Fermented Soy Beverage Research Articles

Effect of Fermented Soy Beverage on Equol Production by Fecal Microbiota.

Soy consumption is associated with health benefits, mainly linked to the ability of the intestinal microbiota to metabolize the glycosylated isoflavones into more bioactive compounds, such as equol. Because Bifidobacterium pseudocatenulatum INIA P815 is able to efficiently deglycosylate daidzin into daidzein, the aim of this work was to confirm the influence of soy beverages fermented by B. pseudocatenulatum INIA P815 for enhancing equol production by fecal microbiota. Firstly, fecal samples from 17 participants were characterized in vitro, and we observed that 35.3% of them were able to produce equol from daidzein. In addition, the kinetics of equol production and degradation by fecal microbiota were evaluated, determining that 30-85% of equol is degraded after 24 h of incubation. Finally, the influence of fermented soy beverage on improving the production of equol by selected equol-producing fecal samples and by the equol-producing strain Slackia isoflavoniconvertens was analyzed through a colonic model. Fermented soy beverage enhanced the equol production from S. isoflavoniconvertens as well as the fecal samples whose microbiota showed high rates of equol degradation. The results obtained confirm that the fermentation of soy beverages with selected bacterial strains improves the functional properties of these beverages in terms of isoflavone metabolism and equol production.

Influence of Modified Cassava Starches on the Rheological and Structural Properties of a Fermented Soy Beverage During Storage

AbstractTraditionally, intensive thermal treatments are applied to process soy beverages, negatively impacting product quality by reducing solubility, and viscosity, while promoting syneresis. Modified cassava starches can prevent these effects. This study evaluates the influence of adding modified cassava starches on syneresis, apparent viscosity, particle size, microstructure, and sensory acceptance of a fermented soy beverage. A commercial culture of starter microorganisms and probiotics is used in the fermentation. Four beverages are produced: one with native cassava starch, one with octenyl succinic anhydride (OSA)‐modified cassava starch, one with crosslinked acetylated distarch adipate (ADA), and one with crosslinked‐substituted cassava starch (mixed); the starch concentration is 1% in each beverage. Samples are stored for 3 weeks at 4 °C. Modified cassava starches significantly alters syneresis compared to the native starch beverage, with no difference among the other treatments. Viscosity shows significant differences among treatments. During storage, the native starch beverage shows an increase in syneresis and a reduction in viscosity, whereas the OSA‐modified starch beverage has higher viscosity but presents significant variation by the end of the 3‐week storage period. The mixed starch beverage has intermediate characteristics with high viscosity and stability during storage. In the sensory evaluation, the consumers prefer the OSA‐modified starch beverage.

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.

The effect of a fermented soy beverage among patients with localized prostate cancer prior to radical prostatectomy

BackgroundFermented soy products have shown to possess inhibitory effects on prostate cancer (PCa). We evaluated the effect of a fermented soy beverage (Q-Can®), containing medium-chain triglycerides, ketones and soy isoflavones, among men with localized PCa prior to radical prostatectomy.MethodsWe conducted a placebo-controlled, double-blind randomized trial of Q-Can®. Stratified randomization (Cancer of the Prostate Risk Assessment (CAPRA) score at diagnosis) was used to assign patients to receive Q-Can® or placebo for 2–5 weeks before RP. Primary endpoint was change in serum PSA from baseline to end-of-study. We assessed changes in other clinical and pathologic endpoints. The primary ITT analysis compared PSA at end-of-study between randomization arms using repeated measures linear mixed model incorporating baseline CAPRA risk strata.ResultsWe randomized 19 patients, 16 were eligible for analysis of the primary outcome. Mean age at enrollment was 61, 9(56.2%) were classified as low and intermediate risk, and 7(43.8%) high CAPRA risk. Among patients who received Q-Can®, mean PSA at baseline and end-of-study was 8.98(standard deviation, SD 4.07) and 8.02ng/mL(SD 3.99) compared with 8.66(SD 2.71) to 9.53ng/mL(SD 3.03), respectively, (Difference baseline – end-of-study, p = 0.36). There were no significant differences in Gleason score, clinical stage, surgical margin status, or CAPRA score between treatment arms (p > 0.05), and no significant differences between treatment arms in end-of-study or change in lipids, testosterone and FACT-P scores (p > 0.05).ConclusionsShort exposure to Q-Can® among patients with localized PCa was not associated with changes in PSA levels, PCa characteristics including grade and stage or serum testosterone. Due to early termination from inability to recruit, study power, was not achieved.

Comprehensive studies on the stability of yogurt-type fermented soy beverages during refrigerated storage using dairy starter cultures.

This study aimed to assess the feasibility of utilizing commercially available dairy starter cultures to produce yogurt-type fermented soy beverages and evaluate the fundamental properties of the resulting products. Sixteen different starter cultures commonly used in the dairy industry for producing fermented milks, such as yogurt, were employed in the study. The study investigated the acidification curves, acidification kinetics, live cell population of starter microflora during refrigerated storage, pH changes, water-holding capacity, texture analysis, carbohydrates content, and fatty acid profile of the yogurt-type fermented soy beverage. The results demonstrated that the starter cultures exhibited distinct pH changes during the fermentation process, and these changes were statistically significant among the cultures. The acidification kinetics of different cultures of lactic acid bacteria showed characteristic patterns, which can be used to select the most suitable cultures for specific product production. The study also revealed that the choice of starter culture significantly influenced the starter microorganisms population in the yogurt-type fermented soy beverage. Additionally, the pH values and water-holding capacity of the beverages were affected by both the starter cultures and the duration of refrigerated storage. Texture analysis indicated that storage time had a significant impact on hardness and adhesiveness, with stabilization of these parameters observed after 7-21 days of storage. Furthermore, the fermentation process resulted in changes in the carbohydrate content of the soy beverages, which varied depending on the starter culture used.

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.

Fermentation Kinetics, Microbiological and Physical Properties of Fermented Soy Beverage with Acai Powder

In this study, the effects of the fermentation kinetics, determination of the number of lactic acid bacteria, texture, water holding capacity, and color of fermented soy beverages with acai powder (3 and 6% w/v) were investigated. The addition of acai powder significantly influenced the fermentation kinetics based on changes in pH, accelerating fermentation in the initial period. The results showed that the acai additive did not affect the enumeration of Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis. The presence of acai inhibited the proliferation of Streptococcus thermophilus compared to the soy beverage without acai powder added. However, the higher the acai additive, the more Streptococcus thermophilus bacteria were detected: 4.39 CFU/g for 6% acai powder sample and 3.40 CFU/g for 3% acai powder sample. The addition of acai to the soy beverage reduced its firmness, consistency, cohesiveness, and viscosity index after fermentation. A slight difference was observed in the lightness and whiteness of fermented soy beverages with 3% and 6% acai powder.

Impact of a fermented soy beverage supplemented with acerola by-product on the gut microbiota from lean and obese subjects using an in vitro model of the human colon

The aim of this study was to evaluate the effects of soy-based beverages manufactured with water-soluble soy extract, containing probiotic strains (Lactobacillus acidophilus LA-5 and Bifidobacterium longum BB-46) and/or acerola by-product (ABP) on pooled faecal microbiota obtained from lean and obese donors. Four fermented soy beverages (FSs) (“placebo” (FS-Pla), probiotic (FS-Pro), prebiotic (FS-Pre), and synbiotic (FS-Syn)) were subjected to in vitro digestion, followed by inoculation in the TIM-2 system, a dynamic in vitro model that mimics the conditions of the human colon. Short- and branched-chain fatty acids (SCFA and BCFA) and microbiota composition were determined. Upon colonic fermentation in the presence of the different FSs formulations, acetic and lactic acid production was higher than the control treatment for faecal microbiota from lean individuals (FMLI). Additionally, SCFA production by the FMLI was higher than for the faecal microbiota from obese individuals (FMOI). Bifidobacterium spp. and Lactobacillus spp. populations increased during simulated colonic fermentation in the presence of FS-Syn in the FMLI and FMOI. FS formulations also changed the composition of the FMOI, resulting in a profile more similar to the FMLI. The changes in the composition and the increase in SCFA production observed for the FMLI and FMOI during these in vitro fermentations suggest a potential modulation effect of these microbiotas by the consumption of functional FSs.Graphical abstractKey points• Soy beverages increased Bifidobacterium abundance in microbiota from obese individuals.• The synbiotic beverage increased Bifidobacterium abundance in microbiota from lean individuals.• The synbiotic beverage changed the microbiota from obese individuals, approaching the lean profiles.

Acerola by-product may improve the in vitro gastrointestinal resistance of probiotic strains in a plant-based fermented beverage

This study evaluated the impact of acerola by-product (ABP) on the viability and resistance to in vitro-simulated gastrointestinal (GI) conditions of Lactobacillus acidophilus LA-5 and Bifidobacterium longum BB-46, individually or in co-culture, in a fermented soy beverage (FSB) during 28 days of storage at 4 °C. Eight trials of FSB were studied, using a factorial 23 design, in which the variables evaluated were Factor 1 (LA5), Factor 2 (BB46), and Factor 3 (ABP). The populations of microorganisms were determined using quantitative Real-Time PCR combined with propidium monoazide (PMA) treatment. Probiotic populations remained above 7.1 log CFU equivalent/mL throughout 28 days in the FSB, and the co-culture (LA5 + BB46) and the addition of ABP did not affect the viability of both probiotic strains (P > 0.05). However, ABP showed a positive effect on the survival of BB46 under in vitro GI conditions. The FSB supplemented with ABP revealed to be a good plant-based vehicle for the probiotics tested, mainly for BB46. Clinical trials are required to confirm the health benefits of the potential synbiotic soy-based product with ABP.

Application of recombinant lactic acid bacteria and bifidobacteria able to enrich soy beverage in dihydrodaidzein and dihydrogenistein

Dihydrodaidzein (DHD) and dihydrogenistein (DHG) are intermediate compounds in the production of equol and 5-hydroxy-equol from daidzein and genistein by certain intestinal bacteria. In this work, we explored the heterologous expression of the daidzein reductase gene from Slackia isoflavoniconvertens DSM22006, responsible for the formation of DHD and DHG, in nine lactic acid bacteria and Bifidobacterium strains under a strong constitutive promoter in the plasmid pNZ:TuR.dzr. All the transformed strains showed high production of DHD and DHG both from pure daidzein and genistein and from the isoflavone glycosides present in soy beverage. In addition, Lactococcus lactis MG1363 pNZ:TuR.dzr, expressing the recombinant daidzein reductase, incremented the production of equol by equol-producing intestinal microbiotas in a colonic environment. Nevertheless, other recombinant strains tested showed the opposite effect to L. lactis MG1363 pNZ:TuR.dzr in the production of equol by intestinal microbiota. Here, we describe for the first time the production of 5-hydroxy-equol by human intestinal microbiota, both from genistein and DHG. The use of DHD and DHG as substrates, compared to daidzein and genistein, resulted in an increment of equol and 5-hydroxy-equol production by intestinal microbiota. The recombinant strains developed would be of value for the development of fermented soy beverage enriched in DHD and DHG with the aim of facilitate equol and 5-hydroxy-equol production by intestinal microbiota.

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.

Fermented Soy Beverage Q-CAN Plus Consumption Improves Serum Cholesterol and Cytokines.

Soy-based beverages are well recognized for their rich nutritional contents and positive health benefits. However, there is little information regarding the composition of various commercially available soy-based beverages and uncertainty among patients regarding the utility of fermented soy products. Current study evaluates the health benefits of QCAN® Plus-an easily available fermented soy drink. This study was performed in lean (n = 10) and obese (n = 10) subjects. The subjects were observed during pre-soy (weeks -2, -1, and 0), on-soy (weeks 1, 2, 3, and 4), and post-soy (weeks 6, 8, 10, and 12) periods. The serum samples during these visits were subjected to lipid profile analysis and multiplex assay for cytokines. The results revealed that total cholesterol and low-density lipoprotein (LDL) cholesterol levels were significantly reduced in both lean and obese individuals during on-soy (P ≤ .05). Furthermore, cytokines such as platelet-derived growth factor (PDGF) AA and AB/BB were significantly lowered on-soy compared with pre-soy (P ≤ .05) in lean subjects and PDGF AA, IL-1RA, and GMCSF were significantly reduced on-soy (P ≤ .05) in obese subjects. In addition, a qualitative and quantitative analysis of the Q-CAN Plus by a third-party laboratory confirmed its chemical and microbial safety. Our preliminary study on Q-CAN Plus ensures its safety for consumption and highlights its hypolipidemic and suppressive effect on certain cytokines. These observations and relevant studies in future might guide clinicians in future to consider Q-CAN Plus as a therapeutic nutritional supplement.

Isoflavone Stability Quality Control Assessment of Q-CAN® Plus, a Novel Fermented Soy Beverage (P12-034-19)

ObjectivesThe purpose of this investigation is to validate the soy isoflavone content, 24 months stability and quality control of “Q-CAN® Plus,” a novel fermented soy beverage imported from China. MethodsQ-CAN® Plus was independently tested through third-party laboratories for: Soy isoflavones, microbial contamination, herbicides, pesticides, fungicides, heavy metals and residual solvents. To evaluate the potency or stability, total soy isoflavones were measured over 24 months through accelerated (40 degrees Celsius 75% relative humidity) and shelf (ambient temperature) and microbial contamination evaluated. ResultsUpon initial analysis Q-CAN® Plus contained 290.12 mg of total soy isoflavones. Microbial contamination, mold and yeast were absent or WNLs. Product was free of herbicides, pesticides, fungicides, heavy metals and residual solvents. The mean total isoflavones was 303.23 mg +/– 11.5 mg (SD). The 24-month stability testing in both the accelerated chamber (12 mo = 294 mg, 24 mo = 318 mg) and shelf (12 mo = 304 mg, 24 mo = 310 mg) determined that total soy isoflavones did not significantly change in potency, and microbiology analysis at each time point revealed no contamination. ConclusionsIn this first independent evaluation of Q-CAN® Plus it was determined that the manufacturer’s Certificate of Analysis was validated, soy isoflavones remained stable over 24 months, and microbial contamination was absent. Q-CAN® Plus is a functional beverage that provides a high quality, clinically relevant dose of soy isoflavones. Future investigations will determine the clinical benefit of this natural fermented soy beverage. Funding SourcesBeso Biological Research, Inc.

Antioxidative and antimicrobial activity of whey based fermented soy beverage with curcumin supplementation

Fermented whey and soy beverages with curcumin supplementation has no cholesterol, low lactose, high protein to fat ratio and ability to fights against several diseases. These beverages are more palatable, digestive and good for lactose intolerant people. Addition of curcumin increases its medicinal and nutritional properties. Soymilk was prepared by adding whey in place of water and supplemented with curcumin. L. acidophilus NCDC195 (LA195) and S. thermophilus NCDC323 (ST323) were used for fermentation. After 24 hour of incubation at 37 0 C their acidity and total count were 1.38, 1.41 and 9.09, 9.39 log cfu/ml respectively. Antimicrobial activity was also analyzed at different levels of curcumin. LA195 and ST323 had shown antimicrobial activity against E.coli, B.cereus, S.aureus, L. monocytogenes, Sh.dysentriae, and S.typhi . Zone of inhibition ranged between 16 to 23 mm. Maximum antioxidant activity was obtained by LA195+ST323 (989.70 TEAC (μM)) with curcumin. Prepared fermented drink was analyzed for sensory properties on the basis of 9 point Hedonic scale. Soy beverage with 12% sugar solution was having more acceptability in terms of colour and flavour. Product was stable for 4 days at 4 0 C and no coliform and yeast and mold were present. Product showed increase in acidity upto 14 days. After 14day of storage acidity and total counts (CFU/ml) were, 1.86 and 8.57 respectively. Antioxidant activity decreased during the storage from initial 986.46 to 702.58 TEAC (μM) on 14 th day. The results showed that the fermented whey and soy based curcumin supplemented beverage had health beneficial biofunctional properties.

Possibility of breast cancer prevention: use of soy isoflavones and fermented soy beverage produced using probiotics.

The various beneficial effects of soybeans, which are rich in phytochemicals, have received much attention because of increasing health awareness. Soy milk that has been fermented using lactic acid bacteria has been used to prepare cheese-like products, tofu (bean-curd), and yogurt-type products. However, the distinct odor of soybeans has limited the acceptance of such foods, particularly in Western countries. In Japan, while tofu and soy milk have long been habitually consumed, the development of novel, palatable food products has not been easy. The unpleasant odor of soy milk and the absorption efficiency for isoflavones can be improved using a recently developed fermented soy milk beverage. Cancer has been the leading cause of death, and breast cancer is the most common malignancy among women. The most common type of breast cancer is estrogen-dependent, and the anti-estrogenic effects of isoflavones are known. The present review focuses on the characteristics of soy milk fermented using probiotics, an epidemiological study examining the incidence of breast cancer and soy isoflavone consumption, and a non-clinical study examining breast cancer prevention using fermented soy milk beverage.

Erratum to: Predictive modelling of Lactobacillus casei KN291 survival in fermented soy beverage

Erratum to: Predictive modelling of Lactobacillus casei KN291 survival in fermented soy beverage

Predictive modelling of Lactobacillus casei KN291 survival in fermented soy beverage

The aim of the study was to construct and verify predictive growth and survival models of a potentially probiotic bacteria in fermented soy beverage. The research material included natural soy beverage (Polgrunt, Poland) and the strain of lactic acid bacteria (LAB) - Lactobacillus casei KN291. To construct predictive models for the growth and survival of L. casei KN291 bacteria in the fermented soy beverage we design an experiment which allowed the collection of CFU data. Fermented soy beverage samples were stored at various temperature conditions (5, 10, 15, and 20°C) for 28 days. On the basis of obtained data concerning the survival of L. casei KN291 bacteria in soy beverage at different temperature and time conditions, two non-linear models (r(2)= 0.68-0.93) and two surface models (r(2)=0.76-0.79) were constructed; these models described the behaviour of the bacteria in the product to a satisfactory extent. Verification of the surface models was carried out utilizing the validation data - at 7°C during 28 days. It was found that applied models were well fitted and charged with small systematic errors, which is evidenced by accuracy factor - Af, bias factor - Bf and mean squared error - MSE. The constructed microbiological growth and survival models of L. casei KN291 in fermented soy beverage enable the estimation of products shelf life period, which in this case is defined by the requirement for the level of the bacteria to be above 10(6) CFU/cm(3). The constructed models may be useful as a tool for the manufacture of probiotic foods to estimate of their shelf life period.

Viability and Resistance of Lactobacilli Isolated from Cocoa Fermentation to Simulated Gastrointestinal Digestive Steps in Soy Yogurt

To study the potential probiotic characteristics such as decrease of pH, microbial viability, and tolerance to simulated digestive steps of fermented soy beverage ("soy yogurt") produced with lactobacilli isolated from cocoa fermentation (Lactobacillus fermentum TcUESC01 and Lactobacillus plantarum TcUESC02) during fermentation and refrigerated storage. The sensory acceptance of the yogurts was also tested. Samples of soy yogurt produced with L. fermentum TcUESC01 or L. plantarum TcUESC02 were collected during fermentation (0, 4, 8, and 12 h) and refrigerated storage (1, 9, 18, and 27 d), and submitted to pH and bacterial viability determinations. Tolerance to simulated digestion steps was done with refrigerated storage samples at 9 °C. Simulated digestion was performed in 3 successive steps: exposure to pepsin-HCl solution, bile shock, and simulated small intestinal juice. During storage, a decrease in pH and lactobacillus viability was observed. L. fermentum TcUESC01 showed to be more resistant than L. plantarum TcUESC02 to simulated gastrointestinal digestion. All soy yogurts showed acceptable hedonic scores (greater than 5 in a 9-point hedonic scale ranging from "like extremely" to "dislike extremely") in sensory evaluation for flavor, aroma, color, consistency, and overall impression. L. plantarum TcUESC02 and, especially, L. fermentum TcUESC01 showed potential probiotic characteristics when considering pH, cell viability, and tolerance to simulated digestive steps and did not affect the sensory characteristics when supplemented to soy yogurt during storage.

Enhancement of the antioxidant capacity of soymilk by fermentation with Lactobacillus rhamnosus

In order to enhance the bioactivity of soy beverages, fermentation of soymilk was assayed using Lactobacillus rhamnosus CRL981 as a β-glucosidase producer. The biological activity of the fermented soy beverage enriched in isoflavone aglycones was determined by several methods to evaluate different antioxidant mechanisms. Fermented soymilk exhibited higher antioxidant activity (71.2±4.0%) determined by β-carotene bleaching method but lower, although significant, DPPH radical scavenging effect (29.5±0.9%) than the unfermented soymilk used as control. The fermented soymilk extracts were able to inhibit the oxidation of DNA induced by Fenton’s reagent. The increase of isoflavone aglycone contents during fermentation was a result of β-glucosidase activity towards isoflavone glucosides. This process allowed obtaining a soy beverage with enhanced antioxidant capacity able to contribute to the health and nutritional status improvement of consumers.

Effect of fermentation by pure and mixed cultures of Streptococcus thermophilus and Lactobacillus helveticus on isoflavone and B-vitamin content of a fermented soy beverage

Enhancement of nutritional or vitamin content of foods is commonly touted as a major benefit of probiotics. In this paper, we examined the ability of three probiotic bacteria either alone or in combination to enhance nutritional content. Pure and mixed cultures of Streptococcus thermophilus ST5 and Lactobacillus helveticus R0052 or Bifidobacterium longum R0175 were used to prepare fermented soy beverages. The effects of strain, acidification and mixed cultures on the deconjugation of soy isoflavones were examined. Acidification to pH 4.7 alone resulted in a 7% drop in isoflavone levels. Deconjugation levels varied between the different glucosides. Fermentation by L. helveticus R0052 resulted in the 50% reduction in total glucosides with O-malonyl glucosides being reduced 64%. Fermentation by S. thermophilus ST5 or B. longum R0175 had no significant effect on isoflavone levels. Combining a S. thermophilus strain with a L. helveticus culture reduced the effectiveness of the latter. Fermentation did not significantly modify vitamin B1 or B6 levels.