A systematic review and meta-analysis of randomized trials of substituting soymilk for cow's milk and intermediate cardiometabolic outcomes: understanding the impact of dairy alternatives in the transition to plant-based diets on cardiometabolic health.

BACKGROUND: Dietary guidelines recommend a shift to plant-based diets. Fortified soymilk, a prototypical plant protein food used in the transition to plant-based diets, usually contains added sugars to match the sweetness of cow's milk and is classified as an ultra-processed food. Whether soymilk can replace minimally processed cow's milk without the adverse cardiometabolic effects attributed to added sugars and ultra-processed foods remains unclear. We conducted a systematic review and meta-analysis of randomized controlled trials, to assess the effect of substituting soymilk for cow's milk and its modification by added sugars (sweetened versus unsweetened) on intermediate cardiometabolic outcomes. METHODS: MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched (through June 2024) for randomized controlled trials of ≥ 3 weeks in adults. Outcomes included established markers of blood lipids, glycemic control, blood pressure, inflammation, adiposity, renal disease, uric acid, and non-alcoholic fatty liver disease. Two independent reviewers extracted data and assessed risk of bias. The certainty of evidence was assessed using GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). A sub-study of lactose versus sucrose outside of a dairy-like matrix was conducted to explore the role of sweetened soymilk which followed the same methodology. RESULTS: Eligibility criteria were met by 17 trials (n = 504 adults with a range of health statuses), assessing the effect of a median daily dose of 500 mL of soymilk (22 g soy protein and 17.2 g or 6.9 g/250 mL added sugars) in substitution for 500 mL of cow's milk (24 g milk protein and 24 g or 12 g/250 mL total sugars as lactose) on 19 intermediate outcomes. The substitution of soymilk for cow's milk resulted in moderate reductions in non-HDL-C (mean difference, - 0.26 mmol/L [95% confidence interval, - 0.43 to - 0.10]), systolic blood pressure (- 8.00 mmHg [- 14.89 to - 1.11]), and diastolic blood pressure (- 4.74 mmHg [- 9.17 to - 0.31]); small important reductions in LDL-C (- 0.19 mmol/L [- 0.29 to - 0.09]) and c-reactive protein (CRP) (- 0.82 mg/L [- 1.26 to - 0.37]); and trivial increases in HDL-C (0.05 mmol/L [0.00 to 0.09]). No other outcomes showed differences. There was no meaningful effect modification by added sugars across outcomes. The certainty of evidence was high for LDL-C and non-HDL-C; moderate for systolic blood pressure, diastolic blood pressure, CRP, and HDL-C; and generally moderate-to-low for all other outcomes. We could not conduct the sub-study of the effect of lactose versus added sugars, as no eligible trials could be identified. CONCLUSIONS: Current evidence provides a good indication that replacing cow's milk with soymilk (including sweetened soymilk) does not adversely affect established cardiometabolic risk factors and may result in advantages for blood lipids, blood pressure, and inflammation in adults with a mix of health statuses. The classification of plant-based dairy alternatives such as soymilk as ultra-processed may be misleading as it relates to their cardiometabolic effects and may need to be reconsidered in the transition to plant-based diets. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT05637866.

Soymilk yogurt fermented using Pediococcus pentosaceus TOKAI 759 m improves mice gut microbiota and reduces pro-inflammatory cytokine production.

This study aimed to determine the anti-inflammatory activities and bioactive compounds of soymilk yogurt prepared using Lactiplantibacillus plantarum TOKAI 17 or Pediococcus pentosaceus TOKAI 759 m. Mice were divided into five groups: normal diet (ND), soymilk (SM), soymilk yogurt using L. plantarum TOKAI 17 (SY 17) or P. pentosaceus TOKAI 759 m (SY 759 m), and 0.5 × 109 cells of each starter strain (BC 17 or BC759m). In the SY 759 m group, the serum pro-inflammatory cytokine levels and the cytotoxicity of natural killer cells were attenuated compared to the ND group. In the cecum microbiota, the abundances of butyrate-producing bacteria increased in the SY 759 m and BC 17 groups. Furthermore, SY 759 m metabolites contained high levels of aglycone isoflavone, adenine and showed a significant decrease in CCL-2 and IL-6 production in LPS-induced macrophage. In conclusion, soymilk yogurt produced using P. pentosaceus TOKAI 759 m modulates the gut microbiota and can potentially prevent pro-inflammatory cytokine production.

Effects of removing phytic acid on the bioaccessibility of Ca/Fe/Zn and protein digestion in soymilk.

BACKGROUND: Soymilk is a high-quality source of protein and minerals, such as calcium (Ca), iron (Fe), and zinc (Zn). However, phytic acid in soymilk restricts mineral and protein availability. We here investigated the effects of removing phytic acid on the physicochemical properties, mineral (Ca, Fe, and Zn) bioaccessibility, and protein digestibility of soymilk. RESULTS: Physicochemical property analysis revealed that the removal of phytic acid reduced protein accumulation at the gastric stage, thereby facilitating soymilk matrix digestion. The removal of phytic acid significantly increased Zn bioaccessibility by 18.19% in low-protein soymilk and Ca and Fe bioaccessibility by 31.20% and 30.03%, respectively, in high-protein soymilk. CONCLUSION: Removing phytic acid was beneficial for the hydrolysis of high-molecular-weight proteins and increased the soluble protein content in soymilk, which was conducive to protein digestion. This study offers a feasible guide for developing plant-based milk with high nutrient bioaccessibility. © 2024 Society of Chemical Industry.

Effect and mechanism of freezing on the quality and structure of soymilk gel induced by different salt ions.

BACKGROUND: The increasing attention toward frozen soy-based foods has sparked interest. Variations exist in the quality and structure of soymilk gels induced by different salt ions, leading to diverse changes post-freezing. This study compared and analyzed the effects of calcium chloride (CC), magnesium chloride (MC) and calcium sulfate (CS) on the quality characteristics and protein structure changes of soymilk gels (CC-S, MC-S and CS-S) before and after freezing, and clarified the mechanisms of freezing on soymilk gel. RESULTS: The formation rate of soymilk gel is influenced by the type of salt ions. In comparison to CS and MC, soymilk gel induced by CC exhibited the fastest formation rate, highest gel hardness, lowest moisture content, and smaller gel pores. However, freezing treatment deteriorated the quality of soymilk gel induced by different salt ions, leading to a decline in textural properties (hardness and chewiness). Among these, the textual state of CC-induced soymilk gel remained optimal, exhibiting the least apparent damage and minimal cooking loss. Freezing treatments prompt a transition of soymilk gel secondary structure from ß-turns to ß-sheets, disrupting the protein's tertiary structure. Furthermore, freezing treatments also fostered the crosslinking between soymilk gel protein, increasing the content of disulfide bonds. CONCLUSION: The quality of frozen soymilk gel is influenced by the rate of gel formation induced by salt ions. After freezing, soymilk gel with faster gelation rates exhibited a greater tendency for the transformation of protein-water interactions into protein-protein interactions. They showed a higher degree of disulfide bond formation, resulting in a more tightly knit and firm frozen gel network structure with denser and more uniformly distributed pores. © 2024 Society of Chemical Industry.

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.

Soymilk stability increase using polyphenols microcapsules.

Functional beverages have aroused a great interest to the food industry. Among the functional ingredients, there is a growing demand for antioxidant incorporation into foods, which implies a challenge to preserve their bioactivity. The health benefits provided by soymilk can be improved by the addition with microcapsules of polyphenols from peanut skin and this procedure is an alternative to protect these natural and bioactive compounds from environmental factors. The aim of this work was to determine the chemical, antioxidant, microbiological and sensory changes during storage of the product. Soymilk samples were prepared without any addition (C); with peanut skin extract (BEA); and with microcapsules with polyphenols (MCBEA) and stored at 4 °C for 30 days. Results showed that the addition of polyphenols (free or microencapsulated) improved the chemical, microbiological and sensory stability of soymilk. The BEA and MCBEA had lower values of hydroperoxides, hexanal, bacterial growth, oxidised flavour, and sweet taste than C. The BEA exhibited higher phenol content (819.72 mg gallic acid equivalents/L), antioxidant activity (64.66% DPPH inhibition) and colour intensity than MCBEA. The study suggested that polyphenol microencapsulation is a procedure that can protect these sensitive compounds and control their release into this food matrix.

Biochemical characterization and insights into the potency of the acidic Aspergillus niger NRC114 purified α-galactosidase in removing raffinose family oligosaccharides from soymilk yogurt.

BACKGROUND: Because humans lack α-galactosidase, foods containing certain oligosaccharides from the raffinose family, such as soybeans and other legumes, may disrupt digestion and cause flatulence. RESULTS: Aspergillus niger NRC114 α-galactosidase was purified using protein precipitation, gel filtration, and ion exchange chromatography steps, which resulted in a 123-fold purification. The purified enzyme was found to be 64 kDa using the SDS-PAGE approach. The optimum pH and temperature of the purified α-galactosidase were detected at pH 3.5 and 60 ºC, respectively. The pure enzyme exhibited potent acidic pH stability at pH 3.0 and pH 4.0 for 2 h, and it retained its full activity at 50 ºC and 60 ºC for 120 min and 90 min, respectively. The enzyme was activated using 2.5 mM of K+, Mg2+, Co2+, or Zn2+ by 14%, 23%, 28%, and 11%, respectively. The Km and Vmax values of the purified enzyme were calculated to be 0.401 µM and 14.65 µmol min-1, respectively. The soymilk yogurt showed an increase in its total phenolic content and total flavonoids after enzyme treatment, as well as several volatile compounds that were detected and identified using GC-MS analysis. HPLC analysis clarified the enzymatic action in the hydrolysis of raffinose family oligosaccharides. CONCLUSION: The findings of this study indicate the importance of A. niger NRC114 α-galactosidase enzyme for future studies, especially its applications in a variety of biological fields.

The effects of soymilk plus probiotics supplementation on cardiovascular risk factors in patients with type 2 diabetes mellitus: a randomized clinical trial.

OBJECTIVE: Type 2 diabetes mellitus (T2DM) is associated with an increased risk of cardiovascular diseases. This study aimed to assess the effects of soymilk plus probiotics co-administration on cardiovascular risk factors in T2DM patients. METHODS: One hundred patients with T2DM (aged 40-75 years old) were randomly assigned into 4 groups (soymilk + probiotics supplement, soymilk + placebo, conventional milk + placebo, and probiotics supplement) for 6 weeks. Standard protocols were followed for the collection of fasting blood samples, dietary intakes, and anthropometric measurements. RESULTS: It was shown that soymilk + probiotics consumption significantly decreased diastolic blood pressure (DBP) (p = 0.001), triglycerides (TG) (P < 0.001), total cholesterol (TC) (p < 0.01), and insulin (P < 0.003) levels and significantly increased high-density lipoprotein cholesterol (HDL-C) (P = 0.002) levels. Soymilk + placebo administration significantly decreased DBP (p = 0.01), insulin (p = 0.006), and TG (p = 0.001) levels and significantly increased HDL-C (p = 0.03) levels. A significant decrease in insulin (p = 0.003) and systolic blood pressure (SBP) (p = 0.01) levels and an increase in HDL-C (p = 0.04) levels were observed after supplementation with probiotics. Findings from between-group comparisons showed a significant decrease in SBP levels in the probiotics supplement group compared to conventional milk group (p < 0.05). CONCLUSION: Soymilk and probiotics consumption might improve some cardiovascular risk factors in patients with T2DM. However, possible synergic effects while consumption of soymilk plus probiotics supplement didn't show in this study which warranted further research.

An Investigation into the Performance and Mechanisms of Soymilk-Sized Handmade Xuan Paper at Different Concentrations of Soymilk.

Invaluable paper relics that embody a rich traditional culture have suffered damage, requiring urgent restoration. In this context, the utilization of soymilk as a sizing agent holds great significance and reverence. This study investigates the use of soymilk as a sizing agent for Xuan paper and evaluates its effects on various properties and the long-term behavior of the paper. The findings reveal that the application of soymilk as a sizing agent for Xuan paper imparts distinct properties, including hydrophobicity, improved mechanical properties, and unique chromaticity. These characteristics-arising from the papillae on the surface of the Xuan paper, the protein folding of the soy protein, and hydrogen-bonding interactions between the soy protein and paper fibers-play a crucial role in shaping the paper's unique attributes. From a physicochemical perspective, the aging process leads to multiple changes in paper properties. These changes include acidification, which refers to a decrease in pH, as well as a decline in mechanical strength, an increase in chromaticity, and a decrease in the degree of polymerization (DP) of the paper. The Ekenstam equation is employed to predict the lifespan of the paper, showing longer lifespans for Sheng Xuan paper and a negative correlation between soymilk concentration and lifespan in soymilk-sized paper. Our work provides valuable insights for the preservation and maintenance of paper, highlighting the potential benefits and challenges of using soymilk for surface sizing.

Production, purification, characterization, and applications of α-galactosidase from Bacillus flexus JS27 isolated from Manikaran hot springs.

α-Galactosidase hydrolyzes the α-1,6-linkage present at the non-reducing end of the sugars and results in the release of galactosyl residue from oligosaccharides like melibiose, raffinose, stachyose, etc. In the present study we report, α-galactosidase from Bacillus flexus isolated from Manikaran hot springs (India). Maximum enzyme production was obtained in guar gum and soybean meal after 72 h at 150 rpm. While, the temperature/pH of production was optimized at 50 °C and 7.0, respectively. Isoenzymes (α-gal I and II) were obtained and characterized based on temperature/pH optima along with their stability profile. JS27 α-Gal II was purified with a final purification fold of 11.54. Native and SDS-PAGE were used to determine the molecular weight of the enzyme as 86 and 41 kDa, respectively, indicating its homodimeric form. JS27 α-Gal II showed optimum enzyme activity at 55 °C and pH 7 (10 min). The enzyme displayed Km value of 2.3809 mM and Vmax of 2.0 × 104 µmol/min/ml with pNPG as substrate. JS27 α-Gal II demonstrated substrate hydrolysis and simultaneous formation of transgalactosylation products (α-GOS) with numerous substrates (sugar/sugar alcohols, oligosaccharides, and complex carbohydrates) which were verified by TLC and HPLC analysis. α-GOS are significant functional food ingredients and can be explored as prebiotics.

Viscosity of evaporated soymilk prepared in the laboratory using normal and 11S-lacking soybean seeds.

BACKGROUND: Soymilk is utilized not only as a beverage but also as an alternative to bovine milk, including products such as yoghurt and cream. Evaporated soymilk is expected to be utilized as condensed milk. Raw and heated soymilk samples prepared in our laboratory were evaporated and then subjected to viscosity measurement. The soymilk samples were made from two different varieties: Fukuyutaka, which contains 7S and 11S globulin proteins; and an 11S-lacking soybean (Nanahomare). RESULTS: Raw Fukuyutaka soymilk had a lower viscosity and could be concentrated to a solids content of over 300 g kg-1 compared to heated soymilk (around 250 g kg-1 ), but the viscosity changes of Nanahomare soymilk showed an opposite trend. Only 7S globulin was denatured during evaporation at 75 °C and likely affected the interaction between proteins and oil bodies. This tendency was remarkable in the Nanahomare soymilk. The strange viscosity change behavior of evaporated Nanahomare soymilk, number of protein particles, intrinsic fluorescence and flow behavior suggest that thermally denatured 7S globulin accelerates the interactions between oil bodies, whereas 11S globulin, which is probably in its native state, suppresses the acceleration by denatured 7S globulin. CONCLUSION: Raw soymilk containing native globulins shows a slower increase in viscosity during evaporation. However, denatured 7S globulin accelerates the increase in viscosity during evaporation through interactions between oil bodies. The effect of the denatured state of individual proteins on interactions is expected to be useful in understanding the interaction between proteins and in controlling their properties and functions. © 2022 Society of Chemical Industry.

Effects of aroma-taste interaction on the sensory attributes of rebaudiosides in soymilk and milk.

BACKGROUND: Rebaudioside A (Reb-A) and rebaudioside M (Reb-M) are intense natural sweeteners but can also elicit bitterness and a bitter aftertaste. In this study, the effect of vanilla and chocolate flavorings on the sensory attributes of Reb-A and Reb-M applied to soymilk and milk was investigated to identify whether the addition of flavoring could enhance the sweetness via aroma-taste interactions. RESULTS: Nine samples each of soymilk and milk were formulated by adding sucrose, Reb-A and Reb-M in three flavor conditions (no flavoring, vanilla, and chocolate). Descriptive analyses were conducted using nine panelists for the soymilk and eight panelists for the milk. Another descriptive analysis was conducted using the same samples with olfactory occlusion via the wearing of a nose clip to check whether the sweetness enhancement was due to olfactory input. The chocolate flavoring significantly enhanced the sweetness of Reb-A and Reb-M and reduced the bitterness, bitter aftertaste and astringency in both soymilk and milk. The vanilla flavoring was not as effective as the chocolate flavoring in enhancing sweetness. When the olfactory passage was closed with a nose clip, the sweetness enhancement and bitterness suppression were not detected in the samples. CONCLUSION: The addition of chocolate flavoring could successfully improve the sensory profile of soymilk sweetened with Reb-A through aroma-taste interactions. © 2023 Society of Chemical Industry.

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

The growing interest of consumers towards nutritionally enriched, and health promoting foods, provoke interest in the eventual development of fermented functional foods. Soymilk is a growing trend that can serve as a low-cost non-dairy alternative with improved functional and nutritional properties. Soymilk acts as a good nutrition media for the growth and proliferation of the micro-organism as well as for their bioactivities. The bioactive compounds produced by fermentation of soymilk with lactic acid bacteria (LAB) exhibit enhanced nutritional values, and several improved health benefits including antihypertensive, antioxidant, antidiabetic, anticancer and hypocholesterolaemic effects. The fermented soymilk is acquiring a significant position in the functional food industry due to its increased techno-functional qualities as well as ensuring the survivability of probiotic bacteria producing diverse metabolites. This review covers the important benefits conferred by the consumption of soymilk fermented by LAB producing bioactive compounds. It provides a holistic approach to obtain existing knowledge on the biofunctional attributes of fermented soymilk, with a focus on the functionality of soymilk fermented by LAB.

Harmful compounds of soy milk: characterization and reduction strategies.

Soymilk is a plant based product which is a rich source of nutrients. However, various harmful compounds including allergens, anti-nutritional factors, and biogenic amines (BAs) exist in soybeans that may be transferred into soymilk. These compounds cause difficulties for consumers from mild to severe symptoms. Soymilk production is considered as a critical step in quantity of harmful compounds in final product. Common steps in soy milk manufacturing include soaking, grinding, and heating process. Allergens contents could be decreased by heating alone or in combination with structural modifiers and fermentation. BAs could be reduced by optimizing fermentation process and using suitable strains, especially BAs degradable types. Soaking, grinding and heating of soybeans in water are considered as effective methods for inactivation of antinutritional factors. Isoflavones are soy phytochemicals, which potentially leads to breast cancer in some women, can be converted to less bioavailable forms during processing. Other treatments such as high hydrostatic pressure and irradiation are also effective in harmful compounds reduction. Combination of the processes is more effective in harmful compounds removal. Considering the increasing trends in soymilk consumption, this review is focused on introduction of harmful compounds in soymilk and investigating the effects of processing condition on their concentration.

Soy yogurt using Lactobacillus plantarum 200655 and fructooligosaccharides: neuroprotective effects against oxidative stress.

This study aimed to evaluate the effect of Lactobacillus plantarum 200655 and fructooligosaccharides (FOS) on soymilk fermentation and the neuroprotective effects of fermented soymilk (FS). The addition of FOS did not affect the physicochemical properties during fermentation. It helped that L. plantarum 200655 survive for 21 days of storage at 4 °C. FOS increased the ß-glucosidase activity of L. plantarum 200655, total phenolic content, and antioxidant activities, such as radical scavenging and reducing power of FS. In addition, FS with FOS exerted neuroprotective effects in SH-SY5Y cells against H2O2-induced oxidative stress. FS with 3% and 5% FOS (FS3 and FS5) significantly increased cell viability and gene expression of neuronal markers, such as brain-derived neurotrophic factor and tyrosine hydroxylase. Moreover, FS3 and FS5 significantly reduced lactate dehydrogenase release and the gene expression of Bax/Bcl-2 ratio, caspase-9, and caspase-3. These results indicated that FS3 and FS5, with enhanced antioxidant properties, could protect SH-SY5Y cells against H2O2-induced damage. Therefore, soymilk fermented with L. plantarum 200655 and FOS can be used as a prophylactic functional food with neuroprotective effects against oxidative stress.

The soymilk diet: A previously unknown etiology of acute pancreatitis.

We present a case of daily, large ingestions of soymilk that likely led to acute pancreatitis. Soybean contains trypsin inhibitor that when ingested will reduce the activity of trypsin in the intestine. A decrease in intestinal proteolytic activity removes the negative feedback on the pancreatic acinar cells, leading to an inappropriate increase in intrapancreatic trypsin secretion. When trypsin activation exceeds the capacity of pancreatic secretory trypsin inhibitor, the subsequent cascade of events can lead to acute pancreatitis.

Synbiotic fermented soymilk with Weissella cibaria FB069 and xylooligosaccharides prevents proliferation in human colon cancer cells.

AIM: Studies on the anticancer effects of synbiotic fermented soymilk are rare. The aim of the present study was to evaluate the effect of synbiotic fermented soymilk supplemented with xylooligosaccharides and inoculated with Weissella cibaria FB069 (FSMXW) in the proliferation of colon cancer cell and compare it with the effect of soymilk inoculated with Lactobacillus rhamnosus GG (LGG). METHODS AND RESULTS: Both FB069 and LGG were able to grow in soy-based products and rapidly reduce their pH as a result of fermentation. The addition of XOS significantly enhanced the acidification rate, viscosity and total cell concentration in fermented soymilk inoculated with W. cibaria FB069. However, the same effect was not observed following inoculation with LGG. Moreover, the synbiotic FSMXW showed higher dextran, folate, GABA and aglycone content. FSMXW inhibited the proliferation of Caco-2 and HCT116 cell lines, by reducing the transcription of MD2, TLR4, MyD88, and NF-κb. CONCLUSIONS: The synbiotic soymilk containing XOS and W. cibaria FB069 increase nutrient and functional compounds through fermentation process. SIGNIFICANCE AND IMPACT OF THE STUDY: Our finding suggests that W. cibaria and XOS can be potentially employed in developing functional foods and health-related products.

Combined isoflavones biotransformation increases the bioactive and antioxidant capacity of soymilk.

Isoflavones are phenolic secondary metabolites mainly occurring in soy and soybean products. Compared to glycoside forms, isoflavone aglycones present higher biological activities. This study evaluated the potential of microbial and enzymatic treatments in biotransformed isoflavones in their biologically active forms in soymilk. Seven different cultures of lactic acid bacteria and bifidobacteria associated with the action of immobilized tannase enzyme were screened for isoflavone glycoside biotransformation ability. The biotransformed soymilk samples were characterized regarding isoflavone profile, total phenolic content, and in vitro antioxidant activities. All bacterial strains showed a good growth capacity in soymilk matrix and produced ß-glucosidase enzyme, which hydrolyzed isoflavone glycosides into aglycones in soymilk after 24 h of fermentation. The microbial fermentation followed by tannase reaction (FT processes) resulted in the highest increase of bioactive aglycones (10.3- to 13.1-fold for daidzein, 10.4- to 12.3-fold for genistein, and 3.8- to 4.7-fold for glycitein), compared to control soymilk. Further, FT processes enhanced the total phenolic content (53-70%) and antioxidant activity by ORAC (69-102%) and FRAP (49-71%) assays of the soymilk matrix. Therefore, the combination of microbial fermentation and tannase treatment is a promising strategy to obtain a fermented soy product rich in bioactive isoflavones with greater health-promoting potential. KEY POINTS: • Bacterial cultures and tannase enzyme displayed isoflavone deglycosylation activity. • The addition of tannase following the fermentation maximized the isoflavone conversion. • Increased isoflavone aglycones contributed to the improved antioxidant activity of soymilk.

Riboflavin-overproducing lactobacilli for the enrichment of fermented soymilk: insights into improved nutritional and functional attributes.

The influence of riboflavin (B2)-overproducing lactobacilli on the antioxidant status, isoflavone conversion, off-flavor reduction, amino acid profile, and viscosity of B2-bio-enriched fermented soymilk was investigated. Results showed that B2 in fermented soymilk was notably increased from 0.2 to 3.8 µg/mL for Lactobacillus fermentum UFG169 and to 1.9 µg/mL for Lactobacillus plantarum UFG10. The apparent viscosity significantly changed with rising acidity and agglutination of protein. The off-flavor volatile substances (hexanal and nonanal) were significantly reduced in fermented soymilk. Furthermore, a large amount of glucoside form isoflavones was deglycosylated into bioactive aglycones after 4 h up to 32 h. B2 content and isoflavones significantly improved the antioxidant status of soymilk. Partial least squares regression analysis correlated the strain activity and fermentation time with the improved nutritional and functional soymilk qualities. This study demonstrated the strategy for strain development for B2-bio-enriched fermentation to extend the health-promoting benefits of soymilk and soy-related foods. KEY POINTS: • B2-enriched fermentation enhanced the nutrition and functional status of soymilk. • Fermentation time significantly affected the apparent viscosity of fermented soymilk. • Off-flavor volatile substances were significantly reduced or even diminished. • Increased B2and bioactive isoflavones contributed to improved antioxidant potential.

A potential flavor culture: Lactobacillus harbinensis M1 improves the organoleptic quality of fermented soymilk by high production of 2,3-butanedione and acetoin.

Lactic acid bacteria (LAB) are commonly used in soymilk fermentation to improve health-related functionality, but their contribution to sensory qualities is less valued. We characterized Lactobacillus harbinensis M1, Lactobacillus mucosae M2, Lactobacillus fermentum M4, Lactobacillus casei M8 and Lactobacillus rhamnosus C1 from naturally-fermented tofu whey, along with Streptococcus thermophilus ST3 from kefir XPL-1 fermented soymilk, to investigate their potential as starter cultures of fermented soymilk. They were characterized for antibiotic susceptibility, probiotic potential and their performance as starter cultures. All the LABs showed sensitivity to the tested antibiotics. L. casei M8 had strongest tolerance to synthetic gastrointestinal juice (<1.0 log CFU/mL loss), as well as antagonistic effects towards five food-borne pathogens. GC/MS analysis showed that L. harbinensis M1 produced significantly higher abundance (P < 0.05) of 2,3-butanedione (2.45 ppm) and acetoin (44.30 ppm), thus improving the overall sensory acceptability of fermented soymilk. The coding genes for the synthesis of 2,3-butanedione/acetoin (alsS, alsD, butA) were predicted from the whole-genome. A co-culture of L. harbinensis M1 and L. casei M8 produced a fermented soymilk product with both markedly improved flavor and good probiotic potential. It appears that L. harbinensis M1 has much potential for improving the organoleptic properties of fermented soymilk.