric analyses effectively distinguished authentic from adulterated samples, with the Extreme Gradient Boosting (XGBoost) model achieving a high classification performance of 95.83% accuracy. The study highlights the critical impact of adulteration on honey’s chemical composition and confirms the efficacy of integrating modern analytical and machine learning tools for rapid, sensitive, and reliable honey authenticity assessment. This methodology offers a valuable framework for food quality control and fraud prevention, addressing current challenges in the honey market and protecting consumer interests. Full article

The flavor profile of Longmen rice vinegar directly influences consumer purchase intention, and understanding its variation during fermentation is crucial for final product quality control. In this study, the flavor dynamics during the fermentation of Longmen rice vinegar were systematically investigated. Sensory evaluation indicated that acidity increased significantly during the acetic acid fermentation stage, while alcoholic and fermented odors decreased continuously. Instrumental analysis identified 129 volatile compounds, predominantly esters, alcohols, and acids. Based on relative odor activity value (r-OAV) analysis, acetic acid, 3-methylbutyl acetate, 2,3-butanedione, benzeneacetaldehyde, phenethyl alcohol, ethyl acetate, 2-phenylethyl acetate, ethyl 4-methyl-pentanoate, 3-methyl-1-butanol, and 3-methylbutanal were determined to be the major contributors to the overall aroma. Orthogonal partial least-squares discriminant analysis (OPLS-DA) further screened 21 key differential compounds. Significant variations in organic acid and amino acid contents during fermentation were also observed. Correlation analysis revealed relationships between key aroma compounds and organic, as well as amino, acids. These findings establish a foundation for monitoring flavor dynamics during the fermentation of Longmen rice vinegar. Full article

The chemical composition and sensory profile of coffee are influenced by brewing method, namely extraction pressure, temperature, contact time, and equipment. This study compared coffee prepared with a traditional moka pot, a conventional espresso machine, and a novel Italian device (Kamira). Volatile compounds were analyzed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC–MS), leading to the determination of furan (34–42%), pyrrole (4–10%), and pyrazine (13–14%) derivatives. The most abundant fatty acids were palmitic (36–37%), linoleic (40%), and oleic (11%) acids. Physicochemical parameters (total solids, pH, and refractive index) were also measured. Caffeine and chlorogenic acids were quantified by liquid chromatography (HPLC). Differences in chlorogenic acids and volatile compounds were associated with variations in bitterness, acidity, astringency, and aroma intensity. Finally, a trained panel performed sensory evaluation to evaluate the olfactory and flavor attributes of the three types of coffee brews. Significant differences emerged among brewing systems. Espresso showed the highest caffeine content (55.3 ± 4.1 mg/100 g) and total solids (2.61 ± 0.11 g/100 g), together with a stable crema and intense sensory attributes. Moka coffee exhibited a rich aromatic profile but limited crema. The Kamira device produced an abundant crema and a chemical profile partially comparable to espresso. These findings confirm that brewing technology markedly affects coffee composition and sensory perception. Full article

This study proposes an integrated and more circular management approach, grounded in the principles of sustainable and green chemical processes, for the food waste leachates management, combining the assessment of biomethane production potential via anaerobic digestion with the evaluation of value-added compound recovery through extraction processes. The food waste leachates were characterized, while total carotenoid profile and total phenolic content were quantified using liquid–liquid extraction with mixed organic solvents. An HS-SPME coupled with GC–MS was employed to identify volatile organic compounds present in the leachates. Prior to the extraction procedure, D-limonene exhibited the highest abundance among identified volatiles. Crucially, the subsequent solvent extraction is highly likely to have effectively removed this inhibitory terpene from the liquid matrix. Extracted leachates exhibited a total carotenoid content of 0.64 mg/100 g and a total phenolic content of 127.0 μg/g, acting as preliminary indicators of significant potential for recovery and utilization in pharmaceutical and cosmetic applications. Biomethane potential tests were conducted in laboratory-scale anaerobic bioreactors using both raw food waste leachate and extracted food waste leachate. Comparable biomethane yields were obtained for both substrates, with FWL yielding 442.5 NmL/g VS_added and FWL_extr yielding 452.2 NmL/g VS_added. These results demonstrate that the liquid–liquid extraction of value-added compounds does not adversely affect biomethane production from food waste leachates enabling the recovery of valuable by-products. Full article