Search Results (160)

The aim of this study was to investigate the dynamic changes in physicochemical properties, microbial community, metabolite profiles, and volatile compounds in watermelon soybean paste (WSP) during natural fermentation. Results showed that total acids, amino nitrogen, reducing sugar content, and umami-taste amino acids were significantly increased in WSP samples during the fermentation process. Various bacterial communities, including Enterobacter, Bacillus, Staphylococcus, Enterococcus, Weissella, and Lactobacillus, were detected as dominant genera. A total of 804 metabolites, mainly including lipids (18.78%) and amino acids and their derivatives (13.56%), were detected across the different fermentation stages. The correlation analysis between volatile compounds and bacterial community at the genus level revealed that 2-methylisoborneol, 1-octen-3-ol, benzene acetaldehyde, tetramethylpyrazine, and phenylethyl alcohol strongly correlated with Enterococcus, Bacillus, Weissella, and Pseudomonas. This study revealed the dynamics of the bacterial community and volatile compounds in the fermentation process and demonstrated their inter-relationship during WSP fermentation. Full article

Cosmetic preservatives should have reduced percutaneous absorption to lower the risk of systemic exposure and skin irritation. In this work, previously synthesized galactosylated derivatives of common cosmetic preservatives were comparatively evaluated for transdermal permeation and preliminary toxicity. Escherichia coli β-galactosidase was used to enzymatically modify several of the commonly used cosmetic preservatives to produce their corresponding galactosylated derivatives: benzyl alcohol β-d-galactopyranoside 7, 2-phenoxyethanol β-d-galactopyranoside 8, chlorphenesin β-d-galactopyranoside 9, 1,2-hexanediol β-d-galactopyranoside 10, 1,2-octanediol β-d-galactopyranoside 11, and 2-phenylethyl β-d-galactopyranoside 12. HPLC and NMR spectroscopy were used to analyze the previously synthesized derivatives. The Franz diffusion cell assay was used to evaluate skin penetration. 2-Phenoxyethanol (PE), chlorphenesin (CPN), and 2-phenylethanol (PhE), showed measurable skin penetration, with flux values ranging from 3.82 to 7.34 µg·h⁻¹·cm⁻² and permeability coefficients (Kp) between 1.38 and 3.00 × 10⁻³ cm·h⁻¹. In contrast, their galactosylated derivatives showed markedly reduced permeation under the same experimental conditions. Moreover, brine shrimp lethality assays indicated that galactosylated derivatives had significantly higher LD₅₀ values (1.6–2.1 mg/mL) than their parent compounds (0.1–0.79 mg/mL), suggesting lower cytotoxicity. These findings suggest that enzymatic galactosylation can significantly decrease skin permeability and the toxicity of cosmetic preservatives, highlighting its potential approach to improve the safety of cosmetic components. 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

This study evaluated the aroma and antioxidant properties of single-origin chocolate produced from cocoa beans sourced from seven regions in Indonesia. Two roasting approaches—dynamic and static—were applied, followed by small-scale chocolate processing using a melanger. Both raw cocoa beans and resulting chocolates were comprehensively characterised to examine relationships between raw material quality and final product attributes. The results show that the cocoa beans exhibited significant regional variation in physicochemical properties, including moisture, protein, pH, phenolic and flavonoid contents, antioxidant activity, and the fermentation index. These differences were reflected in the chocolates, which showed distinct appearance, aroma profiles, and antioxidant capacities. Roasting methods significantly influenced moisture content, colour, and antioxidant properties, with static roasting yielding chocolates with higher moisture, greater antioxidant retention, and lighter colour compared to dynamic roasting. Gas chromatography–mass spectrometry (GC–MS) analysis identified key volatile compounds such as acetic acid, 2-phenylethyl acetate, phenylethyl alcohol, acetoin, and pyranone as dominant contributors to aroma. Regional origin and processing conditions play critical roles in defining the quality of a single-origin chocolate. The knowledge obtained in this study can support the chocolate industry by enabling raw material selection, optimising roasting strategies, and standardising processes to achieve targeted quality attributes. Full article

This study aimed to provide a comprehensive characterization of floral volatile organic compounds (VOCs), perform systematic comparative analysis among multiple fragrant camellias, and establish a classification framework based on aroma components for cultivars derived from Camellia Sect. Theopsis. Volatile compounds were analyzed from 21 fragrant camellias using headspace solid-phase microextraction coupled with gas chromatography–time-of-flight mass spectrometry (HS-SPME-GC-TOFMS), followed by cluster and correlation analyses. A total of 51 volatile compounds were identified, including 20 alcohols, 15 aldehydes, and five esters, among which 27 were designated as major aroma components. Alcohols were the dominant class, and phenylethyl alcohol was detected in all cultivars, with a relative abundance ranging from 1.30% to 45.86%. Certain compounds, such as eugenol and 2-pentylfuran, exhibited cultivar-specific enrichment. Cluster analysis revealed a high degree of similarity in volatile profiles, with the strongest correlation observed between Camellia ‘Himenoka’ and Camellia ‘Minato-no-haru’ (r = 0.97). This similarity may be associated with a shared parental background, particularly the frequent use of Camellia lutchuensis in breeding. These findings provide a systematic understanding of floral VOC composition and offer a chemical basis for the utilization of Camellia Sect. Theopsis germplasm in fragrance-oriented breeding. Full article

Jimo Huangjiu (JMHJ), a Chinese geographical indication product from Shandong Province, is characterized by distinctive burnt-like and smoky aromas. However, the specific odorants responsible for these sensory attributes remain uncharacterized. In this study, the flavor characteristics of Jimo Huangjiu are characterized through static and dynamic sensory evaluation during the drinking process. This study identified the essential odorants of JMHJ through integrated sensomics analysis. Results revealed pyrazines and phenolic compounds as the characteristic aroma markers responsible for the unique smoky and burnt-like aroma of JMHJ. Ethyl 2-methylpropionate, 4-methylphenol, 4-ethyl-2-methoxyphenol, β-phenylethyl alcohol, 2-ethyl-6-methylpyrazine, 2-ethyl-3-methylpyrazine, 2-methylpyrazine, 2-methoxyphenol, 2-methylphenol, 2,3-dimethylpyrazine, and 2-hydroxy-3-methyl-2-cyclopentenone were confirmed as key odorants in JMHJ. Furthermore, the synergistic interactions between nonanoic acid and phenolic compounds were found to contribute to a Qu-like aroma, representing a novel mechanism for this characteristic sensory attribute in Huangjiu. Full article

The wine aromatic profile is influenced by complex interactions between grapevine genotype and enological practices. Thus, the aim of this study was to investigate the combined effects of grapevine clones and yeast strains on the volatile composition and sensory properties of wines produced from the Croatian indigenous variety Moslavac. Wines from five registered Moslavac clones (PUS-017, PUS-026, PUS-030A, PUS-087, and PUS-111) were produced using two commercially available yeast strains (Lalvin QA23 and Zymaflore Xarom). Significant effects of both clone and yeast strain were observed, particularly for yeast-derived compounds, such as isoamyl alcohol, phenylethyl alcohol, and medium-chain fatty acids. Ester production was generally enhanced by the Xarom yeast strain, although clone differences were also observed. Grape-derived volatile compounds differed significantly among clones, with wines from clones PUS-030A and PUS-087 having higher concentrations of norisoprenoids and terpenes, while PUS-017 wines consistently displayed lower concentrations of volatile compounds. Furthermore, PCA and MLF analyses revealed a clear differentiation between clones, with the yeast strain having a secondary modulatory effect. The sensory results were consistent with chemical data, demonstrating that clonal selection plays a key role in defining aromatic expression and typicity of Moslavac wines. Full article

The brewing of Traditional Hakka Huangjiu (THHJ) is usually divided into saccharification and post-fermentation. Microbial succession during saccharification is the major factor influencing the development of the volatile and non-volatile substances in THHJ during post-fermentation. This study systematically investigated the dynamic changes in microbial community, volatile substances and microbial metabolites by using absolute quantitative sequencing and multi-omics analysis. This study also reported that the correlation between microorganisms and substance biosynthesis was analyzed using PICRUSt. Absolute quantitative sequencing results showed that Pediococcus, Saccharomycopsis, Rhizopus, Weissella, and Limosilactobacillus were the dominant microbial genera during saccharification. 737 volatile compounds (170 esters, 94 hydrocarbons, 82 organoheterocyclic compounds) and 4370 metabolites (18 organic acids, 22 amino acids, 1124 peptides and 9 categories of functional compounds) were identified throughout the post-fermentation period. Sensory profiling revealed six main flavor attributes (Balsamic, sweet, rose, green, fruity, bitter) in THHJ and phenylethyl alcohol exerted the most prominent effect on the overall flavor of THHJ. Correlation analysis revealed that the biosynthesis of phenylethyl alcohol was potentially correlated with Saccharomyces, Cyberlindnera, Pichia, Pediococcus, Pseudomonas and Lactococcus. The biosynthesis of flavonoids was potentially correlated with Pediococcus, Lactococcus, and Lactiplantibacillus. These findings contribute to monitoring product quality and optimizing the processing techniques of THHJ. Full article

This study investigates the influence of grape pomace pressing on the chemical composition and sensory characteristics of Trepat grape pomace distillates from two consecutive vintages (2012 and 2013). Distillates obtained from pressed pomace showed higher ethanol strengths than those from unpressed pomace (64% v/v versus 54% v/v) and higher concentrations of several volatile compounds, including methanol, hexanols, aldehydes, and acetate esters. In contrast, distillates from unpressed pomace retained higher levels of terpenes and farnesols. Principal component analysis (PCA) highlighted differences among samples according to both vintage and pomace treatment, reflecting technological and vintage-dependent variability. Pressed pomace distillates contained higher concentrations of fruity and floral acetate esters (2-phenylethyl acetate and 3-methylbutyl acetate) than unpressed pomace distillates; however, sensory evaluation by an expert panel indicated that their fruity expression was often masked by undesirable notes such as rancid and solvent-like aromas. Unpressed distillates tended to be described as more harmonious and mellow and were perceived as having higher overall quality. Although several compounds exceeded their odor activity values (OAV > 1), their potential positive sensory contribution was frequently counterbalanced by elevated concentrations of aldehydes and higher alcohols. Overall, the results indicate that pomace pressing influences the volatile composition of Trepat pomace distillates and may affect sensory balance, suggesting that careful control of pressing conditions could contribute to improving the aromatic quality of grape pomace spirits. Full article

Nowadays, there is a global trend of consuming lower-alcohol beverages, while there is a market trend for consuming ready-to-drink products. The present study describes the development of new alcoholic beverages by the simple addition of rose water to the traditional marc spirit tsipouro. New beverages have lower alcohol content (30% v/v) than the mother tsipouro (40% v/v), exhibiting noteworthy antioxidant activity. Tsipouro–rose water beverages exhibited several aroma volatiles which originated from rose water, as determined by SPME GC-MS. Among them were the phenylethyl alcohol, eucalyptol, linalool, citronellol, geraniol, alpha-terpineol, which are known as rose water aroma compounds. The antioxidant activity of tsipouro–rose water beverages as estimated by the Folin, FRAP and DPPH assays appeared to be higher than the diluted tsipouro of the same alcohol content in a dose-dependent manner after mixing and after storage for 30 and 60 days. Preliminary organoleptic evaluation indicated that tsipouro–rose water products exhibit a rose-like aroma and were of acceptable organoleptic quality, especially that with a lower concentration of rose water. Full article

Biocontrol, a practice for using living organisms to target plant pathogens, offers a promising, sustainable agricultural strategy. This study involves epiphytic yeasts isolated from Vitis vinifera ssp. sylvestris and ssp. vinifera as natural antagonists against Aspergillus carbonarius, Botrytis cinerea, and Penicillium expansum. Twenty-one of 37 yeasts were chosen based on the Pathology Intensity (PA) score during preliminary in vivo screening. Following identification, dual-culture assays, VOC production, copper tolerance, and commercial fungicide resistance were assessed. On YPD and GJ medium, Saccharomyces isolates were the strongest antagonists, whereas P. terricola UMY197 inhibited Penicillium and Aspergillus. H. uvarum UMY1473 was notably effective against B. cinerea. VOC analysis confirmed that S. cerevisiae UMY1430 was the most effective against Aspergillus, likely owing to its production of oxalic acid, while S. cerevisiae UMY1438 was a producer of various esters and phenylethyl alcohol. C. intermedia UMY189, M. pulcherrima UMY1472, H. uvarum UMY1473, and S. cerevisiae UMY1436 were the most copper-resistant. Yeast activity on chemical fungicide SWITCH (up to 1 g/L) depended on culture media usage; in fact, a higher viability on YPD than on GJ was observed, where only 4 yeasts were able to grow. Thus, since several yeasts exhibit promising inhibitory activity through various mechanisms and against different molds, the use of synthetic consortia could represent a powerful and essential tool in field trials to limit fungicide use while preventing the emergence of resistance. Full article

Objectives: The aroma profile is a key determinant of fruit quality. Methods: In this study, mature ‘Summer Black’ grape berries were collected from 36 major producing areas in southern China to evaluate regional differences in fruit quality, volatile compounds were analyzed by via GC-MS, and a representative volatile profile was established. Furthermore, transcriptome sequencing was employed to identify key genes involved in the phenylpropanoid biosynthesis pathway related to aroma formation. Results: The results showed the following: (1) Samples from CD-2 exhibited the highest soluble solid content and the largest TSS/TA ratio. (2) A total of 20 volatile compounds were selected as indicators for the aroma fingerprint. MS-1 samples contained the most diverse aroma compounds (19 types), while CS-2 had the fewest (12 types). (3) Eight aroma compounds were consistently detected across all regions: hexanal, trans-2-hexenal, n-hexanol, β-citronellol, geraniol, nerol, benzyl alcohol, and phenethyl alcohol. Among these, hexanal and trans-2-hexenal were the most abundant; phenylethyl alcohol exhibited the most significant variation in percentage content across all samples, and was determined to be the representative and dominant volatile compound in ‘Summer Black’ grapes. (4) A transcriptome analysis of six representative regions identified 15 differentially expressed genes associated with phenylpropanoid biosynthesis and metabolism. Among them, PAO (Vitvi04g01467) was significantly correlated with phenethyl alcohol content. Conclusions: These findings provide a basis for evaluating the aroma quality of ‘Summer Black’ grapes and offer insights for regional cultivation selection. Full article

Milk beer, a modern Chinese dairy beverage, is usually fermented by the co-culture of lactic acid bacteria (LAB) and Kluyveromyces marxianus (K. marxianus), with the latter known for its ability to produce aroma compounds. However, the accumulation of lactic acid produced by LAB can inhibit the growth of K. marxianus, which inevitably hinders the diversity and intensity of flavor compounds in milk beer. In this study, adaptive laboratory evolution (ALE) was applied to the parental strain Kluyveromyces marxianus CICC1953 (Km-P) under different concentrations of lactic acid to obtain an evolved strain Km-ALE-X20 with enhanced acid tolerance and increased titer of phenylethyl alcohol, which has a floral, rose-like aroma. Km-ALE-X20 demonstrated a 16-fold increase in OD₆₀₀ and a 28-fold increase in phenylethyl alcohol production compared with Km-P in chemically defined medium (CDM) containing 20 g/L lactic acid. Comparative genomics analysis suggested that mutated genes CTA1, TSL1, ERG2 were related to enhanced acid tolerance, while ARO8, ARO9, FKS2 were related to increased production of aroma compounds. Furthermore, Km-ALE-X20-fermented milk beer showed 33.87% and 32.43% higher production in alcohol and ester compounds than that of Km-P-fermented milk beer. Interestingly, sensory analysis showed that while Km-ALE-X20-fermented milk beer had higher sensory scores for rose and fruity aroma attributes, Km-P-fermented milk beer possessed a more balanced aroma profile. This paper highlights the first application of ALE to enhance the signature rose aroma of K. marxianus-fermented milk beer and provides an efficient framework for ALE-based breeding of aroma-producing food microorganisms. Full article

The color and scent of flowers are vital ornamental attributes influenced by a complex interaction of metabolic and transcriptional mechanisms. Comparative analyses were performed to determine the molecular rationale for these features in Hydrangea arborescens, between the white-flowered variety ‘Annabelle’ (An) and its pink-flowered variant ‘Pink Annabelle’ (PA). Gas chromatography–mass spectrometry (GC–MS) detected 25 volatile organic compounds (VOCs) in ‘An’ and 21 in ‘PA’, with 18 chemicals common to both types. ‘An’ exhibited somewhat higher VOC diversity, whereas ‘PA’ emitted much bigger quantities of benzenoid and phenylpropanoid volatiles, including benzaldehyde, benzyl alcohol, and phenylethyl alcohol, resulting in a more pronounced floral scent. UPLC–MS/MS metabolomic analysis demonstrated obvious clustering of the two varieties and underscored the enrichment of phenylpropanoid biosynthesis pathways in ‘PA’. Transcriptomic analysis revealed 11,653 differentially expressed genes (DEGs), of which 7633 were elevated and linked to secondary metabolism. Key biosynthetic genes, including PAL, 4CL, CHS, DFR, and ANS, alongside transcription factors such as MYB—specifically TRINITY_DN5277_c0_g1, which is downregulated in ‘PA’ (homologous to AtMYB4, a negative regulator of flavonoid biosynthesis)—and TRINITY_DN23167_c0_g1, which is significantly upregulated in ‘PA’ (homologous to AtMYB90, a positive regulator of anthocyanin synthesis), as well as bHLH, ERF, and WRKY (notably TRINITY_DN25903_c0_g1, highly upregulated in ‘PA’ and homologous to AtWRKY75, associated with jasmonate pathway), demonstrating a coordinated activation of color and fragrance pathways. The integration of metabolomic and transcriptome data indicates that the pink-flowered ‘PA’ variety attains its superior coloring and aroma via the synchronized transcriptional regulation of the phenylpropanoid and flavonoid pathways. These findings offer novel molecular insights into the genetic and metabolic interplay of floral characteristics in Hydrangea. Full article

Pelargonium graveolens (rose geranium) essential oil contains numerous aroma-active esters that are challenging to identify at low abundance. We obtained by preparative chromatography an ester-rich fraction of the essential oil and constructed a synthetic reference library of 159 structurally related esters (spectral/GC data provided; 102 newly synthesized). This enabled dereplication and detection of constituents not apparent in direct GC–MS of the unfractionated oil. Nine esters (5-methylhexyl formate, (Z)-hex-3-en-1-yl 3-methylpentanoate, 3-methylbutyl 3-methylpentanoate, 3-methylpentyl 4-methylpentanoate, 5-methylhexyl hexanoate, 3-methylbutyl 6-methylheptanoate, 2-phenylethyl 6-methylheptanoate, 5-methylhexyl tiglate, and 6-methylheptyl tiglate) were confirmed as new natural products (eight of them new compounds overall), by combined evidence from retention indices, EI mass spectra, co-injections with synthesized references, and, in selected cases, by 1D/2D NMR. Systematic RI trends across acid and alcohol isomers were delineated, aiding rapid differentiation of regio-isomeric esters that share similar EI patterns. This library-guided workflow offers a robust path to differentiate structurally close volatiles in complex matrices and provides transferable RI/spectral benchmarks for future natural product identification. Full article