Yogurt Fermentation Research Articles

Exploring the physicochemical, structural, metabolic, and flavor compounds of Limosilactobacillus fermentum in fermented yogurt through comparative genomics

Adding specific lactic acid bacteria to yogurt has been known to enhance both its benefits and flavor. However, differences among the strains of the same species present significant challenges. In this study, we constructed a phylogenetic tree of 232 Limosilactobacillus fermentum strains and selected seven strains with distinct evolutionary relationships for yogurt fermentation. L. fermentum FFJ12, which possesses more glycoside hydrolases (GH), had the highest growth rate and acid production. Conversely, L. fermentum FBJSY21_1, containing less GH, showed poor acid production. Yogurt texture might be related to amino acid synthesis. L. fermentum induced a high abundance of dibenzoyl-L-tartaric acid anhydride, leading to a wine-like flavor in yogurt. Additionally, L. fermentum upregulated citric acid and 4-acetamidobenzoic acid levels; and downregulated phenylalanine abundance. This study provided novel insights into the selection of potential probiotics for yogurt fermentation, thereby promoting the development of precision yogurt.

Effect of the Fermentation Time of Purple Sweet Potato (Ipomea Batatas L) Synbiotic Yoghurt with Probiotic Starter on Product Quality and Antioxidant Activity

Purple sweet potato (Ipomea batatas L) has the potential as a fermentation medium because it has a high carbohydrate content of around 20.1%. The combination of purple sweet potato extract, skimmed milk, and probiotic starter is expected to be a synbiotic yogurt that can help the digestive system. This study aims to determine the effect of long-term fermentation of purple sweet potato synbiotic yogurt with probiotic starter culture on product quality and antioxidant activity. The observed quality was chemical, microbiological, and organoleptic, with variations in fermentation time of 0, 4, 8, and 12 hours. The study's results showed a long-term effect of the fermentation of purple sweet potato synbiotic yogurt with probiotic starter culture on the quality of yogurt. The variation of 0-hour fermentation time did not meet the pH chemical quality standard with a value of 5.16. Still, it met the TAT chemical quality standard with a value of 0.513%, while the variation of fermentation time of 4-12 hours met the pH quality standard with a value of 3.88-4.33 and a TAT of 1.268-1.967%. In the quality of microbiology, there was a total increase in BAL, which was 46.2×107 - 90.61×107. The best organoleptic quality of color, taste, and aroma was obtained in the 8-hour fermentation variation, while the best texture organoleptic quality was obtained in the 12-hour fermentation variation. The best antioxidant activity was received at 12 hours of fermentation with an IC50 value of 62.727 ppm. From this study, it can be concluded that the best yogurt results are obtained with a fermentation time of 12 hours.

Metabolomics-based biomarkers of fermented dairy and red meat intake: a randomized controlled trial in healthy adults.

Dietary assessment is usually performed through imprecise tools, leading to error-prone associations between diet and health-related outcomes. Metabolomics has been applied in recent years to develop biomarkers of food intake (BFIs) and to study metabolites in the diet-microbiome crosstalk. Candidate BFIs exist to detect intake of meat and to a lesser extent dairy, but validation and further development of BFIs are needed. Here, we aim to identify biomarkers that differentiate between intakes of red meat and dairy, to validate previously reported BFIs for these foods, and to explore the effect of protein-matched meals on selected microbial metabolites. We conducted a randomized, controlled, cross-over single-meal study comparing a meal with highly fermented yogurt and cheese, and a meal with beef and pork meatballs. Postprandial urine samples from 17 subjects were collected sequentially after each meal up to 24h and analyzed by untargeted metabolomics through ultra-high-performance-liquid chromatography (UHPLC) coupled via electrospray (ESI) source to a qTOF mass spectrometer. Univariate (repeated measures ANOVA) and multivariate (PLSDA, ML-PLSDA) data analyses were used to select BFIs differentiating the two meals. 3-Indoxyl sulfate, p-cresol sulfate, and several other microbial amino acid catabolites were additionally explored within the urine profiles. Thirty-eight markers of meat and dairy intake were selected and are presented along with their excretion kinetics. Carnosine, taurine, and creatine, as well as hydroxyproline-based dipeptides are confirmed as meat BFIs. For dairy, previously reported metabolites such as acyl-glycines are confirmed, while proline-based dipeptides are reported as novel putative BFIs. Microbial metabolites showed only marginal evidence of differential formation after the two meals. This study allowed us to validate the postprandial kinetics of previously suggested biomarkers of meat and dairy intake and to identify new potential biomarkers. The excretion kinetics are useful to ensure that the collection of urine covers the correct time window in future dietary studies. The BFIs add to the existing body of biomarkers and may further be used in combination to provide a more reliable assessment of meat and dairy intake. Proteolytic microbial metabolites should be further investigated to assess the effect of different protein sources on health.

Genomic and metabolomic analysis of Latilactobacillus sakei DCF0720 for black soybean yogurt fermentation

Lactic acid bacteria are commonly used in plant-based fermentation to reduce off-flavor and improve sensory characteristics. However, there have been few studies on Latilactobacillus sakei for plant-based yogurt fermentation and, particularly, its metabolic features at the genomic level remain unclear. This study aims to analyze the fermentation characteristics of the L. sakei DCF0720 strain and compare genetics and metabolic relations. For this, DCF0720 was used to ferment the black soybean milk and conduct the physicochemical analysis and sensory test. The genomic and metabolic analyses were performed by complete genome sequencing and 500 MHz 1H NMR, respectively. As a result, DCF0720 exhibited enhanced fermentation performance and sensory evaluations at 37 °C compared to 30 °C, which is generally recognized as the optimal growth temperature for most L. sakei strains. It also produced flavor enhancing volatile compounds such as acetoin and hydroxyacetone, possessing all three key genes for acetoin biosynthesis. DCF0720 lacks 2,3-butanediol dehydrogenase, which leads to the inhibition of acetoin production. DCF0720 possesses a complete pathway to utilize primary black soybean carbon sources such as sucrose, raffinose, and stachyose. DCF0720 also possesses genes for the GH28 family, including the key enzymes in the hydrolysis of pectin substances, which means eliminating the main soybean nonstarch polysaccharides. This study demonstrates that DCF0720 is a suitable starter for plant-based yogurt fermentation, providing a better understanding of fermentation conditions with genetic and metabolic features for black soybean yogurt. Various carbon source utilization abilities with depth metabolic pathway analysis provide that DCF0720 can be employed to develop enhanced starter cultures for black soybean yogurt and diverse plant-based yogurts.

Aqua Extracts of Lyophilized Sea Buckthorn Modify Fermentation and Quality Properties of Set-Type Yogurt

Aqua Extracts of Lyophilized Sea Buckthorn Modify Fermentation and Quality Properties of Set-Type Yogurt

The acceleration of yoghurt fermentation using peptides derived from proteolytic pre-treatment of milk

The acceleration of yoghurt fermentation using peptides derived from proteolytic pre-treatment of milk

Value addition to dietetic frozen yoghurt through use of fruit peel solids

The study pertains to preparing value added frozen yoghurt through use of orange peel powder (OPP). The quality aspects of medium-fat (6.0% fat) frozen yoghurt prepared using OPP at three levels (1.5, 2.5, 3.5% as T1, T2 and T3 respectively) was studied. Frozen yoghurt was prepared by freezing blend of fermented yoghurt base with ice cream mix (25:75 w/w); other ingredients were sugar, stabilizer-emulsifier and orange crush. Inclusion of OPP in frozen yoghurt impacted the orange flavour favorably and enriched product with β-carotene and dietary fiber. The control product (TC) was prepared in similar manner, avoiding OPP. As the level of OPP was raised in formulation, there was a marked increase in the protein, carbohydrate, ash and total solids when compared with TC. Presence of OPP markedly affected the acidity, viscosity, overrun and melting resistance of the product; maximum overrun was associated with TC. Product T3 had the maximum acidity and viscosity; T2 had maximum total sensory score. It is recommended to prepare medium-fat frozen yoghurt utilizing 2.5% OPP along with orange crush as flavouring. Such inclusion of peel solids enriched the product with β-carotene and dietary fiber, contributed to stabilization of product and enhanced the products sensory acceptance.

Potential antidiabetic activity of probiotic and Garcinia kola-yoghurt and its role in regulation of male fertility-stimulating hormones in high-fat diet/low dose streptozotocin-treated rats

Garcinia kola Heckel seed is widely used in the African traditional medicine as a aphrodisiac and male fertility enhancer. Probiotics can reestablish glucose homeostasis and improve blood lipid profiles by altering the composition of the intestinal flora. The study was planned to assess the efficacy of co-administration of Garcinia kola seed aqueous infusion and probiotic yoghurt in the management of diabetes and associated male fertility-stimulating hormones abnormalities. G. kola seed infusion was prepared, assessed for radical scavenging capacity, total phenolic content and phenolic profile using HPLC. Fermented yoghurt was prepared and inoculated with probiotic mixture. Rats were given a high-fat diet for four weeks and received an intraperitoneal injection of streptozotocin (30 mg/kg) to induce type 2 diabetes. Diabetic rats were received 200 mg/kg freeze-dried infusion of G. kola seed, probiotics yoghurt, and probiotic yoghurt mixed with G. kola once a day for four weeks. The levels of glucose, insulin, testosterone, follicle-stimulating hormone, luteinizing hormone, inflammatory indicators, oxidative markers, lipid profiles and liver as well as kidney biochemical indicators were measured. The administration of G. kola seed, probiotic yoghurt, or their combination to diabetic rats demonstrated potential anti-diabetic effects as evidenced by the down-regulation in glucose, insulin, lipid profile, oxidative markers, and inflammatory markers simultaneously with an up-regulation in testosterone, FSH, and LH levels compared to diabetic rats. G. kola seed, probiotic yoghurt, or their combination increased testosterone, FSH, and LH levels and are thought to have therapeutic promise for T2DM and its related oxidative stress.Graphical

Isolation and characterization of probiotic lactic acid bacteria from local yogurt and development of inulin-based synbiotic yogurt with the isolated bacteria

Synbiotic yogurts can offer several potential benefits due to the combination of yogurts probiotics, prebiotics, and the nutritional qualities of milk. Local yogurt variants might add to the variety of probiotic alternatives because they frequently have distinct microbial communities. Employing indigenous strains not only represents cultural preferences but also increases the probability of obtaining bacteria adapted to the surrounding environment. This study was intended to isolate and characterize potential lactic acid bacterial strains from local yogurt and assess the effectiveness of inulin on the physicochemical and microbiological properties during the fermentation of synbiotic yogurt. A total of eight strains were identified and isolated. Two chosen isolates were combined with inulin at 0, 0.5, 1, and 1.5 % concentrations to produce synbiotic yogurts. The physicochemical and microbiological properties were assessed during the fermentation process of synbiotic yogurts. The result showed that the isolated Lactobacillus spp. and Streptococcus spp. strains had probiotic characteristics and good growth. After the fermentation, the yogurt sample containing 1.5 % inulin had the highest count of Lactobacillus spp. (8.17 ± 0.01 log CFU/ml) and Streptococcus spp. (8.03 ± 0.03 log CFU/ml), highest optical density (2.931 ± 0.001), acidity (1.43 ± 0.03), and water-holding capacity (63.54 ± 0.51), and lowest syneresis (34.75 ± 0.48). The addition of inulin did not affect color during the fermentation of synbiotic yogurt. This study concluded that inulin could boost yogurt's stability when combined with local lactic acid bacteria strains.

Production of bioactive peptides during yogurt fermentation, their extraction and functional characterization

This study aimed to evaluate the antioxidant, antibacterial, antidiabetic and angiotensin-converting enzyme (ACE)-inhibitory effects of different fractions of bioactive peptides produced as a result of milk fermentation with yogurt starters and probiotics. In addition to yogurt starters, milk was fermented separately and together with Lacticaseibacillus rhamnosus GG and L. paracasei, then passed through 5 and 10 kDa (kilodalton) filters. A significant difference was observed in the fermentation time between the samples. The antioxidant, antibacterial, antidiabetic and ACE-inhibitory activities of the bioactive peptides were significantly affected by the probiotic strains and the molecular weight of the peptide (p < 0.05). ≤5 kDa fractions of Lactobacillus delbrueckii subsp. bulgaricus + Streptococcus thermophilus + L. rhamnosus GG + L. paracasei had the highest antioxidant activity. The addition of L. rhamnosus GG and L. paracasei to yogurt starter significantly increased ɑ-amylase activity, ɑ-glucosidase activity and ACE inhibitor activity. All samples showed antibacterial activity to Escherichia coli, Staphylococcus aureus, and Salmonella Typhimurium microorganisms and the molecular weight of peptides and sample types were significantly exhibited in antibacterial activity (p < 0.05). Cytotoxic activity showed that bioactive peptides had cytotoxic effect against Caco-2 adenocarcinoma cell and the presence of probiotics increased the cytotoxic effect. The results of the study suggest that the use of L. rhamnosus GG and L. paracasei, together with yogurt starters, could improve the bioactive properties of peptides formed in dairy products.

Innovative approaches to controlled yogurt fermentation using integrated solar PCM systems

ABSTRACT This study aimed to devise a novel fermentation unit for yogurt production utilizing phase change materials (PCM) and primarily powered by solar energy. The unit comprises a solar flat plate collector (FPC), PCM cells, and a fermentation cabinet equipped with trays. High-density polyethylene (HDPE) cylindrical cells were employed to contain paraffin wax for thermal energy storage. The performance of the integrated solar system for the fermentation process was assessed across different air velocities (1.2 to 1.8 m/s), with the most rapid temperature rise observed at 1.8 m/s. The PCM-based thermal storage exhibited an impressive capability of releasing heat autonomously for 6 hours without sunlight, eliminating the need for external energy sources. PCM’s capacity to store and release thermal energy ensures fermentation stability, even without solar radiation. This innovative approach offers a compelling environmentally friendly solution with significant implications for sustainable yogurt production, paving the way for industrial integration.

Phycocyanin-phlorotannin complexes improve the structure and functional properties of yogurt

Adding natural bioactive ingredients to yogurt can improve the nutritional and physiological benefits. In this study, we used ultrasonic-assisted phlorotannin from Ascophyllum nodosum (A. nodosum) modified phycocyanin (PC) to form a complex (UPP) to produce a fortified fermented yogurt. The effects of PC and UPP on the structure, stability, and function of fermented yogurt within 7 days were assessed using physicochemical properties, texture analysis, rheological testing, 16S rDNA sequencing analysis, and lipidomics analysis. Molecular docking indicated that PC might bind to phlorotannin via ARG-77, ARG-84, LEU-120, ALA-81, CYS-82, and ASP-85 sites.When the mass ratio of the complex is 1:1, the ability of UPP1:1 to remove DPPH· scavenging ability in an acid environment increased by about 50 %. UPP1:1 with more acid stability changed the microstructure of the yogurt, enhanced the stability of the yogurt, improved the antioxidant properties, and inhibited the growth of harmful bacteria within 7 days. This work encouraged the extraction and use of phlorotannin from edible brown algae and offered a straightforward method for making yogurt supplemented with PC.

Physicochemical, structural and metabolic products of yogurt as affected by Coriolus versicolor fermented sweet potato pulp water

Sweet potato pulp water (SPPW) is a kind of sweet potato starch processing by-product with rich nutrition but low utilization. The impacts of different proportions of Coriolus versicolor (C. versicolor, CV) fermented sweet potato pulp water (CV-SPPW) on the physicochemical, structural and metabolic properties of yogurt were investigated. Compared with 0% group, the hardness index, elasticity index and cohesion of the 10% sample group increased by 1.9-fold, 55.7% and 1.39-fold, respectively. When CV-SPPW was added at an amount of 10%, the microstructure and sensory scores of yogurts were considered as the optimal. Metabolic pathway analysis indicated that the changes of yogurts were mainly involved in sugar metabolism and amino acid metabolism, and that the carbohydrate metabolites produced mainly included cellobiose, maltitol, d-trehalose and d-maltose. The CV-SPPW improved the structural characteristics of yogurts to varying degrees and the fermented yogurts exhibited better viscosity properties.

Preventive effects of Chinese Xinjiang naturally fermented yogurt separated from Lactobacillus rhamnosusAFY02 on acute gouty arthritis in mice

AbstractLactobacillus rhamnosus AFY02 (LR‐AFY02) is a newly discovered strain isolated and identified from naturally fermented yogurt in Xinjiang, China. This research aims to investigate the mechanism of action of LR‐AFY02 in mice with acute gouty arthritis. We examined the degree of foot swelling, pain threshold, blood biochemical indicators, histopathological changes, and mRNA expression. LR‐AFY02 can decrease the severity of mouse foot edema and raise the pain threshold. LR‐AFY02 can increase the enzyme activity of superoxide dismutase (SOD) and the level of glutathione (GSH) while lowering the enzyme activity of myeloperoxidase (MPO) and the level of malondialdehyde (MDA) in mice with acute arthritis. Interleukin‐6 (IL‐6), IL‐10, interleukin‐1 beta (IL‐1β), and tumor necrosis factor‐alpha (TNF‐α) levels in the blood of mice with acute arthritis are also decreased by LR‐AFY02. Histopathological findings demonstrated that LR‐AFY02 reduced tissue damage in the mouse foot and ankle joints. LR‐AFY02 may suppress the mRNA expression of extracellular signal‐regulated kinase 1/2 (ERK1/2), cyclooxygenase‐2 (COX‐2), prostaglandin E2 (PGE2), IL‐6, interferon gamma (IFN‐γ), and TNF‐α in the tissues of the ankle joints of mice with acute arthritis. Additionally, LR‐AFY02 has the ability to increase the expression of catalase (CAT), manganese superoxide dismutase (Mn‐SOD), and copper/zinc superoxide dismutase (Cu/Zn‐SOD). As a result, it is clear that L. rhamnosus AFY02 is more effective than glucosamine sulfate at preventing acute gouty arthritis.

Microbial Ecology and Fermentation Dynamics of Traditional and Novel Fermented Yogurt in Brazil

Purpose: The aim of the study was to examine microbial ecology and fermentation dynamics of traditional and novel fermented yogurt in Brazil Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study revealed that traditional yogurt production relies on well-established microbial species such as Lactobacillus bulgaricus and Streptococcus thermophilus, which undergo dynamic shifts in population composition throughout fermentation. These shifts are influenced by factors such as temperature, pH, and substrate composition, highlighting the importance of controlling fermentation parameters to optimize product quality and consistency. Novel fermented yogurt products introduce innovative fermentation techniques, starter cultures, and ingredients, resulting in diverse microbial communities and fermentation dynamics. Incorporating prebiotics, specific starter cultures, or probiotics can enhance fermentation efficiency, promote the growth of beneficial microbial species, and improve product texture and flavor. Unique Contribution to Theory, Practice and Policy: Ecological Succession Theory &amp; Metabolic Theory of Ecology may be used to anchor future studies on microbial ecology and fermentation dynamics of traditional and novel fermented yogurt in Brazil. Yogurt producers can optimize fermentation conditions, such as temperature, pH, and fermentation time, to enhance product quality and consistency. Controlling these parameters can promote the growth of desirable microbial species, inhibit the growth of pathogens, and ensure the production of high-quality yogurt. Regulatory agencies should establish guidelines and standards for ensuring the safety of fermented yogurt products. This includes monitoring microbial safety aspects, such as the presence of pathogenic microorganisms and microbial toxins, throughout the production process.

Low-intensity pulsed electric fields pre-treatment on yogurt starter culture: Effects on fermentation time and quality attributes

Low-intensity pulsed electric fields (PEF) were applied to a starter culture mix (Streptococcus thermophilus, Lactobacillus bulgaricus, and partially skimmed milk) before the fermentation stage of natural yogurt. The impact of PEF processing conditions on yogurt fermentation time and quality characteristics was evaluated. PEF parameters were set based on a factorial experimental design; independent variables: electric field strength, pulse-frequency, and pulse-width, were explored, having fermentation time as a response. Most PEF treatments reduced fermentation time by 0.31–0.52 h compared to conventional yogurt processing (CY) (4.70 ± 0.23 h). The shortest time (4.18 ± 0.04 h) resulted from PEF pre-treatment with 8-μs monopolar pulses at 1 kV/cm and 150 Hz during 400 μs. The physicochemical and sensory characteristics of PEF-treated yogurt were similar to those of the CY immediately after processing and during refrigeration storage. Low-intensity PEF could be a promising alternative pre-treatment of yogurt production, reducing fermentation time while maintaining quality attributes of natural yogurt. Industrial relevanceConventional yogurt processing lasts around 4.5–6 h, representing high energy consumption and production costs. The application of pulsed electric fields (PEF) processing to the starter culture before yogurt fermentation represents a potential alternative to diminish production time by stimulating lactic acid bacteria and accelerating fermentation stage. This study demonstrated that low-intensity PEF (1–3 kV/ cm) reduced fermentation time by 0.31–0.52 h without compromising yogurt's quality properties, including physicochemical characteristics and sensory attributes. Obtained results suggest that this technology allows more efficient and sustainable yogurt production methods, positively impacting industry and consumers.

Physicochemical, microbiological and sensory characterization of yogurt fermented by Weissella confusa SW1 and traditional starters

Starter cultures play important roles in the quality and functional activity of yogurt. In this study, a novel strain Weissella confusa SW1 was isolated from naturally fermented milk. The potential application of this strain in yogurt preparation was investigated and the unique qualities it conferred on yogurt was characterized. W. confusa SW1 could efficiently metabolize lactose and galactose, and the whole-genome sequencing showed that it has a complete Leloir metabolic pathway. Besides, W. confusa SW1 had strong antioxidant capacity, and could significantly promote the growth of Streptococcus thermophilus. Subsequently, W. confusa SW1 was co-cultured with traditional starters (Lb. bulgaricus and S. thermophilus) to prepare yogurt. The results showed that the scavenging rates of DPPH and ABTS radicals of W. confusa SW1 fermented yogurt increased from 79.51% to 85.19% and 80.14%–85.47%, respectively. Meanwhile, the viable bacterial counts of Lb. bulgaricus and S. thermophilus were increased in yogurt when co-cultured with W. confusa SW1. Furthermore, the addition of W. confusa SW1 reduced the curd time and improved the water holding capacity of yogurt. Thus, this study laid a theoretical foundation for the development of functional yogurt with the application of W. confusa SW1.

Strategies to Improve the Quality of Goat Yogurt: Whey Protein Supplementation and Milk Pre-Treatment with High Shear Dispersion Assisted by Ultrasound

This work investigated the fermentation kinetics and characteristics of goat yogurt supplemented with bovine whey protein isolate (WPI) (0%, 2.5% and 5.0%) subjected to high shear dispersion (HSD) assisted by ultrasound (US). Protein supplementation and the physical processes increased the electronegativity of the zeta potential (≤60%), whereas particle size reduction was observed only with physical processes (≤42%). The addition of 2.5% WPI reduced yogurt fermentation time by 30 min. After 24 h of storage at 7 °C, lactic acid bacteria counts did not differ between samples (≥8 log CFU/mL), and the supplementation was sufficient to increase the apparent viscosity (≤5.65 times) and water-holding capacity (WHC) of the yogurt (≤35% increase). However, supplementation combined with physical processes promoted greater improvements in these parameters (6.41 times in apparent viscosity and 48% in WHC) (p &lt; 0.05), as confirmed by the denser and better-organized protein clusters observed in microscopic evaluation. Thus, both approaches proved to be promising alternatives to improve goat yogurt quality. Therefore, the decision to adopt these strategies, either independently or in combination, should consider cost implications, the product quality, and market demand.

Screening of a potential probiotic Lactiplantibacillus plantarum NUC08 and its synergistic effects with yogurt starter

This study aims to identify lactic acid bacteria (LAB) isolates possessing physiological characteristics suitable for use as probiotics in yogurt fermentation. Following acid and bile salt tolerance tests, Lactiplantibacillus plantarum (NUC08 and NUC101), Lacticaseibacillus rhamnosus (NUC55 and NUC201), and Lacticaseibacillus paracasei (NUC159, NUC216 and NUC351) were shortlisted based on intraspecies distribution for further evaluation. Their physiological probiotic properties, including transit tolerance, adhesion, auto-aggregation, surface hydrophobicity, biofilm formation, and antibacterial activity, were assessed. Principal Component Analysis (PCA) indicated that L. plantarum NUC08 was the preferred choice among the evaluated strains. Subsequent investigations revealed that co-culturing L. plantarum NUC08 with 2 yogurt starter strains resulted in a cooperative and synergistic effect, enhancing the growth of mixed strains and increasing their tolerance to simulated gastric and intestinal conditions. Additionally, when Vibrio harveyi bioluminescent reporter strain was used, the 3 cocultured strains cooperated to induce the activity of a quorum sensing (QS) molecule AI-2, hinting a potential connection between phenotypic traits and QS in the cocultured strains. Importantly, LAB viable counts were significantly higher in yogurt co-fermented with L. plantarum NUC08, consistently throughout the storage period. In conclusion, the study demonstrates that the probiotic strain L. plantarum NUC08 can be employed in synergy with yogurt starter strains, affirming its potential for use in the development of functional fermented dairy products.

Optimization of watermelon peel yogurt fermentation process and study on antioxidant capacity

This study aims to explore the variation patterns of total flavonoid and other antioxidant activities in watermelon peel yogurt, providing a basis for the production of a functional yogurt. Using watermelon peel as the raw material and total flavonoid content as the indicator, the optimal process of watermelon peel yogurt was optimized through single-factor and orthogonal experiments. The results indicate that yogurt fermented with a mass ratio of watermelon juice to milk at 1:3, fermentation time of 10 hours, and fermentation agent dosage of 0.10% exhibits a refreshing watermelon aroma, excellent texture, and almost no whey separation. After process optimization, the polysaccharide content of watermelon peel yogurt increased by 19%, and water-holding capacity rose to 63.3%. Texture analysis revealed a hardness of 81.50 g, viscosity of 20.00 g, adhesiveness of 1.20 mJ, elasticity of 8.83 mm, and a draw length of 6.76 mm. The physicochemical and microbiological properties of watermelon peel yogurt meet national standards, and it possesses a good free radical scavenging ability.