Streptococcus Thermophilus Research Articles

A Green Approach by Employing Two Bacterial Strains(Streptococcus thermophilus) and (Bacillus coagulans) to Reduce Graphene Oxide

A Green Approach by Employing Two Bacterial Strains(Streptococcus thermophilus) and (Bacillus coagulans) to Reduce Graphene Oxide

Prebiotic and probiotic potential of fermented milk with cashew (Anacardium occidentale) by-products evaluated in microbiome model

This study aimed to assess the functional attributes of the cashew by-product (CB) in fermented milk with the probiotic strain Lacticaseibacillus paracasei subsp. paracasei F19® (F19®) and the starter Streptococcus thermophilus ST-M6® (ST-M6®) using the Simulator of Human Intestinal Microbial Ecosystem (SHIME®). Two formulations of the fermented milk were assayed, in duplicates: Treatment 1 (T1, without CB) and Treatment 2 (T2, with CB). The strains behavior in the formulations and other bacterial groups of interest were assessed in SHIME®. The populations of the microbiota microorganisms and of the starter and probiotic strains were determined by PMA-qPCR. Metabolites produced in SHIME® reactors fermentation associated with nitrogen balance, antioxidant and phenolic compounds, and short-chain fatty acids (SCFA) were also measured. In SHIME®, both formulations had positive effects on the microbiota (an increase in Bifidobacterium spp. and Lactobacillus spp. and a decrease in Clostridium and Gamma Proteobacteria phyla). Considering these findings, probiotic fermented milk with F19®and ST-M6®, with or without cashew by-product, appears promising for a novel food product with enhanced nutrition, potentially classified as a synergistic synbiotic or at least a probiotic product.

PELATIHAN PEMBUATAN YOGHURT KEPADA KELOMPOK TANI PEREMPUAN DI DESA SEPAWON, KECAMATAN PLOSOKLATEN, KABUPATEN KEDIRI

The Sepawon Village Women's Farmers Group is a milk producing farmer group in Sepawon Village who usually sells milk to the cooperative at a price of 8000/L. The aim of UNP Kediri Animal Husbandry Study Program Community Service Team in collaboration with the Sepawon Village Women's Farmers Group to increase the economic value of milk by making fermented dairy products. Yogurt is a dairy product that can add economic value by fermenting it using the bacteria Lactobacillus bulgaricus and Streptococcus thermophilus. The benefit of consuming yoghurt is that it balances good bacteria in digestion and reduces toxic substances in the body. The process of making yoghurt involves heating the milk to be fermented at a temperature of 90°C for 15-30 minutes, after that the milk is cooled until the temperature reaches 40°C, then packaged in plastic bottles. Community Service Activities are carried out by means of Pre-Training, Yoghurt-making Training (Presentation and Demonstration) and post-test to determine participants' understanding. The results of Community Service showed that the Sepawon Village Women's Farmers Group participants were enthusiastic about taking part in the yoghurt making training. The post test results also showed that the participants were committed to independently continuing the practice of making yoghurt at home to increase the economic value of milk and farmer welfare.

Identifikasi Keragaman Mikroflora dan Pengaruhnya pada Kualitas Organoleptik Tempoyak Khas Suku Dayak di Kalimantan Tengah

Tempoyak as local wisdom and national culture is poorly documented. Therefore, it is important to explore the preferences of the millennial generation regarding the organoleptic qualities of Tempoyak. The research design is a one-shot case study. The variables tested were the diversity of microflora in tempoyak, and its influence on the level of organoleptic quality and the level of preference of the millennial generation. Identification of isolates using API-50CHL, biochemical tests and physiological tests. Organoleptic quality uses the hedonic scale test. The research panelists were 120 people from the Dayak, Madura, Jawa and Banjar tribes. Data analysis uses one way Anava analysis. 15 isolates of microflora were found in Tempoyak which affected its taste and organoleptics, 8 isolates including lactic acid bacteria, including Pediococcus acidilactici, Lactobacillus curvatus, Leuconostoc mesenteroides, Lactobacillus plantarum, Streptococcus thermophiles, Lactobacillus pentosus, Enterococcus faecium, and Weissella paramesenteroides. 1 isolate of non-lactic acid bacteria that is Micrococcus varians. 2 isolates from the yeast group consisted of Saccharomyces cereviciae and Kluyveromyces marxianus, and 4 isolates included Rhizopus, Monilia sitophila, and Mucor roxii. All microflora found were capable of producing lactic acid, except Aspergillus repens. The statistical test results show the significance of its influence on the organoleptic quality of all sub-variables, including color, taste, aroma and texture of Tempoyak. The exploration results in this research indicate opportunities for Tempoyak to be more developed, innovative and contemporary, so that it is preferred by the millennial generation.

Isolasi dan karakterisasi bakteri asam laktat dari susu sapi di Indonesia

Cow's milk is a source of nutrition that has a good impact on health and contains a variety of microorganisms, one of which is lactic acid bacteria (LAB) such as Streptococcus thermophilus and Lactobacillus sp. Therefore, this study aimed to isolate and characterize LAB from the milk of Friesian Holstein dairy cows in Indonesia. In addition, BAL enumeration was carried out to determine the population of LAB in cow's milk samples. Based on the results obtained, as many as 4.36 log CFU/mL of LAB was successfully enumerated in the sample. Cell morphology observations showed that there were 15 Streptococcus, and 35 Lactobacillus candidate isolates which were Gram positive, did not form endospores, and did not have a wax coating on their cell walls. Furthermore, negative results of the catalase test were shown by 10 Streptococcus and 35 Lactobacillus candidate isolates. Carbohydrate fermentation test showed that isolate STRP1 and STRP4 were suspected to be Streptococcus sp., while the Lactobacillus isolates were possibly L. delbrueckii, L. acidophilus, and L. helveticus. The hemolytic test indicated that STRP1 is S. thermophilus with alpha hemolytic activity. Confirmation of the species of the isolates should be done through molecular identification and further characterization.

Streptococcus thermophilus iHA318 Improves Dry Eye Symptoms by Mitigating Ocular Surface Damage in a Mouse Model.

Dry eye is a complicated ocular surface disease that causes discomfort, visual disturbance, and frequently observed ocular surface damage. Emerging hypotheses suggest probiotics may help relieve dry eye symptoms by modulating inflammation and oxidative stress. This study aimed to investigate the therapeutic effects of Streptococcus thermophilus iHA318 probiotics on dry eye using in vitro assays and an in vivo murine model of ultraviolet B (UVB) radiation-induced dry eye. In vitro analyses revealed that S. thermophilus iHA318® exhibited antioxidant activity and anti-inflammatory effects by inhibiting reactive oxygen species production and suppressing inflammatory cytokines. For the in vivo study, female ICR mice were assigned to normal control, UVB-induced dry eye, and UVB+iHA318 treatment groups. UVB exposure significantly decreased tear volume and tear film breakup time (TBUT) compared to normal controls. Supplementation with S. thermophilus iHA318® via oral gavage markedly improved tear production and TBUT on day 7 post-UVB exposure. Ocular surface photography demonstrated improved gradings of corneal opacity, smoothness, and lissamine green staining in the iHA318 group versus the UVB group. Topographical analysis further revealed improvement in the UVB-induced corneal irregularities by iHA318 treatment. Collectively, these results indicate that S. thermophilus iHA318 exerts a protective effect against dry eye symptoms by mitigating oxidative stress and inflammation, thereby preserving tear film stability and ocular surface integrity. This probiotic strain represents a promising therapeutic approach for managing dry eye syndrome.

Influence of thermophilic and mesophilic cultures blended with buffalo milk on camel milk cheese quality and proteolysis

SummaryCamel milk and its products are gaining higher demand due to their attractive nutritional and therapeutic profile. However, manufacturing of camel milk cheese (CMC) is a challenging task. This study aimed to compare the quality of camel milk cheese made using different starter cultures. Four groups CM (camel milk + mesophilic cultures), CT (camel milk + thermophilic cultures), CBM (camel milk + 10% buffalo milk using mesophilic cultures), and CBT (camel milk + 10% buffalo milk using thermophilic cultures) were created. The cheeses were stored for 60 days at 4 °C to assess their physicochemical, sensory, and proteolytic properties. Results indicated highest moisture content in CM (70.19%) as opposed to the lowest moisture in CBT (55.19%). In addition, CM and CBM revealed lower acidity (0.63% and 0.66%) in contrast with CT and CBT (0.78% and 0.83%, respectively). On the other hand, CBM and CBT exhibited higher contents of protein (21.04, 21.57%) and fat (17.65, 17.70%) during storage. All quality indices of cheese samples significantly declined (P < 0.01) during storage excluding acidity. Sensory analyses revealed that panellists highly preferred CBT treatment followed by CBM and CT. Furthermore, urea‐PAGE and RP‐HPLC were performed for the proteolytic study of cheese samples. The study revealed that the presence of buffalo milk and thermophilic cultures in cheese resulted in a decrease concentration of intact caseins (αs1, β‐, and κ‐caseins) as storage days passed. The degree of proteolysis was found to be higher in CBT compared to CBM, CT, and CM. Based on the results, it was concluded that the use of pasteurisation at 65 °C for 30 min, pH of 5.5, 0.06% CaCl2, and the incorporation of 10% buffalo milk using thermophilic cultures (Lactobaccilus bulgaricus and Streptococcus thermophilus) resulted in desirable quality characteristics.

Identification of volatile and odor-active compounds in pea protein fractions obtained by a modified extraction method using fermentation.

This study investigates the aromatic composition of pea albumin and globulin fractions obtained through either fermentation or conventional acidification using hydrochloric acid (control) toward the isoelectric point of pea globulins. Different lactic acid bacteria were used including S. thermophilus (ST), L. plantarum (LP), and their coculture (STLP). The volatile compounds were extracted by solvent-assisted flavor evaporation technique and quantified by gas chromatography-mass spectrometry (GC-MS). Odor-active compounds (OAC) were further characterized by gas chromatography-olfactometry (GC-O). In total, 96 volatile and 36 OACs were identified by GC-MS and GC-O, respectively. The results indicated that the protein fractions obtained by conventional acidification were mainly described by green notes for the presence of different volatile compounds such as hexanal. However, the samples obtained by fermentation had a lower content of these volatile compounds. Moreover, protein fractions obtained by coculture fermentation were described by volatile compounds associated with fruity, floral, and lactic notes. PRACTICAL APPLICATION: The insights from this study on pea protein aroma could find practical use in the food industry to enhance the sensory qualities of plant-based products. By utilizing fermentation methods and specific lactic acid bacteria combinations, manufacturers may produce pea protein with reduced undesirable green notes, offering consumers food options with improved flavors. This research may contribute to the development of plant-based foods that not only provide nutritional benefits but also meet consumer preferences for a more appealing taste profile.

Proliferation of probiotics and antioxidant effects of functional oligosaccharides added in fermented dairy product

To obtain functional fermented dairy products with strong probiotic proliferation and high antioxidant ability, the proliferation ability of oligosaccharides on probiotics and their DPPH radical scavenging ability were studied. Key functional oligosaccharides (galactooligosaccharide and galactomannan oligosaccharide) and probiotics (Bifidobacterium bifidum and Lactobacillus acidophilus) were selected. The orthogonal experimental design of L9(34) was employed to study the optimal process, which was adding 5 g/L galactomannan oligosaccharide and 5 g/L galactooligosaccharide in reconstituted milk, inoculating 1% Streptococcus thermophilus, 1% Lactobacillus bulgaricus and 1% probiotics (B. bifidum and L. acidophilus = 2:1) and fermenting for 6 h. This work is important for preparing functional fermented dairy products with a high content of probiotics and strong antioxidant capacity.

Comparison of the physicochemical property and volatile flavour compounds of yoghurt made from ultra-pasteurised and membrane-filtered milk

In this study, we aimed to compare and contrast the physicochemical and flavour attributes of yoghurt crafted from ultra-pasteurised (UPM-yoghurt) and membrane-filtered milk (MFM-yoghurt). The results indicated that MFM-yoghurt required 1.5 h longer than UPM-yoghurt to reach a pH of 4.5 at the end of fermentation, primarily owing to differences in Streptococcus thermophilus growth and lactoferrin (LF) content. UPM-yoghurt exhibited greater hardness, consistency, and water-holding capacity, resulting in a firmer gel texture. Conversely, MFM-yoghurt demonstrated lower viscosity but a smoother texture, possibly due to biologically active components. LF and lactoperoxidase (LPO) were absent in UPM-yoghurt, whereas MFM-yoghurt contained 106.00 mg/L of LF and 2986.25 U/L of LPO. Free amino acid analysis revealed lower levels of umami and bitter amino acids in MFM-yoghurt than those in UPM-yoghurt, while sweet amino acid levels were similar in both. The predominant volatile flavour compounds included aldehydes and ketones, with no significant differences observed in key compounds, such as 2-acetone, ethyl acetate, 3-hydroxy-2-butanone, and 2,3-butanedione, between the two yoghurts. However, notable variations were observed in 41 volatile flavour compounds between the samples, suggesting distinct flavour profiles. This study offers insights and directions for enhancing the nutritional quality of yoghurt.

Introducing Bacillus natto and Propionibacterium shermanii into soymilk fermentation: A promising strategy for quality improvement and bioactive peptide production during in vitro digestion

Herein, the texture properties, polyphenol contents, and in vitro protein digestion characteristics of soymilk single- or co-fermented by non-typical milk fermenter Bacillus natto (B. natto), Propionibacterium freudenreichii subsp. shermanii (P. shermanii), and traditional milk fermenter were evaluated. Co-fermenting procedure containing B. natto or P. shermanii could raise the amounts of gallic acid, caffeic acid, and GABA when compared to the unfermented soymilk. Co-fermented soymilk has higher in vitro protein digestibility and nutritional protein quality. Through peptidomic analysis, the co-work of P. shermanii and Lactobacillus plantarum (L. plantarum) may release the highest relative percentage of bioactive peptides, while the intervention of B. natto and Streptococcus thermophilus (S. thermophilus) resulted in more differentiated peptides. The multi-functional bioactive peptides were mainly released from glycine-rich protein, β-conglycinin alpha subunit 1, and ACB domain-containing protein. These findings indicated the potential usage of B. natto/S. thermophilus or P. shermanii/L. plantarum in bio-enhanced soymilk fermentation.

Description of “Ovino Belmontese”, a new semisoft sheep's milk cheese processed using “Italico” cheese technology

The objective of this study was to create a new semisoft sheep's milk cheese called “Ovino Belmontese” cheese (OBCh) by applying the “Italico” cheese-making technology. The cheese production took place under industrial conditions, with the addition of a commercial starter formulation containing Streptococcus thermophilus. The microbiological, physicochemical, and sensory characteristics of OBCh were assessed and compared to those of a commercially available cow's Italico cheese (CICh). Streptococcus thermophilus dominated the microbial community during the cheese-making process, reaching levels of approximately 9.0 Log CFU/g in both OBCh and CICh. Among physical characteristics, no statistically significant difference (p ≥ 0.05) was registered in terms of lightness, redness, yellowness, and hardness between the two cheeses. OBCh exhibited a twofold higher short-chain fatty acid content compared to CICh. Both cheeses displayed similar classes of volatile organic compounds, although their relative percentages differed. The application of Italico cheese technology to process sheep's milk did not negatively affect sensory attributes. This study highlighted that utilizing a cheese-making technology not commonly used for processing sheep's milk represents a promising strategy to diversify Sicilian dairy productions.

Regulation of gut microbiota and serum neurotransmitters in mice by Streptococcus thermophilus GA8- and Lacticaseibacillus rhamnosus HAO9-fermented milk containing high levels of gamma-aminobutyric acid.

Gamma-aminobutyric acid (GABA) is an important neurotransmitter in the human body, with several negative emotions reported as being associated with GABA dysregulation. This study investigates the safety and modulatory effects of GABA-enriched milk, fermented by Streptococcus thermophilus GA8 and Lacticasebacillus rhamnosus HAO9, on the gut microbiota and neurotransmitter profiles in mice. Through rigorous culturing and fermentation processes, we achieved consistent GABA production in milk, with concentrations reaching 4.6 and 8.5 g L-1 for GA8-fermented and co-fermented milk, respectively, after 48 h. Using SPF male C57BL/6J mice, we administered either mono-culture or combined-culture milk treatments and monitored physiological impacts. The treatments did not affect mouse body weight but induced significant changes in gut microbiota composition. Beta diversity analysis revealed distinct microbial profiles between treatment groups, highlighting fermentation-specific microbial shifts, such as an increase in Verrucomicrobia for the GA8 group and a modulation in Saccharibacteria_genera_incertae_sedis for the GA8 + HAO9 group. Serum neurotransmitter levels were elevated in both treatment groups, with significant increases in l-glutamine, l-tryptophan and, notably, serotonin hydrochloride in the GA8 + HAO9 group. Correlation analysis identified a positive association between specific bacterial genera and neurotransmitter levels, suggesting a probiotic effect on neuroactive substances. These findings suggest that fermented milk has potential as a probiotic supplement for mood improvement and stress relief, highlighting its role in modulating the gut-brain axis. © 2024 Society of Chemical Industry.

The choice of probiotics affects the rheological, structural, and sensory attributes of lupin-oat-based yoghurt

Plant-based yoghurt (PBY) presents an alternative for vegetarians, flexitarians, and individuals with dairy allergies. However, how the bacterial (culture) variations can impact the properties are not yet well investigated. This study aims to investigate the physicochemical attributes, encompassing texture, rheological properties, microstructure, and sensory characteristics, of yoghurt formulated with a lupin-oat base as affected by the addition of commercial probiotics including Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, Lactobacillus rhamnosus, L. casei 431 (Lactobacillus paracasei), Lactobacillus plantarum, BB12 (Bifidobacterium sps) during storage at 4 °C for 28-day. Significantly, lupin-oat yoghurt fermented with a combination of Lactobacillus plantarum, and Bifidobacterium species exhibited rapid metabolic activity, leading to a notable reduction in fermentation time compared to other probiotic strains. Furthermore, this combination conferred similar water-holding capacity, firmness, and consistency with dairy yoghurt (control). Different probiotic strains induced variations in particle size and led to shear-thinning behaviour across all yoghurt samples. Over the refrigerated storage, a decline in apparent viscosity was observed and lupin-oat yoghurt exhibited greater rigidity compared to dairy yoghurt. Changes in the yoghurt microstructure during storage, notably the presence of increased serum pores were associated with its functional attributes. Confocal and scanning electron microscopy revealed distinctive microstructural features in yoghurt fermented with Lactobacillus plantarum and Bifidobacterium species compared to other probiotic combinations. Notably, this combination garnered higher sensory ratings for appearance, taste, flavour, texture, and overall acceptability, positioning it as a suitable dairy yoghurt alternative. These findings provide insights into enhancing the structural and sensory attributes of lupin-oat-based yoghurt.

Formulation and Sensory Evaluation of Non-Dairy Synbiotic Chocolates Enriched with Almond Milk, Oats Powder and Probiotic Microorganism (Streptococcus thermophilus BURD PB 8)

Formulation and Sensory Evaluation of Non-Dairy Synbiotic Chocolates Enriched with Almond Milk, Oats Powder and Probiotic Microorganism (Streptococcus thermophilus BURD PB 8)

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 & 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.

The investigation of the role of oral-originated Prevotella-induced inflammation in childhood asthma.

The oral and gut microbiota play significant roles in childhood asthma pathogenesis. However, the communication dynamics and pathogenic mechanisms by which oral microbiota influence gut microbiota and disease development remain incompletely understood. This study investigated potential mechanisms by which oral-originated gut microbiota, specifically Prevotella genus, may contribute to childhood asthma etiology. Oral swab and fecal samples from 30 asthmatic children and 30 healthy controls were collected. Microbiome composition was characterized using 16S rRNA gene sequencing and metagenomics. Genetic distances identified potential oral-originated bacteria in asthmatic children. Functional validation assessed pro-inflammatory properties of in silico predicted microbial mimicry peptides from enriched asthma-associated species. Fecal metabolome profiling combined with metagenomic correlations explored links between gut microbiota and metabolism. HBE cells treated with Prevotella bivia culture supernatant were analyzed for lipid pathway impacts using UPLC-MS/MS. Children with asthma exhibited distinct oral and gut microbiota structures. Prevotella bivia, P. disiens, P. oris and Bacteroides fragilis were enriched orally and intestinally in asthmatics, while Streptococcus thermophilus decreased. P. bivia, P. disiens and P. oris in asthmatic gut likely originated orally. Microbial peptides induced inflammatory cytokines from immune cells. Aberrant lipid pathways characterized asthmatic children. P. bivia increased pro-inflammatory and decreased anti-inflammatory lipid metabolites in HBE cells. This study provides evidence of Prevotella transfer from oral to gut microbiota in childhood asthma. Prevotella's microbial mimicry peptides and effects on lipid metabolism contribute to disease pathogenesis by eliciting immune responses. Findings offer mechanistic insights into oral-gut connections in childhood asthma etiology.

Replacement of Loops at the Entrance of the Active Pocket of Streptococcus thermophilus 4,6-α-Glucanotransferase Changes Its Catalytic Activity and Product Specificity.

To explore the roles of loops around active pocket in the reuteran type 4,6-α-glucanotransferase (StGtfB) from S. thermophilus, they were individually or simultaneously replaced with those of an isomalto/maltopolysaccharides type 4,6-α-glucanotransferase from L. reuteri. StGtfB with the replaced loops A1, A2 (A1A2) and A1, A2, B (A1A2B), respectively, showed 1.41- and 0.83-fold activities of StGtfB. Two mutants reduced crystallinity and increased starch disorder at 2, 4, and 8 U/g more than StGtfB and increased DP ≤ 5 short branches of starch by 38.01% at 2 U/g, much more than StGtfB by 4.24%. A1A2B modified starches had the lowest retrogradation over 14 days. A1A2 modified starches had the highest percentage of slowly digestible fractions, ranging from 40.32% to 43.34%. StGtfB and its mutants bind substrates by hydrogen bonding and van der Waals forces at their nonidentical amino acid residues, suggesting that loop replacement leads to a different conformation and changes activity and product structure.

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.