Functional relevance and health benefits of soymilk fermented by lactic acid bacteria

Mechanism for improving fermented soymilk gel through high-pressure homogenization: Regulating the structure of heat-induced protein aggregate

Heat-induced aggregation of soybean protein (HIAP) during the preparation of soymilk results in poor texture, diminishes water-holding capacity and decreases the structural homogeneity of the fermented soymilk gel. Therefore, it is necessary to modify the HIAP to improve the texture of fermented soymilk gel. High-pressure homogenization (HPH) is an effective food processing technique and can potentially alter the HIAP conformation. A strain of lactic acid bacteria suitable for fermentation of soymilk was initially screened in this work. Subsequently, soymilk was treated with HPH to investigate the effect of the HPH treatment on HIAP and the gel structure after fermentation. The results demonstrated that HPH treatment led to a significant reduction in particle size (from 425.2 nm to 283.2 nm), protein dispersibility index, and zeta potential of HIAP. Additionally, the multispectral analysis revealed that the spatial structure of HIAP unfolded with increased content of β-sheet and a reduction in random coil in the secondary structure. Furthermore, the formation of a homogeneous and dense three-dimensional network structure of gel was prompted by an increase in hydrophobic interactions and disulfide bonds between the proteins, which not only enhanced the rheology and texture of the gel but also elevated its water-holding capacity from 45.4 % to 61.3 %. HPH treatment was demonstrated to be an effective method for regulating the structure of HIAP, thereby improving the texture of fermented soymilk gel. This study provides a theoretical foundation for developing processing techniques and industrial production of fermented soymilk.

Isolation and Characterization of Probiotic Bacteria from Traditional Foods

A probiotic is a live bacterium that, when given in sufficient proportions, helps to improve the host's gut health. Kimchi and pearl millet, two traditional foods, were used to isolate probiotic bacterial strains. This study's primary goals were to isolate, identify and analyse the microorganisms for potential probiotic traits, tolerance to gastrointestinal environments, and antimicrobial activity, and produce probiotic capsule. The present investigation resulted with identification of two probiotic strains (KAC1 and PAC1) from conventional foods, such as kimchi and pearl millet porridge. The isolated probiotics were identified as Enterobacteriaceae family by 16S rRNA sequencing and are deposited in GenBank (NCBI), accession numbers OQ629827 (KAC1) and OQ629828 (PAC1), respectively. These strains exhibited the characteristics of possible probiotic traits, such as the ability to tolerate simulated gastric juice, inhibits the growth of pathogenic bacteria, auto-aggregation, co-aggregation, and hydrophobicity. Furthermore, spectroscopic analysis divulges some critical findings which corroborate the results obtained. Finally, capsules containing freeze-dried  probiotics was successfully produced.

Soymilk yogurt prepared using Pediococcus pentosaceus TOKAI 759m ameliorates cognitive function through gut microbiota modulation in high-fat diet mice

Recent studies have confirmed that obesity leads to neuroinflammation and cognitive decline. This study aimed to examine whether soymilk yogurt prepared using Pediococcus pentosaceus TOKAI 759m could prevent cognitive decline and neuroinflammation progression in mice fed a high-fat diet (HFD). C57BL/6NJcl male mice were grouped according to the following dietary interventions and monitored for 15 weeks: (1) normal control diet, (2) HFD, (3) HFD with soymilk (SM), (4) HFD with soymilk yogurt (SY), and (5) HFD with bacterial cells of the starter strain (BC). The levels of inflammatory cytokines in serum and hippocampus were measured. Compared to the HFD group, the SY group scored higher in the novel object recognition test and exhibited lower levels of Interleukin-6 (IL-6) and Tumor Necrosis Factor (TNF)-α in the hippocampus. However, the SM and BC groups did not show these significant changes. Proteomic analysis of the hippocampus revealed three enriched protein clusters in the SY group: synaptic proteins, glycolysis, and mitochondrial ATP formation. Fecal samples were also collected to measure the proportion of gut microbiota using 16S rRNA analysis. Interestingly, the proportion of butyrate-producing bacteria, such as Clostridium and Akkermansia, tended to be higher in the SY group than in the HFD group. An additional in vitro study revealed that the components of SY, such as daidzein, genistein, and adenine, could decrease inflammatory cytokine levels in microglial cells. In conclusion, soymilk yogurt prepared using P. pentosaceus TOKAI 759m may modulate gut microbiota and prevent neuroinflammation, thereby leading to a possible improvement in cognitive function.

Fermented Soymilk with Probiotic Lactobacilli and Bifidobacterium Strains Ameliorates Dextran-Sulfate-Sodium-Induced Colitis in Rats

Background: Current treatments for inflammatory bowel disease (IBD) are relatively futile and the extended use of drugs may reduce effectiveness. Several probiotic strains have shown promise in relieving/treating IBD symptoms. Objectives: The current study investigated the impact of fermented soymilk with a mixture of probiotic starter cultures containing Lactobacillus rhamnosus, L. casei, L. plantarum, L. acidophilus, Bifidobacterium longum, and B. animalis subsp. lactis in rats with dextran sulfate sodium (DSS)-induced colitis compared to control. Methods: Rats were randomly assigned to five groups (5 rats/group; n = 25): G1: negative normal control; G2: positive control (DSS); G3: DSS with sulfasalazine (DSS-Z); G4: DSS with soymilk (DSS-SM), and G5: DSS with fermented soymilk (DSS-FSM). Parameters monitored included the following: the disease activity index (DAI), macroscopic and histological assessments of colitis, and a fecal microbial analysis performed to assess the severity of inflammation and ulceration. Results: The DSS-FSM rats group exhibited lower DAI scores (p < 0.05) than other treated groups during the induction period. A macroscopical examination revealed no ulceration or swelling in the intestinal mucosa of rats in the DSS-FSM-treated group, resembling the findings in the negative control group. In the positive control (DSS group), the colon tissue showed increased inflammation (p < 0.05), whereas those in the DSS-SM- and DSS-FSM-treated rats groups did not show significant macroscopic scores of colitis. The positive DSS control and DSS-Z groups had crypt erosion and ulceration areas, severe crypt damage, and epithelial surface erosion, which were absent in the negative control and DSS-FSM groups. The counts of Lactobacillus spp. and Bifidobacterium spp. remained stable in both G1 and G5 over 4 weeks. The consumption of fermented soymilk with a mixture of probiotics could minimize the severity of DSS-induced colitis in rats. Conclusion, it was found that fermented soymilk containing Lactobacilli and Bifidobacterium might be an effective vehicle for reducing the severity of DSS-induced colitis in rats.

Characterization of lactic acid bacteria isolated from human breast milk and their bioactive metabolites with potential application as a probiotic food supplement

The probiotic properties of twenty-five lactic acid bacteria (LAB) isolated from human breast milk were investigated considering their resistance to gastrointestinal conditions and proteolytic activity. Seven LAB were identified and assessed for auto- and co-aggregation capacity, antibiotic resistance, and behavior during in vitro gastrointestinal digestion. Three Lacticaseibacillus strains were further evaluated for antifungal activity, metabolite production (HPLC-Q-TOF-MS/MS and GC-MS/MS) and proteolytic profiles (SDS-PAGE and HPLC-DAD) in fermented milk, whey, and soy beverage. All strains resisted in vitro gastrointestinal digestion with viable counts higher than 7.9 log10 CFU mL-1 after the colonic phase. Remarkable proteolytic activity was observed for 18/25 strains. Bacterial auto- and co-aggregation of 7 selected strains reached values up to 23 and 20%, respectively. L. rhamnosus B5H2, L. rhamnosus B9H2 and L. paracasei B10L2 inhibited P. verrucosum, F. verticillioides and F. graminearum fungal growth, highlighting L. rhamnosus B5H2. Several metabolites were identified, including antifungal compounds such as phenylacetic acid and 3-phenyllactic acid, and volatile organic compounds produced in fermented milk, whey, and soy beverage. SDS-PAGE demonstrated bacterial hydrolysis of the main milk (caseins) and soy (glycines and beta-conglycines) proteins, with no apparent hydrolysis of whey proteins. However, HPLC-DAD revealed alpha-lactoglobulin reduction up to 82% and 54% in milk and whey, respectively, with L. rhamnosus B5H2 showing the highest proteolytic activity. Overall, the three selected Lacticaseibacillus strains demonstrated probiotic capacity highlighting L. rhamnosus B5H2 with remarkable potential for generating bioactive metabolites and peptides which are capable of promoting human health.

Harnessing Fermented Soymilk Production by a Newly Isolated Pediococcus acidilactici F3 to Enhance Antioxidant Level with High Antimicrobial Activity against Food-Borne Pathogens during Co-Culture

In this study, a newly isolated Pediococcus acidilactici F3 was used as probiotic starter for producing fermented soymilk to enhance antioxidant properties with high antimicrobial activity against food-borne pathogens. The objectives of this study were to investigate optimized fermentation parameters of soymilk for enhancing antioxidant property by P. acidilactici F3 and to assess the dynamic antimicrobial activity of the fermented soymilk during co-culturing against candidate food-borne pathogens. Based on central composite design (CCD) methodology, the maximum predicted percentage of antioxidant activity was 78.9% DPPH inhibition. After model validation by a 2D contour plot, more suitable optimum parameters were adjusted to be 2% (v/v) inoculum and 2.5 g/L glucose incubated at 30 °C for 18 h. These parameters could provide the comparable maximum percentage of antioxidant activity at 74.5 ± 1.2% DPPH inhibition, which was up to a 23% increase compared to that of non-fermented soymilk. During 20 days of storage at 4 °C, antioxidant activities and viable cells of the fermented soymilk were stable while phenolic and organic contents were slightly increased. Interestingly, the fermented soymilk completely inhibited food-borne pathogens, Salmonella Typhimurium ATCC 13311, and Escherichia coli ATCC 25922 during the co-culture incubation. Results showed that the soymilk fermented by P. acidilactici F3 may be one of the alternative functional foods enriched in probiotics, and the antioxidation and antimicrobial activities may retain nutritional values and provide health benefits to consumers with high confidence.

Human in vivo assessment of the survival and germination of Heyndrickxia coagulans SNZ1969 spores delivered via gummy candies

Confectionary products hold promise as unconventional food carriers for probiotic microorganisms. This study explored the delivery of Heyndrickxia coagulans SNZ1969, a spore-forming probiotic, using gummy candies. In this study, we prepared gummy candies containing bacterial spores with a viable count that remained stable during a 24-month shelf-life period, meeting the label claim of at least one billion CFUs per serving (24 g). Then, we carried out an intervention trial involving 24 healthy adults who consumed one serving per day for two weeks followed by an additional two weeks of follow-up. Fecal samples were collected and analyzed with a protocol that allowed the viable counts of SNZ1969, both in spore and vegetative forms. The obtained results revealed that bacterial spores germinated in all volunteers. SNZ1969 persistence in the gut was monitored for two weeks after the end of gummy candy consumption, indicating its potential for prolonged colonization. These findings highlight the potential of unconventional food carriers for probiotic delivery and suggest that spore-forming probiotics can be metabolically active in the human intestine. These findings provide information for the development of food products containing spore-forming probiotics and their potential benefits in promoting gastrointestinal health.

Comparing Nutritional Values and Bioactivity of Kefir from Different Types of Animal Milk

The growing interest in fermented dairy products is due to their health-promoting properties. The use of milk kefir grains as a starter culture made it possible to obtain a product with a better nutritional and biological profile depending on the type of milk. Cow, buffalo, camel, donkey, goat, and sheep milk kefirs were prepared, and the changes in sugar, protein, and phenol content, fatty acid composition, including conjugated linoleic acids (CLAs), as well as antioxidant activity, determined by ABTS and FRAP assays, were evaluated and compared. The protein content of cow, buffalo, donkey, and sheep milk increased after 24 h of fermentation. The fatty acid profile showed a better concentration of saturated and unsaturated lipids in all fermented milks, except buffalo milk. The highest content of beneficial fatty acids, such as oleic, linoleic, and C18:2 conjugated linoleic acid, was found in the cow and sheep samples. All samples showed a better antioxidant capacity, goat milk having the highest value, with no correlation to the total phenolic content, which was highest in the buffalo sample (260.40 ± 5.50 μg GAE/mL). These findings suggested that microorganisms living symbiotically in kefir grains utilize nutrients from different types of milk with varying efficiency.

Mapping the evidence of novel plant-based foods: a systematic review of nutritional, health, and environmental impacts in high-income countries

CONTEXT

Shifting from current dietary patterns to diets rich in plant-based (PB) foods and lower in animal-based foods (ABFs) is generally regarded as a suitable strategy to improve nutritional health and reduce environmental impacts. Despite the recent growth in supply of and demand for novel plant-based foods (NPBFs), a comprehensive overview is lacking.

OBJECTIVES

This review provides a synthesis of available evidence, highlights challenges, and informs public health and environmental strategies for purposeful political decision-making by systematically searching, analyzing, and summarizing the available literature.

DATA SOURCES

Five peer-reviewed databases and grey literature sources were rigorously searched for publications.

DATA EXTRACTION

Study characteristics meeting the inclusion criteria regarding NPBF nutrient composition and health and environmental outcomes in high-income countries were extracted.

DATA ANALYSIS

Fifty-seven peer-reviewed and 36 grey literature sources were identified; these were published in 2016-2022. NPBFs typically have substantially lower environmental impacts than ABFs, but the nutritional contents are complex and vary considerably across brands, product type, and main primary ingredient. In the limited evidence on the health impacts, shifts from ABFs to PB meats were associated with positive health outcomes. However, results were mixed for PB drinks, with links to micronutrient deficiencies.

CONCLUSION

If carefully selected, certain NPBFs have the potential to be healthier and nutrient-rich alternatives to ABFs and typically have smaller environmental footprints. More disaggregated categorization of various types of NPBFs would be a helpful step in guiding consumers and key stakeholders to make informed decisions. To enable informed policymaking on the inclusion of NPBFs in dietary transitions as part of a wider net-zero and health strategy, future priorities should include nutritional food standards, labelling, and subdivisions or categorizations of NPBFs, as well as short- and long-term health studies evaluating dietary shifts from ABFs to NPBFs and standardized environmental impact assessments, ideally from independent funders.

Exploring Impact of Probiotic-Fermented Soymilk on Dextran-Sulfate-Sodium-Induced Ulcerative Colitis via Modulating Inflammation and Gut Microbiota Profile

SCOPE

Lactic acid bacteria with probiotic functions and their fermentation products play a role in regulating ulcerative colitis (UC). This study investigates the potential role of fermented soymilk (FSM4) rich in isoflavones on DSS-induced UC.

METHODS AND RESULTS

Mice received 3% DSS and are supplemented daily once for 1 week by NFSM and FSM4. DSS usually causes intestinal inflammation and alters the gut microbiota. FSM4 intervention improves the UC-related inflammation and gut microbiota alteration. It considerably decreases pro-inflammatories such as TNF-α, IL-1β, and IL-6 in serum and COX-2 and MPO in colon tissues and pathogenic bacteria (Escherichia-Shigella). This facilitates gut-healthy bacteria growth. These healthy bacteria negatively correlat with pro-inflammatory factors but positively associated with acetic acid, butyric acid, and propionic acid, which may act for PPAR-γ pathway activating and NF-κB p65 pathway inhibiting, lowering the risk of UC. Overall, FSM4 might alleviate UC and significantly reverse the dysbiosis of gut microbiota via the PPAR-γ activation. It could be a good alternative for developing functional food to protect against UC.

CONCLUSION

FSM4 attenuates intestinal inflammation and modulates the SCFA-producing bacteria growth, which enable the PPAR-γ activation to alleviate the UC target, which could be a dietary intervention strategy for gut health.

Probiotics: Health benefits, food application, and colonization in the human gastrointestinal tract

Probiotics have become increasingly popular over the past two decades due to the continuously expanding scientific evidence indicating their beneficial effects on human health. Therefore, they have been applied in the food industry to produce functional food, which plays a significant role in human health and reduces disease risk. However, maintaining the viability of probiotics and targeting the successful delivery to the gastrointestinal tract remain two challenging tasks in food applications. Specifically, this paper reviews the potentially beneficial properties of probiotics, highlighting the use and challenges of probiotics in food application and the associated health benefits. Of foremost importance, this paper also explores the potential underlying molecular mechanisms of the enhanced effect of probiotics on gastrointestinal epithelial cells, including a discussion on various surface adhesion‐related proteins on the probiotic cell surface that facilitate colonization.

Fermented camel milk influenced by soy extract: Apparent viscosity, viscoelastic properties, thixotropic behavior, and biological activities

During fermentation, camel milk forms a fragile, acid-induced gel, which is less stable compared with the gel formed by bovine milk. In this study, camel milk was supplemented with different levels of soy extract, and the obtained blends were fermented with 2 different starter culture strains (a high acidic culture and a low acidic culture). The camel milk-soy extract yogurt treatments were evaluated for pH value, acidity, total phenolic compounds, antioxidant capacities, degree of hydrolysis, α-amylase and α-glucosidase inhibition, angiotensin-converting enzyme inhibition, antiproliferative activities, and rheological properties after 1 and 21 d of storage at 4°C. The results revealed that some of the investigated parameters were significantly affected by the starter culture strain and storage period. For instance, the effect of starter cultures was evident for the degree of hydrolysis, antioxidant capacities, proliferation inhibition, and rheological properties because these treatments led to different responses. Furthermore, the characteristics of camel milk-soy extract yogurt were also influenced by the supplementation level of soy extract, particularly after 21 d of storage. This study could provide valuable knowledge to the dairy industry because it highlighted the characteristics of camel milk-soy yogurt prepared with 2 different starter culture strains.

The Impacts of Acidophilic Lactic Acid Bacteria on Food and Human Health: A Review of the Current Knowledge

The need to improve the safety/quality of food and the health of the hosts has resulted in increasing worldwide interest in acidophilic lactic acid bacteria (LAB) for the food, livestock as well as health industries. In addition to the use of acidophilic LAB with probiotic potential for food fermentation and preservation, their application in the natural disposal of acidic wastes polluting the environment is also being investigated. Considering this new benefit that has been assigned to probiotic microorganisms in recent years, the acceleration in efforts to identify new, efficient, promising probiotic acidophilic LAB is not surprising. One of these effots is to determine both the beneficial and harmful compounds synthesized by acidophilic LAB. Moreover, microorganisms are of concern due to their possible hemolytic, DNase, gelatinase and mucinolytic activities, and the presence of virulence/antibiotic genes. Hence, it is argued that acidophilic LAB should be evaluated for these parameters before their use in the health/food/livestock industry. However, this issue has not yet been fully discussed in the literature. Thus, this review pays attention to the less-known aspects of acidophilic LAB and the compounds they release, clarifying critical unanswered questions, and discussing their health benefits and safety.

Antioxidative Properties of Fermented Soymilk Using Lactiplantibacillus plantarum LP95

In recent times, there has been a growing consumer interest in replacing animal foods with alternative plant-based products. Starting from this assumption, for its functional properties, soymilk fermented with lactic acid bacteria is gaining an important position in the food industry. In the present study, soymilk was fermented with Lactiplantibacillus plantarum LP95 at 37 °C, without the use of stabilizers as well as thickeners and acidity regulators. We evaluated the antioxidant capacity of fermented soymilk along with its enrichment in aglycone isoflavones. The conversion of isoflavone glucosides to aglycones (genistein, glycitein, and daidzein) was analyzed together with antioxidant activity (ABTS) measurements, lipid peroxidation measurements obtained by a thiobarbituric acid reactive substance (TBARS) assay, and apparent viscosity measurements. From these investigations, soymilk fermentation using Lp. plantarum LP95 as a starter significantly increased isoflavones' transformation to their aglycone forms. The content of daidzein, glycitein, and genistein increased after 24 h of fermentation, reaching levels of 48.45 ± 1.30, 5.10 ± 0.16, and 56.35 ± 1.02 μmol/100 g of dry weight, respectively. Furthermore, the antioxidant activity increased after 6 h with a reduction in MDA (malondialdehyde). The apparent viscosity was found to increase after 24 h of fermentation, while it slightly decreased, starting from 21 days of storage. Based on this evidence, Lp. plantarum LP95 appears to be a promising candidate as a starter for fermented soymilk production.

Effects of Polygonatum sibiricum on Physicochemical Properties, Biological Compounds, and Functionality of Fermented Soymilk

The purpose of this study was to investigate the effects of Polygonatum sibiricum (P. sibiricum) on microbial fermentation, physicochemical properties, and functional properties of fermented soymilk. Three types of fermented soymilk were prepared. The first type was fermented directly from regular soymilk (fermented soymilk, FSM), and the other two were fermented after adding P. sibiricum (P. sibiricum fermented soymilk, P-FSM) or P. sibiricum polysaccharides (P. sibiricum polysaccharides fermented soymilk, PP-FSM). The differences in physical and chemical indexes such as pH value, acidity, and water-holding capacity were mainly compared, and the differences in the contents of functional components such as total phenols, total flavonoids, soy isoflavones, γ-aminobutyric acid, and organic acids were compared. The functionalities of the three samples in terms of antioxidant activity were evaluated, and the relevance of each active substance was explored. Compared with the FSM group, the addition of P. sibiricum and P. sibiricum polysaccharides could not only significantly promote the fermentation of Lactobacillus but also significantly improve the stability of the finished products during storage and prolong the shelf life of the finished product. The conversion rates of glycoside soybean isoflavones in the PP-FSM and P-FSM groups were 73% and 69%, respectively, which were significantly higher than those in the FSM group (64%). At the end of fermentation, the γ-aminobutyric acid contents of the PP-FSM and P-FSM groups were 383.66 ± 1.41 mg/L and 386.27 ± 3.43 mg/L, respectively, while that of the FSM group was only 288.66 ± 3.94 mg/L. There were also great differences in the content and types of organic acids among the three samples, especially lactic acid and acetic acid. By comparing the antioxidant capacity of DPPH (1,1-Diphenyl-2-picrylhydrazyl free radical), AB-TS (2,2'-Azinobis-3-ethylbenzthiazoline-6-sulphonate), and iron chelation, it was found that both PP-FSM and P-FSM were superior to FSM, and the antioxidant capacity had a certain correlation with the contents of total phenols and total flavonoids.

The Radical Scavenging Activities and Anti-Wrinkle Effects of Soymilk Fractions Fermented with Lacticaseibacillus paracasei MK1 and Their Derived Peptides

Soybean-derived peptides exert several beneficial effects in various experimental models. However, only a few studies have focused on the radical scavenging and anti-wrinkle effects of soymilk-derived peptides produced via different processes, such as fermentation, enzymatic treatment, and ultrafiltration. Therefore, in this study, we investigated the radical scavenging and antiwrinkle effects of soymilk fractions produced using these processes. We found that 50SFMKUF5, a 5 kDa ultrafiltration fraction fermented with Lacticaseibacillus paracasei MK1 after flavourzyme treatment, exhibited the highest radical scavenging activity using the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay as well as potent anti-wrinkle effects assessed by type 1 procollagen production and tumor necrosis factor-α production in ultraviolet B (UVB)-treated human dermal fibroblasts and HaCaT keratinocytes. To identify potential bioactive peptides, candidate peptides were synthesized, and their anti-wrinkle effects were assessed. APEFLKEAFGVN (APE), palmitoyl-APE, and QIVTVEGGLSVISPK peptides were synthesized and used to treat UVB-irradiated fibroblasts, HaCaT keratinocytes, and α-melanocyte-stimulating hormone-induced B16F1 melanoma cells. Among these peptides, Pal-APE exerted the strongest effect. Our results highlight the potential of soymilk peptides as anti-aging substances.

Partial Characterization and Immunomodulatory Effects of Exopolysaccharides from Streptococcus thermophilus SBC8781 during Soy Milk and Cow Milk Fermentation

The immunomodulatory properties of exopolysaccharides (EPSs) produced by Streptococcus thermophilus have not been explored in depth. In addition, there are no comparative studies of the functional properties of EPSs produced by streptococci in different food matrices. In this work, EPSs from S. thermophilus SBC8781 were isolated after soy milk (EPS-s) or cow milk (EPS-m) fermentation, identified, and characterized in their abilities to modulate immunity in porcine intestinal epithelial cells. Fresh soy milk and cow milk were inoculated with S. thermophilus SBC8781 (7 log CFU/mL) and incubated at 37 °C for 24 h. The extraction of EPSs was performed by the ethanol precipitation method. Analytical techniques, including NMR, UV-vis spectroscopy, and chromatography, identified and characterized both biopolymer samples as polysaccharides with high purity levels and similar Mw. EPS-s and EPS-m had heteropolysaccharide structures formed by galactose, glucose, rhamnose, ribose, and mannose, although with different monomer proportions. On the other hand, EPS-s had higher quantities of acidic polymer than EPS-m. The biopolymer production of the SBC8781 strain from the vegetable culture broth was 200-240 mg/L, which was higher than that produced in milk, which reached concentrations of 50-70 mg/L. For immunomodulatory assays, intestinal epithelial cells were stimulated with 100 µg/mL of EPS-s or EPS-m for 48 h and then stimulated with the Toll-like receptor 3 agonist poly(I:C). EPS-s significantly reduced the expression of IL-6, IFN-β, IL-8, and MCP-1 and increased the negative regulator A20 in intestinal epithelial cells. Similarly, EPS-m induced a significant reduction of IL-6 and IL-8 expressions, but its effect was less remarkable than that caused by EPS-s. Results indicate that the structure and the immunomodulatory activity of EPSs produced by the SBC8781 strain vary according to the fermentation substrate. Soy milk fermented with S. thermophilus SBC8781 could be a new immunomodulatory functional food, which should be further evaluated in preclinical trials.

Functional Characterization of Fermented Beverages Based on Soy Milk and Sea Buckthorn Powder

Limitations of dairy products, such as lactose intolerance, problems related to a high cholesterol intake in diet, malabsorption, and the requirement for cold storage facilities, as well as an increasing demand for new foods and tastes, have initiated a trend in the development of non-dairy probiotic products. The possibility of producing beverages based on soy milk, sea buckthorn powder, and fermented by Bifidobacterium bifidus (Bb-12^®, Bb) strain at different temperatures (30 °C and 37 °C) was examined. Strain viability, pH, and titratable acidity were measured during the fermentation period while the viability, pH, titratable acidity, and water holding capacity were determined during the storage time at 4 °C ± 1 °C within 14 days. Additionally, the survival and stability of Bb-12^®, inoculated into a functional beverage when exposed to simulated gastrointestinal tract conditions, were assessed. The results obtained in this study revealed that the content of potent bioactive compounds in fermented soy milk and sea buckthorn powder depends on the processing conditions, the bacteria used in the fermentation step, and storage time.

Applicable Strains, Processing Techniques and Health Benefits of Fermented Oat Beverages: A Review

Based on the high nutrients of oat and the demand of health-conscious consumers for value-added and functional foods, fermented oat beverages have great market prospects. This review summarizes the applicable strains, processing techniques and health benefits of fermented oat beverages. Firstly, the fermentation characteristics and conditions of the applicable strains are systematically described. Secondly, the advantages of pre-treatment processes such as enzymatic hydrolysis, germination, milling and drying are summarized. Furthermore, fermented oat beverages can increase the nutrient content and reduce the content of anti-nutritional factors, thereby reducing some risk factors related to many diseases such as diabetes, high cholesterol and high blood pressure. This paper discusses the current research status of fermented oat beverages, which has academic significance for researchers interested in the application potential of oat. Future studies on fermenting oat beverages can focus on the development of special compound fermentation agents and the richness of their taste.

Isoflavone Metabolism by Lactic Acid Bacteria and Its Application in the Development of Fermented Soy Food with Beneficial Effects on Human Health

Isoflavones are phenolic compounds (considered as phytoestrogens) with estrogenic and antioxidant function, which are highly beneficial for human health, especially in the aged population. However, isoflavones in foods are not bioavailable and, therefore, have low biological activity. Additionally, their transformation into bioactive compounds by microorganisms is necessary to obtain bioavailable isoflavones with beneficial effects on human health. Many lactic acid bacteria (LAB) can transform the methylated and glycosylated forms of isoflavones naturally present in foods into more bioavailable aglycones, such as daidzein, genistein and glycitein. In addition, certain LAB strains are capable of transforming isoflavone aglycones into compounds with a greater biological activity, such as dihydrodaidzein (DHD), O-desmethylangolensin (O-DMA), dihydrogenistein (DHG) and 6-hydroxy-O-desmethylangolensin (6-OH-O-DMA). Moreover, Lactococcus garviae 20-92 is able to produce equol. Another strategy in the bioconversion of isoflavones is the heterologous expression of genes from Slackia isoflavoniconvertens DSM22006, which have allowed the production of DHD, DHG, equol and 5-hydroxy-equol in high concentrations by engineered LAB strains. Accordingly, the consequences of isoflavone metabolism by LAB and its application in the development of foods enriched in bioactive isoflavones, as well as health benefits attributed to their consumption, will be addressed in this work.

Antioxidant properties of fermented soymilk and its anti-inflammatory effect on DSS-induced colitis in mice

Lactic acid-fermented soymilk as a new plant-based food has aroused extensive attention because of its effects on nutrition and health. This study was conducted to delve into the antioxidative and anti-inflammatory activities of lactic acid-fermented soymilk. To elucidate the key factors that affect the antioxidant properties of fermented soymilk, the strains and preparation process were investigated. Findings show that the fermented soymilk prepared using hot-water blanching method (BT-80) demonstrated a better antioxidant activity than that using conventional method (CN-20). Besides, a huge difference was observed among the soymilks fermented with different strains. Among them, the YF-L903 fermented soymilk demonstrated the highest ABTS radical scavenging ability, which is about twofold of that of unfermented soymilk and 1.8-fold of that of L571 fermented soy milk. In vitro antioxidant experiments and the analysis of H₂O₂-induced oxidative damage model in Caco-2 cells showed that lactic acid-fermentation could improve the DPPH radical scavenging ability, ABTS radical scavenging ability, while reducing the content of reactive oxygen species (ROS) and malondialdehyde (MDA) in Caco-2 cells induced by H₂O₂, and increasing the content of superoxide dismutase (SOD). Consequently, cells are protected from the damage caused by active oxidation, and the repair ability of cells is enhanced. To identify the role of fermented soymilk in intestinal health, we investigate its preventive effect on dextran sodium sulfate-induced colitis mouse models. Results revealed that the fermented soymilk can significantly improve the health conditions of the mice, including alleviated of weight loss, relieved colonic injury, balanced the spleen-to-body weight ratio, reduced the disease index, and suppressed the inflammatory cytokines and oxidant indexes release. These results suggest that YF-L903 fermented soymilk is a promising natural antioxidant sources and anti-inflammatory agents for the food industry. We believe this work paves the way for elucidating the effect of lactic acid-fermented soymilk on intestinal health, and provides a reference for the preparation of fermented soymilk with higher nutritional and health value.

The Quality and Flavor Changes of Different Soymilk and Milk Mixtures Fermented Products during Storage

This study explored the effects of two mixed fermentation methods: one was fermenting a soymilk and milk mixture by a lactic acid bacteria fermenting agent at 0.1 g/kg and 42 °C until the acidity was 70 °T, which was set as the MFSM method, and the other was fermenting milk alone by lactic acid bacteria at 42 °C for 12 h, placing it in a 4 °C refrigerator after acidification for 24 h and then mixing it with soymilk at a 1.5:1 ratio and storing the mixture at 4 °C, which was set as the SMFSM method. The quality and flavor of the soymilk and milk mixture products were investigated on the 0th, 15th and 30th days during storage. The changes in acidity, pH, number of viable bacteria, viscosity, water-holding capacity, texture, rheological properties, sensory quality and volatile flavors were determined. The results showed that compared with the fermented soymilk and milk mixtures under the MFSM method, the samples of fermented soymilk and milk mixtures under the SMFSM method showed a significant slowdown of acidification during storage, so that the sensory quality of the products was almost unaffected by acidity on the 30th day of storage. Furthermore, the number of viable bacteria was greater than 7 log cfu/mL. The water holding capacity did not change significantly until the 30th day. There was also no whey precipitation, indicating good stability. The samples in SMFSM mode had higher aromatic contents and beans during storage than the fermented soymilk and milk mixtures in MFSM mode. The rich variety of volatile flavors and the presence of acetoin, 2-heptanone, and (E,E)-3,5-octadien-2-one throughout the storage period allowed the samples to maintain a good sensory flavor during storage.

Comparison on Protein Bioaccessibility of Soymilk Gels Induced by Glucono-δ-Lactone and Lactic Acid Bacteria

In this study, the protein bioaccessibility of soymilk gels produced by the addition of glu-cono-δ-lactone (GDL) and fermentation with lactic acid bacteria (LAB) was examined using an in vitro gastrointestinal simulated digestion model. The in vitro protein digestibility, soluble protein content, free amino acids contents, degree of hydrolysis, electrophoretic patterns, and peptide content were measured. The results suggested that acid-induced soymilk gel generated by GDL (SG) showed considerably reduced in vitro protein digestibility of 75.33 ± 1.00% compared to the soymilk gel induced by LAB (SL) of 80.57 ± 1.53% (p < 0.05). During the gastric digestion stage, dramatically higher (p < 0.05) soluble protein contents were observed in the SG (4.79−5.05 mg/mL) than that of SL (4.31−4.35 mg/mL). However, during the later intestinal digestion phase, the results were the opposite. At the end of the gastrointestinal digestion phase, the content of small peptides was not significantly different (p > 0.05) between the SL (2.15 ± 0.03 mg/mL) and SG (2.17 ± 0.01 mg/mL), but SL showed higher content of free amino acids (20.637 g/L) than that of SG (19.851 g/L). In general, soymilk gel induced by LAB had a higher protein bioaccessibility than the soymilk gel coagulated by GDL.

Probiotic fermentation of polyphenols: potential sources of novel functional foods

Fermented functional food products are among the major segments of food processing industry. Fermentation imparts several characteristic effects on foods including the enhancement of organoleptic characteristics, increased shelf-life, and production of novel health beneficial compounds. However, in addition to macronutrients present in the food, secondary metabolites such as polyphenols are also emerging as suitable fermentable substrates. Despite the traditional antimicrobial view of polyphenols, accumulating research shows that polyphenols exert differential effects on bacterial communities by suppressing the growth of pathogenic microbes while concomitantly promoting the proliferation and survival of probiotic bacteria. Conversely, probiotic bacteria not only survive among polyphenols but also induce their fermentation which often leads to improved bioavailability of polyphenols, production of novel metabolic intermediates, increased polyphenolic content, and thus enhanced functional capacity of the fermented food. In addition, selective fermentation of combinations of polyphenol-rich foods or fortification with polyphenols can result in novel functional foods. The present narrative review specifically explores the potential of polyphenols as fermentable substrates in functional foods. We discuss the emerging bidirectional relationship between polyphenols and probiotic bacteria with an aim at promoting the development of novel functional foods based on the amalgamation of probiotic bacteria and polyphenols.

Graphical abstract