Search Results (163)

To investigate the effect of Botrytis cinerea infection severity on the flavor characteristics of Petit Manseng noble rot wine, this study analyzed wines produced from Petit Manseng grapes grown in the eastern foothills of Helan Mountain, Ningxia, China. The grapes were categorized into three groups based on infection status: uninfected, mildly infected, and severely infected with Botrytis cinerea. Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) and an electronic nose were employed to detect and analyze the aroma components of wines under the three infection conditions. Additionally, trained sensory panelists conducted sensory evaluations of the wine aromas. The results revealed that wines made from severely infected grapes exhibited the richest and most complex aroma profiles. A total of 70 volatile compounds were identified, comprising 32 esters, 17 alcohols, 5 acids, 8 aldehydes and ketones, 4 terpenes, and 4 other compounds. Among these, esters and alcohols accounted for the highest contents. Key aroma-active compounds included isoamyl acetate, ethyl decanoate, phenethyl acetate, ethyl laurate, hexanoic acid, linalool, decanoic acid, citronellol, ethyl hexanoate, and methyl octanoate. Sensory evaluation indicated that the “floral aroma”, “pineapple/banana aroma”, “honey aroma”, and “overall aroma intensity” were most pronounced in the severely infected group. These findings provide theoretical support for the harvesting of severely Botrytis cinerea-infected Petit Manseng grapes and the production of high-quality noble rot wine in this region. Full article

The quality of cider is influenced by its phenolic compound content. Apple pomace, an industrial by-product of cider production, is rich in bioactive compounds, including polyphenols. The objective of this study was to determine the potential of apple pomace addition during fermentation to increase the phenolic content in cider. Apple juice from Jonagold apples was divided into a control and three treatment groups. Control cider was fermented with 100% apple juice, while treatments were prepared with different additions of apple pomace to the apple juice. Ciders were fermented for 14 days, followed by chemical and sensory analysis. Ciders with apple pomace addition contained 31–61% higher phenolic compound concentrations than the control. The addition of apple pomace modified the volatile profile of the ciders. Treatment ciders contained higher concentrations of isoamyl alcohol, phenylethyl alcohol, and ethyl acetate, and lower concentrations of acetaldehyde. Ciders with apple pomace addition exhibited lower levels of astringency and sourness, and higher bitterness levels compared to the control. There was no difference in aroma perception and taste acceptance between the ciders. This study demonstrates the potential of apple pomace addition as a cidermaking technique for phenolic compound extraction and sensory profile modification. Full article

The bacterial microbial community composition during wine fermentation is a key contributor to wine quality and flavor. However, studies on the regulatory effects of different grape varieties and co-fermentation processes on the microbial community structure and their synergistic mechanisms remain limited. In this study, Cabernet Sauvignon (CS) was subjected to single-variety fermentation and used as the base wine for co-fermentation with three other grape varieties—Marselan (CSMN), Merlot (CSMT), and Cabernet Gernischt (CSCG)—to systematically compare the differences in the microbial community composition and their effects on the production of metabolic compounds. The results showed that, compared with single-variety fermentation, co-fermentation significantly increased the α-diversity of microbial communities (the Shannon index increased) and exhibited significant differences in β-diversity (PERMANOVA analysis, R² = 0.421, p < 0.001). A neutral model analysis indicated that co-fermentation had a significant impact on microbial community assembly mechanisms, with the contribution of neutral processes to community assembly increasing from 45.5% (in the CSCG process) to 62.3% (in the CSMT process). A microbial co-occurrence network analysis revealed that co-fermentation enhanced the network complexity of microbial communities and strengthened the synergistic interactions between microbial taxa. A metabolic compound analysis revealed that co-fermentation significantly enhanced the production of key aroma compounds, resulting in increased concentrations of isoamyl acetate, ethyl hexanoate, linalool, and geraniol. These findings highlight the differences in microbial communities and their synergistic mechanisms among co-fermented grape varieties, providing theoretical guidance and practical insights for optimizing co-fermentation processes and improving wine quality. Full article

This study aims to delve into the application potential of immobilized lipases in the catalytic synthesis of isoamyl acetate. Through a comparative analysis of various immobilization methods, including physical adsorption, encapsulation, covalent binding, and crosslinking, along with the utilization of nanomaterials, such as magnetic nanoparticles, mesoporous silica SBA-15, and covalent organic frameworks (COFs) as carriers, the study systematically evaluates their enhancing effects on lipase catalytic performance. Additionally, solvent engineering strategies, encompassing the introduction of organic solvents, supercritical fluids, ionic liquids, and deep eutectic solvents, are employed to intensify the enzymatic catalytic process. These approaches effectively improve mass transfer efficiency, activate enzyme molecules, and safeguard enzyme structural stability, thereby significantly elevating the synthesis efficiency and yield of isoamyl acetate. Consequently, this research provides solid scientific rationale and technical support for the industrial production of flavor ester compounds. Full article

Slugs are significant agricultural pests, causing extensive crop damage and economic losses. While chemical molluscicides are commonly used for control, concerns about their environmental impact have driven interest in alternative methods, including beer traps. This study evaluated the effectiveness of different beer types as attractants for slug trapping in field conditions over two consecutive years (2022–2023). Five types of beer—Union Lager, Paulaner Weissbier, BrewDog Punk IPA, Guinness Draught, and Chimay Blue—were tested alongside ethanol (10%) and a control treatment. The results demonstrated that Paulaner Weissbier and Union Lager were the most effective attractants, followed by Guinness Draught and Chimay Blue, while BrewDog Punk IPA had moderate effectiveness. Ethanol (10%) and the control treatment failed to attract slugs, confirming that volatile compounds, rather than alcohol alone, drive slug attraction. Gas chromatography–mass spectrometry (GC-MS) analysis revealed that Paulaner Weissbier contained high levels of isoamyl acetate and limonene, while Union Lager exhibited elevated ethyl esters, which likely contributed to their effectiveness. Environmental factors influenced slug activity, with higher temperatures correlating with increased slug capture rates, while precipitation had no significant effect. These findings highlight the role of fermentation-derived volatile compounds in slug attraction and suggest that optimizing beer traps based on beer composition and environmental conditions could improve their effectiveness as a non-chemical slug control method. Future research should explore the long-term stability of beer attractants, the potential of synthetic formulations, and alternative yeast-based attractants to enhance slug management strategies. Full article

The quality of artisanal bread is strongly influenced by sourdough fermentation, where aroma development and microbial stability are key factors. This study evaluates the use of an electronic nose (E-nose) to monitor cold fermentation, integrating it with microbiological analysis and gas chromatography–mass spectrometry (SPME-GC-MS) to characterize the dough’s volatile profile. A clear correlation was observed between microbial dynamics, pH reduction (from 5.8 to 3.8), and the evolution of volatile compounds, with notable increases in acetic acid (up to 12.75%), ethanol (11.95%), and fruity esters such as isoamyl acetate (33.33%). Linear discriminant analysis (LDA) explained 96.31% of the total variance in a single component, successfully separating the fermentation stages. An artificial neural network discriminant analysis (ANNDA) model achieved 95% accuracy in the validation phase. These results confirm the E-nose’s ability to track biochemical transformations in real time and identify optimal fermentation points. This approach enhances quality control and sensory standardization in sourdough-based bakery products. Full article

In recent years, numerous studies have demonstrated that non-Saccharomyces yeasts hold potential for industrial application and aroma generation during fermentation. Non-Saccharomyces wild yeasts can be important tools in the development of new products, and the objective of this work was to obtain and characterize novel yeast isolates for their ability to produce beer. Traditional fermented beverages serve as a vital source of yeast strains that can exhibit unique characteristics during the brewing process. Thus, 22 strains of Saccharomycopsis fibuligera were isolated from traditional fermented foods in this work. Subsequently, through primary and secondary screening, S. fibuligera G02 was identified as a promising candidate for beer brewing, attributed to its advantageous physiological traits and notable potential for beer production. Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC–MS) was employed to analyze the volatile flavor substances in beer fermented using the S. fibuligera G02 strain. Chemometric analysis revealed that S. fibuligera G02 had a unique influence on beer aroma. Accordingly, isoamyl alcohol, phenyl-1-ethanol, ethyl acetate, isoamyl acetate, and 4-ethyl guaiacol (4EG) were the key aroma components of S. fibuligera G02. This work provides useful insights into the non-Saccharomyces yeasts to reference the targeted improvement of beer aroma. Full article

Kluyveromyces marxianus is a yeast that can be used as a microbial factory. However, little is known about its response to stress conditions. This work evaluated the response of this yeast against ethanol, acetic acid, isoamyl alcohol, and hydrogen peroxide as stress agents. Cytotoxicity assays were performed to assess the residual viability using a direct method (CFU counting) and an indirect method based on the reduction in MTT. Then, fermentation kinetics were performed at IC30 and IC50 for each stress factor to evaluate the effect of moderate and intense stress. This work is the first report presenting IC50 values for ethanol (21.82 g/L), acetic acid (1.19 g/L), isoamyl alcohol (2.74 g/L), and hydrogen peroxide (0.09 g/L) in K. marxianus. The IC50 values for the indirect method are between 3.7 and 68% higher than those for the direct method. Hydrogen peroxide and ethanol were the stress agents showing the highest overestimations. The results presented here demonstrated the overestimation of cell viability by the indirect method. Direct CFU counting is an adequate method to determine yeast viability during toxicity studies of chemical compounds. It was also established that ethanol and hydrogen peroxide have the highest toxicity against K. marxianus ITD-01005 during fermentation at concentrations equivalent to IC30 and IC50 of each stress agent. Full article

Besides the other factors, the microclimate (terroir) influences the quality characteristics of wine. The Assyrtiko variety has adapted to the volcanic soil of Santorini but under climate change, finding an ideal location for full grape ripening represents a challenge in preserving the PDO quality of Santorini wines. Thus, this study aims to evaluate the effect of location and harvesting time on the quality of Assyrtiko wine. It assessed the location effect (three distant plots of land in three distant areas of the island) on the composition of grapes (water uptake, pH, sugar, and organic acid accumulation) during the ripening. The grapes were vinified using the same procedure. The aromatic volatile profile of the wines was evaluated with GC-MS. A two-way ANOVA revealed that besides location and harvest time, their interaction is also significant for the parameters studied, except for the interaction effect involving sugar content. The analysis of volatile aromatic compounds revealed that the wine from grapes harvested at a later date had a higher aromatic intensity with notes of citrus, white-fleshed, and tropical fruits. This wine surpasses the levels of 2-phenylethanol, isoamyl acetate, linalool, and 2-phenylethyl ester with 17.8%, 7.7%, 21.1%, and 15.6%, respectively, compared to the immediate next in descending order. Results suggest that the grape variety is better suited to the local climatic conditions when full grape ripeness is reached by the end of the growing season. Full article

Saccharomyces cerevisiae is one of the important species of traditional fermented foods and beverages. However, incorporating non-Saccharomyces in the fermentation process is a promising strategy to improve the organoleptic profile. In this study, we assessed the potential of a wild Pichia kluyveri strain (PKL) to augment the aromatic profile in beer brewing while maintaining high fermentation attenuation through inoculation with Saccharomyces cerevisiae var. diastaticus yeast (SY) in both simultaneous (SI-PKL/SY) and sequential (SE-3-PKL/SY) approaches. The fermentation performance was analyzed by residual sugar content, volatile organic compounds, and sensory evaluation. The results indicated that both co-fermentation methods yielded residual sugar levels comparable to those of SY monoculture fermentation. The 2-phenethyl acetate, isoamyl acetate, and linalool in SE-3-PKL/SY increased 12.00, 12.37, and 1.17 folds than the SY monoculture, respectively. Furthermore, the incremental concentrations of these compounds contributed to the highest acceptability and prominent fruity notes in the SE-3-PKL/SY coculture. The current study is the first to report on the co-fermentation with Pichia kluyveri and Saccharomyces cerevisiae var. diastaticus in beer brewing. These findings highlighted the importance of Pichia kluyveri in shaping the ameliorative aroma profile of fermentation production. Full article

Marselan wine is characterized by distinctive flavors of blackcurrant, cranberry, and spice, which are significantly influenced by environmental factors such as region and climate. In this study, we analyzed the dynamic changes in the microbial community, physicochemical indices, and flavor compounds during the spontaneous fermentation of Marselan wine in Xinjiang using high-throughput sequencing (HTS), high-performance liquid chromatography (HPLC), and headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS). The results indicated that the sugar content decreased from 259.12 g/L to 22.45 g/L, while the ethanol content increased to 13.63 ± 0.15% vol after 12 days of fermentation. The predominant aromatic components identified in Marselan grapes include isophorone, 2,3-pentanedione, 2-hexenal, and melonal. After fermentation, ethanol, phenethyl alcohol, isoamyl acetate, ethyl acetate, and ethyl hexanoate were produced, imparting rose, cream, and fruit flavors to wine. The key microorganisms involved in the spontaneous fermentation of Marselan wine include Saccharomyces, Starmerella, Pichia, Pseudomonas, Sphingomonas, and Aspergillus. These microorganisms contributed substantially to the main physicochemical indices and flavor profiles. Saccharomyces and Pichia enhanced the formation of most alcohols and esters, whereas Aspergillus, Acremonium, and Fusarium inhibited the synthesis of numerous volatile compounds. These findings provide valuable theoretical references for improving the quality of Marselan wines in Xinjiang. Full article

Greek wines made from the indigenous grape varieties Assyrtiko, Malagousia, Moschofilero and Roditis are attracting the interest of wine producers and consumers due to their aromatic characteristics. However, there are few studies that focus on the unique wine characteristics of each variety and the relationship between the composition of volatile compounds and sensory properties. Monovarietal white wines (2018 vintage) were analyzed by gas chromatography–mass spectrometry to quantify 34 volatile compounds. Multivariate statistical analyses were used to investigate correlations between volatiles and sensory attributes identified by a trained panel. The results showed that the strongest aroma compounds were a group of terpenes, isoamyl acetate and phenylethyl acetate. Terpenes such as geraniol, α-terpineol, linalool and cis-rose oxide correlated with floral notes, especially in Moschofilero wines. In addition, isoamyl acetate contributed to the aroma of tropical fruits, especially banana, in the Roditis wines, while phenylethyl acetate correlated with rose, vanilla and fruity notes in both the Moschofilero and Roditis samples. The Assyrtiko wines and the Malagousia wines were mainly associated with compounds such as cis-3-hexen-1-ol and cis- and trans-furan linalool oxides, which may enhance fresh fruit and citrus aromas through synergistic effects. The common background aroma of the studied wines was mainly determined by higher alcohols, fatty acids and ethyl esters. This study provides a basis for understanding the typical aroma of white wines from indigenous Greek grape varieties, which will help producers develop targeted wine styles and will be useful for consumer promotion. Full article

This study aimed to isolate a thermotolerant acetic acid bacteria (AAB) strain from Zhenjiang aromatic vinegar (ZAV) and evaluate its potential as a starter culture for high-temperature solid-state vinegar fermentation. Acetobacter pasteurianus TCBRC 103 was successfully isolated and demonstrated superior thermotolerance compared to the industrial strain A. pasteurianus Huniang 1.01. A. pasteurianus TCBRC 103 exhibited robust growth and acetic acid production at 42 °C. When employed in the solid-state fermentation of ZAV, inoculation with A. pasteurianus TCBRC 103 resulted in higher fermentation temperatures, leading to enhanced accumulation of organic acids and volatile compounds. Notably, the concentrations of flavor compounds such as isoamyl acetate, acetic acid 2-phenylethyl ester, and acetoin were significantly higher in vinegar fermented by A. pasteurianus TCBRC 103 compared to those fermented by A. pasteurianus Huniang 1.01. Orthogonal partial least squares-discriminant analysis (OPLS-DA) identified 14 discriminative flavor compounds that could serve as potential markers for distinguishing between vinegars fermented by A. pasteurianus TCBRC 103 and A. pasteurianus Huniang 1.01. These findings highlight the promising application of A. pasteurianus TCBRC 103 as a starter culture for the production of high-quality ZAV under high-temperature conditions, with implications for reducing cooling costs and improving vinegar productivity in industry. Full article

Cyberlindnera rhodanensis J52, a non-Saccharomyces yeast isolated from edible roses, markedly improves the organoleptic qualities of fermented foods. To facilitate the development and application of this strain, this study sequenced and assembled the genome of C. rhodanensis J52, subsequently conducting functional annotation of its genes utilizing the NR, Swiss-Prot, COG, GO, KEGG and CAZy databases. The findings revealed that this yeast harbors genes involved in the biosynthesis of flavor compounds, including higher alcohols, acetate esters, ethyl esters, volatile organic acids, aromatic amino acids and benzyl alcohol or benzaldehyde. Furthermore, it possesses β-glucosidase, an extracellular enzyme which enhances the flavor profile of fermented products. Further analysis revealed that the yeast features biosynthetic pathways for the production of isoamyl acetate, isoamyl 2-methylbutyrate, benzyl acetate, phenethyl acetate, ethyl butanoate and ethyl decanoate, which verifies its ability to produce esters at the genetic level. Additionally, the yeast was found to have the capacity to biosynthesize selenoproteins, suggesting that it not only enhances flavor but also imparts functional benefits. These findings provide a theoretical foundation for the further exploration and application of C. rhodanensis J52. Full article

The chemical ecology and host plant preferences of the different Conistra species (Lepidoptera: Noctuidae, Xylenini) are mostly unknown, even though they are essential components of the herbivorous assemblages of temperate zone forests. During field studies, (Z)-7-tetradecenyl acetate (Z7-14Ac) was identified as a sex attractant of Conistra vaccinii. Phenylacetaldehyde-based synthetic and iso-amyl alcohol-based semi-synthetic lures also attracted C. vaccinii, C. rubiginea, and C. rubiginosa, and in the case of C. vaccinii, they performed better than the newly identified sex attractant. The different efficiencies of the two bisexual lures probably reflected the different feeding source preferences of the species caught. The tested lures attracted both sexes and, thus, we can estimate the actual sex ratio. These traps can be used especially in applications where female samples are needed, i.e., surveys on the reproduction biology of moths (e.g., polyandry), or in surveys of population dynamics. Full article