Search Results (164)

This study developed a two-step statistically integrated optimization framework to identify the effects of key fermentation medium components controlling hyaluronic acid (HA) biosynthesis by Streptococcus zooepidemicus. As an initial phase, the Plackett–Burman design was employed to identify the most influential components among yeast extract, casein, peptone, beef extract, MgSO₄·7H₂O, K₂HPO₄, KH₂PO₄, and (NH₄)₂SO₄ by conducting 12 fermentation runs, and 30 g/L of glucose was used as the carbon source. Among the eight ingredients, yeast extract, MgSO₄·7H₂O, and KH₂PO₄ were identified as the most significant factors in enhancing HA production. The following steps were based on the selection of the best carbon and yeast extract sources. Sucrose was selected as the optimal carbon source among glucose and lactose, and Tastone 900-Baker’s yeast extract was selected as the optimal nitrogen source among various yeast extract sources. The final phase of the optimization procedure employed the Box–Behnken design to determine the optimal concentrations of three ingredients: yeast extract (10–30 g/L), MgSO₄·7H₂O (0.2–2.0 g/L), and KH₂PO₄ (1–4 g/L). The results depicted that the optimized media formulation, composed of 30.0 g/L of yeast extract, 1.16 g/L of MgSO₄·7H₂O, and 4.0 g/L of KH₂PO₄, enhanced HA production and biomass OD600 to 545.9 mg/L with 1250–1500 kDa and 2.53 OD600 in a 250 mL shake flask scale, which was around a 10-fold increase in HA production compared with run #10 of Plackett–Burman (57.42 mg/L). This study provided preliminary results for future process conditions optimization, scale-up studies, and techno-economic evaluation. Full article

The increasing demand for sustainable and affordable surfactants requires the exploration of novel bio-based alternatives. In this context, this work investigates the potential of baker’s yeast (Saccharomyces cerevisiae) as a surface-active agent. To this purpose, the performance of commercial dry, commercial fresh, and cultivated yeast was evaluated by characterizing their wetting behavior and formulating emulsions with a fixed oil-to-water ratio. Microscopic and macroscopic stability was monitored over 24 h and quantified via the creaming index (CI). The experimental results demonstrate that both the yeast source and concentration significantly dictate the surface properties and emulsion stability. Notably, commercial dry yeast exhibited the highest degree of hydrophobicity, likely attributed to the presence of sorbitan monostearate (SMS) in the formulation. Consequently, this was the main variant capable of producing stable emulsions, with microscopic evidence suggesting a Pickering-like stabilization mechanism driven by the irreversible adsorption of yeast cells at the oil–water interface. Conversely, commercial fresh and cultivated yeast failed to exert significant stabilizing activity. These results demonstrate that S. cerevisiae biomass can be effectively repurposed as a functional constituent in green emulsion technology, offering a scalable pathway for the development of biocompatible, particle-stabilized industrial formulations. 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

Two wild Saccharomyces cerevisiae strains, 9-3 and 10-2, isolated from nectarine and apple leaves, show high fermentation performance in standard breadmaking but their utility in enriched-dough products remained untested. This study evaluated their performance in kouglof production against a commercial baker’s yeast as a control. Fermentation was monitored by weight loss (reflecting CO₂ production) and pH changes. Finished loaves were evaluated for macroscopic traits (weight, height, appearance), crust/crumb color, texture, and microstructure via 3D/2D analysis of gas-cell morphology. Sensory acceptance was also assessed. While size-related traits were similar across all samples, strain 10-2 significantly outperformed 9-3. Kouglof made with 10-2 exhibited commercial-grade softness, characterized by lower hardness and gumminess, lower residual sugar content, and a finer, more uniform gas-cell structure with a darker, well-developed crust, whereas 9-3 yielded a firmer crumb with fewer, larger gas cells. Sensory acceptance was comparable across variants, with all samples rated as highly acceptable. Strain 10-2 demonstrated high sucrose tolerance and performed comparably to or better than the control across multiple product-quality metrics in enriched-dough kouglof. These findings support the potential of wild yeast 10-2 for sweet bread production with high-sucrose and high-fat formulations, though further optimization is warranted. Full article

Background/Objective: Dietary polysaccharides are increasingly recognized as functional nutritional components that support human health through modulation of immune function. However, clinical evidence linking their intake to site-specific upper respiratory mucosal immune health in humans remains limited. This study investigated whether dietary β-1,3/1,6-glucan (SC-BG) from baker’s yeast may support upper respiratory mucosal immune health in healthy adults. Methods: Following in vitro assays on human dendritic cells (DCs), a randomized, double-blind, placebo-controlled parallel-group trial was performed in healthy adults (18–69 years) who consumed either SC-BG or placebo capsules for 12 weeks in Japan. The primary outcome was circulating DC activation. Secondary outcomes were mucosal immune markers including secretory immunoglobulin A (s-IgA) and lysozymes from site-specific mucosal swabs (posterior oropharyngeal wall/nasopharynx) and salivar, and self-perceived upper respiratory tract symptoms. Results: SC-BG increased CD80 expression in DCs in vitro. In the clinical trial, 40 participants were randomized (n = 20 per group), and 39 (SC-BG: n = 19, placebo: n = 20) were analyzed. At week 8, the SC-BG group showed higher cDC1 CD80 expression than placebo. SC-BG intake also attenuated declines in s-IgA levels in the posterior oropharyngeal wall and nasopharynx and increased salivary lysozyme concentrations. Participants receiving SC-BG reported fewer cumulative days with upper respiratory tract-related local and systemic symptoms. No test food-related adverse events were observed. Conclusions: These findings provide preliminary clinical and mechanistic observations suggesting that dietary SC-BG may enhance circulating cDC1 activation and may help support upper respiratory local mucosal immune health in healthy adults, highlighting the potential of dietary polysaccharides as functional nutritional strategies for maintaining immune resilience. Full article

While Saccharomyces cerevisiae (baker’s yeast) offers a safe, non-animal source of chitin-glucan (CG), its potential as a functional cosmetic ingredient has been overshadowed by industrial sources like Aspergillus niger. This study advances the existing literature by establishing a critical structure–function relationship for CG micro/nano particles extracted via three physical disruption methods: ultrasonic bath, ultrasonic probe, and autoclaving. The obtained CG was systematically characterized by physicochemical and biological tests. A significant trade-off was identified: while autoclaving (40 min) resulted in lower mass yield compared to ultrasonication, it produced particles with the highest crystallinity, an enriched chitin/glucan ratio, and the smallest particle size (~70% of particles with mean diameter of 480 ± 33 nm). Structurally, these sub-micron particles demonstrated superior colloidal stability and a physical “barrier effect” for sustained hydration, outperforming the amorphous structures typically associated with mild extraction. The anti-wrinkle efficacy was validated through a specific “triad” mechanism: (1) the insoluble 3D network ensures prolonged water retention, (2) the particles exhibit robust free radical scavenging activity (~67%), and (3) most notably, the specific nano-structure significantly upregulated Collagen Type I-α1 expression in human dermal fibroblasts (HDF) and human skin fibroblasts (HSF), surpassing commercial chitin controls. These findings prove that the extraction-induced nano-structure, rather than mass yield, is the determinant factor for bioactivity, positioning S. cerevisiae CG as a high-performance, multi-target ingredient for anti-aging formulations. Full article

Beetroot by-product (BBP), an industrial residue rich in bioactive compounds, offers a sustainable solution to reduce food waste while enhancing the nutritional profile. The aim of the study was to evaluate the effect of different leavening agents (baking powder and baker’s yeast) and geometry (rectangular and oval) on bioactive compound stability and antioxidant capacity when incorporating beetroot by-products into gluten-free bread formulations. Rectangular and oval-shaped gluten-free breads were produced using 3D printing. Moisture content, pH, color parameters, bioactive compounds (betalains and phenolic compounds), and antioxidant activity were analyzed in both crust and crumb. BBP addition significantly increased total phenolic content, antioxidant capacity, and betalain content in all formulations. Breads with baker’s yeast exhibited higher bioactive retention due to acidic pH levels that favor phenolic and betanin stability. Bread with baking powder showed a higher retention of betaxanthins (yellow pigments), while those with baker’s yeast retained betacyanins (red-violet pigments). Oval geometry improved moisture retention and bioactive preservation due to reduced surface exposure. This research demonstrates the feasibility of developing nutritionally enhanced gluten-free products using additive manufacturing. Bread enriched with beetroot by-product and baker’s yeast represents a suitable option to improve functionality and pigment retention while valorizing industrial waste. Full article

Genetic variation underlies the capacity of populations to adapt, yet what drives how this variation is generated and maintained in natural populations remains poorly understood. Fundamental processes such as mutation, ploidy, and recombination are known to shape genetic variation and adaptive potential but are typically studied in isolation and under controlled laboratory conditions. How these processes act together under varying environmental conditions to structure genetic variation across complex natural populations remains unresolved. In yeasts, these processes are dependent on reproductive mode, ploidy shifts, and environmental stressors, which jointly shape genomic stability and adaptive potential. Here, we review our current knowledge on the roles of mutation, ploidy, and recombination in adaptation in the model yeasts Saccharomyces cerevisiae and the human pathogenic Cryptococcus. We highlight heterogeneity in mutation rates, recombination, and ploidy states across strains, environments, and populations, challenging the assumption that these parameters are uniform. We argue that fluctuating environments, increasingly driven by climate change, are likely to intensify interactions among these processes to impact evolution in ways that remain difficult to predict. Integrating population genomics with ecologically realistic frameworks will be essential for understanding natural evolutionary dynamics and anticipating fungal adaptation and disease emergence. Full article

Baker’s yeast beta-glucan (BYBG) supplementation improves various aspects of immune system function, readiness, and response. The purpose of this study was to determine if the expression of immune maturation mRNA was also changed over the course of 6 weeks of BYBG supplementation at rest. In this exploratory study, a small group of participants (N = 20) were randomized into two groups: BYBG (weeks 0–2 = 50 mg/d; 2–4 = 125 mg/d; and 4–6 = 250 mg/d) or placebo. Blood samples were collected at 0, 2, 4, and 6 weeks and analyzed for the expression of 785 mRNA (NanoString nCounter platform and Nanotube software; R v3.3.2). A total of 42 mRNAs in 21 annotated pathways (antigen presentation, apoptosis, B cell memory, cell cycle, chemokine signaling, cytotoxicity, DAP12 signaling, hypoxia response, IL-1 signaling, IL-10 signaling, MAPK signaling, myeloid immune response, NF-kB signaling, NK activity, Notch Signaling, PD1 signaling, Senescence/Quiescence, T cell checkpoint signaling, TCR signaling, TLR signaling, and TNF signaling), were significantly affected by BYBG at various time points. It is reasonable to speculate that the observed mRNA and associated pathways may underlie previously reported improvements in immune function with BYBG. Full article

Background/Objectives: Animal and fungal sterols and stanols exhibit remarkable structural diversity, driven by variations in the number and position of C=C bonds within the steroidal tetracyclic core and side chain, along with diverse branching patterns of the latter. Similarly to phytosterols, these metabolites produce highly complex tandem mass spectra, whose interpretation has so far been limited. To address this gap, the fragmentation behavior of selected animal/fungal sterols and stanols was studied in this paper. Methods: Higher-Collisional-energy Dissociation–High-resolution tandem mass spectrometry (HCD-HRMS/MS) of protonated/dehydrated species generated via atmospheric pressure chemical ionization (APCI) was performed on structurally diverse compounds, including lathosterol, desmosterol, zymosterol, lanosterol, ergosterol, chalinasterol, and the stanols coprostanol and cholestanol. Results: Structurally diagnostic product ions originating from the side chains were unveiled, shedding light on the intramolecular migration of positive charge from the initial ionization site at C3 to alternative stable sites across the molecular structure, which is a typical mechanism also noted in cholesterol and phytosterols. In addition, characteristic fragmentation patterns related to the steroidal backbone were found and discussed for Δ⁷, Δ^5,7 and Δ⁸-sterols, and a novel elucidation of the fragmentation behavior of 4,4-dimethyl-Δ⁸-sterols, based on lanosterol as a model compound, was achieved. The relative intensities of diagnostic product ions allowed a correlation with specific structural motifs, and “cholesterol-like” and “stigmasterol-like” fragmentations pathways were recognized. These findings were integrated with prior data on cholesterol and plant sterol fragmentation acquired under identical analytical conditions. Moreover, as a proof of its relevance for novel sterol identification, MS/MS-related information was successfully applied to the identification of a positional isomer (Δ⁷) of zymosterol in baker’s yeast extract, along with typical fungal major sterols. Conclusions: The comprehensive archive of sterol/stanol fragmentations obtained by APCI-HCD-MS/MS might prove very useful for the future characterization of novel sterol/stanol species in complex matrices. Full article

Carob pulp flour (Ceratonia siliqua) is gaining attention as a sustainable ingredient with nutritional and functional potential. This study evaluated the partial replacement of soft wheat flour with 10% carob pulp flour in breadmaking, focusing on the role of different leavening strategies: commercial baker’s yeast (LB), a selected starter culture, Lactiplantibacillus plantarum SL31 and Saccharomyces cerevisiae SY17 (LI), and a type I sourdough (LS). Dough rheology, microbial dynamics, bread quality, acceptability, and shelf-life were assessed. Results showed that the inclusion of carob pulp flour enhances the nutritional profile while maintaining satisfactory technological performance. The leavening strategy strongly influenced the final products: breads made with commercial yeast displayed high volume and softness but were less stable during storage; LS breads achieved greater microbial stability but were limited by excessive acidity and reduced sensory acceptance; breads obtained with the selected starter culture offered the most balanced outcome, combining moderate structure with enhanced flavor and consumer preference. Overall, the findings demonstrate the feasibility of incorporating carob pulp flour into bakery products and highlight the potential of tailored starter cultures as a promising compromise between technological performance, sensory quality, and shelf-life. Future work should optimize fermentation approaches to further enhance consumer appeal and support industrial application. Full article

Cereal grains have been dietary staples for millennia, providing essential nutrients alongside their primary carbohydrate content. Recently, the search for sustainable, nutrient-rich alternatives has drawn attention to spelt (Triticum aestivum ssp. spelta L.), a low-input crop with promising nutritional properties. Spelt supplies a higher content of unsaturated fatty acids and minerals, such as iron, zinc, and magnesium and exhibits lower levels of phytic acid compared to common wheat. This study explores the nutraceutical potential of fermented bakery products made from spelt and wheat flours using sourdough fermentation, a process driven by lactic acid bacteria (LAB) and yeasts. Breads produced with baker’s yeast were included for comparison. Specifically, this manuscript focuses on the generation of bioactive peptides (BPs), which have demonstrated anti-oxidant, anti-inflammatory, and gut-protective effects by modulating oxidative stress and inflammatory signaling pathways. By comparing aqueous extracts from breads prepared with varying flours and fermentation methods, optimal conditions for producing functional baked goods could be defined. The findings may offer new avenues for developing bakery products that potentially increase intestinal health while promoting sustainable agriculture through the use of spelt. Full article

This study aimed to identify and evaluate yeasts and lactic acid bacteria (LAB) isolated from Mexican cocoa mucilage (Theobroma cacao) and coffee pulp (Coffea arabica) for their potential use as sourdough starter co-cultures to improve bread quality. Functional screens included assessments of amylolytic, proteolytic, and phytase activities, CO₂ production, acidification capacity, and exopolysaccharide (EPS) synthesis. Saccharomyces cerevisiae YCTA13 exhibited the highest fermentative performance, surpassing commercial baker’s yeast by 52.24%. Leuconostoc mesenteroides LABCTA3 showed a high acidification capacity and EPS production, while Lactiplantibacillus plantarum 20B3HB had the highest phytase activity. Six yeast–LAB combinations were formulated as mixed starter co-cultures and evaluated in sourdough breadmaking. The B3Y14 co-culture (LABCTA3 + YCTA14) significantly improved the bread volume and height by 35.61% and 17.18%, respectively, compared to the commercial sourdough starter, and reduced crumb firmness by 59.66%. Image analysis of the bread crumb revealed that B3Y14 enhanced the crumb structure, resulting in greater alveolar uniformity and a balanced gas cell geometry. Specifically, B3Y14 showed low alveolar regularity (1.16 ± 0.03) and circularity (0.40 ± 0.01), indicating a fine and homogeneous crumb structure. These findings highlight the synergistic potential of selected allochthonous yeast and LAB strains in optimizing sourdough performance, positively impacting bread texture, structure, and quality. Full article

Molasses, a by-product of raw sugar production, is widely used as a cost-effective carbon and nutrient source for industrial fermentations, including the production of baker’s yeast (Saccharomyces cerevisiae). Due to the cost and limited availability of molasses, efforts have been made to replace molasses with cheaper and more readily available substrates such as corn syrup. However, the quality of dry yeast drops following the replacement of molasses with corn syrup, despite the same amount of total sugar being provided. Our understanding of how molasses replacement affects yeast physiology, especially during the dehydration step, is limited. Here, we examined changes in gene expression of a strain of baker’s yeast during fermentation with increasing corn syrup to molasses ratios at the transcriptomic level. Our findings revealed that the limited availability of the key metal ions copper, iron, and zinc, as well as sulfur from corn syrup (i) reduced their intracellular storage, (ii) impaired the synthesis of unsaturated fatty acids and ergosterol, as evidenced by the decreasing proportions of these important membrane components with higher proportions of corn syrup, and (iii) inactivated oxidative stress response enzymes. Taken together, the molecular and metabolic changes observed suggest a potential reduction in nutrient reserves for fermentation and a possible compromise in cell viability during the drying process, which may ultimately impact the quality of the final dry yeast product. These findings emphasize the importance of precise nutrient supplementation when substituting molasses with cheaper substrates. Full article

Surplus bread accounts for a significant proportion of food waste in many countries. The focus of this study was twofold: firstly, to investigate the use of carasau bread residue as a sourdough substrate, and secondly, to reuse this sourdough into a new carasau baking process. Selected lactic acid bacteria (Lactiplantibacillus plantarum) and yeast strains (Saccharomyces cerevisiae and Wickerhamomyces anomalus) were used to inoculate three substrates: bread residue (S1), bread residue supplemented with durum wheat middlings (S2), and semolina (S3). Sourdoughs were refreshed for five days by backslopping, and microbiological and physicochemical analyses were performed. Results indicated that incorporating wheat middlings into bread residue enhanced microbial performance, as evidence by a decrease in pH from 6.0 to around 4.5 compared to using bread residue alone as a substrate. Carasau bread produced with the sourdough derived from bread residue and wheat middlings exhibited comparable physicochemical properties to commercial baker’s yeast carasau bread, but had better sensory properties, scoring a mean acceptability of 7.0 versus 6.0 for baker’s yeast bread. These results show that bread residue supplemented with wheat middlings can serve as a sourdough substrate, allowing its reuse in the baking process to produce high-quality carasau bread and promote the circular economy. Full article