Effects of multiple-stage membrane process designs on the achievable performance of automatic control

There is limited information from literature on the dynamic operability of membrane processes with multiple stages or loops. Such information is useful for assessing the performance achievable by an automatic controller proposed for a process design before the actual controller is implemented. Based on dynamic modeling of an industrial whey ultrafiltration process with an increasing number of stages up to a maximum of 12, the dynamic responses of the flowrate and concentration of the retentate were obtained. Features of the dynamic responses were used to determine the performance, in terms of quality and speed, that can be achieved by automatic controllers. In particular, limitations on the performance are indicated by features of dynamic responses such as effective time delay and inverse responses. Changes in effective time delay and inverse responses with the number of stages in the whey ultrafiltration process demonstrate a trade-off between process performance and control performance. This trade-off should be considered during process and controller design to maximize the economic return from the production of whey protein concentrates.     

Influence of reaction medium composition on enzymatic synthesis of galactooligosaccharides and lactulose from lactose concentrates prepared from whey permeate

The paper presents the results of investigations into the technological possibilities of controlling the transgalactosylation process of lactose in permeate after whey ultrafiltration in order to improve the efficiency of galactooligosaccharides or lactulose synthesis. The synthesis efficiency was influenced by the selection of a β-galactosidase preparation, substrate concentration and, in the synthesis of lactulose, also by the ratio of lactose and fructose added to the reaction mixture. The obtained synthesis efficiency of GOS and, most of all, of lactulose (65 g L⁻¹), may be found satisfactory. The study also resulted in a proposed GOS or lactulose concentrates (concentrated or dried) production technology using permeate after ultrafiltration of milk or whey as lactose sources. Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May 2008.     

Multiple reaction monitoring-based determination of bovine α-lactalbumin in infant formulas and whey protein concentrates by ultra-high performance liquid chromatography–tandem mass spectrometry using tryptic signature peptides and synthetic peptide standards

The determination of α-lactalbumin in various dairy products attracts wide attention in multidiscipline fields because of its nutritional and biological functions. In the present study, we quantified the bovine α-lactalbumin in various infant formulas and whey protein concentrates using ultra-high performance liquid chromatography coupled to tandem mass spectrometer in multiple reaction monitoring mode. Bovine α-lactalbumin was quantified by employing the synthetic internal standard based on the molar equivalent relationship among the internal standard, bovine α-lactalbumin and their signature peptides. This study especially focused on the recovery rates of the sample preparation procedure and robust quantification of total bovine α-lactalbumin in its native and thermally denatured form with a synthetic internal standard KILDKVGINNYWLAHKALCSE. The observed recovery rates of bovine α-lactalbumin ranged from 95.8 to 100.6% and the reproducibility was excellent (RSD < 6%) at different spiking levels. The limit of quantitation is 10 mg/100 g for infant formulas and whey protein concentrates. In order to validate the applicability of the method, 21 brands of infant formulas were analyzed. The acquired contents of bovine α-lactalbumin were 0.67–1.84 g/100 g in these infant formulas in agreement with their label claimed values. The experiment of heat treatment time showed that the loss of native α-lactalbumin enhanced with an increasing intensity of heat treatment. Comparing with Ren's previous method by analysis of only native bovine α-lactalbumin, the present method at the peptide level proved to be highly suitable for measuring bovine α-lactalbumin in infant formulas and whey protein concentrates, avoiding forgoing the thermally induced denatured α-lactalbumin caused by the technological processing.     

Use of membrane processing to concentrate TGF-β2 and IGF-I from bovine milk and whey

The aim of this study was to evaluate the potential of using membrane processing such as microfiltration and ultrafiltration to concentrate TGF-β2 and IGF-I from milk and whey. Cheese wheys were obtained from Cheddar and Mozzarella cheeses made from pasteurized or thermized milk. Microfiltered or unheated whey (MF-whey) obtained by microfiltration of raw skim milk was used as control. Important losses of TGF-β2 were observed during clarification of pasteurized cheese wheys by microfiltration using a 1.4 μm pore size membrane. The ratio of IGF-I/TGF-β2 decreased from >3500 to 17 upon concentration of cheese whey by ultrafiltration (UF) and diafiltration (DF). UF concentration of MF-whey showed an increased concentration of TGF-β2 by a 13× factor. Lymphocyte proliferations increased upon MF/UF concentration and reached 25.5% inhibition at a 100 μg/mL concentration for MF-WPI, whereas a maximum of 8.5% of lymphocyte proliferation's inhibition was observed for cheese-WPI. Our results suggest that that UF/DF concentration of MF-whey may be a suitable method to prepare whey protein isolates enriched in TGF-β2 and IGF-I.     

Separation of glycosylated caseinomacropeptide at pilot scale using membrane adsorption in direct-capture mode

A direct-capture anion-exchange membrane adsorption process for the separation of a pure glycosylated (gCMP) fraction of caseinomacropeptide (CMP) was successfully developed at pilot plant scale. The method was evolved using a commercial CMP isolate as feedstock as well as fresh sweet whey from skim milk. The former resulted in a binding capacity (BC) of 0.28 mg gCMP/cm² membrane surface with a purity of 97% while the latter afforded a gCMP fraction with a purity of 91% and a BC of 0.21 mg gCMP/cm² membrane surface. The main difference was a significant fouling of the membrane adsorber module when the whey was applied, which resulted in a loss of 46% BC after at least five loading/elution cycles. This effect was not observed using the pure CMP isolates and indicates a blocking of the ion-exchange ligands. Triglycerides, as detected by lipid analysis, as well as protein aggregates and casein-flocculates, are mainly responsible for the fouling process. The fouling was decreased using microfiltered whey or by increasing the temperature of the adsorption process. Additionally, a method of repeated elution was shown to decrease the volume of the eluate as well as the NaCl consumption of the elution buffer. The process development further included a desalting and concentration step, which was performed by a 10 kDa ultrafiltration/diafiltration (UF/DF). The efficiency of the UF was strongly influenced by the pH of the solutions and showed best performance at pH 4.1 for the eluate. The residual solution had to be adjusted at pH 6.5 as there was a strong decrease of flux at lower pH levels.     

Fractionation of whey-derived peptides using a combination of ultrafiltration and nanofiltration

This paper describes the fractionation and further isolation and characterisation of peptides and proteins present in sweet whey by means of ultrafiltration using a regenerated cellulose membrane with a nominal molar mass cut-off value of 10 kg/mol and nanofiltration through sulphonated polyether sulphone membrane with a cut-off of 1 kg/mol. The concentration of whey proteins was done below the critical flux. The sieving coefficients for the whey components (proteins, lactose and salts) were estimated. Whey proteins were completely rejected by the ultrafiltration membrane. Size exclusion chromatography (SEC) and matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry were used to evaluate the molar masses of the peptide fractions that were present in the whey permeates. Nanofiltration of whey permeates obtained after ultrafiltration was conducted at two pH values (9.5 and 3.0) that corresponded to the different charged states of the membrane and of the peptides. The transmission of peptides, amino acids and lactose was found to be mainly affected by the permeability of the fouling layer. The selectivity of the nanofiltration membranes toward peptides compared to lactose was calculated as 0.82 and 6.81 at pH 9.5 and 3.0, respectively.     

Integrated Downstream Processing of Lactoperoxidase from Milk Whey Involving Aqueous Two-Phase Extraction and Ultrasound-Assisted Ultrafiltration

The present work involves the adoption of an integrated approach for the purification of lactoperoxidase from milk whey by coupling aqueous two-phase extraction (ATPE) with ultrasound-assisted ultrafiltration. The effect of system parameters of ATPE such as type of phase system, polyethylene glycol (PEG) molecular mass, system pH, tie line length and phase volume ratio was evaluated so as to obtain differential partitioning of contaminant proteins and lactoperoxidase in top and bottom phases, respectively. PEG 6000-potassium phosphate system was found to be suitable for the maximum activity recovery of lactoperoxidase 150.70% leading to 2.31-fold purity. Further, concentration and purification of enzyme was attempted using ultrafiltration. The activity recovery and purification factor achieved after ultrafiltration were 149.85% and 3.53-fold, respectively. To optimise productivity and cost-effectiveness of integrated process, influence of ultrasound for the enhancement of permeate flux during ultrafiltration was also investigated. Intermittent use of ultrasound along with stirring (2 min acoustic and 2 min stirring) resulted in increased permeate flux from 0.94 to 2.18 l/m² h in comparison to the ultrafiltration without ultrasound. The use of ultrasound during ultrafiltration resulted in increase in flux, but there was no significant change in activity recovery and purification factor. The integrated approach involving ATPE and ultrafiltration may prove to be a feasible method for the downstream processing of lactoperoxidase from milk whey.     

Focus on the Protein Fraction of Sports Nutrition Supplements

Increasing awareness of balanced diet benefits is boosting the demand for high-protein food and beverages. Sports supplements are often preferred over traditional protein sources to meet the appropriate dietary intake since they are widely available on the market as stable ready-to-eat products. However, the protein components may vary depending on both sources and processing conditions. The protein fraction of five commercial sports supplements was characterized and compared with that of typical industrial ingredients, i.e., whey protein concentrates and isolates and whey powder. The capillary electrophoresis profiles and the amino acid patterns indicated that, in some cases, the protein was extensively glycosylated and the supplemented amino acids did not correspond to those declared on the label by manufacturers. The evaluation by confocal laser scanning microscopy evidenced the presence of large aggregates mainly enforced by covalent crosslinks. The obtained findings suggest that, beside composition figures, provisions regarding sports supplements should also consider quality aspects, and mandatory batch testing of these products would provide more reliable information to sport dieticians.     

A study of oil-in-water emulsions stabilized by whey proteins

Like many other emulsifiers, whey protein concentrates stabilize oil-in-water emulsions. However, the emulsifying capacity of whey proteins is affected by several factors, e. g., type of homogenizer, degree of homogenization, protein concentration, oil volume fraction, pH and ionic strength of the aqueous phase. For the present study, oilin-water emulsions were made by homogenizing known amounts of whey protein concentrate with a vegetable oil (i. e. grapeseed oil) at different pH. The emulsifying properties of whey proteins are expressed as a function of the particle size and size distribution of oil droplets as measured by light scattering, and of the surface charge density derived from the electrophoretic mobility.The whey protein concentrate was shown to have an isoelectric point at pH 4.4. Near this pH value, the oil-in-water emulsions exhibited poor stability as expected from the low surface coverage.     

Capillary Zone Electrophoresis of some organic acids in milk whey

This paper describes a method for analysing some acids of milk whey by Capillary Zone Electrophoresis. After eliminating the whey proteins by ultrafiltration, the whey underwent electrophoretic separation in the presence of anodic electroosmotic flow. The following analytes were detected: citric, orotic, uric, and hippuric acids. A procedure is described for sample preparation and the operating conditions for electrophoretic capillary separation established. Finally, orotic acid is quantitatively determined.     

Constant Cwall ultrafiltration process control

Ultrafiltration processes normally operate with constant transmembrane pressure. The tradition of such control derives from its inherent simplicity. Both fundamental and practical considerations suggest, however, that ultrafiltration processes should be controlled by maintaining a constant wall concentration (C_w) of fully retained solutes. Since protein sieving, solubility, and adsorption losses as well as time and area optimization are dependent on C_w, we investigated a control strategy using constant C_w instead of constant transmembrane pressure. We explored three different strategies for such control and evaluated the theoretical and industrial implications for single solute systems. The effects of solute wall concentration on process time and product yield were also evaluated. Implementation of this technology required the development of a novel methodology for determination of mass transfer coefficients. The use of C_w technology also led to the development of new optimization schemes for both concentration and diafiltration. Industrial scale processes using constant C_w control have been successfully implemented on several recombinant DNA derived human protein pharmaceuticals. Constant C_w control has eliminated variability in process time, enhanced product yields, and provided insurance of tight protein product quality specifications. Optimum process design based on fundamental filtration theory has replaced empirical development procedures.     

Improvement in the Purification Process of the Capsular Polysaccharide from Haemophilus influenzae Type b by Using Tangential Ultrafiltration and Diafiltration

Capsular polysaccharide produced by Haemophilus influenzae b (Hib) is the main virulent agent and used as the antigen in the vaccine formulation. In this study, an improved process of polysaccharide purification was established based on tangential flow ultrafiltration using detergents (cocamidopropyl betaine and sodium deoxycholate), two selective ethanol precipitations steps, and extensive enzymatic hydrolysis as strategy. The relative purity (RP) related to protein and nucleic acids were 122??263 and 294??480, respectively, and compatible with the specifications established by the World Health Organization for Hib vaccine, RP????100. These results make this process simple, cheaper, efficient, environmentally friendly, and prone to be scaled up.     

Fouling during constant flux crossflow microfiltration of pretreated whey. Influence of transmembrane pressure gradient

Pretreatment of whey by microfiltration (MF) has emerged as a necessary step in producing high purity whey protein concentrates. In the MF of pretreated whey using a Carbosep M14 membrane (pore diameter 0.14 μm), proteins and calcium phosphate aggregates were responsible for fouling, which increased according to the “complete blocking” filtration law and accounted for a progressive decrease of the active filtering area. An operating mode with dynamic counter pressure (recirculation of the permeate co-current to the retentate), as opposed to static counter pressure, allowed lower overall fouling, a longer time of operation and better protein recovery because of more evenly distributed fouling along the membrane tube. At shorter times of operation, fouling was greater under higher transmembrane pressure (TP), so that the less fouled areas under lower TP were forced to filter larger volumes and consequently became fouled more rapidly. This involved a movement of the effective filtering area along the membrane tube, as evidenced by the systematic evolution of fouling heterogeneity as measured by infra-red spectroscopy.     

Bovine lactoferrin purification from whey using Yellow HE‐4R as the chromatographic affinity ligand

The worldwide production of whey increases by around 186 million tons each year and it is generally considered as a waste, even when several whey proteins have important economic relevance. For its valorization, inexpensive ligands and integrated chromatography methods need to be developed for specific and low‐cost protein purification. Here, we describe a novel affinity process with the dye Yellow HE‐4R immobilized on Sepharose for bovine lactoferrin purification. This approach based on a low‐cost ligand showed an efficient performance for the recovery and purification of bovine lactoferrin directly from whey, with a yield of 71% and a purification factor of 61.     

Foliar Spray with Pepsin-and Papain-Whey Protein Hydrolysates Promotes the Productivity of Pea Plants Cultivated in Clay Loam Soil

Papain and pepsin-hydrolyzed whey protein (PAH and PEH, respectively) were prepared and characterized for its degree of hydrolysis, chemical constituents (amino acid and peptides) and antioxidant activity. A field experiment was conducted at El Salheya El Gedida City, Sharqia, Egypt, during the seasons 2019 and 2020, to investigate the biological action of the foliar spray of PAH and PEH on the growth and yield of pea plants cultivated in a clay loam soil. Foliar application of the papain and pepsin-hydrolyzed whey protein (PAH and PEH, respectively) at 1000 and 2000 mg/L was applied three times after 25, 35 and 45 days from planting. All protein foliar spray treatments had significant positive effects on the uptake of N, P and K, simultaneously increasing the contents of all the photosynthetic pigments (Chlorophyll a, Chlorophyll b and Carotenoids) in a concentration-dependent manner. The most conspicuous increase was seen in Chlorophyll b (105% increase), followed by Carotenoids (91% increase). Generally, the favorable increases caused by the second level of application (2000 mg/L) were nearly 2–3 times that of the low level (1000 mg/L). Pod growth and formation indicators, e.g., no. of pod/plant, pod length and no. of seeds/pod, responded more evidently to the hydrolyzed than the intact form of whey protein treatments. Hydrolyzed whey protein foliar spray treatments achieved significantly higher increases in the global field yield components of Pisum sativum plants than the intact form, where peptic hydrolysates were significantly superior to papain hydrolysate. The treatment PEH (2000 mg/L) can be recommended as the most effective bio-stimulating foliar spray treatment for higher plant productivity when applied 25, 35 and 45 days after planting.     

Oil-in-water emulsions stabilized by whey protein aggregates: Effect of aggregate size,pH of aggregation and emulsion pH

Oil-in-water emulsions (60% oil (w/w)) were prepared using whey protein aggregates as the sole emulsifying agent. The effects of whey protein aggregate size (the diameter between 0.92 and 10.9?µm), the pH of emulsions (4–8.6) and storage time on physical properties, droplet size, and stability of emulsions were investigated. The results indicate that increment of whey protein aggregate size caused an increase in the firmness, droplet size, and viscosity of emulsions, and also a decrease in the emulsion creaming. The emulsion viscosity, firmness, and droplet size were reduced by increasing the emulsion pH; however, the creaming process was accelerated. Viscosity, creaming, and droplet size of emulsions were increased slightly during 21 days storage at 40°C.     

The relationship between membrane cleaning efficiency and water quality

Impurities such as particulates and some dissolved salts present in the water used for cleaning of a polysulphone ultrafiltration membrane have been found to affect the efficiency of the cleaning. A cationic surfactant, CTAB (cetyl-trimethyl-ammonium bromide), was used for membrane cleaning after ultrafiltration of a 0.1 wt% reconstituted whey protein solution. Colloidal-free water used for cleaning was doped with a known amount of the ions: calcium, sodium, chloride, nitrate and sulphate. The presence of calcium in water, at the usual concentrations found in tap water, did not greatly affect cleaning efficiency while chloride was found to reduce cleaning efficiency. Sodium, nitrate and sulphate appeared to improve the flux recovery during membrane cleaning. The cleaning efficiency was also improved at higher ionic strengths. Calculations were carried out to demonstrate that the differences were statistically significant.     

Comparison of digestibility and quality of intact proteins with their respective hydrolysates

Quality of proteins depends on their composition in essential amino acids and on the availability of amino acids. Great interest has been shown in the role played by hydrolysates of proteins in clinical diets for pathologies with reduced absorptive capacity and food allergies caused by intact protein epitopes. Milk proteins are the most important protein source used in the development of protein hydrolysates designed for nutritional support of patients. Several studies have shown that casein and whey hydrolysates have a composition in amino acids equivalent to that in native milk proteins and that digestibility is similar or better. Among plant proteins, soy is the major source of hydrolysates. Soy hydrolysates are also used in infant formulas. Plant hydrolysates have good functional properties and a nutritional quality similar to that of starting material. Some technical improvements in production of hydrolysates, particularly for plants, are nevertheless necessary to improve product palatability.     

Dynamic modelling of milk ultrafiltration by artificial neural network

Artificial neural networks (ANNs) have been used to dynamically model crossflow ultrafiltration of milk. It aims to predict permeate flux, total hydraulic resistance and the milk components rejection (protein, fat, lactose, ash and total solids) as a function of transmembrane pressure and processing time. Dynamic modelling of ultrafiltration performance of colloidal systems (such as milk) is very important for designing of a new process and better understanding of the present process. Such processes show complex non-linear behaviour due to unknown interactions between compounds of a colloidal system, thus the theoretical approaches were not being able to successfully model the process. In this work, emphasis has been focused on intelligent selection of training data, using few training data points and small network. Also it has been tried to test the ANN ability to predict new data that may not be originally available. Two neural network models were constructed to predict the flux/total resistance and rejection during ultrafiltration of milk. The results showed that there is an excellent agreement between the validation data (not used in training) and modelled data, with average errors less than 1%. Also the trained networks are able to accurately capture the non-linear dynamics of milk ultrafiltration even for a new condition that has not been used in the training process.     

Determination of disialoganglioside GD3 and monosialoganglioside GM3 in infant formulas and whey protein concentrates by ultra-performance liquid chromatography/electrospray ionization tandem mass spectrometry

A method of ultra-performance liquid chromatography combined with electrospray ionization triple quadrupole tandem mass spectrometry (UPLC-ESI-MS/MS) has been established for simultaneous determination of major disialoganglioside 3 (GD3) and monosialoganglioside 3 (GM3) in infant formulas and whey protein concentrates. Gangliosides were extracted by using the technique of Svennerholm and Fredman and then cleaned up with OASIS HLB solid-phase extraction (SPE) cartridges. The various molecular species of gangliosides were separated on an Acquity UPLC BEH C8 column and analyzed under the negative ion mode. GD3 and GM3 were rapidly quantified using internal standard (IS) method. The developed method was further validated by determining the linearity, average recovery, sensitivity (limit of quantification), and precision. The results presented high correlation coefficients (R(2) > 0.993) of the selected 16 gangliosides molecular species and provided the respective linear ranges. The limit of quantification was 0.325-0.734 mg/100 g for eight molecular species of GD3 and 0.008-0.312 mg/100 g for eight molecular species of GM3, respectively. The reasonable average recoveries (81-95%) and precision (relative standard deviation [RSD] ≤15%) were also demonstrated in three different spiked levels. This new method would be very useful in the quantitative determination of gangliosides in infant formulas and whey protein concentrates.