Search Results (646)

Whisky is well-known worldwide owing to its unique flavor, and its fermentation and distillation conditions have a significant effect on its aroma. In this paper, new-make spirits were prepared by four fermentation conditions (two distilling yeasts and two fermentation temperatures), and the different stages (wort, wash, low wine, and new-make spirit) of the samples were collected. The main aroma compounds and their precursors were initially determined in wort and wash samples by GC-MS, UPLC-MS and HPLC. Results showed that Strecker degradation, reduction, and esterification occurred during the fermentation process, leading to decreased contents of amino acids and increased contents of volatile esters, alcohols, and acids. Moreover, the two distilling yeasts exhibited their respective optimal fermentation temperatures. Then, the distillation process was evaluated by two-dimensional gas chromatography–olfactory–mass spectrometry (GC×GC-O-MS), and 74 aroma compounds were found in different stages of new-make whiskies fermented by the two distilling yeasts and one brewer’s yeast. The contents of most compounds were enhanced by at least ten times after two distillations, while the contents of some sulfur compounds decreased. Finally, the feature aroma-active compounds of each new-make whisky were identified according to rOAV. These results provided theoretical and methodological support for yeast selection and process control in whisky production. Full article

Daqu is a key starter used in Baijiu production, and its microbial composition and associated metabolic functions play critical roles in fermentation performance and flavor development. This work aimed to reveal how Daqu-making temperature regulates microbial community divergence and subsequent metabolite formation via multi-omics analysis so as to provide theoretical guidance for Daqu quality control. In this study, physicochemical analysis, metagenomic sequencing, and metabolomic profiling were combined to investigate the microbial community structure, functional differentiation, and metabolite characteristics of nine Daqu samples collected from six major Baijiu-producing regions in China. The temperature during Daqu preparation was found to be a primary factor driving microbial community assembly and functional specialization. Medium-temperature Daqu exhibited higher saccharifying activity (up to 867 U) and greater microbial diversity with the enrichment of amino acid metabolism-related pathways, indicating enhanced protein degradation and amino acid utilization for the formation of flavor precursors. In contrast, high-temperature Daqu showed stronger capacities for carbohydrate degradation and conversion, particularly in starch and sucrose metabolism, which were closely associated with the enrichment of thermotolerant fungi and bacteria. LEfSe analysis identified 47 distinct microbial biomarkers (LDA score > 3.0), which could differentiate between medium- and high-temperature Daqu. Redundancy analysis indicated that environmental factors (moisture and acidity) together with functional properties (fermentation, esterification, liquefaction, and saccharification) act as key drivers of microbial functional patterns. Metabolomic analysis further revealed that medium-temperature Daqu had higher abundances of esters and fatty acids, whereas high-temperature Daqu had higher proportions of alcohols and ketones. Taken together, these results provide a multi-omics perspective on temperature-driven microbial functional differentiation in Daqu and offer a scientific basis for quality-oriented regulation and process optimization in Baijiu production. Full article

Pigskin, a major byproduct of pork processing, has high protein content and low fat, endowing it with considerable market value for food applications. In this study, bioaugmented fermentation with Latilactobacillus sakei YBZY-W5, a strain previously isolated from traditional fermented pigskin, was applied to pigskin to systematically evaluate its effects on physicochemical parameters, microbial community succession, and volatile flavor compound (VFC) profiles over 20 days. The results showed that moisture and pH significantly decreased, while total volatile basic nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARSs) increased with fermentation time. High-throughput sequencing revealed that Lactobacilli, Fusarium and Aspergillus dominated early fermentation and were gradually replaced by Bacillus, Hanseniaspora and Debaryomyces. A total of 493 VFCs were identified, among which terpenoids, heterocyclic compounds, and alcohols were the most abundant classes. Orthogonal partial least squares discriminant analysis (OPLS-DA) identified numerous differentially changed VFCs (DCVFCs) during fermentation. Odor activity value (OAV) analysis indicated that green, meaty, and woody notes dominated initially, while sour, floral, sweet, and fruity characteristics became increasingly prominent after fermentation. Pearson correlation analysis demonstrated significant associations between key microorganisms (Lactobacilli, Bacillus, Hanseniaspora, Debaryomyces) and DCVFCs (e.g., β-myrcene, ethyl hexanoate, hexanoic acid, ethyl ester, pyrazines). Collectively, bioaugmented fermentation with Ltb. sakei YBZY-W5 effectively modulated the physicochemical and microbial profiles of pigskin, enriched desirable flavor compounds, and reduced unpleasant odor, confirming its feasibility for producing high-quality fermented pigskin products. This study provides an experimental basis for the value-added utilization of pigskin and promotes sustainable development of the pork industry. Full article

The alcoholic fermentation of wine is a complex, multivariable chemical process. This study proposes a cognitive system for the dynamic control of the industrial wine fermentation process based on acoustic emission signals. The core of the system uses machine learning algorithms to perform perception tasks and predict density as a relevant chemical parameter for control and decision-making during the process. A hydrophone submerged in the fermentation tank is used to monitor the process. At the TRL4 stage we are currently at, measurements were taken at a winery in the Rioja Designation of Origin and were acquired and stored during the alcoholic fermentation process to be used as input data. Manual measurements collected by the winemaker throughout the fermentation process were used to train and validate the results. The performance of the machine learning model was measured using statistical metrics. The results of the experiments show a high correlation between the density calculated using the model and the densities measured by the winemaker. The proposed system is a valid and innovative tool for controlling a process as multivariable as alcoholic fermentation. The anticipatory nature of the acoustic signal with regard to the evolution of temperature in the process is used as the starting point for the new proposal. Its application helps to ensure stable fermentation by reducing the thermal stress on yeasts caused by the thermal shocks of current temperature control systems, improving process control in wineries and serving as a cognitive system for control and decision-making. 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

2-Phenylethanol (2-PE) is a key aromatic alcohol contributing to the rose-like odor in brewed wines, primarily synthesized by yeast metabolism with a typical yield of less than 100 mg/L. To enhance the 2-PE content in brewed wines, this study used CRISPR-Cas9 gene editing technology to delete the ARO8 gene (encoding aromatic transaminase I) in Saccharomyces cerevisiae SY. The single-factor experiments were performed to optimize the fermentation process, and the 2-PE content in the brewed wine was measured by high-performance liquid chromatography. The results demonstrated that the 2-PE content in whisky fermented by the SY-A8 was 0.73 g/L, increasing 23.73% compared to SY. The fermentation conditions of SY-A8 were optimized through single-factor experiments and the Box–Behnken design. The optimal conditions were a sugar concentration of 46.30 g/L, a fermentation time of 6 days, and an L-phenylalanine concentration of 1.43 g/L. The high 2-phenylethanol aroma whisky was brewed with a higher 2-phenylethanol content of 3.68 g/L in a 1 L fermenter at the optimal conditions. In conclusion, the modification of Saccharomyces cerevisiae by CRISPR-Cas9 gene editing combined with fermentation process optimization provides an effective technical strategy for improving the 2-PE content in whisky, thereby providing a research perspective for the flavor enhancement of whisky and other brewed wines. Full article

Because of the rising occurrence of extremely hot summers linked to climate change, there is a mass appearance of heat-damaged fruits of ‘Čačanska Lepotica’, which are unsuitable for fresh consumption and processing into products in which the fruits’ appearance is a critical quality attribute. To address this issue, the aim of the study was to examine the possibility of producing plum spirits from such fruits as one of the potential ways to utilize them. Heat-damaged fruits were processed in nine different ways, including a traditional one. All produced plum spirits met legal requirements. GC-MS analysis of 39 volatile compounds revealed that the plum spirits made from heat-damaged fruits had different aromatic profiles depending on the processing method applied. However, the plum spirit produced in the traditional way had various sensory defects; the most notable were a lack of freshness and a distinctly unpleasant ‘cooked plum’ aroma. Modifications to the production method led to an improvement in the sensory characteristics of the plum spirits. The obtained results indicate that modifications in small distilleries should include fruit crushing, stone removal and usage of baker’s yeast. In large distilleries, though, the best sensory characteristics for plum spirits made from heat-damaged fruits could be obtained using a production method that includes fruit pulping with stone removal and spontaneous alcoholic fermentation, with one additional step: lowering the pH of the mash before alcoholic fermentation to 3.0. Full article

The objective of this study was to examine the impact of using a rotary jet head (RJH) on the biosynthesis of byproducts of yeast metabolism and their role in shaping the flavor and aroma profile of bottom fermentation beer (lager style). The tests were conducted on an industrial scale, with fermentation in 3800 hL fermentation tanks. Experiments were conducted in a minimum of six replicates. The main quality indicators, including ethanol concentration and pH, were analyzed, along with key volatile compounds such as acetaldehyde, esters, higher alcohols, and DMS. Additionally, beer samples—both those fermented using forced mixing and those produced conventionally—were subjected to sensory evaluation. The study found that RJH did not cause changes in either the final ethyl alcohol concentration (6.74% in both samples) or the pH measurement results. The rotary jet head increased synthesis of certain volatile components, such as fusel alcohols by 5% and acetate esters by 14% for ethyl acetate and by almost 12% for isoamyl acetate. On the other hand, a more than threefold (8.23 to 2.54 mg/L) decrease in the undesirable acetaldehyde was observed in samples fermented with forced mixing. The resulting beers exhibited statistically significant differences in chemical composition; however, sensory analysis did not reveal these differences. This finding underscores the efficacy of the rotary jet head in expediting the beer production process without compromising its sensory quality. Full article

The present study examined for the first time the effect of native yeasts on the fermentation of artisanal Spondias purpurea L., wine produced in Santa Elena, Ecuador. To achieve this goal, three inoculation strategies were compared: a mixed culture containing Saccharomyces cerevisiae and Candida spp. (CLX), commercial S. cerevisiae (CL), and a spontaneous fermentation without added inoculum (SL). Five yeast isolates were identified from the fermentations, four belonging to Candida spp. and one to Kloeckera spp., using microbiological and biochemical methods. The CLX treatment showed the greatest yeast proliferation on PDA plates (2.7 × 10⁶ CFU/mL) and yielded the highest levels of higher alcohols, while the CL treatment produced the highest ethanol (3.72% ABV) and glycerol content (0.46%). All treatments were free of total and fecal coliforms, and their pH values (2.49–2.56) satisfied the requirements of the current Ecuadorian standard for wine production NTE INEN 374. Residual glucose content was specifically quantified using an enzymatic colorimetric (GOD-POD) assay, confirming the dry character of the wines. Molecular analysis of the final preparation obtained from the variant corresponding to the spontaneous fermentation without inoculum (SL) confirmed the presence of Hanseniaspora spp. (Kloeckera spp.), Diutina rugosa (C. rugosa), C. zeylanoides and Pichia kudriavzevii, after the obtained PCR amplicons using ITS1 and ITS4 were subjected to a blast analysis. Sensory evaluation by panelists (n = 15) favored the CLX wine, particularly for aroma and flavor attributes. The final glucose content reached a low value of 0.28 g/L, indicative of an extremely dry wine, with almost no fermentable sugar. Due to the lack of information related to wines produced from Spondias purpurea L., this study could contribute to a better understanding of the biological behavior and biodiversity of the microorganisms present in this fermentation process. These findings will help to improve wine regionality production, supporting the potential application of native regional yeasts in Spondias purpurea L. wine biotechnology. Full article

(1) Background: Flavored craft beer is favored for its diverse and distinctive aroma compounds; however, traditional fermentation processes are often plagued by poor yeast flocculation, which leads to substantial beer losses and compromised production efficiency. Yeast immobilization technology has emerged as a promising strategy to improve fermentation performance, shorten the primary fermentation period, and mitigate beer loss. (2) Methods: In this study, a natural material–based carrier was developed for the immobilization of yeast, and its application in mango craft beer fermentation was systematically investigated. The optimal fermentation conditions were screened, and the physicochemical properties, nutritional composition, and volatile flavor profiles of the resulting mango craft beer were comprehensively evaluated. (3) Results: The results showed that the maximum mass gain of yeast after immobilization on the natural carrier reached 13.3%. Compared with free yeast, the immobilized yeast exhibited a 1.58-fold higher average extract consumption rate and a 1.39-fold higher alcohol production rate based on the overall fermentation system, while the primary fermentation period was shortened by approximately 33%. Under the optimized fermentation conditions, the mango craft beer achieved a sensory score of 81 points, with a β-carotene retention rate of 91.25%. Furthermore, the mango craft beer exhibited a more diverse profile of volatile flavor compounds and enhanced nutritional composition compared with the control. (4) Conclusions: Overall, fermentation conditions were optimized using Response Surface Methodology (RSM) based on Box–Behnken Design (BBD). Natural immobilization carrier developed in this study effectively enhanced yeast fermentation efficiency and shortened the primary fermentation cycle, and these findings demonstrate its significant potential for cost reduction and efficiency enhancement in the production of flavored craft beer, providing a practical technical support for the industrial application of natural carrier-based yeast immobilization technology. Full article

The transition towards a circular bioeconomy is essential to mitigate the environmental pressures caused by the increasing global demand for food and energy. Agro-food waste (AFW) is a plentiful, inexpensive feedstock, exploitable in biorefineries to produce valuable molecules. The aim of this study was to isolate native non-conventional yeasts (NCY) from various AFW and to evaluate their potential for the ‘natural’ synthesis of aroma compounds via fermentation. Ten strains were isolated and identified as belonging to Saccharomyces cerevisiae, Pichia kluyveri, Pichia californica and Wickerhamomyces anomalus species. The fermentative performance and production of aroma volatile compounds were tested using different household wastes as substrates. Figs containing substrate, which is the richest in fermentable sugars, allowed for the fastest microbial adaptation and highest yields of volatile compounds. HS-SPME-GC/MS analysis revealed that the most prominent compounds were isoamyl alcohol, ethyl acetate and isoamyl acetate with the highest production levels showed by W. anomalus YDSCYP4 and P. kluyveri YDSCYP5. Enzymatic profiling revealed significant arylamidase and esterase activities in the selected strains, related to their role in the hydrolysis of aroma precursors. These findings demonstrate the efficiency of these autochthonous yeasts for the sustainable production of aroma compounds, supporting the development of eco-friendly biotechnological processes. Full article

Lycium barbarum–Polygonatum cyrtonema composite jiaosu (LBPCJ) was prepared by sequential dual-species fermentation and evaluated in a mouse model of alcohol-induced liver injury. Following process optimization, a yeast-first sequential strategy with intermediate pasteurization was selected, comprising an initial Saccharomyces cerevisiae fermentation step, intermediate pasteurization, and a subsequent Lactiplantibacillus plantarum fermentation step. Fermentation reduced pH from 4.68 to 3.51 and increased total acidity from 61.06 to 135.39 g LA/L and total phenolic content from 3.01 to 9.39 mg GAE/mL. In vitro antioxidant-related activities were also higher after fermentation, with DPPH, ABTS, and •OH scavenging rates increasing by 39.90%, 29.78%, and 11.10%, respectively. In mice, LBPCJ administration was associated with lower liver index and serum aminotransferase levels, together with attenuated hepatic histopathological alterations, with the high-dose group (15 mL/kg BW) showing the clearest response. These changes were accompanied by higher hepatic SOD and GSH levels and lower MDA, TNF-α, IL-1β, and IL-6 levels. LBJ and PCJ also improved several measured indicators, while LBPCJ showed changes across multiple endpoints under the tested conditions. Overall, sequential fermentation markedly altered the physicochemical and antioxidant-related properties of LBPCJ, and LBPCJ administration improved multiple indicators related to alcohol-induced liver injury in mice, although the specific constituents and underlying mechanisms remain to be clarified. Full article

The 1st International Online Conference on Fermentation (IOCFE2025), held on 12–13 November 2025, convened a global assembly of researchers to explore the multifaceted roles of microorganisms in biotechnology, food safety, and human health. Under the chairmanship of Professor Antonio Morata, the symposium was structured around four pivotal tracks: biotechnological tools in fermentation, sensory profile impacts, food safety and drink innovation, and the nutraceutical implications of fermented products. A significant portion of the discourse focused on enology, specifically the use of Saccharomyces and non-Saccharomyces yeast derivatives to mitigate climate-related challenges such as high alcohol content and acidity, alongside emerging biopreservation strategies like kefir-enriched coatings and natural antifungal agents. The award-winning research highlighted the breadth of the field, ranging from the development of agri-food biostimulants and enhanced carotenoid production under LED illumination to the genomic characterization of glucose transport in Torulaspora delbrueckii. Furthermore, the sessions on health and nutrition provided a critical appraisal of meta-analytic studies, examining the probiotic potential of Enterococcus faecium and the role of fermented dairy in the Mediterranean diet. By integrating traditional fermentation practices with high-tech interventions like ultra-high pressure homogenization (UHPH) and solid-state biorefinery processes, IOCFE2025 underscored the vital contribution of fermentation science to sustainable agriculture and the global functional food market. Full article

The diversification of craft beer styles has stimulated interest in innovative yeast-driven strategies to enhance sensory complexity while maintaining process robustness and stylistic integrity. In this context, non-Saccharomyces yeasts represent promising biotechnological tools for modulating fermentation performance and flavor development in brewing systems. This study evaluated the application of Lachancea thermotolerans and Torulaspora delbrueckii in the production of a Porter-style beer using sequential inoculation with Saccharomyces cerevisiae. All fermentations were conducted in triplicate from a wort with an original gravity of 1042. The final alcohol content ranged from 4.82 to 4.99% (v/v), and apparent attenuation varied between 84.1 and 88.9%, with no significant differences among treatments (p > 0.05). Color (92–94 European Brewery Convention (EBC) and bitterness (~18 International Bitterness Units (IBU) remained within Porter-style parameters across all fermentations. Total acidity ranged from 0.19 to 0.21% (lactic acid equivalents), while volatile acidity was significantly higher in the L. thermotolerans treatment (0.55 g L⁻¹) compared with the control (0.22 g L⁻¹) (p < 0.05). Sequential inoculation influenced early fermentation kinetics and modulated selected sensory attributes. Quantitative Descriptive Analysis (n = 18 panelists) indicated higher aroma intensity and foam quantity in beers produced with L. thermotolerans, whereas T. delbrueckii was associated with moderate increases in foam persistence. The roasted character and overall stylistic perception remained stable across treatments. These findings indicate that sequential inoculation with selected non-Saccharomyces yeasts enables measurable sensory differentiation in dark beer matrices without compromising fermentative performance or stylistic integrity. The results support their controlled integration as technological tools for sensory innovation in Porter-style beers. Full article

Roasted coffee silverskin (RCSS) is a by-product of coffee production characterized by its content of phenolic compounds, including those contributing to bitterness. The aim of this study was to evaluate RCSS as an analog for hops in the production of non-alcoholic beer. Beers were developed using hops, RCSS, or a combination of both. Their sensory and physicochemical properties were evaluated, including bitterness, total phenolic content, and antioxidant capacity. Compared to hopped beer, the RCSS beer exhibited a significantly higher original gravity (7.11°P vs. 6.70°P), apparent extract (6.52°P vs. 6.20°P), and darker color (18.02 vs. 4.65 EBC). The total phenolic content was also significantly higher in the RCSS beer, reaching 0.51 ± 0.03 mg CGA/mL, which represents a 34% increase compared to the hopped variant. Importantly, the addition of RCSS had no negative effect on fermentation process. Moreover, the RCSS beer was characterized by improved overall sensory quality. These results indicate that RCSS is an innovative, sustainable alternative to hops, enhancing both sensory and functional properties while supporting zero-waste brewing strategies. Full article