kDa Molecular Weight Cut-off Membrane Research Articles

Bovine Serum Albumin Rejection by an Open Ultrafiltration Membrane: Characterization and Modeling.

The classic application of ultrafiltration (UF) is for the complete retention of proteins, and in that situation, the transport behavior is well established. More open membranes with fractional retention are used when separating different proteins. However, protein transport has not been well documented yet in the literature. The bovine serum albumin (∼69 kDa) observed rejection ranges from 0.65 to 1 using a 300 kDa molecular weight cut-off membrane at different pH, ionic strength, and pressure. We demonstrated that, especially with open UF, the transport of proteins through the membrane is dominated by advection, with insignificant diffusion effects (p value > 0.05). We showed that with open UF, retention is not only caused by size exclusion but also to a large extent by electrostatic interactions and oligomerization of the proteins. Mass transfer in the polarization layer was relatively independent of the pH and ionic strength. It was underestimated by common Sherwood relations due to a relatively large contribution of the reduction in the flow turbulence near the membrane by the removal of fluid through the membrane. We propose a model that allows relatively quick characterization of the rejection of proteins without prior knowledge of the pore sizes and charges based on just a limited set of experiments. Therefore, protein rejection with the open UF system can be targeted by tuning the processing conditions, which might be useful for designing protein fractionation processes.

Diagnostic Performance of Dengue NS1 and Antibodies by Serum Concentration Technique

Dengue infection has been a public health problem worldwide, especially in tropical areas. A lack of sensitive diagnostic methods in the early phase of the illness is one of the challenging problems in clinical practices. We, herein, analyzed 86 sera of acute febrile patients, from both dengue and non-dengue febrile illness, to study the diagnostic performance of dengue diagnostics. When compared with detection by Polymerase Chain Reaction (PCR), dengue NS1 detection by enzyme-linked immunosorbent assay (ELISA) had the highest sensitivity of 82.4% (with 94.3% specificity), while NS1 by rapid diagnostic test (RDT) had 76.5% sensitivity. IgM detection by ELISA and RDT showed only 27.5% and 17.9% sensitivity, respectively. The combination of NS1 and IgM in RDT yielded a sensitivity of 78.4%, with 97.1% specificity. One of the essential steps in making a diagnosis from patient samples is the preparation process. At present, a variety of techniques have been used to increase the number of analytes in clinical samples. In this study, we focused on the sample concentration method. The sera were concentrated three times with the ultrafiltration method using a 10 kDa molecular weight cut-off membrane. The results showed an increase in the sensitivity of RDT-NS1 detection at 80.4%, with 100% specificity. When combining NS1 and IgM detection, the concentration method granted RDT an 82.4% sensitivity, with 100% specificity. In conclusion, serum concentration by the ultrafiltration method is a simple and applicable technique. It could increase the diagnostic performance of point-of-care dengue diagnostics.

Investigating the cellular antioxidant and anti-inflammatory effects of the novel peptides in lingzhi mushrooms

The lingzhi mushroom (Ganoderma lucidum) is well known for its medicinal properties and has long played a role in traditional oriental medicine due to its health-giving benefits and potential to extend life expectancy. The mushroom contains a number of highly bioactive compounds and can also act as an excellent source of protein. This research investigated the peptides obtained from the protein hydrolysates of lingzhi mushrooms to assess their free radical scavenging abilities. These peptides were acquired via different proteases (Alcalase, Neutrase, papain, and pepsin-pancreatin) and were tested at a range of different concentrations (1.0%, 2.5%, and 5.0% w/v). The highest levels of 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) radical scavenging activities were presented by lingzhi mushroom hydrolysate using 2.5% (w/v) pepsin-pancreatin after 6 h of digestion. The hydrolysate was then fractionated using 10, 5, 3, and 0.65 kDa molecular weight cut-off membranes. The results showed that the MW 0.65 kDa fraction had the highest level of free radical scavenging activity. Further analysis of this MW 0.65 kDa fraction began with another RP-HPLC fractionation technique to obtain three further sub-fractions. De novo peptide sequencing using electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-Q-TOF-MS/MS) was chosen as the optimum method for studying the F3 sub-fraction. DRVSIYGWG and ALLSISSF were discovered as new peptides with different antioxidant properties. Adenocarcinoma colon (Caco-2) cells showed the antioxidant action of these synthesized peptides. This activity was linked to peptide concentration. The peptides and their pure synthetic counterparts were found to reduce NO generation by RAW 264.7 macrophages without causing cytotoxicity. The results of gene expression reveal that the DRVSIYGWG and ALLSISSF peptides were able to cut the expression of the proinflammatory cytokine genes iNOS, IL-6, TNF-α, and COX-2 in the context of RAW 264.7 macrophages.

Process development of sugar beet enzymatic hydrolysis with enzyme recycling for soluble sugar production

Enzymatic hydrolysis of sugar beets for achieving liquefaction and sugar release is a critical step for beet-ethanol production. An enzyme recycling process was developed in this study to reduce the economic uncertainty raised by the high costs of enzymes by reducing the fresh enzyme usage. A mixture of cellulases and pectinases was used in the beet hydrolysis. The hydrolysate was centrifuged and then processed through a 50 kDa molecular weight cut-off polyethersulfone membrane to recover enzymes from the liquid. Liquid enzyme recycling with 50% fresh enzyme addition achieved a similar liquefaction extent and sugar yield compared to the positive control with 100% fresh enzyme. Solid enzyme recycling showed a lower liquefaction efficiency, requiring at least 75% of fresh enzyme addition for a comparable liquefaction extent. Five sequential batches of hydrolysis with liquid enzyme recycling were successfully conducted to hydrolyze sugar beets with similar liquefaction extents and sugar yields.

Physicochemical and Functional Properties of Membrane-Fractionated Heat-Induced Pea Protein Aggregates.

This study was carried out to investigate the effect of heat pre-treatment of pea proteins at different pH values on the formation of functional protein aggregates. A 10% (w/v) aqueous mixture of pea protein concentrate (PPC) was adjusted to pH 3.0, 5.0, 7.0, or 9.0 followed by heating at 100°C for 30 min, cooled and centrifuged. The supernatant was sequentially passed through 30 and 50 kDa molecular weight cut-off membranes to collect the <30, 30–50, and >50 kDa fractions. The >50 kDa fractions from pH 3.0 (FT3), 5.0 (FT5), 7.0 (FT7), and 9.0 (FT9) treatments had >60% protein content in contrast to the ≤20% for the <30 and 30–50 kDa fractions. Therefore, the >50 kDa fractions were collected and then compared to the untreated PPC for some physicochemical and functional properties. Protein aggregation was confirmed as the denaturation temperature for FT3 (124.30°C), FT5 (190.66oC), FT7 (206.33oC) and FT9 (203.17oC) was significantly (p < 0.05) greater than that of PPC (74.45oC). Scanning electron microscopy showed that FT5 had a compact structure like PPC while FT3, FT7, and FT9 contained a more continuous network. In comparison to PPC, the >50 kDa fractions showed improved solubility (>60%), oil holding capacity (~100%), protein content (~7%), foam capacity (>10%), foam stability (>7%), water holding capacity (>16%) and surface hydrophobicity (~50%). Least gelation concentration of PPC (18%), FT3 (25%), FT5 (22%), FT7 (22%), and FT9 (25%) was improved to 16, 18, 20, 16, and 18%, respectively, after addition of NaCl.

Extraction of the Bacterial Extracellular Polysaccharide FucoPol by Membrane-Based Methods: Efficiency and Impact on Biopolymer Properties.

In this study, membrane-based methods were evaluated for the recovery of FucoPol, the fucose-rich exopolysaccharide (EPS) secreted by the bacterium Enterobacter A47, aiming at reducing the total water consumption and extraction time, while keeping a high product recovery, thus making the downstream procedure more sustainable and cost-effective. The optimized method involved ultrafiltration of the cell-free supernatant using a 30 kDa molecular weight cut-off (MWCO) membrane that allowed for a 37% reduction of the total water consumption and a 55% reduction of the extraction time, compared to the previously used method (diafiltration-ultrafiltration with a 100 kDa MWCO membrane). This change in the downstream procedure improved the product’s recovery (around 10% increase) and its purity, evidenced by the lower protein (8.2 wt%) and inorganic salts (4.0 wt%) contents of the samples (compared to 9.3 and 8.6 wt%, respectively, for the previously used method), without impacting FucoPol’s sugar and acyl groups composition, molecular mass distribution or thermal degradation profile. The biopolymer’s emulsion-forming and stabilizing capacity was also not affected (emulsification activity (EA) with olive oil, at a 2:3 ratio, of 98 ± 0% for all samples), while the rheological properties were improved (the zero-shear viscosity increased from 8.89 ± 0.62 Pa·s to 17.40 ± 0.04 Pa·s), which can be assigned to the higher purity degree of the extracted samples. These findings demonstrate a significant improvement in the downstream procedure raising FucoPol’s recovery, while reducing water consumption and operation time, key criteria in terms of process economic and environmental sustainability. Moreover, those changes improved the biopolymer’s rheological properties, known to significantly impact FucoPol’s utilization in cosmetic, pharmaceutical or food products.

Serial fractionation of spent brewer's yeast protein hydrolysate by ultrafiltration: A peptide-rich product with low RNA content

Spent brewer's yeast (SBY) application as a new source of peptides depends on the development of proper downstream processes. This work aimed to separate yeast hydrolysate peptides from sugars and ribonucleic acids (RNA) by a 3-step designed fractionation process using ceramic ultra and nanofiltration following two sequences: (1) 50, 8 and 1 kDa and (2) 15, 8 and 1 kDa molecular weight cut-off (MWCO) membranes. In step one, 15 kDa MWCO membrane retained more components and increased performance of subsequent steps, when compared to 50 kDa. Peptide composition of the initial hydrolysate was gradually changed until 90% of the peptides smaller than 1 kg mol −1 were found in the final permeate. Fractionation increased peptide purity regarding RNA and total sugars up to 1.7 and 2.7-fold, respectively. Innovative protein-rich ingredients from SBY residue with an RNA content as low as 1.4% were produced by membrane separation technology. High quality ingredients presented different peptide profiles and great potential in food and pharmaceutical industries applications. • Efficient RNA reduction was achieved using membrane separation technology. • RNA content in protein-rich fraction was as low as 1.4% (dry weight). • Membranes of 15–1 kDa range were adapted to spent yeast ultrafiltration. • Protein purity of obtained fractions increased 1.7 and 2.7-fold for RNA and sugars. • A fraction with bioactive potential (65% of the peptides < 1 kg mol −1 ) was produced.

Identification of Antimicrobial Peptides Isolated From the Skin Mucus of African Catfish, Clarias gariepinus (Burchell, 1822).

Antimicrobial peptides (AMPs) constitute a broad range of bioactive compounds in diverse organisms, including fish. They are effector molecules for the innate immune response, against pathogens, tissue damage and infections. Still, AMPs from African Catfish, Clarias gariepinus, skin mucus are largely unexplored despite their possible therapeutic role in combating antimicrobial resistance. In this study, African Catfish Antimicrobial peptides (ACAPs) were identified from the skin mucus of African Catfish, C. gariepinus. Native peptides were extracted from fish mucus scrapings in 10% acetic acid (v/v) and ultra-filtered using 5 kDa molecular weight cut-off membrane. The extract was purified using C18 Solid-Phase Extraction. The antibacterial activity was determined using the Agar Well Diffusion method and broth-dilution method utilizing Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922). Thereafter, Sephadex G-25 gel filtration was further utilized in bio-guided isolation of the most active fractions prior to peptide identification using Orbitrap Fusion Lumos Tribrid Mass Spectrometry. The skin mucus extracted from African Catfish from all the three major lakes of Uganda exhibited antimicrobial activity on E. coli and S. aureus. Lake Albert’s C. gariepinus demonstrated the best activity with the lowest MIC of 2.84 and 0.71 μg/ml on S. aureus and E. coli, respectively. Sephadex G-25 peak I mass spectrometry analysis (Data are available via ProteomeXchange with identifier PXD029193) alongside in silico analysis revealed seven short peptides (11–16 amino acid residues) of high antimicrobial scores (0.561–0.905 units). In addition, these peptides had a low molecular weight (1005.57–1622.05 Da) and had percentage hydrophobicity above 54%. Up to four of these AMPs demonstrated α-helix structure conformation, rendering them amphipathic. The findings of this study indicate that novel AMPs can be sourced from the skin mucus of C. gariepinus. Such AMPs are potential alternatives to the traditional antibiotics and can be of great application to food and pharmaceutical industries; however, further studies are still needed to establish their drug-likeness and safety profiles.

Antifungal Activity and Major Bioactive Compounds of Water Extract of Pangium edule Seed against Aspergillus flavus.

Pangium edule seeds are widely used as spices in Southeast Asia in a fresh and fermented form and are reported to have active compounds for food preservation. However, scientific data on the active compounds of P. edule seed that can prevent the growth of toxigenic Aspergillus flavus have not been widely reported. This research subjected to determine the antifungal activity and identify the active compounds of water extract of old and fermented seed of P. edule against A. flavus. The water extract was compared to the extracts obtained by multilevel maceration using 50% ethanol, ethyl acetate, and n-hexane as solvents. Alkaloid, saponin, phenolic compound, flavonoid, triterpenoid, and glycoside were detected qualitatively in the crude extracts. The water extract showed the best activity to suppress the growth of A. flavus, determined by the agar dilution method, with the minimum inhibitory concentration (MIC) of 12.5 and 25 mg/mL for old and fermented seed, respectively. The water extracts showed a moderate toxicity with LC50 of 100-500 μg/mL, determined by the brine-shrimp toxicity test. After fractionation using 3 kDa molecular-weight (MW) cut-off ultrafiltration membrane, two fractions, i.e., fraction with MW < 3 kDa and >3 kDa, were obtained. The fraction with MW < 3 kDa showed the best antifungal activity with the MIC of 6.25 and 12.5 mg/mL for old and fermented seed, respectively. LC-MS/MS profile showed that different compounds belong to fatty acid, amino acid, glycoside, and peptide were found as major active compounds in the fractionated water extract. The principal compounds and partial least-square analysis, however, suggested that fatty acid and glycoside are responsible for the antifungal activity. Hence, this study concluded that the water extract of P. edule seed had promising antifungal activity against A. flavus which was due to presence of particular compounds belong to fatty acid and glycoside.

Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry Analysis for Molecular Characterization of Chitosan

Chitosan oligosaccharides designated to COS were derived from the hydrolysis of high molecular weight chitosan (HMWC). The range of molecular weight of COS was estimated to be approximately 0.5 to 2.5 kDa after the fractionation performed through gel-filtration, followed by MALDI-TOF mass spectrometry analysis. It was confirmed through the results that significant separation or fractionation was not observed well. Also, both dialyzed COS using a 12~14 kDa molecular weight cut-off (MWCO) membrane and salting-out COS were also showed no significant difference in the molecular weight of COS by MALDI-TOF mass spectrometry analysis. These results suggested that it is difficult to separate the chitosan hydrolysates bigger than 1 kDa according to the size (6-glucosamine) due to their high affinity between molecules which may tightly be associated together by hydrophobic or van der Waals force. Therefore, further examination on chitosan hydrolysis and fractionation for the production of COS with various sizes i.e., 7 or 8 units of glucosamine in large-scale, should be carefully considered for various applications.

Characteristics of some beverages adjusted with stevia extract, and persistence of steviol glycosides in the mouth after consumption

With the increase of obesity and diabetes, low-calorie, and natural sweeteners that can be used instead of sugar have become urgent. Stevia rebaudiana is used as an alternative natural sweetener in many countries because it is 200–300 times sweeter than sucrose, has no negative impact on human health, is low-calorie and natural, and is suitable for the use of obesity and diabetes patients. Recently, some studies have been conducted on the favorable properties of steviol glycosides on oral health, as well.In this study, 100 kDa and 5 kDa molecular weight cut-off membranes were used to concentrate stevia extracts, remove herbaceous odor, and remove bitter aftertaste. The enriched extracts obtained were used in the formulation of some beverages and were sensually tested. The sugar equivalent of the obtained retentate flux of 5 kDa nanofiltration was calculated and used in the production of nectar and fruit beverages with different energy levels, and some quality properties were determined. During the sensory evaluation of nectar samples, saliva samples were taken from the panelists at specific intervals. Change in steviol glycoside concentration was detected in saliva samples depending on time. Thus, the persistence of steviol glycosides in the mouth was determined. Consequently, it was proved that whole stevia extracts could be successfully used in products, and rebaudioside A was more persistent in the mouth than stevioside after consumption.

The apoptotic and free radical–scavenging abilities of the protein hydrolysate obtained from chicken feather meal

This study examined the antioxidant capabilities of peptides derived from chicken feather meal (CFM) protein hydrolysates which were produced using 3 different microbial proteases (Neutrase, Alcalase, and flavourzyme) and tested at varying concentrations, namely 1, 2, and 5% by weight. The highest levels of 2,2-diphenyl-1-picrylhydrazl (DPPH) and 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging activities were presented by CFM hydrolysate derived using 5 wt% Neutrase and digested for 4 h. Fractionation of this particular hydrolysate was then performed by applying 10, 5, 3, and 0.65 kDa molecular weight cutoff membranes. It was then determined that the molecular weight (MW) < 0.65 kDa fraction achieved the greatest level of free radical scavenging activity in the context of DPPH and ABTS. The MW < 0.65 kDa fraction then underwent additional fractionation using reverse-phase high-performance liquid chromatography to derive 3 main fractions designated as F1, F2, and F3. All of these fractions presented a high level of activity in DPPH radical scavenging, although no significant ABTS scavenging was observed. Quadrupole time-of-flight tandem mass spectrometry was used in determining the peptide contents of the fractions as Phe-Asp-Asp-Arg-Gly-Arg-X for F1 (FDDRGRX, 875 Da), Val-Thr-Leu-Ala-Val-Thr-Lys-His for F2 (VTLAVTKH, 868 Da), and Val-Ser-Glu-Ile-X-Ser-Ile-Pro-Ile-Ser for F3 (VSEIXSIPIS, 1,055 Da). Moreover, the F2 fraction was shown to be capable of preventing DNA damage induced by hydroxyl radicals, as indicated in tests using the plasmids pKS, pUC19, and pBR322 via the Fenton reaction. This outcome was demonstrated through in vitro antiproliferative activity in human cell lines based on SW620 colon cancer, using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. The F2 fraction at 0.5 wt.% was also shown to be capable of inducing weak early apoptosis, which could be measured by using the Fluorescein isothiocyanate Annexin V Apoptosis Detection Kit with Propidium Iodide Solution. Furthermore, an increase in caspase-3 and caspase-8 activity was observed in SW620 cells following exposure for 24 h and 48 h.

A strategy to identify mixed polysaccharides through analyzing the monosaccharide composition of disaccharides released by graded acid hydrolysis

It is still a challenge to identify mixed polysaccharides isolated from biological tissues. The present study aimed to develop a protocol that allowed for quick characterization of mixed polysaccharides by selecting Cyclina sinensis polysaccharides as test beds. Disaccharides were gradually released by graded acid hydrolysis, separated with 3 kDa molecular weight cut-off membrane, and analyzed by HPLC-ESI-MSn. Furthermore, the monosaccharide composition of the filtrate during the gradient acid hydrolysis process and the final retentate were also determined to provide composition information of these disaccharides. Thus, 6 disaccharides were detected and identified, indicating the existence of polysaccharides constructed of corresponding repeated disaccharide fragments in C. sinensis. The present study demonstrated a potential strategy to characterize mixed polysaccharides without separation and purification.

Extraction and purification of humic acids from lignite wastes using alkaline treatment and membrane ultrafiltration

Abstract The cleaner production of high purity and safe humic acid (HA) with very low concentration of heavy metals leads to achieve a final product with potential economic value in agriculture, biomedicine, environment and so on. This can be obtained by environmental-friendly separation of low molecular weight fulvates and inorganic elements present in humic alkaline solutions. The aim of this study is the alkaline extraction of solutions containing humates and fulvates derived from lignite wastes followed by purification of humates using membrane processes. A polysulfone 5 kDa molecular weight cut-off membrane in a plate and frame module was used for ultrafiltration of lignite coals-derived alkaline extracts. The effects of operating parameters including transmembrane pressure (TMP) at four levels (1, 2, 3, and 4 bar), feed flow rate (FFR) at five levels (5, 15, 25, 35, and 45 ml s−1) and processing temperature at three levels (35, 45, and 55 °C) were investigated on permeate flux of fulvate compounds, membrane fouling, purity percentage and ash contents of the HA product. Results showed that the highest permeate flux, the lowest membrane fouling, and the most desirable qualitative/quantitative properties of the purified HA was obtained at TMP of 3 bar, FFR of 45 ml s−1 and temperature of 45 °C. The results of ICP-OES analysis showed very low concentrations of heavy metals and inorganic elements in the purified HA while the FT-IR results confirmed the ICP-OES findings and revealed the rich carboxylic and phenolic functional groups of the final product.

A comparative assessment of water-soluble selenium metabolites in commercial selenised yeast supplements by liquid chromatography-electrospray ionisation QTOF-MS

Liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS) was utilised for the screening of organoselenium metabolites in the water extracts of selenised yeast products. Four different commercially available yeast products and a reference Se-enriched yeast standard, (SELM-1) were analysed. Total selenium and selenomethionine concentrations were determined by ICP-MS and LC-ICP-MS, respectively. Ultrafiltration using a 3 kDa molecular weight cut-off membrane was used in the present study for sample clean-up. The water-soluble extracts were lyophilised to increase analyte concentration, resuspended in water and analysed by liquid chromatography-electrospray ionisation quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS). Selenium-containing species were confirmed using selenium’s unique isotopic pattern. This approach allowed for the detection of approximately 129 previously unreported selenium metabolites across the different yeast samples. Determination of the elemental composition of 14 previously unreported selenocompounds was advanced through MS2 analysis and accurate molecular mass determination (Δ ppm<1.6 for all proposed elemental compositions).

Antihypertensive and Antioxidant Properties of Moringa Oleifera Seed Enzymatic Protein Hydrolysate and Ultrafiltration Fractions

The aim of this study was to evaluate the in vitro antioxidant and antihypertensive as well as potential cardioprotective properties of peptides generated from enzymatic hydrolysis of Moringa oleifera seed. Moringa protein isolate was digested with alcalase and the hydrolysate fractionated by ultrafiltration using 1, 3, 5, and 10 kDa molecular weight cut-off membranes. Results showed that membrane separation led to decreased free radical (DPPH, hydroxyl) scavenging but enhanced ferric reducing antioxidant power and metal ion chelation properties. The 1–3 kDa peptide fraction was the most active against angiotensin converting enzyme and renin with 6.70% and 24.62% increases, respectively when compared to the hydrolysate. Oral administration (200 mg/kg body weight) to spontaneously hypertensive rats (SHR) resulted in significant decreases in systolic (SBP), diastolic and mean arterial (MAP) blood pressure for the hydrolysates and peptide fractions when compared to the negative control. The 1–3 kDa peptide fraction also showed the greatest (–35 mm Hg) in SBP along with fastest (2 h) reduction of SBP and MAP in the SHR. The hydrolysate produced the most persistent SBP reduction with up to –34 mm Hg after 24 h. However, the longer peptides (&gt;10 kDa) were the most effective (–78 beats per min) in reducing SHR heart rate. The results suggest that the alcalase-hydrolyzed M. oleifera seed peptides could function as potential ingredients for the formulations of functional foods and nutraceuticals with antihypertensive benefits.

Antioxidant and antihypertensive activities of wonderful cola (Buchholzia coriacea) seed protein and enzymatic protein hydrolysates

The aim of this work was to produce wonderful cola protein hydrolysate fractions with in vitro antioxidant properties coupled with blood pressure-reducing ability when orally administered to spontaneously hypertensive rats (SHRs). Wonderful cola protein isolate (WCI) was hydrolyzed with pancreatin to produce a hydrolysate (WCH), which was subjected to ultrafiltration separation using 1, 3, 5, and 10 kDa molecular weight cut-off membranes to obtain &lt;1, 1–3, 3–5 and 5–10 kDa peptide fractions, respectively. The &lt;1 and 1–3 kDa fractions had higher contents of arginine when compared to the 3–5 and 5–10 kDa peptides. The WCH and &lt;1 kDa peptide fraction had significantly (p &lt; 0.05) better DPPH radical scavenging (55–67%) and metal chelation (83–93%) activities but lower hydroxyl radical scavenging power (10–32%) than the WCI (46, 46 and 63%, respectively). The &lt;1 kDa had significantly (p &lt; 0.05) higher in vitro inhibition (80%) of angiotensin converting enzyme (ACE) activity while the 5–10 kDa was the most active inhibitor (90%) of renin activity. All peptide fractions so produced had better systolic and diastolic blood pressure-lowering effects than WCH and WCI. However, the &lt;1 kDa fraction produced significantly (p &lt; 0.05) stronger systolic (−33 mmHg) and diastolic (−30 mmHg) blood pressure reductions 6 h after oral gavage to SHRs. Thus, wonderful cola proteins contain encrypted bioactive peptides that may be used to formulate antioxidant and antihypertensive products.

Enhancing lead removal from water by complex-assisted filtration with acacia gum

In this work, for the first time, the use of AG as a natural, widely available and cheap material to enhance the removal of lead from contaminated water using polymer-enhanced membrane filtration (PEMF) has been carried out. In this technique, heavy metal ions are chelated with high molecular weight water-soluble polymers with following rejection of the formed polymer-metal complexes with the wide-porous and high flux polymer membranes. Acacia gum (AG) is a natural gum, which is collected from the hardenedsapof some species of the acacia tree. The surface area particle sizes, zeta potential and elemental composition of AG were evaluated using BET, FE-SEM, zeta potential analyzer, EDS and XPS methods. The effect of AG dosage, lead concentration, feed pH, and contact time on lead-AG complex formation has been studied. The highest binding capacity of AG was about 12.2 mg/g when 1000 ppm AG was added to 35 ppm lead solution at pH 7. It was found that, with a dosage of 1000 mg/L of AG at pH 7, successful lead removal efficiencies of 97.5%, 98.3% and 99.9% were achieved using microfiltration polytetrafluoroethylene (PTFE), 30 kDa and 3 kDa molecular weight cut-off ultrafiltration cellulose membranes, respectively. The possible mechanism of lead removal with AG has been discussed. The obtained data have shown that AG can be used as a safe and cheap chelating agent for lead removal from water.

Filter-Based Protein Digestion (FPD): A Detergent-Free and Scaffold-Based Strategy for TMT Workflows.

High-throughput proteome profiling requires thorough optimization to achieve comprehensive analysis. We developed a filter aided sample preparation (FASP)-like, detergent-free method, termed Filter-Based Protein Digestion (FPD). We compared FPD to protein extraction methods commonly used in isobaric tag-based proteome profiling, namely trichloroacetic acid (TCA) and chloroform-methanol (C-M) precipitation. We divided a mammalian whole cell lysate from the SH-SY5Y neuroblastoma cell line for parallel protein processing with TCA (n = 3), C-M (n = 2), and FPD using either 10 kDa (n = 3) or 30 kDa (n = 3) molecular weight cutoff membranes. We labeled each sample with tandem mass tag (TMT) reagents to construct a TMT11-plex experiment. In total, 8654 proteins were quantified across all samples. Pairwise comparisons showed very little deviation for individual protein abundance measurements between the two FPD methods, whereas TCA and FPD showed the most difference. Specifically, membrane proteins were more readily quantified when samples were processed using TCA precipitation than other methods tested. However, globally, only 4% of proteins differed greater than 4-fold in the most divergent pair of protein extraction methods (i.e., FPD10 and TCA). We conclude that the detergent-free FPD strategy, particularly using the faster-flowing 30 kDa filter, is a seamless alteration to high-throughput TMT workflows.

Downstream processing of an oxidized industrial kraft liquor by membrane fractionation for vanillin and syringaldehyde recovery

Abstract A membrane fractionation study of an oxidized industrial kraft liquor was performed with 50, 5 and 1 kDa molecular weight cut-off membranes to study the productivity of each membrane and the respective apparent rejection coefficients (Ri) to total solids (TS), ashes and low molecular weight phenolates (TP). Cleaning efficiency of each membrane was evaluated and the contribution of fouling for flux decline was analyzed by applying the resistances-in-series approach. During membrane fractionation sequence, TS content in the permeate stream gradually decreased from 86.5 g L−1 to 75.3 g L−1 (50 kDa), 64 g L−1 (5 kDa) and 58.6 g L−1 (1 kDa). The Ri values observed for TS were 25.3%, 29.1% and 15.1% for 50, 5 and 1 kDa membrane processing, respectively. TP were not retained by the 50 kDa membrane while, for the 5 and 1 kDa membranes, Ri of 11.5% and 9.0% were observed, respectively. The initial TP concentration (2.4 g L−1) was maintained in the first membrane stage, while for the other stages decreased slightly for 2.22 g L−1 (5 kDa) and 2.15 g L−1 (1 kDa). Nevertheless, in terms of composition (%w/wTS), an enrichment in TP was observed in all three stages from 2.8% (feed) to 3.2% (50 kDa), 3.5% (5 kDa) and 3.7% (1 kDa). The initial water fluxes were recovered within 2–3 cycles of chemical cleaning and fouling evaluation indicated that reversible fouling was very relevant component for the 50 and 1 kDa membrane processing while irreversible fouling component was more pronounced for the 5 kDa membrane processing.