Search Results (82)

With growing emphasis on antibiotic-free poultry production, functional probiotics represent a promising strategy to improve gut health and reduce pathogen transmission. This study characterized three lactic acid bacteria (LAB) strains Lactobacillus delbrueckii subsp. bulgaricus NRRL-B-548 (LD), Lacticaseibacillus paracasei DUP-13076 (LP), and Lacticaseibacillus rhamnosus NRRL-B-442 (LR) for their probiotic potential and evaluated their efficacy against Salmonella enterica in poultry. The LAB strains were assessed for acid and bile tolerance, lysozyme resistance, cholesterol assimilation, antimicrobial activity, surface hydrophobicity, epithelial adherence, hemolysis, and antibiotic susceptibility. Genomic analysis was performed to identify genes associated with probiotic functionality. The protective potential of LR and LP was further validated in hatchlings using a hatchery spray model challenged with Salmonella Enteritidis. All strains survived simulated gastric and intestinal conditions, exhibited strong adhesion to epithelial cells, and demonstrated high hydrophobicity, indicating robust colonization capacity. The LAB significantly inhibited Salmonella Enteritidis, S. Typhimurium, and S. Heidelberg growth in vitro and remained sensitive to clinically relevant antibiotics. In vivo application of LR and LP to hatching eggs markedly reduced S. Enteritidis colonization in the liver, spleen, and ceca of hatchlings. Further, genomic profiling of the LAB strains revealed genes for bacteriocin production, exopolysaccharide synthesis, and carbohydrate metabolism supporting probiotic function. In summary, the evaluated LAB strains exhibit multiple probiotic attributes and strong anti-Salmonella activity, confirming their potential as safe, hatchery-applied probiotics for improving gut health and biosecurity in poultry production systems. Full article

The valorization of food processing by-products is a key strategy for advancing sustainability in the agri-food sector. This study developed a fermented milk product incorporating tomato powder (TP) obtained from surplus tomatoes not meeting retail appearance standards. Four yogurt formulations were prepared containing TP (2% and 4%, w/v) and two controls with skim milk powder adjusted to equivalent total solids. Samples were inoculated with a commercial starter culture and fermented at 42 °C to a final pH of 4.6. TP addition did not hinder fermentation but altered acidification kinetics, as the 4% TP yogurt exhibited a faster initiation (T_m ≈ 80 vs. 120 min in the control) yet a slower rate of pH decline (V_max = 0.009 vs. 0.019 pH units/min). TP-fortified yogurts exhibited higher water holding capacity (98% vs. 83%), increased firmness (87 g vs. 47 g), and substantially elevated viscosity (63,000–68,000 mPa·s) while lycopene enrichment enhanced color attributes. Viable counts of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus remained within typical ranges (~6.8 and ~4.9 log CFU/g, respectively, after 24 h), confirming that TP did not compromise microbial activity. Overall, incorporating TP improved structural and functional properties while simultaneously providing tomato-derived antioxidants and promoting a sustainable, circular utilization of surplus tomato streams in fermented dairy products. Full article

Microparticles (MPs) are delivery systems for bioactive compounds with particle sizes in the micrometer range (1–1000 μm). This study reports a green protocol for the biosynthesis of ZnO-, MgO-, and CaO-MPs using the probiotic strains Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and Leuconostoc mesenteroides. Ultraviolet–visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), and dynamic light scattering (DLS) were used for the preliminary characterization of the metal oxide MPs. Antimicrobial activity was evaluated against pathogenic and phytopathogenic microorganisms, including Salmonella typhimurium, Staphylococcus aureus, Escherichia coli, and Ralstonia solanacearum. UV-Vis analysis revealed previously reported blue shifts in the ZnO- and CaO-MPs. DLS measurements showed particle sizes larger than 1000 nm in 95% of the cases, while smaller sizes were observed by SEM. The stability of the MPs, based on their zeta potential values, ranged from relatively to moderately stable. This study demonstrates that the six probiotic lactic acid bacteria strains are capable of synthesizing ZnO-MPs, CaO-MPs, and MgO-MPs. All MPs exhibited antimicrobial activity against pathogens and phytopathogens at different concentrations. Although similar antimicrobial effects have been reported for metal oxide nanoparticles produced by probiotic bacteria, considering the potential environmental and human health impacts of nanoparticles, the use of safer materials obtained through green synthesis—such as metal oxide MPs—may represent a more suitable alternative. Full article

Off-odors produced by volatile compounds remain a major barrier to consumer acceptance of plant-based proteins. This study presents a novel two-stage fermentation strategy to effectively reduce undesirable volatiles in eight plant proteins. A sequential fermentation process was developed using Lactobacillus plantarum in Stage 1 and a traditional yogurt culture, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. Bulgaricus and Lactobacillus acidophilus, in Stage 2. This method was applied to solutions of 9% soy, pea, chickpea, mung bean, faba bean, rice, barley-rice, and hemp proteins. Volatile profiles were analyzed via Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) and sensory evaluation before and after fermentation. The two-stage fermentation resulted in significant deodorization, with 95–99% reduction in key odorants such as hexanal, 2-pentylfuran, methoxypyrazines, and sulfur compounds across all proteins. The sequential approach significantly outperformed a one-stage fermentation. Allulose enhanced L. plantarum activity while strawberry preserves supported traditional yogurt culture performance. Non-fermentable additives such as pectin, xanthan gum, and oil had minimal effects on volatiles. The proposed fermentation method offers an effective, scalable, and clean-label solution for mitigating off-odors in plant-based proteins. By leveraging microbial metabolism and formulation synergies, this strategy provides a foundation for developing more palatable plant-based dairy alternatives. Full article

Background: scleroglucan, an extracellular polysaccharide with gel-forming, thickening, and stabilizing properties, was used as a structure-forming agent in low-fat yogurt formulations. The aim of this study was to evaluate its influence on the fermentation process and the physicochemical, rheological, textural, microstructural, and sensory properties of the yogurts. Methods: control samples were formulated with the addition of skim milk powder (SMP), whereas experimental yogurts contained scleroglucan at concentrations of 0.25%, 0.5%, and 1.0% (w/w). The fermentation kinetics, acidity, color, syneresis, rheological behavior, texture profile, microstructure, and volatile compounds were analyzed during storage. Results: the results showed that scleroglucan slowed acidification and increased the apparent viscosity, yield stress, and firmness of yogurts, while completely eliminating syneresis. Scleroglucan also modified the volatile profile by decreasing acetaldehyde and increasing 2,3-pentanedione levels during storage. The survival of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus was not affected. Conclusions: the yogurt containing 1.0% scleroglucan was rated highest in overall acceptability. These findings demonstrate that scleroglucan can serve as a natural, clean-label stabilizer and an alternative to skim milk powder in low-fat set-style yogurts. Full article

The sustainable valorisation of agro-industrial by-products offers a promising pathway to address global protein demand while supporting circular food systems. This study explored the biotechnological potential of pumpkin (Cucurbita pepo), sunflower (Helianthus annuus), and walnut (Juglans regia L.) oilseed cakes as substrates for developing vegan yoghurt-like fermented beverages. Each formulation was fermented with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, and comprehensively evaluated for composition, functionality, sensory properties, and bioactivity. The oilseed-based beverages exhibited protein levels between 3.7–4.6%, fibre content up to 1.9%, and reduced syneresis (14–18%) compared with the commercial almond-based product (21.5%). The walnut-based variant (WOCY) showed the highest total polyphenol content (1108.97 mg GAE kg⁻¹) and antioxidant activity (412.54 mg Trolox kg⁻¹ DPPH; 51.5 mg TE g⁻¹ DW ABTS), surpassing both the almond-based vegan yoghurt (238.82 mg GAE kg⁻¹) and dairy reference (96.10 mg GAE kg⁻¹). Preliminary sensory profiling through the Check-All-That-Apply (CATA) method indicated that pumpkin- and walnut-based samples were most associated with “creamy texture,” “nutty aroma,” and “very pleasant” descriptors, achieving acceptance comparable to or higher than conventional yoghurts. Microbiological analyses confirmed product safety and high viable cell counts (<10⁸ CFU mL⁻¹) after 14 days of storage. Oilseed cakes serve as efficient substrates for producing nutrient-dense, antioxidant-rich, and sensorially appealing plant-based fermented beverages, supporting functional food innovation and promoting circular bioeconomy through the sustainable valorisation of agro-industrial by-products. Full article

The aim of this study was to investigate the effects of the addition of guar gum (GG) and xanthan gum (XG) on the proximate composition, texture, viscosity, syneresis, color characteristics, microbiological stability, sensory evaluation, rheological properties, and microstructure of a low-fat yogurt sample. The results showed that adding GG and XG at concentrations of 0.5 and 1% increased the hardness and viscosity of yogurt significantly (p < 0.05), with XG having a more pronounced effect. There was no significant difference (p > 0.05) in color characteristics between all treatments during the storage period. The viability of probiotics was enhanced in gum-supplemented yogurts, with XG providing better protection for Lactobacillus delbrueckii subsp. bulgaricus and Bifidobacterium bifidum during storage. Sensory evaluation results showed that XG samples gained higher scores as compared to GG samples. Rheological analysis revealed that both the hydrocolloids guar gum (GG) and xanthan gum (XG) significantly increased the parameters such as viscosity and yield stress of low-fat yogurt, with xanthan gum having a more pronounced effect on enhancing the flow behavior. Microstructural analysis using scanning electron microscopy revealed that XG supplementation improved the yogurt gel network, developing a more compact and cohesive structure; however, GG produced a looser and more dispersed network. Overall, both GG and XG enhanced the rheological, textural, and microstructural characteristics of low-fat yogurt, with XG showing superior effects on texture, gel structure, and probiotic stability. Full article

With growing consumer demand for functional dairy products, developing yogurts enriched with natural bioactive ingredients has become a research focus. Millet, a traditional cereal rich in polyphenols and dietary fiber, remains understudied in fermented dairy applications. This study evaluated the physicochemical properties, sensory quality, and functional activities of yogurt co-fermented with millet. Millet liquid, pre-treated through gelatinization and α-amylase liquefaction, was co-fermented with milk at addition ratios of 40% and 60% (w/w). The results indicated that millet liquid increased Lactobacillus delbrueckii subsp. Bulgaricus viability (8.55–8.58 log CFU/g vs. 8.26 log CFU/g in the control), improved viscosity (up to 1.0–1.6-fold higher than the control), enhanced texture properties (51–65-fold increase in springiness, 4.3–4.6-fold higher chewiness), and reduced syneresis (18.6–49.2% lower than the control). Sensory evaluation revealed superior flavor and sweetness in millet-enriched yogurt, achieving significantly higher scores than plain yogurt (p < 0.05). Functionally, the 60% millet yogurt showed 77.8% and 84.3% higher DPPH and ABTS radical scavenging capacities, respectively. Additionally, it suppressed DSS-induced inflammatory cytokine secretion in Caco-2 cells (27.2–69.7% inhibition of TNF-α, IL-6, and IL-1β). The improved antioxidant and anti-inflammatory activities may be attributed to polyphenol release from millet. This work highlights the potential of millet–milk co-fermentation for developing yogurts with enhanced texture, sensory appeal, and bioactive properties. Full article

Streptococcus thermophilus is a Gram-positive, homofermentative lactic acid bacterium classified within the Firmicutes phylum, recognized for its probiotic properties and significant role in promoting human health. This review consolidates existing understanding of its metabolic pathways, functional metabolites, and diverse applications, highlighting evidence-based insights to enhance scientific integrity. S. thermophilus predominantly ferments lactose through the Embden-Meyerhof-Parnas pathway, resulting in L(+)-lactic acid as the primary end-product, along with secondary metabolites including acetic acid, formic acid, and pyruvate derivatives. Exopolysaccharides (EPS) are composed of repeating units of glucose, galactose, rhamnose, and N-acetylgalactosamine. They display strain-specific molecular weights ranging from 10 to 2000 kDa and contribute to the viscosity of fermented products, while also providing antioxidant and immunomodulatory benefits. Aromatic compounds such as acetaldehyde and phenylacetic acid are products of amino acid catabolism and carbohydrate metabolism, playing a significant role in the sensory characteristics observed in dairy fermentations. Bacteriocins, such as thermophilins (e.g., Thermophilin 13, 110), exhibit extensive antimicrobial efficacy against pathogens including Listeria monocytogenes and Bacillus cereus. Their activity is modulated by quorum-sensing mechanisms that involve the blp gene cluster, and they possess significant stability under heat and pH variations, making them suitable for biopreservation applications. In food applications, S. thermophilus functions as a Generally Recognized as Safe (GRAS) starter culture in the production of yogurt and cheese, working in conjunction with Lactobacillus delbrueckii subsp. bulgaricus to enhance acidification and improve texture. Specific strains have been identified to mitigate lactose intolerance, antibiotic-related diarrhea, and inflammatory bowel diseases through the modulation of gut microbiota, the production of short-chain fatty acids, and the inhibition of Helicobacter pylori. The genome, characterized by a G + C content of approximately 37 mol%, facilitates advancements in Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas technology and heterologous protein expression, with applications extending to non-dairy fermentations and the development of postbiotics. This review emphasizes the adaptability of S. thermophilus, showcasing the variability among strains and the necessity for thorough preclinical and clinical validation to fully utilize its potential in health, sustainable agriculture, and innovation. It also addresses challenges such as susceptibility to bacteriophages and limitations in proteolytic activity. Full article

Agricultural by-products, such as banana pseudostems (BPS), present a sustainable solution for waste reduction and the recovery of valuable metabolites with biotechnological applications. This study investigated the potential of BPS as a substrate for bio-fermentation, specifically for the cultivation of lactic acid bacteria (LAB). Maçã cultivar BPSs (MBPS) and Nanica cultivar BPSs (NBPS) flour samples showed differences in carbohydrate composition, especially in resistant starch (16.7 and 2.7%), cellulose (27.0 and 52.4%), and hemicellulose (25.4 and 33.8%), respectively. Phenolic compound content in NBPS was higher than in MBPS (193.9 and 153.5 GAE/100 g, respectively). The BPS starches and flour were well assimilated by the probiotic LAB cultures. Limosilactobacillus fermentum SJRP30 and SJRP43 showed significant growth in media with gelatinized Maçã flour (GMF) and non-gelatinized Nanica flour (NGNF) BPS by-products (Log 9.18 and 9.75 CFU/mL, respectively), while Lacticaseibacillus rhamnosus GG exhibited the highest growth (Log 11.31 CFU/mL) in the medium with NGNF BPS by-products. The probiotic Lbs. casei SJRP146 and Lmb. fermentum SJRP30 and SJRP43 presented high enzymatic activity and the ability to assimilate D-xylose. Only Lactobacillus delbrueckii subsp. bulgaricus SJRP57 and SJRP49 were able to assimilate starch. Their prebiotic potential under in vitro gastrointestinal digestion was evidenced by promoting the selected probiotic bacteria’s protection and maintaining their viable cells after challenging conditions, likely associated with the BPS composition. Lab. delbrueckii subsp. bulgaricus SJRP57, Lacticaseibacillus casei SJRP145, and Lmb. fermentum SJRP43 performed similarly to the commercial strain Lbs. rhamnosus GG. These results demonstrate the feasibility of using cost-effective and abundant agricultural waste as a promising sustainable ingredient with potential prebiotic activity, via eco-friendly production methods that do not require chemical or enzymatic extraction. Full article

The demand for plant-based fermented beverages is being driven by dietary restrictions, health concerns, and environmental concerns. However, the use of plant substrates, such as oats, presents challenges in terms of fermentation and texture formation. The effects of enzymatic hydrolysis, homogenization and the addition of 1% pectin on oat-based beverages fermented with Lactobacillus delbrueckii subsp. bulgaricus were evaluated in this study. The samples were evaluated for a number of characteristics, including physicochemical, rheological, antioxidant and sensory properties. After 6 h fermentation, pectin-containing samples showed a statistically significant decrease in pH (to 3.91) and an increase in titratable acidity (to 92 °T). Homogenization and the addition of pectin were found to significantly increase viscosity (by 1.5–2 times) and water-holding capacity (by 2 times) while reducing syneresis by 96%. The antioxidant activity of L. bulgaricus-fermented samples increased significantly: the radical scavenging activity (RSA) and OH-radical inhibition increased by 40–60%, depending on the treatment. Extractable polysaccharides (PSs) inhibited lipase and glucosidase by 90% and 85%, respectively; significantly higher inhibition was observed in the fermented and pectin-containing groups. Sensory evaluation showed that the homogenized, pectin-enriched samples (Homog+) scored highest for consistency (4.5 ± 0.2), texture (4.9 ± 0.2), and overall acceptability (4.8 ± 0.2); these scores were all statistically higher than those for the untreated samples. These results suggest that combining enzymatic hydrolysis, homogenization and fermentation with L. bulgaricus significantly improves the structural, functional and sensory properties of oat-based beverages, providing a promising approach to producing high-quality, functional non-dairy products. Full article

To improve the quality and functional properties of yogurts, a multi-starters co-fermentation system was used during yogurt preparation. In this work, Weissella cibaria G232 (added at 0%, 3%, 5%, and 7%) was involved as a co-fermenter with a traditional starter (Lactobacillus delbrueckii subsp. bulgaricus G119 and Streptococcus thermophilus Q019). The results showed that W. cibaria G232 co-fermentation could shorten the fermentation time and significantly enhance the viable counts of yogurt (p < 0.05). Moreover, the incorporation of W. cibaria G232 improved the water holding ability, viscosity, and texture of yogurt. Notably, the highest levels of firmness, consistency, and cohesiveness of yogurt were observed at the 5% addition level of W. cibaria G232. Furthermore, co-fermentation with W. cibaria G232 significantly enhanced the antioxidant activity of yogurt, as evidenced by increased free radical scavenging capacity and ferric ion reducing antioxidant power (FRAP) value. The intelligent sensory technology and Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) indicated that co-fermentation with W. cibaria G232 and a traditional starter notably altered the accumulation of aldehydes, ketones, and alcohols in yogurt. These findings suggest that co-fermentation of W. cibaria G232 with a traditional starter present the potential for the quality and functionality improvement of yogurt and also lay the foundation for the application of W. cibaria G232. Full article

The consumption of microalgae-based foods is growing due to their exceptional nutritional benefits and sustainable cultivation. However, their strong off-flavors and odors hinder their incorporation into food products. Lactic acid fermentation, a traditional method known for modifying bioactive and aromatic compounds, may address these challenges. This study aims to evaluate the impact of lactic acid fermentation on the aromatic profiles of four distinct Chlorella vulgaris biomasses, each varying in protein, carbohydrate, lipid, and pigment content. Six lactic acid bacteria (LAB) strains, Lacticaseibacillus casei, Lcb. paracasei, Lcb. rhamnosus, Lactiplantibacillus plantarum, Lactobacillus delbrueckii subsp. bulgaricus, and Leuconostoc citreum, were used for fermentation. All biomasses supported LAB growth, and their volatile profiles were analyzed via HS-SPME-GC-MS, revealing significant variability. Fermentation notably reduced concentrations of compounds responsible for off-flavors, such as aldehydes. Specifically, hexanal, associated with a green and leafy aroma, was significantly decreased. Lcb. paracasei UPCCO 2333 showed the most effective modulation of the volatile profile in Chlorella vulgaris, significantly reducing undesirable compounds, such as aldehydes, ketones, pyrazines, and terpenes, while enhancing ester production. These results highlight lactic acid fermentation as an effective method to improve the sensory characteristics of C. vulgaris biomasses, enabling their broader use in innovative, nutritionally rich food products. Full article

Starter culture significantly influences the texture and flavor of yogurt, making the selection of appropriate fermentation strains a key focus in yogurt starter research. In this study, protease-producing Lactiplantibacillus plantarum NH-24, identified in prior experiments, was combined with Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophiles for yogurt fermentation. Indicators such as coagulation state, acidity, and water-holding capacity were measured to determine the optimal fermentation temperature and starter ratio. Additionally, the effects of this strain on the yogurt’s texture, sensory properties, and volatile flavor compounds were evaluated. The results indicate that a fermentation temperature of 37 °C and a starter ratio of 4:4:3 were most suitable for yogurt production. Further analysis demonstrated that incorporating Lp. plantarum NH-24 improved the yogurt’s texture and flavor while reducing post-acidification during storage. Thus, protease-producing Lp. plantarum NH-24 holds significant promise as a yogurt starter culture. Full article

The growing demand for plant-based and hybrid dairy–plant beverages has driven interest in optimizing their fermentation processes. This study investigates the effects of selected lactic acid bacteria (LAB) cultures on the quality characteristics of fermented dairy, dairy–oat, and oat beverages. The term ‘dairy-oat beverage’ refers to a hybrid product composed of cow’s milk and an oat-based drink in a 1:1 ratio. Cow’s milk, an oat beverage, and a 1:1 mixture of both were inoculated with traditional yogurt cultures (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) and/or probiotic strains (Lactiplantibacillus plantarum 299v and Lactobacillus acidophilus La-5). Fermentation was conducted for 6 h at 37 °C, followed by 28 days of cold storage. pH, texture (hardness and adhesiveness), syneresis, carbohydrate content, and bacterial viability were assessed. The selection of lactic acid bacteria cultures had a significant impact on the quality attributes of the beverages. Both the bacterial culture type and the base material played a crucial role in determining the beverages’ texture, stability, and overall quality. Mixed bacterial cultures exhibited higher hardness, while milk and dairy–oat samples fermented with the yogurt culture demonstrated better structural stability. Fermentation influenced sugar levels, and bacterial viability depended on the beverage type and storage conditions. The selection of lactic acid bacteria cultures significantly impacts the quality of fermented beverages. Further optimization of bacterial culture combinations could improve these products’ stability and sensory properties. Full article