Soymilk Protein Research Articles

The role of pH decrease in tofu-like precipitate formation using magnesium chloride

Uncertainty surrounds the role of pH in tofu-like precipitate (TLP) formation using MgCl2. In this study, to clarify the role of MgCl2-induced pH decrease in TLP formation, the protein concentration in the supernatant, weight of wet precipitate, and the solubility in 2 M urea at constant pH (6.5 or 6.2) were measured using a buffer and comparing the buffering effect under variable pH conditions to the effect observed without buffer. Analysis of protein concentration in the supernatant showed no precipitation of soymilk proteins under stable pH conditions of 6.5. Wet precipitate formation varied substantially during TLP formation at three different pHs; the weight slightly increased with the increase in MgCl2 concentration up to 20 mM at a constant pH of 6.5. However, wet precipitation was substantially enhanced by MgCl2 (≥ 10 mM) at a constant pH of 6.2 but rapidly increased by MgCl2 (≥ 7 mM) under variable pH conditions. The protein concentrations and wet precipitate weight at 20 mM MgCl2 under constant pH conditions showed contrasting patterns. However, the weight of dry precipitate was almost the same under both constant pH (6.5 and 6.2) conditions. Urea solubility under constant and variable pH conditions differed; no urea-insoluble precipitates were produced under constant pH conditions. These results suggest that pH decrease is essential for bringing proteins closer together for MgCl2-mediated TLP formation. This study will aid in understanding the mechanisms underlying TLP formation and support further discovery of new coagulants for the effective production of new tofu-like and tofu-based foods.

Effects of high-quality protein supplementation on cardiovascular risk factors in individuals with metabolic diseases: A systematic review and meta-analysis of randomized controlled trials

BackgroundUncertainties still existed about the effect of high-quality protein supplementation on cardiovascular disease (CVD) risk factors, although high-quality proteins such as soy and milk proteins have proposed to be beneficial for cardiometabolic health. MethodsA systematic search in PubMed, Web of Science, Cochrane Library, Scopus, and Embase was conducted to quantify the impact of high-quality protein on CVD risk factors. Results63 RCTs on 4 types of high-quality protein including soy protein, milk protein, whey, and casein were evaluated. Soy protein supplementation decreased systolic blood pressure (SBP, -1.42 [-2.68, -0.17] mmHg), total cholesterol (TC, -0.18 [-0.30, -0.07] mmol/L), and low-density lipoprotein cholesterol (LDL-C, -0.16 [-0.27, -0.05] mmol/L). Milk protein supplementation decreased SBP (-2.30 [-3.45, -1.15] mmHg) and total cholesterol (-0.27 [-0.51, -0.03] mmol/L). Whey supplementation decreased SBP (-2.20 [-3.89, -0.51] mmHg), diastolic blood pressure (DBP, -1.07 [-1.98, -0.16] mmHg), triglycerides (-0.10 [-0.17, -0.03] mmol/L), TC (-0.18 [-0.35, -0.01] mmol/L), LDL-C (-0.09 [-0.16, -0.01] mmol/L) and fasting blood insulin (FBI, -2.02 [-3.75, -0.29] pmol/L). Casein supplementation decreased SBP (-4.10 [-8.05, -0.14] mmHg). In the pooled analysis of four high-quality proteins, differential effects were seen in individuals with different health status. In hypertensive individuals, high-quality proteins decreased both SBP (-2.69 [-3.50, -1.87] mmHg) and DBP (-1.34 [-2.09, -0.60] mmHg). In overweight/obese individuals, high-quality proteins improved SBP (-1.40 [-2.22, -0.59] mmHg), DBP (-2.59 [-3.20, -1.98] mmHg), triglycerides (-0.09 [-0.15, -0.02] mmol/L), TC (-0.14 [-0.22, -0.05] mmol/L), LDL-C (-0.12 [-0.16, -0.07] mmol/L), and HDL-C levels (0.02 [0.01, 0.04] mmol/L). According to the benefits on CVD risks factors, whey ranked top for improving cardiometabolic health in hypertensive or overweight/obese individuals. ConclusionOur study supports a beneficial role of high-quality protein supplementation to reduce CVD risk factors. Further studies are still warranted to investigate the effects of different high-quality proteins on CVD risks in individuals with cardiometabolic disorders.

In vitro assessment of addition of soy protein isolate on milk protein digestion and conformational behaviour

Soy protein (SP) and milk protein are nutritionally complementary proteins, while they have different postprandial kinetic manifestations. In this study, different sources of proteins (casein, whey protein and SP isolate) were compounded in different concentrations and ratios. An in vitro dynamic gastrointestinal digestive system for children was used to study the digestive behaviour. For all the concentrations assessed, a consistently high level of small peptide release was demonstrated at 2.67 g/100 mL protein concentration, while the addition of 10% SP isolate would increase the release of small peptides. Overall, the study offers novel perspectives on children's products with diverse protein sources.

Novel strategy to raise the content of aglycone isoflavones in soymilk and gel: Effect of germination on the physicochemical properties

Germination holds the key to nutritional equilibrium in plant grains. In this study, the effect of soybean germination on the processing of soymilk (SM) and glucono-δ-lactone (GDL) induced soymilk gel (SG) was investigated. Germination promoted soybean sprout (SS) growth by activating the energy metabolism system. The energy metabolism was high during the three-day germination and was the most vigorous on the second day of germination. After germination, protein dissolution was improved in SM, and endogenous enzymes produced small molecule proteins. Small molecule proteins were more likely to aggregate to produce SM protein particles. Germination increased the water-holding capacity of SG induced by GDL but weakened the strength. Furthermore, the dynamic fluctuations in isoflavone content were closely monitored throughout the processing of soybean products, including SS, SM, and SG. Although the total amount of isoflavones in SM and SG processed from germinated soybeans decreased, a significant enrichment in the content of aglycone isoflavones was observed. The content of aglycone isoflavones in SG processed from germinated soybeans on the second day of germination was 736.17 ± 28.49 µg/g DW, which was 83.19 % higher than that of the control group. This study demonstrates that germination can enhance the nutritional value of soybean products, providing innovative opportunities for the development of health-promoting soybean-based products.

Abstract MP78: A Comprehensive Investigation of the Effect of Dietary Intervention on Perfluorooctanoic Acid and Perfluorooctane Sulfonate

Introduction: The US Environment Protection Agency has proposed National Primary Drinking Water Regulation for six per- and polyfluoroalkyl substances including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). The health effects of the two chemicals need to be thoroughly evaluated. In addition, few studies have investigated interventions that can help clear the two chemicals from the human body. Hypothesis: We hypothesize that the plasma metabolome reflects reactions of the human body to PFOA/PFOS exposures and dietary supplements can reduce PFOA/PFOS. Methods: In the Protein and Blood Pressure (ProBP) trial, 80 participants were randomly assigned to take 40 grams/day of soy protein, milk protein, or carbohydrate supplementation each for 8 weeks in a cross-over design. Plasma PFOA and PFOS levels were tracked from baseline to each of the three intervention phases. We analyzed the associations of serum PFOS and PFOA with a total of 964 known metabolites at baseline and each dietary intervention, respectively. Age, sex, and race were adjusted in all analyses. ProBP findings were evaluated for replication among 1261 participants of the Bogalusa Heart Study (BHS). Results: PFOA and PFOS were significantly reduced after phase I and were decreased further with intervention phases. Soy protein showed the strongest reduction on both PFOA (net change: -0.13, p=1.13х10 -5 ) and PFOS (net change: -0.18, p=4.32х10 -5 ) compared with carbohydrate and milk protein. After Bonferroni correction for 77 independent metabolite clusters (p<6.49х10 -4 ), PFOS was positively associated with 54 metabolites (47 at baseline, 9 at soy protein, 8 at milk protein, and 6 at carbohydrate, respectively). Of which, 20 associations were replicated in BHS ( Table ). PFOA was positively associated with 3-methyladipate at soy protein and bilirubin (E,E) at milk protein. Conclusions: Dietary intervention reduced serum PFOA and PFOS. Several metabolites may play important roles in PFOA/PFOS related health effects.

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

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). 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. 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.

Enhancing the anti-freezing properties of glucono-δ-lactone induced tofu through the incorporation of curdlan

To improve the water retention capacity and texture stability of tofu induced by glucose-δ-lactone (GDL) during frozen storage, the effect of adding polysaccharide was evaluated in this study. The results showed that when 3% curdlan was added, the water retention of tofu frozen at −18 °C for 4 weeks (64.42%) closely resembled that of unfrozen tofu (66.16%). Simultaneously, the texture of the tofu was notably conserved in comparison to the fresh tofu, and the gel network exhibited a persistent density and uniformity. There is a discernible difference between the freezing and thawing onset points of tofu with the incorporation of curdlan gum, and curdlan combines with water to fill in the interstitial spaces and pores of the protein network, which effectively hinders the migration and flow of water. Further infrared studies demonstrated that the hydrogen bonds in the network were strengthened, which contributed to the stability of the tofu structure integrity. Meanwhile, the further cross-linking of protein molecules in the gel network and the formation of rough networks during the freezing process were prevented. This study reveals that curdlan forms a robust, tightly bound association with water, generating an intricate and interwoven network alongside soymilk protein aggregates, empowering the frozen tofu to effectively retain its quality and texture, closely resembling that of the fresh tofu.

Investigating thermal denaturation kinetics of 7S and 11S proteins and lipoxygenase in soymilk through ohmic heating

AbstractThe purpose of this study is to investigate denaturation kinetics of 7S and 11S proteins as well as lipoxygenase in soymilk during ohmic heating treatment. Because denaturation kinetics of 7S and 11S are nth‐order reaction, a reaction order was estimated based on experimental data and simulation results using Arrhenius parameters calculated through differential scanning calorimetry dynamic method. Denaturation kinetic of lipoxygenase was determined by denaturation ratio which estimated based on oxygenase activity of its after ohmic heating treatment at 65, 70, and 72.5°C. The reaction orders of 7S and 11S proteins during ohmic heating of raw soymilk were determined as 3.25 and 1.52, respectively; while the reaction order of 11S protein in preheated soymilk at 75°C for 1 h was found to be 1.94 with a good correlation between experimental data and simulation result. Electrophoresis results indicated that trypsin inhibitor might affect the denaturation of 11S protein during ohmic heating. The denaturation of lipoxygenase during ohmic heating followed a first‐order reaction at all temperatures, and denaturation simulation using the Arrhenius parameters corresponded well with the experimental data.Practical ApplicationsThis study provides valuable insights into improving a quality of soymilk products. 7S and 11S proteins play a critical role in determining viscosity of soymilk and tofu made from soymilk, which together account for a large proportion of the total proteins in soymilk. Understanding the thermal denaturation kinetics of 7S and 11S proteins can help food manufacturers optimize their processing parameters to achieve the desired physical properties of soymilk. Moreover, lipoxygenase is responsible for producing beany flavor components in soymilk, and understanding its thermal denaturation kinetic can lead to production of soymilk with high consumer acceptance. Our research supports a practical application of ohmic heating technology in the processing of soymilk.

High pressure processing of whole soymilk: Effect on allergenicity, anti-nutritional factor, lipoxygenase activity and E-nose-aroma characteristics

Soymilk was subjected to high pressure processing (HPP) at different pressure levels (300–600 MPa) and time (5, 15 and 25 min) intervals. After the HPP treatment, a mild reduction was observed in soymilk pH and conductivity values; however, a sudden surge in the protein content (17.34±0.10 mg/ml) was recorded at 600 MPa (5 min) treatment. When soymilk proteins were evaluated for their structural changes, FTIR (amide regions), CD spectra, and UV inflorescence showed the positive responses and as the result, soy Kunitz trypsin inhibitor (SKTI) antigen binding ability reduced from 100% to 44.39±8.50% at 300 MPa (5 min). However, prolong exposure at 300 MPa had a negative effect on allergenicity. Nevertheless, HPP treatment reduced the lipoxygenase (100.00% to 68.13±12.80%) and trypsin inhibitor (100.00% to 91.30±1.45%) activities. In addition, the treatment also slightly altered the viscosity, whiteness, and volatile aroma components of soymilk after HPP treatment. Principal component analysis revealed that among 22 selected volatiles, only those belong to PC1 and PC2 caused 68% variance in aroma changes. Overall, HPP treatment reduced allergenicity, trypsin inhibitor activity and lipoxygenase activity without modifying the soymilk nature. Further, it also reduced the beany flavor inducing hexanal volatile content after the treatment.

Nutritional, physical and sensorial properties of food-grade emulsion powder enriched with soy milk and whey protein permeates

Protein deficiency is a common chronic malnutrition in Bangladesh, and it is linked to low socio-economic status. The study was to develop a high calorie powder based on soy milk (SM) and whey protein permeates (WPP). Soy milk was extracted soaking it at 55ºC and 60ºC for 1 h and blanching it at 80ºC for 10 min. The chemical composition of extracted SM and WPP along with developed high calorie emulsion (HCE) powder was analyzed. The result suggested that soaking at 60ºC for 1 h and blanching at 80ºC for 10 min had higher solid content. The moisture, ash, protein, fat, lactose and carbohydrate content in SM at 60ºC were 90.02 %, 1.20 %, 5.38 %, 2.15 %, 0.0 % and 1.25 % respectively, whereas WPP contained 8.18 %, 7.85 %, 16.1 %, 0.0 %, 42.92 % and 24.95 %, respectively. Four emulsions were formulated to develop HCE powder to supply 1 Kcal /ml. Nutritional analysis suggested that formula C (70 % SM and 30 % WPP) shows the highest amino acid and mineral contents except zinc. The sensory analysis showed that formula D (50 % SM and 50 % WPP) and formula C were equally acceptable. Only formula A (100 % SM) was less accepted by the panelists because of the deep brown color and off flavor of soy milk liquid. However, high calorie powder can be prepared by using SM and WPP to supply a sufficient amount of nutrition.

Conjugation of soymilk protein and arabinoxylan induced by peroxidase to improve the gel properties of tofu

Arabinoxylan (AX) can form stable covalent bonds with protein to improve gel properties. We aimed to prepare a conjugate between soymilk protein (SMP) and AX by peroxidase, followed by the addition of transglutaminase (TG) to prepare tofu gels. The conjugate’s properties and their effects on the mechanical properties, rheological properties, and microstructure of tofu gels were evaluated. Results revealed that the α-helix content decreased, the β-sheet content increased, and the surface hydrophobicity reduced from 1.60 × 105 to 1.27 × 105. The optimal amount of AX required to improve the properties of tofu gel was 1.0%. The tofu gel showed better hardness (118.44 g), water holding capacity (WHC) (86.17%), and higher storage modulus (G′) and loss modulus (G″). Low-Field NMR (LF-NMR) showed that the water was evenly distributed. Scanning electron microscopy (SEM) revealed a denser and more regular three-dimensional gel network.

Effect of protein concentration on thermal aggregation and Ca2+-induced gelation of soymilk protein

The concentration of protein in soymilk is a key element in the production of soy products. In this study, the thermal aggregation behavior of soymilk proteins and the properties of aggregates formed at different concentrations (33 mg/g-56 mg/g) were analyzed. Results showed that the soymilk proteins formed two kinds of aggregates which demonstrated different properties at particular concentrations. In the low concentration range (<40 mg/g), rod-like aggregates were formed. The content and size of the aggregates increased with growing protein concentration, but the morphology didn't change. Additionally, the surface hydrophobic groups, sulfhydryl groups(-SH) and electrostatic charge of the protein aggregates exposed to the outside also increased, which drastically (20%) reduced the activation energy of the Ca2+-induced gelation and led to the cross-linkage of protein aggregates to form a dense, cluster-like network structure, which facilitated the formation of gels with high levels of hardness and increased water holding capacity (WHC). At protein concentrations greater than 40 mg/g, however, the protein subunits formed aggregates, which also combined with each other along an axial direction through the hydrophobic groups and -SH on the surface, thereby forming linear or even micro-network agglomerates. In this way, the surface hydrophobicity(S0) and -SH content decreased linearly with the rising protein concentration, while the surface charge density increased, the activation energy required for soymilk gelation increased, and the protein aggregates crosslinked to form a coarse network structure with large voids. Hence, the hardness, elasticity, toughness and WHC of the gel decreased with the increase in protein concentration. This study reveals the mechanism by which protein concentration changes the gel-forming ability of soymilk, and have important theoretical reference for enterprises to select the appropriate protein concentration for soymilk preparation, or to optimize the “concentration dilution method” to meet the processing requirements of different types of soy products.

Effects of sprouted soybeans and ginger on soymilk quality attributes via a developed dual-powered milk pasteurizer

Soymilk market has achieved tremendous progress in consumption and sales due to its inexpensiveness and soymilk protein content. However, due to the present global health crisis, there is a need to further devise means of enriching the quality of soymilk. This study aimed to evaluate the effects of sprouted soybeans and ginger on soymilk quality and sensory attributes. A developed dual -powered milk pasteurizer was used to produce the soymilk. Soybeans, a mixture of soybeans and sprouted soybeans, and sprouted soybeans were interacted with peeled ginger and whole ginger rhizome using Taguchi experimental design to produce nine soymilk samples. The proximate composition, calorific value, total phenolic content and phytic acid content of the soymilk samples were determined using standard procedures. The moisture content of the soymilk samples ranged from 80.85 to 83.78%, crude protein content (7.47 – 9.54%), ash content (0.72 – 1.27%), fibre content (0.24 – 0.73%), crude fat (0.24 - 5.44%), carbohydrate content (1.29 -6.82%) and calorific value (67.6 kcal/g - 91.58 kcal/g). The total phenolic content and phytic acid content ranged from 4.81 mg/l to 11.88 GAE mg/l and 26.77 to 41.86 mg/l, respectively. The soymilk produced from the mixture of sprouted soybeans and un-sprouted soybeans with the addition of either whole or peeled ginger significantly increased the crude protein content, ash content, calorific value and total phenolic content to 9.54%, 1.27%, 91.58 kcal/g and 11.88 GAE mg/l, respectively. In addition, it increased the overall sensory acceptability of soymilk. Conclusively, the use of sprouted soybeans and the addition of ginger should be encouraged to promote a more enriched soymilk beverage. Also, the developed dual-powered milk pasteuriser could be adopted for soymilk production.

Effect of cavitation jet technology on instant solubility characteristics of soymilk flour: Based on the change of protein conformation in soymilk

The protein conformation of soymilk is the key to affecting the instant solubility of soymilk flour. This study aimed to evaluate the effect of cavitation jet treatment time (0, 2, 4, 6, and 8 min) on the instant solubility of soymilk flour based on the conformational changes of protein in soymilk. The results showed that the cavitation jet treatment for 0–4 min significantly unfolded the protein structure of soymilk and increased the content of soluble protein, which reduced the particle size and increased the electrostaticrepulsion and the viscosity of soymilk. This was beneficial for soymilk droplets fully atomized and repolymerized in the spray drying tower, forming soymilk flour particles with large size, smooth surface, and uniform distribution. When the cavitation jet treatment time was 4 min, the wettability (from 127.3 ± 2.5 s to 84.7 ± 2.1 s), dispersibility (from 70.0 ± 2.0 s to 55.7 ± 2.1 s), and solubility (from 56.54% to 78.10%) of soymilk flour were significantly improved. However, when the time of the cavitation jet treatment was extended to 8 min, the protein of soymilk aggregated and the stability of soymilk decreased, which reduced the particle size and hurt the surfacecharacteristics of soymilk flour after spraydrying. It resulted in a decrease in the instant solubility of soymilk flour. Therefore, the cavitationjet treatment with proper time increases the instant solubility of soymilk flour by improving the protein conformation of soymilk.

Aggregation and gelation of soymilk protein after alkaline heat treatment: Effect of coagulants and their addition sequences

This study investigated the effect of different coagulants, including the addition sequence, on the aggregation behavior of soymilk protein and the quality of tofu to improve the gel formation ability and conversion efficiency of soymilk protein after alkaline heat treatment (AHT). The results showed that the coagulation reaction of AHT soymilk was delayed compared with normal soymilk when introducing magnesium chloride (MC). The pH (6.7–6.8) was much higher than that of normal soymilk curd (5.7–5.8) when the coagulation reaction reached the endpoint, and a large number of 7S α′ and α subunits and 11S acidic (A) subunits did not coagulate. However, when introducing lactic acid (LA) or LA combined with MC as a coagulant, the proteins could be almost completely converted into curd, and the recovery rate of the protein increased by about 10%. Inducing coagulation by adding LA and MC simultaneously (MIXTURE) or adding LA first, followed by MC (LA-MC), allowed each protein subunit to aggregate into particles indiscriminately, forming a continuous and uniform network structure via salt bridges, disulfide bonds, or hydrophobic interactions. This structure differed from the "cluster-like" network structure of MC-MC tofu or the "fine chain-like" network structure of LA-LA tofu. Furthermore, the textural properties, such as hardness, springiness, water holding capacity (WHC), and cohesiveness of the tofu, were improved. The results of this study reveal that regulating the aggregation patterns of soymilk protein subunits is an effective way to directionally control the quality of gel products. • Lowering the pH of the coagulation endpoint can reduce protein loss of tofu. • Soy protein subunits have different coagulation modes induced by Mg 2+ and H + . • Combined use of MgCl 2 and lactic acid can improve the texture of tofu. • Adjusting aggregation pattern of protein could regulate the product quality.

Phytase influence on soymilk protein colloid stability studied with thermographic method

Coagulation of soymilk is well studied from a technological point of view. However, physicochemical features of the process of soymilk protein colloidal stability destruction may be of interest both from a purely scientific point of view and for improving production processes. In this study, an attempt was made to analyze the role of phytinates in formation of the colloidal stability of soymilk proteins. A possible role of the dissociation of phosphate groups of phytic acid in the rise of an electric charge stabilizing soy protein micelles in water solution has been suggested. The ability of phytase to cut off the phosphate groups of phytic acid was used to substantiate our assumption. To study the kinetics of coagulation of soymilk proteins, a thermographic method was used. The results of the experiments show that the addition of phytase to soymilk can significantly accelerate its acid coagulation, which is an indirect confirmation of the above assumption.

Preparation and characterisation of plant and dairy-based high protein Chinese steamed breads (mantou): Microstructural characteristics and gastro-small intestinal starch digestion in vitro

The effects of dairy and plant protein addition on microstructural characteristics and in vitro gastro-small intestinal starch digestion characteristics of Chinese steamed breads (CSBs) were studied. Breads containing rennet casein (RC) and a mixture of soy protein isolate and milk protein concentrate (SM) at two different levels (RC I, RC II; SM I, SM II) were prepared. Microstructural characteristics of the undigested and digested control (100% wheat flour) bread and high protein steam bread (HPCSB) versions were compared through scanning electron microscopy. The compact microstructure of HPCSBs displayed a network of proteins wrapped around starch granules and had fewer air cells compared to the control. The addition of both proteins influenced the microstructure of HPCSBs, which in turn affected their textural and starch digestion properties. The in vitro starch digestion of control CSB and HPCSBs confirmed that the addition of proteins is capable of lowering the starch hydrolysis (%). The highest starch hydrolysis was observed for the control wheat bread, followed by SM1 > RC I > SM II and RC II at the end of the small-intestinal digestion. The estimated glycaemic indices (eGI) for all HPCSBs were statistically lower than the control CSB. In comparison to control CSB, the microstructure of HPCSBs appeared more irregular, less porous, and compact during gastric and small intestinal digestion.

Abstract 14096: Examination of the Serum Metabolome After Dietary Carbohydrate, Milk Protein, and Soy Protein Interventions Identified Novel Metabolites for Blood Pressure: The ProBP Trial

Introduction: In the Protein and Blood Pressure (ProBP) trial, milk and soy protein supplements reduced blood pressure (BP) compared to carbohydrate intervention. We investigated the underlying mechanisms influencing the effects. Methods: Serum metabolites were profiled at pre-trial baseline and after supplementation with carbohydrate, soy protein, and milk protein, respectively, among 80 ProBP participants. We tested the mediating and modifying effects of metabolites on BP-lowering effects of soy and milk protein interventions. Results: Dietary interventions significantly ( P &lt;6.49х10 -4 ) changed 40 metabolites, of which 29 had reduced levels. Two clusters of metabolites mediated 45.5% and 100% of the effects of soy and milk protein interventions, respectively. Within the clusters, lipid 4-cholesten-3-one had the largest effect and mediated 12.7% ( P =0.03) and 16.3% ( P =0.045) of the effects of soy and milk protein interventions, respectively. At baseline, amino acids 5-oxoproline and taurine, lysophospholipid 1-arachidonoyl-GPA(20:4) , and acylcholines oleoylcholine , dihomo-linolenoyl-choline , and arachidonoylcholine predicted BP increase during carbohydrate intervention; while lipids N-stearoyl-sphinganine(d18:0/18:0) and isoursodeoxycholate and peptide gamma-glutamylserine predicted less reduction of BP during soy protein and milk protein supplements ( P &lt;6.49х10 -4 ). Finally, effects of soy and milk protein interventions on systolic and diastolic BP were influenced by changes of isobutyrylglycine ( P for interaction=0.02 and 9.12х10 -5 , respectively). In the bottom tertile of isobutyrylglycine changes, soy and milk protein reduced 5.10 ( P =0.03) and 4.43 ( P =0.01) mmHg systolic BP and 3.22 ( P =0.03) and 3.12 ( P =0.04) mmHg diastolic BP, respectively; while in the top tertile, the two interventions had no or increasing effects on systolic (β soy protein =-0.04, P =0.98; β milk protein =-2.34, P =0.25) and diastolic BP (β soy protein =3.19, P =0.02; β milk protein =1.08, P =0.43). Conclusions: We documented serum metabolites altered by dietary carbohydrate, milk protein, and soy protein interventions, and identified important metabolites mediating or modifying the BP-lowering effect of milk and soy protein interventions.

Gelation properties of tofu induced by different coagulants: Effects of molecular interactions between nano-sized okara dietary fiber and soybean proteins

Gelation of soybean proteins with different coagulates as affected by okara nano-sized dietary fiber (NDF) were investigated. As compared with the MgCl2 tofu, the tofu induced by glocono-δ-lactone was softer with higher moisture and denser microstructure. As the volumetric ratio of NDF increased, pH, viscosity, particle size, and zeta potential of the NDF soymilk steadily increased. Regardless of coagulate type, tofu proteins’ prevalence of α-helix + β-turn increased with the NDF ratio up to 40 % while β-sheet + random coil decreased. At the same time, intermolecular interactions (predominate hydrophobic interaction) significantly decreased, leading to form more porous structures in the two types of tofu. Accordingly, yield and moisture of tofu increased gradually with the NDF ratio, water holding capacity increased and then decreased, hardness decreased continuously. Results suggested that NDF affected the secondary structure and intermolecular interactions of soymilk proteins, which was independent of coagulate.

Abstract 035: Novel Metabolites Associated With Blood Pressure During Dietary Protein And Carbohydrate Interventions

Introduction: Dietary protein and carbohydrate intake have been associated with blood pressure (BP). However, molecular mechanisms for these associations are not well studied. Hypothesis: We hypothesize that novel metabolites – intermediate products of metabolic reactions of diet or genetic factors, may play a role in BP regulation during dietary protein and carbohydrate interventions. Methods: In the Protein and Blood Pressure (ProBP) trial, 80 participants were randomly assigned to take 40 grams/day of soy protein, milk protein, or carbohydrate supplementation each for 8 weeks in a cross-over design. We analyzed the associations of serum metabolites with BP at baseline and each dietary intervention, respectively. Age, sex, race, education, smoking, drinking, and body mass index were adjusted in all analyses. ProBP findings were evaluated for replication among 1206 participants of the Bogalusa Heart Study. Results: After Bonferroni correction for 77 independent metabolite clusters, we identified 17 metabolites (1 at baseline, 8 at carbohydrate diet, 4 at milk protein diet, and 5 at soy protein diet) positively associated with BP (P&lt;6.49E-4). Furthermore, 12 of these metabolite-BP associations identified at dietary interventions were replicated in the BHS (P&lt;0.05, Table ). Of the 12 metabolites, glycerol and hexadecadienoate (16:2n6) were associated with BP in previous studies, and all other metabolite-BP associations were novel. Conclusions: Several novel metabolites may play an important role in BP regulation during dietary protein and carbohydrate intake.