Yogurt Starter Research Articles

Quality attributes and antioxidant activity of stirred yoghurt fortified with some nano-fruit waste powders

Agro-industrial wastes have emerged as a significant source of bioactive compounds. Therefore, this study was conducted to evaluate the feasibility of using nano-powders of some fruit wastes, namely; apricot (Prunus sp.) and peach (Prunus persica L. Batsch) kernels, watermelon (Citrullus lanatus) rind and banana (Musa spp.) peel as functional ingredients (0.5%) in stirred yoghurt, as well as their effect on the antioxidant activity, quality characteristics, viability of yoghurt starter culture and sensory attributes. Results revealed that the fortification process significantly (P < 0.05) elevated the total solids, fat, protein and ash contents, especially with apricot and peach kernels (AK and PK), which distinctly increased fat by average values of 3.46 and 3.40%, and protein by 3.70 and 3.68% during storage compared to control (3.12 and 3.57%), respectively. The addition of watermelon rind (WMR) increased the titratable acidity (0.97%) and viscosity (463.59 cP) with a significant reduction of syneresis (16.38%), increased the total viable count of starter culture, acetaldehyde and diacetyl contents (167.10 and 18.82 mg/100 g) in yoghurt, followed by banana peel (BP). Stirred yoghurt fortified with BP nano-powder had the highest total phenolic content (20.96 mg gallic acid/g) and DPPH scavenging activity (31.93%) as average values during storage compared to the other nano-fruit wastes. Sensory attributes of stirred yoghurt were improved with the addition of WMR and BP during storage periods, compared to those fortified with AK and PK. All the nano-powders of the studied fruit wastes constitute excellent raw materials for the development of novel functional stirred yoghurt.

Utilizing pomegranate extracts for enhancing yogurt quality and preservation

As consumers become increasingly conscious of synthetic preservatives, the demand for natural antioxidant and antibacterial agents is rising. This study investigates the potential of pomegranate (Punica granatum) extracts to control yogurt spoilage. Methanolic and ethanolic extracts of pomegranate peel, seed, and leaf were analyzed for total phenolic content (TPC), antioxidant activity, and inhibitory effects on ‘yogurt starter strains’ and selected food-related bacteria (Bacillus cereus, Staphylococcus aureus, Staphylococcus sciuri, Escherichia coli, Salmonella enterica subsp. enterica serovar Typhi, and Shigella flexneri). Yogurt samples treated with pomegranate extracts were stored at 4 °C for 28 days. Sensory evaluation was performed on fresh yogurt samples. Physicochemical properties (pH, titratable acidity (TTA), and antioxidant activity) and microbiological changes (aerobic plate count (APC), coliform count, lactic acid bacteria (LAB) count, and total yeast and mold count (TYMC)) were examined weekly. Among the extracts tested, methanolic and ethanolic extracts of peel had the highest TPC (603 and 576.9 mg GAE/g) and the strongest antioxidant activity with the lowest IC50 (141.8 and 183.43 µg/mL). Overall, pomegranate peel, seed, and leaf extracts inhibited foodborne bacteria more effectively than probiotic strains, indicating significant antibacterial potential against spoilage microorganisms. Based on a minimum inhibitory concentration (MIC) test, ethanolic pomegranate extracts were incorporated into lab-made yogurt at 8 mg/mL. Throughout the storage period, all yogurt samples maintained a standard pH (≤ 4.6) and TTA (> 0.5 %). Yogurt fortified with pomegranate peel and leaf extracts exhibited greater antioxidant activity and a significantly lower aerobic plate count while retaining LAB probiotic levels (≥ 106 CFU/g), ensuring safety for consumption (TYMC ≤ 102 CFU/g) and acceptability in terms of five selected quality attributes. Consequently, pomegranate peel and leaf extracts present a promising natural alternative to potassium sorbate in yogurt preservation, maintaining probiotic properties without compromising quality.

The Involvement of Lactic Acid Bacteria in Modulating the Levels of Biogenic Amino Acids within Fermented Tarasas Products

Combining turnip roots and leaves with cooked wheat grits and salt makes Tarasas, a fermented dish from Iraqi Kurdistan. The fermentation process takes 15 days, to produce a ready-to-eat dish. This study aims to identify the bacteria responsible and the role of wheat grits during the 0, 5, 10, and 15 days of fermentation for forming biogenic amines in Tarasas. The results demonstrate that pH levels during the fermentation periods decreased gradually. Microbial analysis showed an increased lactic acid bacteria count during Tarasas fermentation. The study also investigates how adding Lactobacillus plantarum, and yogurt starters (Lactobacillus bulgaricus and Streptococcus thermophilus) affects the process. The current study shows that adding yogurt starters at 3% increased biogenic amine levels, On the other side, using Lactobacillus plantarum as a starter at 3% reduced biogenic amine levels compared with treatments that ferment spontaneously. Additionally, decreasing the wheat grit content to 50% (of the total weight of wheat grits) was associated with a decrease in biogenic amines in the Tarasas. The sensory evaluation results also revealed that the treatments containing Lactobacillus plantarum were more acceptable to the consumer than the traditional treatment or the one with added yogurt.

The effect of three different preservatives on the numbers and types of bacteria, Brix percentage, pH and nutritional composition of bovine colostrum sourced from New Zealand dairy farms

ABSTRACT Aims To investigate the effect of preservation by addition of yoghurt starter, potassium sorbate and citric acid on counts of aerobic bacteria, Lactobacillus spp., Streptococcus thermophilus and coliforms, Brix percentage, pH, protein, fat and anhydrous lactose concentrations at 0, 7 and 14 days after collection for colostrum stored at ambient temperature. Method Approximately 2 L of first milking colostrum was collected from 10 farms in the Waikato region. Following mixing, it was split into five 400-mL sub-samples and allocated randomly to a control (two sub-samples), or treatment with yoghurt, potassium sorbate, or citric acid preservative. Throughout the trial samples remained in the laboratory at ambient temperature with the lids slightly ajar, and were stirred daily for 15–30 seconds using a sterile spatula. Sub-samples were tested on Days 0, 7 and 14. On Days 0 and 14 aerobic bacteria (by aerobic plate count (APC)), Lactobacillus spp., coliforms and Streptococcus thermophilus counts, pH, Brix percentage, protein, fat and anhydrous lactose were measured. On Day 7 only bacterial counts were completed. The data were analysed using non-parametric clustered bootstrap sampling to estimate the effect of treatment, time, and their interaction on the outcome variables. Results Compared to control samples, on Day 7 the APC for potassium sorbate (1.0 (90% CI = 0.6–1.6) × 108 cfu/mL) was approximately seven-fold lower than for yoghurt (7.3 (90% CI = 4.1–11) × 108 cfu/mL), and approximately three-fold lower than citric acid (3.2 (90% CI = 0.2–4.3) × 108 cfu/mL) remaining low to Day 14. All preservatives reduced coliform growth compared to control samples at Day 7 but growth was lower for potassium sorbate than the other preservatives. For Lactobacillus spp., at Day 7, samples with yoghurt preservative had greater counts than the other two preservatives. Potassium sorbate reduced growth of S. thermophilus compared to the other treatments, especially at Day 7, with 7–10 times fewer S. thermophilus per mL compared to the other three groups. All groups showed an obvious acidification over time, with very little variation within days and treatment groups. There was no evidence for change in fat or protein percentage over time regardless of treatment. Conclusion and clinical relevance Aerobic and coliform bacteria proliferate extensively in unpreserved colostrum. All preservatives decreased coliform counts compared to un-preserved colostrum, but potassium sorbate was more effective at decreasing both coliforms and aerobic bacteria than either yoghurt or citric acid.

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.

Biofunctional attributes and storage study of milk fermented by Enterococcus italicus

Lactic acid bacteria are probiotics in the intestines and have been widely used as natural antioxidants in the food industry. In this study, Enterococcus italicus FM5 with strong antioxidant ability was isolated from fresh milk. The safety evaluation showed that E. italicus FM5 was sensitive to ampicillin, chloramphenicol, erythromycin, vancomycin, rifampicin, and tetracycline, and was not hemolytic. Meanwhile, the whole genome information and biofunctional attributes of this strain were determined and analyzed. Subsequently, E. italicus FM5 was co-cultured with traditional yogurt starters (Streptococcus thermophilus and Lactobacillus bulgaricus) to make fermented milk. The results showed that the addition of E. italicus FM5 could improve the oxygen free radical scavenging ability of the fermented milk, and the scavenging rates of DPPH, ABTS, OH−, and O2− radicals reaching up to 95.54 %, 88.35 %, 93.65 %, and 60.29 %, respectively. Furthermore, the addition of E. italicus FM5 reduced the curd time and improved the water holding capacity of the fermented milk. Besides, the growth of Lb. bulgaricus was significantly promoted when co-cultured with E. italicus FM5, thus the survival cells were increased compared with the traditional fermentation processes. Therefore, this study emphasized the potential to manufacture fermented milk by the co-cultivation of E. italicus with traditional yogurt starters.

Production of yoghurt from kefir beverage: Analysis of fermentation kinetics, volatile organic compounds, texture, and microbial characteristics

The study aims to produce yoghurt from kefir beverage and evaluate its fermentation kinetics, volatile organic compounds, texture, and microbial characteristics. Kefir, a fermented milk product, is known for its health benefits due to probiotic microorganisms. To improve its sensory properties, kefir was combined with yoghurt starter cultures (Lactobacillus delbrueckii and Streptococcus thermophilus), sodium caseinate, and lactose, and incubated for 12 and 24 h. Comprehensive analyses were conducted on the obtained yoghurts, encompassing fermentation parameters (pH and acidity), volatile organic compounds, and textural properties. The levels and viability of specific microorganisms within the samples were examined through propidium monoazide quantitative PCR (PMA-qPCR). The results showed that samples with Na-caseinate had higher firmness, consistency, and cohesiveness. Viscosity increased with the addition of Na-caseinate and lactose after 24 h. PMA-qPCR analysis revealed higher microorganism levels in samples with Na-caseinate and lactose. Solid-phase microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) analysis showed that diacetyl was the most common compound, and acetaldehyde and diacetyl levels decreased in yoghurts compared to kefir beverages. PMA-qPCR revealed that Streptococcus thermophilus had higher viability in samples with both Na-caseinate and lactose, while Lactobacillus delbrueckii had the highest viability in samples that contained only Na-caseinate incubated for 12 h. The study suggests that kefir-based yoghurt can be developed into a product with better sensory qualities and increased consumer appeal due to improved texture and aroma.

Development of probiotic yogurt products incorporated with Lactobacillus kefiranofaciens OSU-BSGOA1 in mono- and coculture with Kluyveromyces marxianus

The bacterium Lactobacillus kefiranofaciens OSU-BDGOA1 and yeast Kluyveromyces marxianus bdgo-ym6 were previously isolated from kefir grains and have shown probiotic traits in mono- and coculture. This research evaluates the effect of introducing probiotic kefir microorganisms in monoculture and in coculture alongside yogurt starter cultures on the physicochemical and rheological properties, volatile flavor compounds, survival of the microorganisms during simulated digestion, and sensory attributes of the final fermented products. The incorporation of L. kefiranofaciens OSU-BDGOA1 in monoculture showed promising outcomes, resulting in a final product showing more solid-like characteristics and potentially improving the texture of the product. There was also a significant increase in the concentration of desirable volatile flavor compounds in the yogurt with the monoculture, particularly 2,3-butanedione, displaying a positive correlation with buttery flavor in the sensory analysis. The inclusion of L. kefiranofaciens in monoculture also promoted better sensory attributes and was significantly better than the yogurt with the coculture with the yeast, showing promising results for the incorporation of this probiotic bacterium into functional fermented dairy products.

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.

Fortification of goat milk yogurts with date palm (Phoenix dactylifera L.) coproducts: Impact on their quality during cold storage

The aim of this study was to investigate the impact of different concentrations (3% and 6%) of two ingredients (paste and flour) obtained from the valorization of date fruit coproducts on the nutritional (proximate composition and mineral profile), technological (coagulation curve, pH, acidity, sugar and organic acid content and syneresis), physicochemical (color, water activity and texture), microbiological and sensory properties of goat's yogurt during 21 days of refrigerated storage. Both ingredients enhanced the growth and stability of the yogurt starter culture, thereby improving the probiotic potential of date-added yogurts. Physicochemically, the addition of date flour (at both concentrations) induces stronger modifications (texture, color and syneresis) in yogurts than the date paste. During storage, date paste reduced the syneresis and hence maintained yogurts' physical quality. Consumers preferred the yogurts with date paste (3% and 6%) rather than with date flour, because its addition led to a more brownish color and granular texture.

Enhancing Bifidobacterium and lactic acid bacteria activity, and improving oxidative stability in functional algal concentrated yoghurt with Spirulina platensis powder

The purpose of this study was to examine the growing demand for healthy functional dairy products by investigating the incorporation of Spirulina platensis into concentrated yoghurt and evaluating its impact on starter cultures and product properties. A comprehensive analysis demonstrated the potential of spirulina to enhance bifidobacteria growth, acidity, PUFA content, and antioxidant activity in yoghurts, indicating its potential to improve the nutritional quality and oxidative stability of dairy products. The study investigated the impact of different Spirulina ratios on the activity of yoghurt starter cultures, including Lb. casei, Lb. plantarum, Lb. acidophilus, and Bifidobacterium mix. Three concentrated yoghurt samples were prepared, including a control, a probiotic sample, and a sample incorporating Spirulina powder. The findings suggest that while Spirulina did not significantly affect lactic acid bacteria, it noticeably stimulated the growth of Bifidobacterium. Treated samples showed increased acidity and TVFAs, with pH values displaying an inverse trend compared to the control. Clear differences in colour parameters and sensory evaluations distinguished control from treated samples. Additionally, Spirulina supplementation demonstrated a pronounced effect in enhancing antioxidant activity, as observed through DPPH radical scavenging activity, and influencing the peroxide value, reflecting improved oxidative stability in the yoghurt. This successful utilisation of Spirulina suggests its potential application in diverse edible algae in the food sector, especially in dairy products, enhancing both nutritional and sensory aspects, as well as contributing to improved oxidative stability

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.

Development of Shelf Life for Labaneh Using Protective Cultures of L. paracasei and Propionibacterium freudenreichii subsp. shermanii

Labaneh (strained yogurt) is a traditional dairy product. It is usually produced without chemical preservatives as Jordanian standards for this product prevent their addition. Its shelf life is limited to two weeks. This research aims to develop the shelf life of labaneh using eco-friendly methods, via the addition of protective probiotic cultures. Protective probiotic cultures were prepared by activating DVI freeze-dried Propionibacterium freuendereichii, subsp. shermanii and Lactobacillus paracasei in sterilized skim milk. Fifty kg of fresh milk was divided into two portions, the first containing the traditional yogurt starter culture (2%) and the second processed by adding both the starter (2%) and protective probiotic cultures (1%). After fermentation, two types of yogurts were produced, and refrigerated for several hours. They were then salted, strained separately to about 25% total solids in a special cloth to produce labaneh paste. The paste was then distributed into two groups of sterilized jars (21 for each) and placed in refrigerated storage. Both types of labaneh (traditional and developed) were evaluated at different time intervals of refrigerated storage (0, 3, 7, 10, 14, 21, 30 days) for their counts of coliform bacteria, yeast and mould, and lactic acid bacteria (LAB), and for their pH, ash, acidity, moisture, protein, fat and titratable acidity. The probiotic count was also evaluated for the developed labaneh. The shelf life of the developed labaneh was determined based on the acidity, yeast and mould counts and organoleptic characteristics. No obvious and significant undesirable changes were seen at 30 days of refrigeration or went beyond the Jordanian standard for the developed labaneh, compared to the traditional one which started to spoil after 14 days. No coliform bacteria were found after 30 days of refrigerated storage in the traditional and developed labanehs. The counts of yeast and mould were generally higher in the traditional labaneh than in the developed one, while the number of LAB was lower in the traditional labaneh than in the developed one. The pH and moisture of the developed labaneh were generally lower than that of the traditional labaneh, but the titratable acidity, ash, protein and fat were higher in the developed one. Regarding the sensory properties, most of the panelists organoleptically preferred the developed one during the storage period. Therefore, it is concluded that the protective probiotic cultures were effective in extending the shelf life of labaneh.

The Ability of Lacticaseibacillus paracasei MSMC 36-9 Strain with Probiotic Potential to Ferment Coconut Milk and Produce a Yogurt-Type Beverage

The efficacy of the Lacticaseibacillus paracasei MSMC 36-9 strain with probiotic potential to ferment coconut milk and produce coconut milk yogurt-type beverages was examined. Tapioca starch was used as a stabilizer at concentrations of 0, 1.0, and 2.0% (w/w). The samples were stored at 4 °C for 21 days and analyzed for viability and resistance to in vitro gastrointestinal conditions of L. paracasei MSMC 36-9, pH changes, radical scavenging activity using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, and apparent viscosity. The viability of the strain with probiotic potential in the samples remained stable during storage and ranged between 12 and 13 log CFU/g by the end of the storage period. The strain L. paracasei MSMC 36-9 from all samples survived under simulated gastrointestinal conditions. The pH levels of all samples decreased during storage due to post-acidification. The radical scavenging activity of the products fermented with L. paracasei MSMC 36-9 was higher than that of the sample fermented with the commercial yogurt starter culture. The addition of tapioca starch to fermented coconut milk increased the viscosity of the samples. The results suggested that L. paracasei MSMC 36-9 can be used as a starter culture in the production of coconut milk yogurt-type beverages with antioxidant potential.

New generation of functional yogurts fermented with probiotic lactic acid bacteria isolated from human milk

Background: The cultures used in the production of "bio-yoghurts" typically consist of a blend of traditional yogurt starters, such as S. thermophilus and L. delbrueckii subsp. bulgaricus, along with probiotics like L. acidophilus, L. casei, L. reuteri, and Bifidobacterium spp. These probiotics, although beneficial, face challenges thriving in milk due to its short fermentation time (4–5 hours). The rapid acidification caused by the starter’s results in probiotic levels dropping below the "therapeutic minimum" during the intended refrigerated shelf life of the product. A potential solution to this issue lies in leveraging lactic acid bacteria isolated from the human milk which possess both robust probiotic characteristics and starter properties. Incorporating such strains in yogurt starter could address the acidity imbalance and contribute to maintaining optimal probiotic levels throughout the refrigerated shelf life of the product. Objective: This research aims to develop a new generation of sustainable functional yoghurts suitable for consumers of all ages using as starters predominant probiotic lactic acid bacteria isolated from the breast milk of healthy women. Results: This study marks the first implementation of the critical dilution culture method in sterile cow milk for the selection of predominant lactic acid bacteria (LABs) from women's breast milk. Remarkably, all samples yielded LAB capable of independently fermenting milk. Although breast milk is a good medium for the growth of residential lactic acid bacteria, it never coagulates due to low concentration of caseins. The isolated strains, identified as belonging to the species L. delbrueckii subsp. lactis, L. fermentum, L. casei subsp. sakei, Streptococcus thermophiles and Lactococcus lactis, exhibited probiotic and adaptive properties essential for gut colonization in humans. Utilizing symbiotic LAB starters were created functional yogurts with heightened technological, physicochemical, and sensory characteristics. Conclusions: Yogurts fermented using human milk LABs are safe and can be recommended as a functional dairy food, for pregnant women as well as for pre-term and full-term infants as a substitute/supplement for mother's milk. Moreover, these LABs can be included in infant formulas or used in pre-treatment of infant formula milk to improve its nutritional value and safety. Keywords: Breast milk, lactic acid bacteria, probiotic, milk fermentation, functional yogurt

Effects of 2'-fucosyllactose on the viability of starter cultures and Bifidobacterium strains of human origin in yogurt during refrigerated storage.

2'-Fucosyllactose (2'-FL) is postulated to provide health benefits and promote the growth of probiotics. This work was undertaken to study the effects of 2'-FL on the viability of starter cultures and Bifidobacterium strains of human origin in yogurt during refrigerated storage. Yogurts were produced containing 2'-FL (0 or 2g/L) and Bifidobacterium strains of human origin (Bifidobacterium longum subsp. longum BB536 or Bifidobacterium longum subsp. infantis ATCC 15697) at a concentration of at least 109 CFU/mL. All yogurts were stored at 4°C for 5weeks. Results showed that 2'-FL was stable in yogurts for at least 5 weeks of cold storage, and the addition of 2'-FL did not significantly alter yogurt fermentation parameters, associated metabolites, and the viability of mixed yogurt starter cultures and Bifidobacterium strains (p>0.05). The addition of bifidobacteria had a negative impact (p<0.05) on the survival rate of starter cultures, Streptococcus thermophilus and Lactobacillus delbureckii subsp. bulgaricus. Meanwhile, it is difficult to maintain a high survival rate of bifidobacteria in final yogurt products, and the addition of 2'-FL could not enhance the viability of bifidobacteria. B. longum BB536 survived at a level higher than 106 CFU/g for 28 days, while B. infantis ATCC15697 maintained this level for only 7 days. In summary, this study has shown the impact of 2'-FL and bifidobacterial species on yogurt properties, and results suggest that it is promising to use 2'-FL in yogurt products as a prebiotic. PRACTICAL APPLICATION: Yogurt is known for its beneficial effects on human health and nutrition. This study reported the production of symbiotic yogurt containing bifidobacteria and 2'-fucosyllactose (2'-FL) as a functional food for specified health uses. The viability of yogurt starter cultures and probiotic bifidobacterial strains was analyzed in this study. Moreover, this research demonstrated that 2'-FL could be added to yogurt without affecting the characteristics of yogurt significantly.

Protective Mechanism of Rosa roxburghii Tratt Fermentation Broth against Ultraviolet-A-Induced Photoaging of Human Embryonic Skin Fibroblasts.

This study takes the fruit of Rosa roxburghii Tratt (RRT) as a fermentation substrate and carries out a quantitative visual analysis of the domestic and foreign literature on screenings of five different lactic acid bacteria to obtain a fermentation broth. Systemic anti-photoaging effects are analyzed at the biochemical, cellular, and molecular biological levels. DPPH and ABTS free radical scavenging activities are used to verify the antioxidant capacity of the RRT fruit fermentation broth in vitro. Human embryonic skin fibroblasts (HESs) are used to establish a UVA damage model, and the antioxidant capacity of the RRT fruit fermentation broth is verified in terms of intracellular reactive oxygen species (ROS) and antioxidant enzyme activity. RT-qPCR and ELISA are used to detect the expression of TGF-β/Smad, MMPs, and the MAPK/AP-1 and Nrf2/Keap-1 signaling pathways in order to explore the anti-oxidation and anti-photoaging effects of the RRT fruit fermentation broth by regulating different signaling pathways. The results show that an RRT fruit fermentation broth can effectively protect cells from oxidative stress caused by UVA and has significant anti-photoaging effects, with the co-cultured Lactobacillus Yogurt Starter LYS-20297 having the highest overall effect.

Lactobacillus paracasei ZFM54 alters the metabolomic profiles of yogurt and the co-fermented yogurt improves the gut microecology of human adults

Gut microbiota imbalance could lead to various diseases, making it important to optimize the structure of the gut flora in adults. Lactobacillus paracasei ZFM54 is a bacteriocin- and folic acid-producing Lactobacillus strain. Herein, L. paracasei ZFM54 was used as the potentially probiotic bacterium to ferment milk together with a yogurt starter. We optimized the fermentation conditions, and the obtained yogurts were then subjected to volatile and nonvolatile metabolome analysis, showing that L. paracasei ZFM54 can not only improve the acidity, water holding capacity and live lactic acid bacteria counts, but also improve many volatile acid contents and increase some beneficial nonvolatile metabolites, such as N-ethyl glycine and l-lysine, endowing the yogurt with more flavor and better function. The regulatory effects of the co-fermented yogurt on the intestinal microecology of volunteers were investigated by 16S rRNA sequencing and short-chain fatty acid (SCFA) analysis after consuming the yogurt for a 2-wk period, showing a better effect to increase the relative abundance of beneficial bacteria such as Ruminococcus and Alistipes, decrease harmful bacteria (Escherichia-Shigella and Enterobacter), and enhance the production of SCFA (acetate, propionate, and butyric acid) compared with the control yogurt. We found that L. paracasei ZFM54 can significantly improve the health benefits of yogurt, laying the foundation for its commercial application in improving gut microbiota.

Probiotics screening from selected Nigerian prebiotics: Alternative starter culture sources for yoghurt production

The rise of functional foods has expanded food production, offering not just essential nutrition but also potential health and longevity benefits. This study aimed to identify probiotics from common Nigerian fermented foods as potential starter cultures for yogurt production. Ten local fermented food were screened for suitable starter culture(probiotics) for yogurt production, including fresh milk from cow (CM), sheep (SM), and goat (GM), as well as pap made from maize, millet, sorghum, cassava products (garri, fufu, and lafun), and Kunuzaki. Probiotic isolates with desired characteristics underwent tests for tolerance to acidic pH and bile conditions; antioxidative properties. Test yogurt was produced using Lactobacillus (LAB) isolates and physicochemical and organoleptic scores were determined for the yogurt samples. LAB species from CM, SM, and Lafun samples showed tolerance to both acidic pH (pH 3.0) and 0.5 percent bile. CM isolates exhibited strong antioxidant effects comparable to vitamin C. Yogurt samples had pH ranging from 4.77 to 5.45 and titratable acidity from 5.56 to 8.06. Sensory characteristics of the test yogurt did not significantly differ from commercial yogurt (p ≤ 0.05). Thus, probiotics (LAB) from common Nigerian fermented foods like CM, SM, and lafun could serve as cost-effective, nutrient-rich alternatives for yogurt starter cultures.

Duality Effect of Bee Products in Dealing with Yoghurt Starter, Probiotics and Food Borne Pathogenic Bacteria

Duality Effect of Bee Products in Dealing with Yoghurt Starter, Probiotics and Food Borne Pathogenic Bacteria