Effect of pH on the fractionation of whey proteins with a ceramic ultrafiltration membrane

A New Method for Growth Factor Enrichment from Dairy Products by Electrodialysis with Filtration Membranes: The Major Impact of Raw Product Pretreatment

This study is focused on fractionation of insulin-like growth factor I (IGF-I) and transforming growth factor-β2 (TGF-β2) using a new electro-based membrane process calledelectrodialysis with filtration membranes (EDFM). Before EDFM, different pretreatments were tested, and four pH conditions (4.25, 3.85, 3.45, and 3.05) were used during EDFM. It was demonstrated that a 1:1 dilution of defatted colostrum with deionized water to decrease mineral content followed by the preconcentration of GFs by UF is necessary and allow for these compounds to migrate to the recovery compartment during EDFM. MS analyses confirmed the migration, in low quantity, of only α-lactalbumin (α-la) and β-lactoglobulin (β-lg) from serocolostrum to the recovery compartment during EDFM. Consequently, the ratio of GFs to total protein in recovery compartment compared to that of feed serocolostrum solution was 60× higher at pH value 3.05, the optimal pH favoring the migration of IGF-I and TGF-β2. Finally, these optimal conditions were tested on acid whey to also demonstrate the feasibility of the proposed process on one of the main by-products of the cheese industry; the ratio of GFs to total protein was 2.7× higher in recovery compartment than in feed acid whey solution, and only α-la migrated. The technology of GF enrichment for different dairy solutions by combining ultrafiltration and electrodialysis technologies was proposed for the first time.

Optimization of fractionation with membranes of antioxidant enzymatic hydrolysate of Californian red worm (Eisenia fetida) protein

Problem

Earthworm is a valuable source of biologically and pharmacologically active compounds, with applications in the treatment of various types of diseases; however, the main application they have been given is in the production of organic fertilizer. One of the alternatives for obtaining bioactive compounds is by means of enzymatic hydrolysis.

Aim

This study proposes the optimization of the fractionation of the antioxidant enzymatic hydrolysate from Californian red worm (Eisenia fetida) protein.

Methodology

For this purpose, the worms were separated and hydrolyzed using the enzyme Alcalase 2.4L for 4000s. The obtained hydrolysate was fractionated by means of a crossflow tangential ultrafiltration system, with a 3 kDa molecular weight cut-off ceramic membrane. A response surface design of the composite central factorial type was implemented to evaluate the effect of pH, transmembrane pressure, and flow factors on the response variables transmission, volume reduction factor (VRF) and permeate flow resistance. The transmissions focused on the antioxidant peptides, measured by three conventional methods such as TEAC, FRAP, ORAC, also known as TTEAC, TFRAP and TORAC, respectively. The evaluated resistances were the total resistance (Rtotal), fouling resistance (Rfouling), and gel resistance (Rgel).

Result

The results showed that the three factors evaluated affect all the response variables either in their linear or quadratic terms or by some interaction. For each response variable, a mathematical model was obtained, with statistical significance and a non-significant lack of adjustment. The models obtained were used for a multi-objective optimization process in which transfers were maximized, and resistances were minimized. The efficiency of the optimum ultrafiltration process was 25 %.

Conclusion

The neutral-alkaline pH is ideal for the ultrafiltration process of bioactive peptides, as it is where the highest transmissions of peptides with antioxidative capacity are found. Under optimal conditions, the 3 kDa membrane permeate was found to exhibit higher antioxidant capacity than the retentate and feed. Based on this, the fraction of less than 3 kDa emerges as a potential multifunctional ingredient, thanks to its antioxidant properties.

Separation Technologies for Whey Protein Fractionation

Whey is a by-product of cheese, casein, and yogurt manufacture. It contains a mixture of proteins that need to be isolated and purified to fully exploit their nutritional and functional characteristics. Protein-enriched fractions and highly purified proteins derived from whey have led to the production of valuable ingredients for many important food and pharmaceutical applications. This article provides a review on the separation principles behind both the commercial and emerging techniques used for whey protein fractionation, as well as the efficacy and limitations of these techniques in isolating and purifying individual whey proteins. The fractionation of whey proteins has mainly been achieved at commercial scale using membrane filtration, resin-based chromatography, and the integration of multiple technologies (e.g., precipitation, membrane filtration, and chromatography). Electromembrane separation and membrane chromatography are two main emerging techniques that have been developed substantially in recent years. Other new techniques such as aqueous two-phase separation and magnetic fishing are also discussed, but only a limited number of studies have reported their application in whey protein fractionation. This review offers useful insights into research directions and technology screening for academic researchers and dairy processors for the production of whey protein fractions with desired nutritional and functional properties.

Recent Advancements of UF-Based Separation for Selective Enrichment of Proteins and Bioactive Peptides—A Review

Proteins are one of the primary building blocks that have significant functional properties to be applied in food and pharmaceutical industries. Proteins could be beneficial in their concentrated products or isolates, of which membrane-based filtration methods such as ultrafiltration (UF) encompass application in broad spectra of protein sources. More importantly, selective enrichment by UF is of immense interest due to the presence of antinutrients that may dominate their perspicuous bioactivities. UF process is primarily obstructed by concentration polarization and fouling; in turn, a trade-off between productivity and selectivity emerges, especially when pure isolates are an ultimate goal. Several factors such as operating conditions and membrane equipment could leverage those pervasive contributions; therefore, UF protocols should be optimized for each unique protein mixture and mode of configuration. For instance, employing charged UF membranes or combining UF membranes with electrodialysis enables efficient separation of proteins with a similar molecular weight, which is hard to achieve by the conventional UF membrane. Meanwhile, some proposed strategies, such as utilizing ultrasonic waves, tuning operating conditions, and modifying membrane surfaces, can effectively mitigate fouling issues. A plethora of advancements in UF, from their membrane material modification to the arrangement of new configurations, contribute to the quest to actualize promising potentials of protein separation by UF, and they are reviewed in this paper.

Whey protein membrane processing methods and membrane fouling mechanism analysis

Whey is a byproduct with nutritional value and high organic and saline content. It is an important source of organic contamination in dairy industry. In this paper, we gave an overview of the current use of membrane materials and membrane processing in cheese whey protein recovery and discussed recent developments in membrane technology. Different types of membranes, such as polymers, ceramic membranes and modification membranes, are used for various purposes, such an increasing permeation flux, reducing membrane fouling, and increasing the protein rejection rate, concentration, fractionation and purification of whey protein. New membrane processing methods and integrated membrane methods to recover whey protein were reviewed. Membrane fouling factors during whey protein ultrafiltration process, which included whey protein conformation, membrane filtration conditions and the interaction between proteins and the membrane surface or pores, were also discussed and analyzed to reveal membrane fouling mechanism.

Optimization of pH, temperature and CaCl2 concentrations for Ricotta cheese production from Buffalo cheese whey using Response Surface Methodology

The recovery of milk constituents from cheese whey is affected by various processing conditions followed during production of Ricotta cheese. The objective of the present investigation was to optimize the temperature (60-90 °C), pH (3-7) and CaCl2 concentration (2·0-6·0 mm) for maximum yield/recovery of milk constituents. The research work was carried out in two phases. In 1st phase, the influence of these processing conditions was evaluated through 20 experiments formulated by central composite design (CCD) keeping the yield as response factor. The results obtained from these experiments were used to optimize processing conditions for maximum yield using response surface methodology (RSM). The three best combinations of processing conditions (90 °C, pH 7, CaCl2 6 mm), (100 °C, pH 5, CaCl2 4 mm) and (75 °C, pH 8·4, CaCl2 4 mm) were exploited in the next phase for Ricotta cheese production from a mixture of Buffalo cheese whey and skim milk (9 : 1) to determine the influence of optimized conditions on the cheese composition. Ricotta cheeses were analyzed for various physicochemical (moisture, fat, protein, lactose, total solids, pH and acidity indicated) parameters during storage of 60 d at 4 ± 2 °C after every 15 d interval. Ricotta cheese prepared at 90 °C, pH 7 and CaCl2 6 mm exhibited the highest cheese yield, proteins and total solids, while high fat content was recorded for cheese processed at 100 °C, pH 5 and 4 mm CaCl2 concentration. A significant storage-related increase in acidity and NPN was recorded for all cheese samples.

Membrane processing technology in the food industry: food processing, wastewater treatment, and effects on physical, microbiological, organoleptic, and nutritional properties of foods

Membrane processing technology (MPT) is increasingly used nowadays in a wide range of applications (demineralization, desalination, stabilization, separation, deacidification, reduction of microbial load, purification, etc.) in food industries. The most frequently applied techniques are electrodialysis (ED), reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF). Several membrane characteristics, such as pore size, flow properties, and the applied hydraulic pressure mainly determine membranes' potential uses. In this review paper the basic membrane techniques, their potential applications in a large number of fields and products towards the food industry, the main advantages and disadvantages of these methods, fouling phenomena as well as their effects on the organoleptic, qualitative, and nutritional value of foods are synoptically described. Some representative examples of traditional and modern membrane applications both in tabular and figural form are also provided.

Cheese whey tangential filtration using tubular mineral membranes

Membrane separation techniques are extensively used in dairy industry both for milk and cheese whey processing. However, cheese whey might still be considered as a problematic waste despite its high content of many valuable substances, such as proteins, lactose or minerals, which can be further used, e.g. in human nutrition, pharmacy or biotechnologies. Another problem, which food technologists have to face, is variable quality, composition and properties of food materials bringing high demands on manufacturing industry. In this paper, filtration kinetics and separation efficiency during purification and fractionation of cheese whey (sweet and salty) from Czech dairies by pilot-plant filtration (Bollene, France) was studied using tubular membranes (Membralox, USA). Various mineral membranes’ cut-offs were tested and all experiments ran in the retentate recycling mode. The obtained mass concentration factors were between 1.9 and 16.5. Steady state fluxes were calculated from the experimental data using a mathematical model. Fine ultrafiltration on a 5 kDa membrane gave steady state fluxes of 14-19 L m

Polyethersulfone/polyacrylonitrile blended ultrafiltration membranes: preparation, morphology and filtration properties

Polyethersulfone (PES)/polyacrylonitrile (PAN) membranes have been paid attention among membrane research subjects. However, very few studies are included in the literature. In our study, asymmetric ultrafiltration (UF) membranes were prepared from blends of PES/PAN with phase inversion method using water as coagulation bath. Polyvinylpyrrolidone (PVP) with Mw of 10,000 Da was used as pore former agent. N,N-dimethylformamide was used as solvent. The effects of different percentage of PVP and PES/PAN composition on morphology and water filtration properties were investigated. Membrane performances were examined using pure water and lake water filtration studies. Performances of pure water were less with the addition of PAN into the PES polymer casting solutions. However, long-term water filtration tests showed that PES/PAN blend membranes anti-fouling properties were much higher than the neat PES membranes. The contact angles of PES/PAN membranes were lower than neat PES membranes because of PAN addition in PES polymer casting solutions. Furthermore, it was found that PES/PAN blend UF membranes' dynamic mechanical analysis properties in terms of Young's modules were less than neat PES membrane because of decreasing amount of PES polymer.

Membrane applications in functional foods and nutraceuticals

The functional foods and nutraceuticals market is growing at a rapid pace. Membrane processing offers several advantages over conventional methods for separation, fractionation, and recovery of those bioactive components. In this review, membrane applications of lipid-, carbohydrate-, and protein-based nutraceuticals and some minor bioactive components have been critically evaluated. Both non-porous and porous membranes were employed for lipid-based nutraceuticals separations. The use of non-porous membranes together with non-aqueous solvents brought about the impact of solution-diffusion theory on transport through membranes. Both organic and inorganic membranes gave encouraging results for the recovery of lipid components with single- and/or multi-stage membrane processing. Two-stage ultrafiltration (UF)-nanofiltration (NF) systems with polymeric membranes provided an efficient approach for the removal of high- and low-molecular weight (MW) unwanted components resulting in higher purity oligosaccharides in the NF retentate. The charged nature of protein-based nutraceutical components had a major effect on their separation. Operating at optimizal pH levels was critical for fractionation, especially for low MW peptide hydrolysates. Processing of minor components such as polyphenols, utilized all types of porous membranes from prefiltration to concentration stages. Coupling of membrane separation and supercritical fluid technologies would combine unique advantages of each process resulting in a novel separation technology offering great potential for the nutraceutical and functional food industry.

Membrane-based techniques for the separation and purification of proteins: an overview

Membrane processes are increasingly reported for various applications in both upstream and downstream technology, such as microfiltration, ultrafiltration, emerging processes as membrane chromatography, high performance tangential flow filtration and electrophoretic membrane contactor. Membrane-based processes are playing critical role in the field of separation/purification of biotechnological products. Membranes became an integral part of biotechnology and improvements in membrane technology are now focused on high resolution of bioproduct. In bioseparation, applications of membrane technologies include protein production/purification, protein-virus separation. This manuscript provides an overview of recent developments and published literature in membrane technology, focusing on special characteristics of the membranes and membrane-based processes that are now used for the production and purification of proteins.