Feed Protein Concentration Research Articles

CFD modeling of braid-reinforced hollow fiber membranes for efficient water and bovine serum albumin (BSA) separation

This study presents a comprehensive investigation into the performance optimization of a braid-reinforced hollow fiber membrane (BHFM) system for protein separation from milk wastewater. Extensive CFD simulations were conducted to examine the effects of various effective parameters on system performance. The results reveal that at a feed protein concentration of 100 mg/l, the average water flux increases from 149.16 to 453.68 l/m2.h as the inlet feed pressure rises from 100 to 300 kPa. Similarly, for a feed protein concentration of 300 mg/l, the average flux rises from 98.69 to 299.84 l/m2.h. However, higher feed concentrations lead to increased fouling and lower water fluxes. Additionally, an increase in feed pressure results in a decrease in the protein rejection rate, particularly in the initial stages of separation. The study highlights that variations in membrane porosity and thickness significantly affect both protein rejection rate and water flux. Increasing membrane porosity from 0.2 to 0.8 leads to a decrease in protein rejection rate from 94.57 % to 78.47 % at an inlet pressure of 100 kPa, and from 93.33 % to 73.43 % at 300 kPa. Similarly, increasing membrane thickness from 0.1 to 1.0 mm decreases the time-averaged water flux from 105.76 to 8.64 l/m2.h at 100 kPa, and from 321.39 to 25.99 l/m2.h at 300 kPa. However, increasing membrane thickness also increases the protein rejection rate. The study's novelty lies in the quantitative results obtained through CFD simulations, providing valuable insights into BHFM system performance. Future research should focus on exploring innovative braid architectures and material selection to enhance the mechanical stability and durability of braid-reinforced structures under various operational conditions.

The influence of supplemental feed protein concentration on growth and carcass characteristics of Short Horn Zebu bulls grazing natural pastures

In Uganda, beef production is mainly based on local cattle breeds like the Short Horn Zebu (SHZ) which graze unimproved natural pastures. Sole grazing on natural pastures cannot meet the annual nutrient requirements of SHZ due to seasonal variability in quantity and quality of the pastures resulting in delayed attainment of market slaughter weight. In order to meet the nutrient requirements of SHZ and hence to shorten the time to attain market weight, we evaluated the effect of providing ad libitum supplements of varying crude protein (CP) levels (90, 110 and 130 g CP kg−1 dry matter (DM)) on the performance and carcass characteristics of grazing SHZ bulls. Ninety-six SHZ (6 ± 2 months old) were allocated to one of four treatment diets including the control T1 (sole grazing), T2, T3 and T4 grazing plus a supplement containing 90, 110 and 130 g CP kg−1 DM, respectively. Crude protein of natural pastures ranged between 103.9 to 158.4 g kg−1DM. Dry matter intake (DMI) varied with month (P<0.001) and increased (P<0.001) level of protein supplementation. For supplemented groups, the supplement contributed more than 75% of DMI even though supplement intake did not vary (P>0.05) with level of CP in supplement. However, CP intake of animals increased with level of CP of the supplement offered. Final live weight and average daily weight gain (ADG) increased (P<0.001) with level of CP in supplement. Feed conversion ratio (FCR) varied (P<0.01) with level of CP in the supplement (13.7 for T4 vs 18.5 for T1). The supplement with 110 g CP kg−1 DM resulted in higher α-linoleic acid and ratio of n6:n3 polyunsaturated fatty acids (PUFAs) in meat compared to meat from unsupplemented cattle. It is concluded that providing grazing SHZ cattle with a supplement containing 110 g CP kg−1 DM improves feed intake, ADG, carcass yield and carcass composition.

Process development and optimization of continuous capture with three-column periodic counter-current chromatography.

Continuous capture with affinity chromatography is one of the most important units for continuous manufacturing of monoclonal antibody (mAb). Due to the complexity of three-column periodic counter-current chromatography (3C-PCC), three approaches (experimental, model-based, and simplified approaches) were studied for process development and optimization. The effects of residence time for interconnected load (RT C ), breakthrough percentage of the first column for interconnected load (s) and feed protein concentration (c 0 ) on productivity and capacity utilization were focused. The model-based approach was found superior to the experimental approach in process optimization and evaluation. Two phases of productivity were observed and the optimal RT C for the maximum productivity was located at the boundary of the two phases. The comprehensive effects of the operating parameters (RT C , s, and c 0 ) were evaluated by the model-based approach, and the operation space was predicted. The best performance of 34.5 g/L/h productivity and 97.6% capacity utilization were attained for MabSelect SuRe LX resin under 5 g/L concentration at RT C = 2.8 min and s = 87.5%. Moreover, a simplified approach was suggested to obtain the optimal RT C for the maximum productivity. The results demonstrated that model-assisted tools are useful to determine the optimum conditions for 3C-PCC continuous capture with high productivity and capacity utilization.

Milk protein fractionation by spiral-wound microfiltration membranes in diafiltration mode - Influence of feed protein concentration and composition on the filtration performance

Washing steps by adding diafiltration medium are needed to completely fractionate caseins and whey proteins from skim milk by microfiltration. The amount of diafiltration medium and the fractionation performance depend on the feed concentration factor (CF). However, an investigation on the optimum process conditions during fractionation by spiral-wound membranes (SWMs) has not been carried out yet. At the optimum transmembrane pressure, CF 2 performed best with regard to the whey protein mass flow. The protein concentration in the permeate and the flux were limiting factors at lower and higher CFs, respectively. Regarding industrial plants with multiple stages for the fractionation, the casein to whey protein ratio varies in each stage. Since no changes in the length-dependent filtration behaviour was observable with the casein to whey protein ratio at a constant axial pressure drop, the optimisation of SWMs regarding length dependency can be conducted independently of the stage.

Effects of process parameters on the efficiency of chromatographic separations using a cuboid packed-bed device

In recent papers we have proposed cuboid packed-bed devices as viable alternatives to preparative columns with low bed-height to diameter ratios that are typically used for biopharmaceutical purification processes. In this case study, we systematically examined operating parameters such as mobile phase flow rate, sample injection volume and feed protein concentration on the characteristics of flow-through and bound-and-eluted protein peaks. The current study was carried out using strong anion exchange media packed in a cuboid packed-bed device and its equivalent column, i.e. with identical volume and bed-height. Our experimental results showed that the cuboid packed-bed device outperformed its equivalent column at all conditions examined. However, the improvement in performance in flow-through experiments was more significant at lower flow rates, and when smaller sample volumes (i.e. less than 20% of bed volume) were injected. Also, the performance of the cuboid packed-bed was significantly better when a concentrated protein sample was injected using a small volume loop. In bind-and-elute experiments, the flow rate had a very significant impact on the performance of the cuboid packed-bed device, with better results being obtained at the lower flow rates examined. By choosing appropriate experimental conditions, significantly sharper peaks and thereby efficient separations could be achieved using the cuboid packed-bed device than with its equivalent column.

Nitrogen, Phosphorus, and Carbon Concentrations in Some Common Aquaculture Feeds

AbstractNitrogen, phosphorus, and carbon concentrations were measured from 203 samples of starter, fingerling, and grower aquaculture feeds from several countries and for several common species. The feed protein concentrations reported by manufacturers often were slightly greater than the measured crude protein concentrations. The correlation coefficients (R2) between feed nitrogen and carbon concentrations were less than 0.50, and nitrogen and phosphorus concentrations in feed were not correlated. There were considerable differences in elemental concentrations among feeds, but the overall averages for carbon, nitrogen, and phosphorus concentrations, respectively, were as follows: starter feed 41.36, 7.78, and 1.57%; fingerling feed 39.75, 5.95, and 1.36%; grower feed 39.97, 5.36, and 1.22%. Concentrations of carbon, nitrogen, and phosphorus in feeds are required in estimating the pollution potential of aquaculture facilities. The crude protein concentration – if provided by the manufacturer – can be used to estimate nitrogen concentration in feed, but carbon and phosphorus concentrations should be measured.

Factors that influence the membrane area of a multistage microfiltration process required to produce a micellar casein concentrate

The objective of the work reported in this paper was to develop a theoretical model to determine the effect of type of microfiltration (MF)-process feed, number of stages, and flux on the minimization of the MF membrane area required to produce a 95% serum protein–reduced micellar casein concentrate. The MF feed, number of stages, and flux were all factors that had an effect on the MF membrane area and should be taken into consideration when designing a MF system to produce a 95% serum protein–reduced micellar casein concentrate. Feeding the MF process with a diluted ultrafiltration retentate (DUR) diluted to the protein concentration of skim milk, as opposed to skim milk, reduced the required membrane area by 36% for a 5-stage process. When DUR was the MF feed, feed protein concentration, which depended on the number of MF stages, was optimized. The DUR protein concentration that minimized the required MF membrane area was 2.47, 3.85, 4.77, and 5.41% for a 2-, 3-, 4-, or 5-stage MF process, respectively. For a 5-stage process, increasing the protein concentration of the feed from 3.2 to 5.4% decreased the required MF membrane area by 10%. It was also found that as the number of stages increased from 2 to 5, the required MF membrane area decreased by 39%, when the MF feed was DUR at the optimal feed protein concentration. Finally, increasing the flux from 50 to 60kg/m2 per hour decreased the required MF membrane area by 17% when the MF feed was DUR at the optimal MF feed protein concentration. Overall, using DUR as a feed for MF could reduce the amount of MF membrane area required to make a 95% serum protein–reduced micellar casein concentrate.

Investigation of Consecutive Fouling and Cleaning Cycles of Ultrafiltration Membranes Used for Whey Processing

Abstract Development of resistance during multiple foulings and three-step Cleaning-In-Place (CIP) operations, simulating an industrial cleaning regime of polysulfone ultrafiltration membranes, was investigated. The study explored how trans-membrane pressure (150 and 300 kPa) and feed protein concentration (0.9 and 10%) influenced resistance reduction during filtration and flux recovery by the cleaning procedures. New membranes, pre-cleaned with a full CIP cycle, were used for each experiment. Subsequent fouling (simulating production) and CIP were done three times in a row and the development of fouling layer resistance was monitored and evaluated. Results show that filtration performance decreased during the first days of usage, possibly related to build-up of internal fouling. Cleaning success based on flux recovery was negatively influenced by a high protein concentration in the feed, but independent of the trans-membrane pressure during filtration.

Application of an Escherichia coli green fluorescent protein - based lysine biosensor under nonsterile conditions and autofluorescence background

To examine the utility of an Escherichia coli green fluorescent protein (GFP) containing biosensor for quantification of bioavailable lysine in selected feed samples under nonsterile conditions and to estimate the background fluorescence of analyzed feed samples and evaluate the risk of confounding GFP emission from the lysine assay organism. Escherichia coli lysine auxotroph GFP based biosensor was used to determine the percentage of bioavailable lysine in two samples of soybean-, cottonseed-, and meat and bone meal under nonsterile conditions. The fluorescence emitted by GFP was successfully measured using a spectrofluorimeter to monitor bacterial growth response to protein-derived lysine and lysine containing small peptides. The autofluorescence of analyzed feed samples at different concentrations could also be estimated. When feed protein concentrations are decreased, autofluorescence interference can be avoided. The E. coli lysine auxotroph GFP-based biosensor can successfully be used for the determination of bioavailable lysine in these selected animal feed proteins under nonsterile conditions. E. coli GFP biosensor for lysine has potential for routine application in animal feeds.

Modeling of expanded-bed protein adsorption by taking into account the axial particle size distribution

A mathematical model was established to describe protein adsorption behavior in expanded-bed chromatography by taking into account the axial size classification of adsorbent within the bed. This model has been used to simulate the expanded-bed adsorption (EBA) of bovine serum albumin (BSA) to Streamline DEAE under various operating conditions, such as different feed protein concentrations, liquid velocities and liquid viscosities. The parameters involved in the model are determined by the independent experiments or calculated from correlation to ensure a reliable comparison between the experimental and simulated results. Using these independently determined parameters, the model prediction agreed reasonably well to the experimental data. Moreover, the model was found more precise than that without considering the axial particle size distribution.

A study of the separation of proteins from multicomponent mixtures by a semi-batch foaming process

Foam fractionation offers an attractive method of separating/concentrating proteins (or their mixtures) from dilute solutions which are typical of many dairy, food and biological process streams. Experiments were conducted to obtain the values of the average bubble size, gas holdup, interfacial area, the bulk phase concentration and the heat of desorption (which determines the concentration of adsorbed components) in the liquid solution using a 75 mm diameter, 530 mm long glass column fitted with a stainless steel sparger for bubble generation. The mass transfer coefficient for Bovine Serum Albumin (BSA), K, was determined from the analysis of the concentration of foam and feed at different times using the above mentioned parameters. The values vary with the feed concentration, i.e. K=4.34×10 −6 mol cal −1 cm −2 s −1 at 60 mg l −1 and K= 3.62×10 −6 at 25 mg l −1. The separation performance, expressed as enrichment ratio, selectivity and percentage recovery, was investigated for a binary and ternary protein mixtures of BSA, α-lactalbumin and lactoferrin. The effects of the operating factors, i.e. air flow rate, initial feed protein concentration ratio, bubble size and solution pH on separation performance were examined. The results provided some guidelines in producing a fraction, enriched in the target protein lactoferrin, from its mixture with other proteins.

Protein degradation during anaerobic wastewater treatment: derivation of stoichiometry.

The stoichiometry of reactions that describe protein degradation in anaerobic treatment systems were investigated. A methodology was developed to describe protein degradation to organic acids using a single reaction step. The reactions for individual amino acid fermentation and their mediating organisms were reviewed. The dominant fermentation pathways were selected based on a number of assumptions. Using the amino acid content of a model protein, it was then possible to determine stoichiometric coefficients for each major organic acid product in the overall degradation of the protein. The theoretical coefficients were then compared to those determined from two experimental runs on a continuously-fed, well-mixed, laboratory-scale anaerobic wastewater treatment system. In general, the coefficients compared well thus validating the use of a single reaction step for the overall catabolic reaction of protein degradation to organic acids. Furthermore, even when the protein concentration in feed or the feed flow rate was doubled, the amino acid fermentation pathways were found to occur predominantly by only one pathway. Although the choice of Stickland reactions over uncoupled degradation provided good comparisons, an electron balance showed that only about 40% of the amino acids could have proceeded coupled to other amino acid reactions. Uncoupled degradation of the remaining amino acids must have relied on the uptake of hydrogen produced from these reactions by hydrogen-consuming methane bacteria.

Measurement of bubble size distribution in protein foam fractionation column using capillary probe with photoelectric sensors.

Bubble size is a key variable for predicting the ability to separate and concentrate proteins in a foam fractionation process. It is used to characterize not only the bubble-specific interfacial area but also coalescence of bubbles in the foam phase. This article describes the development of a photoelectric method for measuring the bubble size distribution in both bubble and foam columns for concentrating proteins. The method uses a vacuum to withdraw a stream of gas-liquid dispersion from the bubble or foam column through a capillary tube with a funnel-shaped inlet. The resulting sample bubble cylinders are detected, and their lengths are calculated by using two pairs of infrared photoelectric sensors that are connected with a high-speed data acquisition system controlled by a microcomputer. The bubble size distributions in the bubble column 12 and 1 cm below the interface and in the foam phase 1 cm above the interface are obtained in a continuous foam fractionation process for concentrating ovalbumin. The effects of certain operating conditions such as the feed protein concentration, superficial gas velocity, liquid flow rate, and solution pH are investigated. The results may prove to be helpful in understanding the mechanisms controlling the foam fractionation of proteins.

Microfiltration of Protein Precipitate from Clarified Yeast Cell Homogenate for the Recovery of a Soluble Product

A crossflow microfiltration unit was used to recover the soluble proteins from a protein precipitate suspension prepared from disrupted yeast. The effects of the process parameters transmembrane pressure (TMP), crossflow velocity, and suspension concentration on the permeate flux and transmission (sieving coefficient) of soluble proteins were determined. Flux increased with increasing crossflow velocity and decreasing concentration, and increased with increasing TMP up to a critical value at which the flux became independent of pressure. Protein transmission also increased with increasing crossflow and decreasing concentration, but had a maximum value at a critical TMP, near the critical value for flux, and declined at higher pressures. A simple analysis based on film theory indicated that the pattern of variation in measured transmission (i.e., permeate protein concentration divided by feed protein concentration) with increasing TMP was due to two competing factors: increasing protein concentration at the membrane surface and decreasing intrinsic transmission (i.e., transmission calculated with respect to the concentration at the membrane surface). Although flux and transmission both increased with decreasing concentration, it was found that an intermediate concentration gave the best rate of soluble protein recovery. Differences were also noted between the transmission of a target enzyme, alcohol dehydrogenase (ADH), and the overall transmission of total soluble protein.

Modeling a protein foam fractionation process.

A simple staged model for the protein foam fractionation process is proposed in this article. This simplified model does not detail the complex foam structure and gas-liquid hydrodynamics in the foam phase but, rather, is built on the conventional theoretical stage concept considering upward bubbles with entrained liquid and downward liquid (drainage) as counter-current flows. To simulate the protein concentration distribution in the liquid along the column by the model, the bubble size and liquid hold-up with respect to the position must be known, as well as the adsorption isotherm of the protein being considered. The model is evaluated for one stage by data from the semibatch foam fractionation of egg albumin and data from the continuous foam fractionation of bovine serum albumin. The effect of two significant variables (superficial gas velocity and feed protein concentration) on enrichment is well predicted by the model, especially for continuous operation and semibatch operation when initial concentration is high.

Continuous foaming for protein recovery: part I. Recovery of beta-casein.

Foam separation is known to have potential for separation of biological molecules with a range of surface activities. A statistical study (factorial design) was carried out to establish the optimum operating conditions for the continuous foam separation of beta-casein. Maximum values of enrichment of beta-casein into the foam phase were found for low levels of initial feed protein concentration, gas flow rate, feed-flow rate, and high foam heights. Maximum values of protein recovery, were generally found at high levels of initial feed protein concentration, gas-flow rate, feed-flow rate, and low foam heights. The highest values obtained for enrichment and separation ratio were 54.7 and 181.3, respectively, with a simultaneous protein recovery of 62%; thus, illustrating the potential effectiveness of this technique. The effect of foaming on protein conformation is also important, and in this study protein structure was analyzed before and after foam separation experiments. Techniques used were: native polyacrylamide gel electrophoresis (PAGE), UV absorbance spectroscopy, circular dichroism, and fluorescence. Native PAGE showed no detectable changes in protein structure. However, absorbance scanning, fluorimetry, and circular dichroism revealed some conformational changes over a range of concentration effects.

Design of affinity membrane bioseparations

AbstractAffinity separations rely on the highly specific binding between a protein in solution and an immobilized ligand to achieve a high degree of protein purification. A mathematical model including convection, diffusion, and rate kinetics is formulated to analyze the design and operation of affinity membrane bioseparation. The model equations are solved by orthogonal collocation method. Danckwerts' boundary conditions are used. The results obtained from model simulation show that the breakthrough of the protein is significantly influenced by Péclet number, feed protein concentration, Ligand number, Damköhler number, membrane thickness, and flow rate. Breakthrough profiles are quantitatively discussed in terms of protein recovery efficiency, ligand utilization efficiency, thickness of unused membrane, and width of the mass transfer zone.

Protein Band Dispersion in Axial and Radial Flow Chromatography

Abstract Radial flow (RF) column configurations have been developed for larger scale production liquid chromatography, with the primary purpose of increasing throughput rates and decreasing trans-bed pressure drops in comparison to conventional axial flow (AF) columns. The RF columns have been quite successful in attaining these two objectives. In this work, we investigated the nature of protein band dispersion in both axial and radial flow chromatography column configurations, utilizing S-200 Sephacryl gel filtration media with bovine serum albumin as the applied protein. The effects of input feed flow rate as well as input feed albumin concentration on the nature of protein band dispersion were studied. Protein band dispersion was quantified by examining the shape of the eluting protein peak and measuring peak height-to-width (HTW) ratio's for the various flow rates and feed concentrations used in the study. Our results indicate that protein dispersion was larger in RF columns as indicated by smaller peak HTW ratio's than those obtained for AF columns, operated at the same flow rates and feed protein concentrations. We also found that moderately increasing the flow rate increased peak HTW ratio's and resulted in sharper peaks for both AF and RF columns.

Dynamic modelling, simulation and control of continuous adsorption recycle extraction

A simple and effective process control scheme to regulate the continuous adsorption recycle extraction of proteins is presented. A dynamic mathematical model, based on unsteady mass balances, is derived and used in the study of the steady state and dynamic behaviour of the system, and to assist in the synthesis of appropriate control schemes. Sensitivity analysis show that performance is strongly affected by the feed flowrate and feed protein concentration. The eluent flowrate is shown to be the most suitable manipulated variable. The protein concentration in the product stream can be successfully controlled using a conventional PI feedback controller, when measurement time delays are not significant (less than 50% of sampling interval). Model-based feedforward compensation further improves performance in those cases where the main disturbances can be measured on-line in the feed stream.

Isolation and purification of protease from human placenta by foam fractionation

The effect of operating parameters like pH, protein concentration, column geometry, and gas flow rate on the separation efficiency of proteolytic enzymes from crude human placental homogenate has been studied in a batch foam column. Purification has been found to be optimum at pH 8.0, close to the isoelectric pH, at which the surface adsorption of the protein on the foam bubbles is maximum. Both purification and recovery varied significantly with total protein concentration. Stable bubble formation was hindered at lower protein concentrations, while extraneous proteins rather than the protease were preferentially adsorbed at higher protein concentrations, decreasing the purification efficiency. Column diameter and column height should be optimized for any specific feed protein concentration and gas flow rate. However, the enrichment ratio was found to decrease with the increase in flow rate. The results indicate that foam fractionation is an effective separation process for recovering valuable biochemicals from biological materials.