Search Results (658)

Chinese steamed bread (CSB) is an important fermented wheat product, but controlled strategies for modulating its volatile profile remain limited. This study evaluated defined composite sourdoughs comprising Wickerhamomyces anomalus CRFSZY16 or Kluyveromyces marxianus FYY7 in combination with Lactiplantibacillus plantarum SDgsM3 for CSB production using the direct fermentation method (DFM) and the refrigerated sponge-dough method (RSDM). Technological stress tolerance, preliminary safety-related phenotypes, acidification capacity, volatile organic compounds (VOCs), multivariate profiles, and specific volume were assessed. SDgsM3 showed dough-relevant stress tolerance and rapid acidification, while both yeasts tolerated moderate fermentation stresses. Headspace solid-phase microextraction coupled with gas chromatography-triple quadrupole mass spectrometry (HS-SPME-GC-TQ-MS) revealed stage-dependent remodeling of volatile profiles from mature sourdough to fully proofed main dough and final CSB. RSDM selectively modified representative alcohols, aldehydes, furans, ketones, and esters rather than uniformly increasing all VOCs. In the final CSB, the K. marxianus-based RSDM system showed relatively higher levels of 3-methyl-1-butanol, whereas the W. anomalus-based RSDM system showed relatively higher levels of hexanal, nonanal, 1-hexanol, and 2-pentylfuran. Composite sourdough treatments also yielded specific volumes of 2.56–2.66 mL/g versus 2.44 mL/g for the commercial yeast control. These findings demonstrate strain- and process-dependent modulation of CSB volatile profiles and support flavor-oriented composite sourdough design. Full article

Consumer behavior is increasingly shifting toward non-alcoholic beers. However, dealcoholized beers often have a reduced aroma compared to their alcoholic counterparts. An alternative for producing non-alcoholic beers is the use of special yeasts with reduced sugar metabolization; however, there are still significant gaps in our knowledge regarding the molecular contribution of non-Saccharomyces yeasts to beer aroma. Applying a comparative aroma extract dilution analysis to two non-alcoholic beers brewed with Kluyveromyces marxianus or Cyberlindnera saturnus resulted in 31 odor-active compounds, among which 27 were detected in both beer samples. Sensory evaluation showed well-balanced aromas in the two beers, with a more intense banana note in the beer brewed with C. saturnus. Among the 22 odorants that exceeded their odor threshold concentrations in the C. saturnus beer was the banana-like smelling 3-methylbutyl acetate, which showed a significantly lower odor activity value in the K. marxianus beer (OAVs 830 vs. 8.2). Its decisive role in the banana note of the C. saturnus beer was finally confirmed in a spiking experiment. Full article

Fungal nitrogen metabolism is a central determinant of yeast growth, fermentative performance, and secondary metabolism in fungi associated with fermented environments. For Saccharomyces cerevisiae, the assimilation of nitrogen sources found in grape must, including ammonium, free amino acids, and peptides, has been widely characterized, establishing a consumption hierarchy in which proline is considered a non-preferential nitrogenous source. However, the regulation and hierarchy of nitrogen-source utilization in non-conventional fungi remain poorly characterized, particularly in yeasts adapted to anthropized fermentative niches. In this context, Brettanomyces bruxellensis represents a useful fungal model to study the different nitrogen sources that are used, strain-dependent physiology, and survival under nutrient-limited fermentative conditions. We hypothesized that apparent depletion of amino acid and the expression of selected amino acid permease genes are strain-dependent traits linked to the survival of B. bruxellensis. In this study, we evaluated the strain-dependent physiology and amino acid depletion patterns of two B. bruxellensis strains from wine (LAMAP2480 and LAMAP1359). In both cases, the highest apparent depletion values under the 20 amino acid condition were observed for arginine, glutamine, tryptophan and proline, indicating that these compounds contributed substantially to the organic nitrogen pool under the assayed conditions. Only LAMAP2480 isolate was able to grow in the condition without added amino acids, indicating strain and nitrogen source dependence under limited organic nitrogen availability. Transcriptional analysis of GAP1, GNP1, and TAT1 permeases showed expression patterns dependent on both the strain and the available nitrogen source. This is the first study to combine the evaluation of physiological performance, amino acid consumption, apparent nitrogen depletion derived from amino acids normalized to OD₆₀₀ (OD-AA-N depletion), and the transcriptional responses of selected amino acid permease genes. This knowledge may contribute to understanding the survival of B. bruxellensis in fermentation environments with limited nutritional resources. Full article

This study employed sequential inoculation of native non-brewing yeasts Kluyveromyces marxianus YC-T7 and Pichia kudriavzevii QC-P3 to co-ferment dry white wine from Munage, a unique fresh-eating grape variety native to Xinjiang, providing technical support for the development of regionally distinctive wines in Xinjiang. To investigate how mixed fermentation with indigenous Xinjiang non-Saccharomyces (NS) yeasts and Saccharomyces cerevisiae (SC) influences the aromatic profile of Munage wine, two NS strains—K. marxianus YC-T7 and P. kudriavzevii QC-P3—previously isolated and selected by our group were sequentially co-inoculated with S. cerevisiae CEC01. Strain growth dynamics were first characterized in a synthetic grape juice (SGJ) system under varying inoculation protocols; subsequently, Munage grapes were fermented under optimized sequential inoculation to assess physicochemical parameters, volatile aroma composition, and sensory attributes of the resulting dry white wine. Results demonstrated that, under sequential inoculation, the QC-P3 + SC consortium entered the late logarithmic phase on day 4 and achieved a final ethanol concentration of 10.29%vol, whereas the YC-T7 + SC consortium reached the same growth stage on day 5 with 10.27%vol ethanol—confirming robust and timely alcoholic fermentation for both consortia. Consequently, sequential inoculation was adopted as the standard protocol for Munage wine production. All key physicochemical parameters complied with China’s national standards for dry white wine. Relative to pure SC fermentation, the YC-T7 + SC treatment increased tartaric acid, α-ketoglutaric acid, and citric acid contents by 3.15%, 12.16%, and 2.18%, respectively; the QC-P3 + SC treatment induced more pronounced enhancements—22.58%, 51.64%, and 14.70%, respectively. A total of 54 volatile compounds were identified, including 29 esters, 12 alcohols, 7 organic acids, 4 phenolic compounds, and 2 others. Integrated analysis using odor activity values (OAVs), principal component analysis (PCA), and descriptive sensory evaluation consistently revealed that the YC-T7 + SC wine exhibited the highest concentrations of fruit- and flower-associated esters, while the QC-P3 + SC wine was distinguished by a distinctive pineapple-like aroma driven predominantly by ethyl butyrate. Collectively, sequential co-inoculation of indigenous Xinjiang NS strains YC-T7 and QC-P3 with S. cerevisiae significantly improved Munage wine quality—particularly in acidity balance, polyphenol retention, and aromatic complexity—thereby offering both novel microbial resources and a validated technical framework for stylistically authentic vinification of terroir-expressive wines from the Xinjiang region. Full article

Among the many concerns surrounding global health, antimicrobial resistance (AMR) is widely recognized as a major threat, especially critical within livestock production, where restrictions on antibiotic use demand effective preventive alternatives. The documented health benefits and structural stability have positioned yeast-derived postbiotics as an attractive alternative, but research has largely focused on Saccharomyces cerevisiae, leaving non-Saccharomyces yeast species underexplored. To this end, in this study nine non-conventional yeast strains were selected and subjected to different thermal and chemical inactivation methods to determine the most suitable conditions for postbiotic obtention. Based on their physicochemical characterization and scalability potential, heat-treated postbiotics were selected for subsequent in vitro evaluation. Immunomodulatory assays demonstrated that heat-inactivated postbiotics from the different yeast strains were internalized by macrophages and induced dose-and-species-dependent expression of maturation markers CD40 and CD86, as well as TNF-α production, eliciting a proinflammatory response in vitro. Moreover, among all the species evaluated in this work, Rhodotorula mucilaginosa and Wickerhamomyces anomalus stood out for their ability to significantly reduce the adhesion of the enteropathogen enterotoxigenic Escherichia coli (ETEC) to intestinal cells in vitro. These results highlight the species-dependent immunomodulatory and anti-infective properties of selected yeast-derived postbiotics. Full article

Coffee fermentation is a critical yet under-optimized stage of the coffee value chain, with significant implications for beverage quality, process consistency, and smallholder livelihoods. Pichia species, together with several non-Saccharomyces yeasts historically associated with the genus, are frequently detected in natural and semi-dry coffee fermentation; however, their functional roles remain insufficiently characterized, constraining evidence-based starter-culture design. Direct coffee evidence implicates P. kudriavzevii, P. kluyveri, and Meyerozyma guilliermondii (formerly Pichia guilliermondii) in substrate transformation, fermentation dynamics, and sensory quality development. However, these findings are derived exclusively from studies conducted on single farms during single harvest seasons, without independent validation across multiple farms, harvest seasons, origins, or production environments, limiting their broader applicability. In contrast, ecologically prevalent species, including P. fermentans, Wickerhamomyces anomalus (formerly Pichia anomala), and Debaryomyces hansenii (formerly Pichia hansenii), remain largely unexplored in the context of coffee fermentation. To contextualize the current knowledge and identify promising avenues for future research, this review synthesizes evidence from cocoa, Baijiu, bakery, vinegar, dairy, and other solid-state fermentation systems. Across these diverse matrices, Pichia and related non-Saccharomyces yeasts frequently exert a disproportionate influence on flavor development, microbial succession, and process stability relative to their population abundance. The reported mechanisms include ester and higher-alcohol production, modulation of bacterial community dynamics, extracellular enzymatic activity, and bioprotective effects. Notably, functional impact often occurs without numerical dominance; ester production can increase alongside declining ethanol yield, and ecological persistence may increase despite declining absolute abundance, implicating community-level interactions in addition to direct metabolic activity. However, both the mechanisms and the magnitudes of these effects vary across fermentation systems, underscoring that functions demonstrated in one matrix cannot be assumed to translate directly to coffee without experimental validation. Future progress will require strain-level characterization, mechanistic studies, deliberate multi-species consortium design, process optimization, and field-scale validation in diverse coffee-producing environments. Such efforts will provide a scientific foundation for evidence-based starter-culture development capable of improving coffee quality, consistency, and producer value. Full article

Hanseniaspora uvarum is consistently observed as the dominant non-Saccharomyces species in grape juice leading to spontaneous fermentations and is often considered a detrimental factor due to the increased volatile acidity associated with its abundance. This study investigated how fermentation temperature affects the competitive interaction between H. uvarum and Saccharomyces cerevisiae, and how these shifts influence microbial community structure during spontaneous grape juice fermentations. Defined single- and co-inoculated fermentations were conducted across a range of temperatures (17, 23, and 25 °C), and cell abundance was quantified by flow cytometry. In parallel, spontaneous fermentations were monitored using ITS metabarcoding to assess temperature-driven changes in fungal community composition. At 17 °C, H. uvarum dominated early fermentation due to its faster growth rate, resulting in slower sugar consumption and prolonged fermentations. Increasing fermentation temperature enhanced the early growth of S. cerevisiae. Consistent patterns were observed in spontaneous fermentations, where higher temperatures increased the relative abundance of S. cerevisiae and shortened fermentation time. These results demonstrate that fermentation temperature is a major driver of yeast competition and suggest that moderate increases in fermentation temperature may help limit excessive H. uvarum proliferation during spontaneous fermentations. Full article

Cider is a low-alcohol fruit wine produced by partial or complete fermentation of apple juice. In recent years, its consumption has grown significantly, especially in Asia. Its distinctive flavor profile reflects a complex interplay of aroma and non-volatile components. The composition of cider is mainly influenced by three factors: raw materials, starter cultures, and production process. This review begins by outlining the composition of cider, covering both its aromatic compounds and non-volatile components. The primary aroma profile is defined by higher alcohols, esters, fatty acids, and carbonyl compounds, while sugars, organic acids, and polyphenols are the key determinants of its taste. Subsequently, it provides a detailed analysis of how the raw material, the choice of starter cultures, and the applied production processes collectively shape the cider’s flavor. Research shows that apple variety and maturity influence the levels of sugars, organic acids, and polyphenols, shaping the flavor foundation of cider. To enhance flavor diversity, inoculation strategies have shifted from single-strain fermentation with Saccharomyces cerevisiae to mixed fermentations using non-Saccharomyces yeasts and lactic acid bacteria, either simultaneously or sequentially. Currently, screening non-Saccharomyces strains has become a key strategy to increase cider flavor complexity. Precise micro-oxygenation and nutrient supply regulate microbial metabolism, thereby controlling the fermentation process and the production of specific flavor compounds. In the future, given the untapped diversity of non-Saccharomyces yeasts and lactic acid bacteria in winemaking traits, research in this direction may be key to improving cider quality. In addition, selecting apple cultivars tailored to specific cider styles and exploring pre-fermentation treatments such as cold maceration and enzymolysis may also contribute to enhancing the flavor diversity of cider. Full article

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit to the host. Research has traditionally focused on bacterial species, particularly Lacticaseibacillus and Bifidobacterium, whose mechanisms are well-characterised. However, probiotic yeasts represent a functionally distinct category, with Saccharomyces boulardii as the most studied representative and Kluyveromyces marxianus as an emerging candidate. Bacterial and yeast probiotics differ in cell biology, antibiotic susceptibility, immune receptor engagement, and metabolic output. Bacterial strains provide mucosal adhesion and direct short-chain fatty acid (SCFA) generation but are susceptible to antibacterial therapy. Yeast strains are intrinsically antibiotic-resistant, offer enzymatic activities such as β-galactosidase and glycosidases, and exert indirect bifidogenic effects that amplify luminal SCFA concentrations beyond what either category achieves alone. These non-overlapping profiles support a complementary rather than competitive conceptualisation of their use. When combined with prebiotic substrates such as fructooligosaccharides or galactooligosaccharides, this integrated approach addresses the principal axes of intestinal homeostasis more comprehensively than any single-organism intervention. Prospective randomised trials are needed to determine whether this mechanistic complementarity translates into additive or synergistic clinical benefit. This review synthesises the available evidence and proposes a framework for their complementary use. The proposed framework is hypothesis-generating: it rests largely on mechanistic and preclinical data, and its clinical validity requires confirmation in adequately powered controlled trials. Full article

Yeast-assisted mixed-culture fermentations have gained attention for their ability to enhance fermentation efficiency and modulate metabolite production. There is little knowledge on the impact of magnetic nanoparticle-assisted immobilization on yeast–yeast interactions during alcoholic fermentation. The co-culture platforms of Saccharomyces cerevisiae and Kluyveromyces marxianus, immobilized on chitosan-coated manganese ferrite nanoparticles, were applied in the fermentation of sugarcane molasses and sugarcane juice in the present study. The chitosan-coated MnFe₂O₄ nanoparticles were prepared using a one-step coprecipitation reaction followed by hydrothermal treatment and were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and scanning electron microscopy. An immobilized co-culture system has been shown to provide faster sugar consumption and higher ethanol production than non-immobilized-cell fermentations. Operational stability of the immobilized biomass and higher ethanol production by reuse were confirmed by repeated fermentation cycles. Bioproduction of volatile metabolites varies among monoculture, co-culture, non-immobilized-cell, and immobilized systems, with yeast interactions and magnetic immobilization also affecting secondary metabolite production during fermentation. The findings confirm that magnetic nanoparticle-assisted co-culture fermentation would be an attractive nanobiotechnological tool for enhancing alcoholic fermentation and shed new light on yeast interactions with the nanostructured system when combined with the immobilized solution. Full article

The industrial use of non-Saccharomyces yeasts offers a robust bioprocess strategy for modulating volatile biochemical profiles and reducing climate-driven ethanol production in fermented beverages. This study explores the metabolic diversity of indigenous non-Saccharomyces, with a particular focus on Starmerella bacillaris MI151, selected for sequential inoculation with Saccharomyces cerevisiae MI118. Pilot-scale bioreactor fermentations (25 L) of two Romanian matrix-specific aromatic grape cultivars, Busuioacă de Bohotin and Tămâioasă Românească, exhibited clear strain-dependent carbon flux changes. The sequential culture actively triggered the glycerol-pyruvic pathway, which consistently reduced the final ethanol concentration to up to 0.94% (v/v) and maintained a balanced profile of volatile compounds. GC-MS-based metabolomic profiling revealed substantial changes in the esterification kinetics and glycosidic precursor cleavage. The sequential fermentation resulted in a synergistic increase in n-hexyl acetate (up to 2310.01 µg/L) and bypassing of the standard enzymatic repression, freeing highly volatile monoterpenes (β-citronellol and β-geraniol) in the analyzed matrices. This targeted microbial system successfully modulated the organic acid–phenolic balance, neutralizing harsh structural finishes, as confirmed by quantitative sensory mapping. Finally, these specific local yeast strains exhibit strong bioprocess scalability, offering a predictable, non-engineered strategy to lower the ethanol yield while driving targeted flavor enhancement in climate-vulnerable viticultural regions. Full article

The principal critical issue in the production of Vin Santo passito wine is the high likelihood of fermentation arrests or sluggish fermentation, resulting in low sensory quality. A potential solution is to select indigenous yeasts from well-conducted spontaneous fermentations. In this study, a novel mixed starter culture consisting of two indigenous strains, Saccharomyces cerevisiae Ris III and Zygosaccharomyces rouxii Zr186, was evaluated. After selecting the strains and testing their compatibility, the mixed culture was used as a starter in the winemaking process of dried grapes, which was conducted in barrels of various sizes. The fermentations were monitored microbiologically for a period of 100 days to verify the ability of the inoculated strains to dominate and thus facilitate the fermentation process. Both strains dominated the fermentations: S. cerevisiae showed a 100% isolation rate immediately, while Z. rouxii achieved dominance within a month. The mixed starter demonstrated a 25% improvement in fermentation purity for the same barrel size. Sensory analyses revealed that the wines produced with the mixed starter were very consistent with one another, contrasting with those obtained through spontaneous fermentations, and received the highest scores for gustatory descriptors. In conclusion, this mixed culture represents an effective strategy for standardizing fermentation and improving the sensory quality of Vin Santo. Full article

Kombucha is a reservoir of health-promoting yeast strains. In this study, molecular characterization of the Kombucha microbiota led to the identification of 52 distinct yeast isolates, highlighting a complex community, where Brettanomyces anomalus was identified as the dominant yeast species. Other key species were identified, such as Pichia membranifaciens, Torulaspora delbrueckii, Zygosaccharomyces bailii, Starmerella bacillaris, and Meyerozyma guilliermondii. These isolated yeasts were screened for essential probiotic requirements, demonstrating excellent functional traits showing over 80% survival rate under simulated gastric and gastrointestinal conditions. Regarding the surface properties, wide cell hydrophobicity and auto-aggregation capabilities were seen. Broad antioxidant ability and robust antimicrobial activity against Escherichia coli and Staphylococcus aureus were observed, highlighting a protective function. Two strains of T. delbrueckii and one strain of Z. bailii stood out as probiotic candidates and were technologically evaluated in different culture combinations: yeast formulation pools using a specialized “probiotic pool” (PP) and a broader “yeast pool” (YP) both yielded successful analytical and sensory profiles. A strain of Lachancea thermotolerans, isolated from a distinct natural matrix, was employed as a technological booster to drive a yeast-based, bacteria-free kombucha. This study confirmed that specialized kombucha yeasts were not just fermentation drivers, but sustainable assets for developing novel functional plant-based probiotic beverages. Full article

The production of fermented beverages using different fruits has attracted increasing interest due to evolving consumer preferences (e.g., health consciousness and demand for low-alcohol products) and technological advances in the production process. Yeasts play a fundamental role in determining the sensory, chemical and functional properties of these beverages. This review aims to summarize the latest scientific publications on the selection and use of Saccharomyces and non-Saccharomyces starter yeasts for juice processing. It illustrates and discusses the most recent findings on isolation and characterization techniques, from phenotypic screening to sophisticated ‘omics’ approaches, which allow precise identification and engineering of yeast strains. The impact of various inoculation strategies, such as single-strain inoculation, sequential inoculation, and co-fermentation with different strains, is analyzed according to its effect on the quality and complexity of the final product. Recent advances in the application of genomics and metabolomics to re-evaluate fruit by-products highlight the importance of innovation in developing new, sustainable, diverse fermented fruit beverages. Full article

Xylitol is a sugar alcohol of interest in the food, pharmaceutical, and healthcare industries due to its applications as a food sweetener and sugar substitute. A wild-type Saccharomyces cerevisiae yeast strain designated 202-3 was isolated from a Colombian distillery located near sugarcane fields. This diploid 202-3 strain showed non-common, modest but noticeable xylose consumption and xylitol production in lignocellulosic hydrolysates. To enhance its natural xylose consumption ability, the strain was genetically engineered and submitted to adaptive laboratory evolution (ALE). Firstly, it was considered the deletion of the GAL80 gene to enable continuous expression of GAL genes, enhancing the uptake and assimilation of xylose. While the deletion of one copy of GAL80 (strain 202-3/∆) showed improved xylose consumption and xylitol production, better results were obtained when both copies of GAL80 were silenced (strain 202-3/∆∆). Subsequently, ALE experiments were conducted for these three strains in rich medium containing 20 g/L xylose. While the parental 202-3 strain consumed 2.46 g/L xylose and produced 0.42 g/L xylitol, the evolved 202-3/∆∆/ALE strain was able to consume 5.61 g/L xylose and produced 4.87 g/L xylitol, with a xylitol yield of 0.87 g xylitol/g xylose, and also the highest xylitol volumetric productivity (0.034 g xylitol/L/h) among the strains. Thus, our engineered and evolutionary experiments allowed a significant improvement in terms of xylose consumption, xylitol production and xylitol yield. Full article