Effects of pH and salt concentration on freeze-thaw fractionation of soymilk protein.

BACKGROUND: The two major storage proteins of soymilk are the globulins 7S and 11S. Freeze-thaw fractionation is a simple method for separating these proteins in raw soymilk. In this study, we assessed the freeze-thaw fractionation ability of raw soymilk under various pH (4.3-11.6) conditions and added salt (sodium chloride) concentrations (0.00-0.67 mol L-1). RESULTS: We successfully achieved fractionation within a pH range of 5.8-6.7 and when the salt concentration was 0.22 mol L-1 or lower. Analysis of particle size distribution and microscopic examination of soymilk revealed no direct correlation between particle size and freeze-thaw fractionation ability. Interestingly, it was confirmed that the ranges of zeta potential values associated with successful freeze-thaw fractionation in raw soymilk remained consistent across different pH and salt concentration conditions. These ranges were between -23 and -28 mV at pH levels ranging from 5.8 to 6.7 and between -18 and -29 mV at added salt concentrations ranging from 0 to 0.22 mol L-1. CONCLUSION: The pH and salt concentration in raw soymilk markedly influence the freeze-thaw fractionation process. We confirmed that the range of zeta potential values where fractionation was possible remained consistent under various pH and salt concentration conditions. These findings suggest that the zeta potential value might serve as an indicator for evaluating the freeze-thaw fractionation ability of raw soymilk. © 2024 Society of Chemical Industry.

Probiotic Lactiplantibacillus plantarum KU210152 and its fermented soy milk attenuates oxidative stress in neuroblastoma cells.

We evaluated the probiotic properties and neuroprotective effects of Lactiplantibacillus plantarum KU210152 and its application in soy milk. L. plantarum KU210152 exhibited high tolerance to artificial gastrointestinal conditions, high adhesion to intestinal cells (HT-29), and safe enzyme production. Conditioned medium acquired from HT-29 cells treated with heat-killed lactic acid bacteria (LAB-CM) was used to evaluate the neuroprotective effects. The CM exhibited neuroprotective effects via cell viability assay, morphological observations, and suppression of ROS production. Heat-killed L. plantarum KU210152 increased brain-derived neurotrophic factor (BDNF) and tyrosine hydroxylase (TH) expression in HT-29 cells. In SH-SY5Y cells, pretreatment with L. plantarum KU210152 CM decreased Bax/Bcl-2 ratio and upregulated BDNF and TH expression. The CM inhibited caspase-9 and caspase-3 activities. The neuroprotective effects of L. plantarum KU210152 were also confirmed in fermented soy milk. Therefore, both L. plantarum KU210152 and the fermented soy milk can be used as functional ingredients with neuroprotective effects against oxidative stress.

Enhanced Cholesterol-Lowering and Antioxidant Activities of Soymilk by Fermentation with Lactiplantibacillus plantarum KML06.

This study aimed to evaluate the cholesterol-lowering and antioxidant activities of soymilk fermented with probiotic Lactobacillaceae strains and to investigate the production of related bioactive compounds. Lactiplantibacillus plantarum KML06 (KML06) was selected for the fermentation of soymilk because it has the highest antioxidant, cholesterol-lowering, and ß-glucosidase activities among the 10 Lactobacillaceae strains isolated from kimchi. The genomic information of strain KML06 was analyzed. Moreover, soymilk fermented with KML06 was evaluated for growth kinetics, metabolism, and functional characteristics during the fermentation period. The number of viable cells, which was similar to the results of radical scavenging activities and cholesterol assimilation, as well as the amount of soy isoflavone aglycones, daidzein, and genistein, was the highest at 12 h of fermentation. These results indicate that soymilk fermented with KML06 can prevent oxidative stress and cholesterol-related problems through the production of soy isoflavone aglycones.

Effect of fermented soy beverage in aged female mice model.

Soy beverage is a rich source of phytoestrogens isoflavones, with potential benefits on health. The effect of those compounds depends greatly on their bacterial metabolization into their aglycone forms. This study evaluated the health effects of two soy beverages, non-fermented (SB) and fermented with Bifidobacterium pseudocatenulatum INIA P815 (FSB), in acyclic and cyclic C57BL/6J aged female mice as a model of menopause and premenopause, respectively. SB and FSB treatments were administrated for 36 days and, subsequently, body weight, lipid and inflammatory profile and fertility were analyzed and compared. In addition, hepatic gene expression and faecal microbiota composition were also assessed. After fermentation, FSB presented a high content in the aglycones daidzein and genistein and a higher antioxidant activity. FSB treated cyclic mice showed a significant increase in the number of retrieved oocytes and zigotes. Differences in serum lipids were observed in triglycerides, which were lower in FSB than in SB groups. None of the treatments influenced the inflammatory profile or caused a dramatic change in the intestinal microbiota profile or hepatic gene expression in any of the groups. Our data showed that FSB provided greater health benefits than SB in lipid profile and fertility in cyclic mice. These beneficial effects could be attributed to the fermentation process, which produces more bioavailable and bioactive compounds, achieving a greater impact on health.

Engineering of Leuconostoc citreum for Efficient Bioconversion of Soy Isoflavone Glycosides to Their Aglycone Forms.

Soy isoflavones are phytochemicals that possess various beneficial physiological properties such as anti-aging, anti-tumor, and antioxidant properties. Since soy isoflavones exist in glycoside forms, their bioavailability requires initial hydrolysis of the sugar moieties bound to them to be efficiently absorbed through the gut epithelium. Instead of conventional chemical hydrolysis using acids or organic solvents, alternative strategies for enhancing the bioavailability of soy isoflavones using biological methods are gaining attention. Here, we engineered Leuconostoc citreum isolated from Korean kimchi for efficient bioconversion of soy isoflavone glycosides into their aglycone forms to enhance their bioavailability. We first constructed an expression module based on the isoflavone hydrolase (IH)-encoding gene of Bifidobacterium lactis, which mediates conversion of isoflavone glycosides to aglycone forms. Using a high copy number plasmid and bicistronic expression design, the IH was successfully synthesized in L. citreum. Additionally, we determined enzymatic activity of the IH using an in vivo ß-glucosidase assay and confirmed its highly efficient bioconversion efficiency for various types of isoflavone glycosides. Finally, we successfully demonstrated that the engineered L. citreum could convert isoflavone glycosides present in fermented soymilk into aglycones.

Fermentation of soymilk by Lactobacillus acidipiscis isolated from Chinese stinky tofu capable of efficiently biotransforming isoflavone glucosides to dihydrodaidzein and dihydrogenistein.

BACKGROUND: The soy isoflavone microbial metabolites dihydrodaidzein (DHD), dihydrogenistein (DHG), equol and 5-hydroxy-equol are generally more biologically active than their precursors daidzein and genistein. Bacteria responsible for isoflavone metabolism have been isolated and identified. Fermented soymilk is a potential functional food; however, there are few lactic acid bacteria capable of metabolizing soy isoflavones. RESULTS: A newly isolated Gram-positive facultative anaerobic bacterium, which was named Lactobacillus acidipiscis HAU-FR7, was isolated from the traditional Chinese fermented soy product 'stinky tofu'. Bacterium strain HAU-FR7 can grow under aerobic conditions and can also convert most of the daidzin and genistin in soymilk into DHD and DHG, respectively. The concentrations of DHD and DHG produced were 183 and 134 µmol L-1 , respectively, after fermentation for 24 h. Strain HAU-FR7 does not produce the biogenic amines cadaverine, putrescine, histamine or tyramine, and an antibiotic susceptibility test showed that HAU-FR7 is sensitive to nine of the ten tested antibiotics, except for vancomycin. Moreover, the 1,1-diphenyl-2- picrylhydrazyl free radical scavenging capacity of soymilk fermented with HAU-FR7 was significantly higher than that of unfermented soymilk. CONCLUSION: A facultative anaerobic lactic acid bacterium, designated Lactobacillus acidipiscis HAU-FR7, is capable of reducing the soy isoflavone glucosides daidzin and genistin in soymilk to DHD and DHG efficiently, even in the presence of atmospheric oxygen. The biotransformation activity of HAU-FR7 grown in soymilk is higher than that in de Man-Rogosa-Sharpe liquid culture medium. © 2022 Society of Chemical Industry.

Effects of lactic acid bacteria fermented yellow whey on the protein coagulation and isoflavones distribution in soymilk.

This study investigated the soymilk coagulation induced by fermented yellow whey (FYW), which is extensively used as a natural tofu coagulant in China. The aggregations involving proteins and isoflavone particles caused by FYW were analyzed using the proteomic technology and high-performance liquid chromatography, respectively. As indicated, the FYW-induced coagulation of soy proteins mainly occurred at pH 5.80-5.90. When the pH of soymilk decreased, the 7S ß, 11S A3 and some of 11S A1a subunits and SBP, Bd, lectin and TA aggregated the earliest, and later did the 11S A4, other 11S A1a, 11S A2 and 11S A1b subunits. The 7S α and α' subunits and TB showed an obvious delay in aggregation. Moreover, isoflavones in the form of aglycones were more likely to coprecipitate with proteins, compared with glycosides. These results could provide an important reference and assistance for future research on the development of traditional FYW-tofu.

Bioconversion and bioaccessibility of isoflavones from sogurt during in vitro digestion.

This study investigated the bioconversion and bioaccessibility of soy isoflavones produced in sogurt fermented with S. thermophilus and L. bulgaricus during in vitro digestion. The highest survivability of S. thermophilus (6.49 log cfu/mL) and L. bulgaricus (6.48 log cfu/mL) was in oral phase. In gastric phase, the total aglycones of sogurt (26.73 g/L) increased up to 20 times than control (1.21 g/L), with a significant increase in daidzein (17.05 g/L) and genistein (9.68 g/L). Addition of 8U of ß-glucosidase into soymilk significantly increased the conversion of isoflavone in ENTII (daidzein: 0.46 g/L; genistein: 0.18 g/L) than in ENTI (daidzein: 0.33 g/L; genistein: 0.20 g/L). The particle size analysis and confocal micrographs of digesta also suggest the size of fat and protein in gastric phase to be smaller than in intestinal phase. The results indicate the prospective to develop soy-based fermented products capable of releasing high isoflavone in the digestive system.

(E)-2-Heptenal in Soymilk: A Nonenzymatic Formation Route and the Impact on the Flavor Profile.

Flavor is an essential quality characteristic of soymilk. (E)-2-Heptenal has a fatty and fruity flavor with the sensory threshold value of 13 µg/L in water. This study demonstrated that the formation of (E)-2-heptenal was independent of the lipoxygenase (LOX) and hydroperoxide lyase (HPL) activity as well as oxygen concentration but was related to the presence/absence of Fe2+ and chelators. In a dry matter base, soybean hypocotyls generated a much higher amount of (E)-2-heptenal than cotyledons. A phospholipid hydroperoxide was purified from the chloroform/methanol extract of soybean hypocotyls and was identified as 1-palmitoyl-2-(12-hydroperoxyoctadecadienoyl)-sn-glycerol-3-phosphatidylethanol-amine (12-PEOOH). The decomposition of 12-PEOOH in the presence of ferrous ions to form (E)-2-heptenal was studied in a model system. The rate of decomposition decreased sharply at pH values higher than 6, but the molar conversion of 12-PEOOH to (E)-2-heptenal increased with an increase of pH. At a constant pH of 5.8, the decomposition rate of 12-PEOOH was positively linearly related to the Fe2+ concentration, while the molar conversion to (E)-2-heptenal was 74% and independent of the Fe2+ concentration. The formation of radicals LOO• and R• showed similar pH and Fe2+ concentration dependence with those of (E)-2-heptenal. (E)-2-Heptenal displayed an enhancement of bean aroma and fruity flavor of soymilk at low concentrations, but a fatty flavor was noticed at high concentrations.

Streptococcus thermophilus growth in soya milk: Sucrose consumption, nitrogen metabolism, soya protein hydrolysis and role of the cell-wall protease PrtS.

Societal demand for plant-based foods is increasing. In this context, soya products fermented using lactic acid bacteria (LAB) are appealing because of their potential health and nutritional benefits. The thermophilic LAB Streptococcus thermophilus is an essential starter species in the dairy industry. However, while its physiology is well characterized, little is known about its general metabolic activity or its techno-functional properties when it is grown in soya milk. In this study, S. thermophilus LMD-9 growth, sugar production, and lactic acid production in soya milk versus cow's milk were measured. Additionally, the main metabolic pathways used by the bacterium when growing in soya milk were characterized using a proteomic approach. Streptococcus thermophilus LMD-9 growth decreased soya milk pH, from 7.5 to 4.9, in 5 h. During fermentation, acidification thus occurred in tandem with lactate production and increasing population size (final population: 1.0 × 109 CFU/ml). As growth proceeded, sucrose was consumed, and fructose was produced. The proteomic analysis (LC-MS/MS) of the strain's cytosolic and cell envelope-associated proteins revealed that proteins related to amino acid transport and nitrogen metabolism were the most common among the 328 proteins identified (63/328 = 19.2% of total proteins). The cell-wall protease PrtS was present, and an LMD-9 deletion mutant was constructed by interrupting the prtS gene (STER_RS04165 locus). Acidification levels, growth levels, and final population size were lower in the soya milk cultures when the ΔprtS strain versus the wild-type (wt) strain was used. The SDS-PAGE profile of the soluble proteins in the supernatant indicated that soya milk proteins were less hydrolyzed by the ΔprtS strain than by the wt strain. It was discovered that S. thermophilus can grow in soya milk by consuming sucrose, can hydrolyze soya proteins, and can produce acidification levels comparable to those in cow's milk. This study comprehensively examined the proteomics of S. thermophilus grown in soya milk and demonstrated that the cell-wall protease PrtS is involved in the LAB's growth in soya milk and in the proteolysis of soya proteins, which are two novel findings. These results clarify how S. thermophilus adapts to soya milk and can help inform efforts to develop new fermented plant-based foods with better-characterized biochemical and microbiological traits.

Lactobacillus plantarum TWK10-fermented soymilk improves cognitive function in type 2 diabetic rats.

BACKGROUND: The brain is especially sensitive to diabetes-induced damage. Chronic hyperglycemia can potentially lead to brain dysfunctions, affecting spatial learning and memory. RESULTS: The type 2 diabetes (T2D) rats were administered TWK10-fermented soy milk water extract (WE) and ethanol extract (EE) for 6 weeks. WE and EE treatment attenuated T2D-induced alteration in cognitive function assessed using the Morris water maze. Moreover, administration of WE and EE significantly elevated superoxide dismutase activity (166.96% and 181.21%, P < 0.05, respectively) and reduced malondialdehyde concentration (35.03% and 43.97%, P < 0.05, respectively) in the hippocampus of the rats. Additionally, the calmodulin level and nitric oxide concentration were regulated by WE and EE. CONCLUSION: This study provides scientific evidence that WE and EE enhance anti-oxidative enzyme activity, which subsequently regulates factors associated with cognitive function in T2D rats. © 2020 Society of Chemical Industry.

Gelling behavior of bio-tofu coagulated by microbial transglutaminase combined with lactic acid bacteria.

The aim of this study was to investigate the gelling behavior of proteins in bio-tofu (soymilk-cow milk mixture gel) coagulated by microbial transglutaminase (MTGase) combined with lactic acid bacteria (LAB). It was shown that MTGase (3.0 U/g protein) treatment of soymilk-cow milk mixture (SCMM) could not induce gelation at 43℃ even if the incubation was lasting 4 h. However, the concomitant use of LAB (0.025 UC/L) along with MTGase could induce the formation of denser and finer gel network with smaller pores and higher storage modulus (G') compared to SCMM treated with only LAB. Electrophoresis and mass spectrometry results indicated that LAB improve MTGase-dependent polymerization of proteins. In addition, this study investigates the effect of LAB and MTGase treatment on the rheology behavior of the derived gel products. In general, the use of both bio-coagulants for the manufacture of a mixed protein gel, might open new horizons in the field of novel nutrional and functional foods.

Effect of carbon dots in combination with aqueous chitosan solution on shelf life and stability of soy milk.

Use of carbon dots (CDs) in combination with aqueous chitosan solution to extend shelf life and improve stability of soy milk was investigated. Soy milk samples with chitosan solution (0.00%, 0.08%, 0.12%, 0.16% and 0.20%) and banana-based CDs (4%, 6% and 8%) were prepared and stored at room temperature (25-30 °C) for shelf life evaluation. Soy milk with 0.16% chitosan solution exhibited improved stability as evident by increased viscosity, stability coefficient, zeta potential and decreased centrifugation rate compared with soy milk without chitosan. The suitable amount of carbon dots could effectively inhibit the growth of Escherichia coli, Staphylococcus aureus and Bacillus subtilis. Soy milk with 0.16% chitosan and 8% CDs exhibited longer shelf life and significantly lower total bacterial count after storage at room temperature for up to 4 days. Electronic nose-based flavor characteristics of all treated soy milk samples were not far from that of the control sample.

Analysis on physicochemical and sensory qualities of soymilk prepared by various cultivars: Application of fuzzy logic technique.

Soymilk has a complicated system, and its sensory and physicochemical characteristics are influenced by the components of the soybean seeds. Thirty-five soybean cultivars were selected, and correlation analysis and clustering analysis were applied to determine the significant correlations between soybean seed traits and soymilk physiochemical properties. Four sensory quality attributes of soymilk, including taste, odor, appearance, and mouthfeel, were quantified in numerical values and scored based on a weighting criterion which was constructed via the fuzzy logic technique. Soymilk prepared from the soybean seeds with the lower crude protein and the higher crude fat content displayed better sensory qualities. A multivariate linear regression analysis was used to establish a predictive model for overall sensory scores of soymilk, which could be the reference for soybean cultivars selection in soymilk processing. To comprehensively optimize the processing costs, nutritional values, and sensory qualities, a set of detailed attributes of soybean seeds were recommended based on this study: 100-seed weight is higher than 20 g; ash content is less than 5.5 g/100 g; crude fat content is 20 to 24 g/100 g; and crude protein content is as high as possible, while the maximum limit is 40 g/100 g. PRACTICAL APPLICATION: The established predictive model can be a reference for soybean cultivars selection in soymilk processing. Moreover, the soybean composition range that is revealed by this study also provides a recommendation for the soybean breeding.

Production of O-desmethylangolensin, tetrahydrodaidzein, 6'-hydroxy-O-desmethylangolensin and 2-(4-hydroxyphenyl)-propionic acid in fermented soy beverage by lactic acid bacteria and Bifidobacterium strains.

Isoflavones intake is associated with health benefits. The metabolism of isoflavones by bacteria plays a key role in their biotransformation. Therefore, commercial soy drink was fermented by 11 lactic acid bacteria (LAB) and 9 bifidobacteria strains. The majority of the strains showed deglycosylation of the isoflavone glycosides present in soy drink and appearance of the aglycones daidzein, genistein and glycitein. Moreover, we observed the further transformation of daidzein into O-desmethylangolensin (O-DMA) and tetrahydrodaidzein, alongside with dihydrodaidzein (DHD) and a putative isomer of DHD. On the other hand, genistein was transformed by nearly all strains into 6-hydroxy-O-desmethylangolensin (6-hydroxy-O-DMA), but no dihydrogenistein production was registered. A high concentration of 2-(4-hydroxyphenyl)-propionic acid was observed, suggesting the degradation of O-DMA and 6-hydroxy-O-DMA. The potential of LAB and Bifidobacterium strains to produce functional soy drink enriched with bioactive isoflavones is demonstrated in this work.

Characterization of novel α-galactosidase in glycohydrolase family 97 from Bacteroides thetaiotaomicron and its immobilization for industrial application.

Bacteroides thetaiotaomicron (B. thetaiotaomicron), which resides in the human intestinal tract, has a number of carbohydrate enzymes, including glycoside hydrolase (GH) family 97. Only a few GH 97 enzymes have been characterized to date. In this study, a novel α-galactosidase (Bt_3294) was cloned from B. thetaiotaomicron, expressed in Escherichia coli, and purified using affinity chromatography. This novel enzyme showed optimal activity at 60 °C and pH 7.0. Enzyme activity was reduced by 94.4% and 95.7% in the presence of 5 mM Ca2+ and Fe2+, respectively. It is interesting that Bt_3294 specifically hydrolyzed shorter α-galactosyl oligosaccharides, such as melibiose and raffinose. The D-values of Bt_3294 at 40 °C and 50 °C were about 107 and 6 min, respectively. After immobilization of Bt_3294, the D-values at 40 °C and 50 °C were about 37.6 and 29.7 times higher than those of the free enzyme, respectively. As a practical application, the immobilized Bt_3294 was used to hydrolyze raffinose family oligosaccharides (RFOs) in soy milk, decreasing the RFOs by 98.9%.

Direct-immersion SPME in soy milk for pesticide analysis at trace levels by means of a matrix-compatible coating.

This study demonstrates a newly developed PDMS/DVB/PDMS fiber's suitability for the determination of pesticides in soy milk via direct-immersion solid-phase microextraction (SPME) combined with gas chromatography-mass spectrometry, eliminating the need for extensive sample pre-treatment procedures. Fouling accumulation on the coating surface was further minimized by implementing rapid and effective pre- and post-desorption cleaning steps. Under optimum conditions, the fiber was used to perform over 120 extractions while maintaining RSD values of less than 24.5% for 10 extracted pesticides. By comparison, the RSD values ranged from 8.4% to 42.8% over 80 extractions using a commercial PDMS/DVB fiber. The optimized conditions were used to fully validate a quantitative method for the targeted analytes by matrix-matched calibration and isotopically labeled internal standard correction. Significantly, the proposed method was able to achieve limits of quantitation (1-2.5 µg/kg) for the targeted analytes that were below the Maximum Residue Levels mandated for soy-based products. Accuracy, intra- and inter-day repeatability were also satisfactory. The proposed PDMS/DVB/PDMS fiber dramatically improved repeatability and suitability for direct-immersion SPME in soy milk, and represents a good alternative to other extraction methods for high-throughput quantitative analysis of pesticide residues in soy-based products.

Effects of different satiety levels on the fate of soymilk protein in gastrointestinal digestion and antigenicity assessed by an in vitro dynamic gastrointestinal model.

This study was designed to compare the effects of different satiety levels on the digestion and antigenicity of soymilk protein. The DIVRSD-II dynamic in vitro digestion model (DIVD) was employed to simulate different satiety degrees by changing the amount of food intake, namely full satiety (DIVD-FS), semi-satiety (DIVD-SS) and limited-satiety (DIVD-LS). A standardized static in vitro digestion method (SIVD) was used as a reference. Coupled with 60 min of gastric digestion and 120 min of intestinal digestion, the pH, particle size, soluble protein content, peptide content, gel electrophoresis, and antigenicity of soymilk digesta were monitored. The results showed that different satiety degrees altered soymilk protein digestive patterns in terms of gastric transit time, hydrolysis degree and antigenicity. The results of soluble protein content suggested that soymilk protein in DIVD-FS showed faster gastric transition than DIVD-SS and DIVD-LS. Gel electrophoresis and peptide content indicated that DIVD-FS digesta showed predominantly lower hydrolysis degrees in gastric and early intestinal stages. This further led to the persistence of major allergens at the early stage of intestinal digestion for DIVD-FS digesta. Soymilk protein digested using SIVD showed mostly intermediate values which indicated a good reference to the different satiety degrees of DIVD, although a descriptive result was obtained at early intestinal digestion. The results of this study showed for the first time the effect of different satiety degrees on hydrolysis kinetics, digestive degree and antigenicity of soy protein. The results suggested that the knowledge-base of soy protein digestibility depends on different satiety degrees and will be useful for guiding a healthy diet mode.

Effects of Lactic Acid Bacteria-Fermented Soymilk on Isoflavone Metabolites and Short-Chain Fatty Acids Excretion and Their Modulating Effects on Gut Microbiota.

Lactobacillus rhamnosus strain ASCC 1520 with high soy isoflavone transformation ability was used to ferment soymilk and added to the diet of mice. The impact of L. rhamnosus fermentation on soy isoflavone metabolites and intestinal bacterial community, in conjunction with fecal enzyme activity and short-chain fatty acids (SCFA) excretion was evaluated. Antibiotics intervention resulted in a decrease in fecal enzyme activities and SCFA. Although long-term intake of soymilk or L. rhamnosus-fermented soymilk did not affect the fecal ß-glucuronidase and ß-galactosidase activities, it improved the ß-glucosidase activity when antibiotics were concomitantly administered. Soymilk or fermented soymilk administration increased the isoflavone metabolites (O-DMA and equol) excreted in urine. Antibiotics decreased the daidzein excretion and its metabolites but showed little effect on glycitein and genistein excretion. Principal coordinates analysis (PCoA) of the 16s rRNA gene sequencing data found a remarkable shift in gut microbiota after soymilk administration and antibiotics treatment. Matastats test of the relative abundance of bacterial taxa revealed Odoribacter (Bacteroidales family), Lactobacillus (Lactobacillales order), and Alistipes (Rikenellaceae family) were enriched in soymilk while bacterial taxa from Bacteroides and Lactobacillus were enriched in L. rhamnosus-fermented soymilk. Furthermore, there was less decrease in bacterial taxa with fermented soymilk group even when antibiotics were concomitantly administered. Overall, this study revealed that the gut microbiota of a healthy host is enough for the whole isoflavone metabolism under normal conditions. Feeding mice with L. rhamnosus-fermented soymilk improved fecal enzyme activity and kept the balance of the gut mirobiota when antibiotics were used. PRACTICAL APPLICATION: Feeding mice with L. rhamnosus-fermented soymilk improved fecal enzyme activity and kept the balance of the gut mirobiota when antibiotics were used.

Soy Intake Since the Prepubertal Age May Contribute to the Pathogenesis of Endometriosis in Adulthood.

High prevalence of endometriosis was reported in Asian women as a result of their traditionally high intake of soy foods during infancy. Soy is widely used in infant feeding after weaning from breast milk or cow milk. This study thus aimed to determine to what extent soy intake before puberty may contribute to the development of endometriosis. For this purpose, immature (6-week old) female rats were fed with various soy formulas (0%, 10%, 20%, 30%, 40%, 50%, and 60%). Normal control animals were fed with a soy-free diet. At 13 weeks of age, animals (except the normal control) underwent a transplantation surgery to establish endometriosis. Estradiol valerate and oxytocin were used to induce pelvic pain. Endometrial implant levels of glutathione (GSH) and malondialdehyde (MDA) allowed estimating tissue oxidative status. Physiological ovarian function was assessed by histological analysis of ovaries. Results showed that soy-fed animals grew faster than animals receiving a soy-free diet (P < .001). In animals supplemented with more than 10% of soy, the intensity of pelvic pain increased (P < .001) as well as the volume of ectopic foci. In addition, tissue levels of MDA and GSH increased (P < .001). The ovarian function was altered and the number of luteinized unruptured follicles increased. In conclusion, although animals supplemented with soy at the prepubertal stage displayed a good growth performance, regular soy consumption may promote the development and progress of endometriosis in adulthood, especially when soy content in food is more than 10%.