Mayyada M. H. El-Sayed

Trends in whey protein fractionation

Whey is a by-product of cheese manufacture that is normally treated as a waste. However, it contains a mixture of proteins with important nutritional and biological attributes. To extract these valuable proteins, whey fractionation has been developed using three main techniques; namely chromatographic (e.g., ion-exchange and hydrophobic adsorption), membrane (e.g., traditional pressure-driven and electro-separation)-, or combined methods. Recently, new promising techniques have been introduced such as aqueous two-phase separation (ATPS) and magnetic fishing. This article reviews the use of these techniques together with an evaluation of their performance regarding the yield and purity of two major proteins in whey.

Purification of the two major proteins from whey concentrate using a cation‐exchange selective adsorption process

The packed‐bed adsorption and elution of aqueous solutions of whey concentrate powders were investigated at pH 3.7 using a 5‐mL SP Sepharose FF column to separate and isolate two major proteins namely, α‐lactalbumin (ALA) and β‐lactoglobulin (BLG) from these solutions. ALA displaced and eluted BLG from the column in a pure form. Pure ALA could then be eluted with good recovery. A novel consecutive two‐stage separation process was developed to separate ALA and BLG from whey concentrate mixtures. Almost all of the BLG in the feed was recovered, with 78% being recovered at 95% purity and a further 20% at 86% purity. In addition, 67% of ALA was recovered, 48% at 54% purity and 19% at 60% purity.

Assessment of Food Processing and Pharmaceutical Industrial Wastes as Potential Biosorbents: A Review

There is a growing need for the use of low-cost and ecofriendly adsorbents in water/wastewater treatment applications. Conventional adsorbents as well as biosorbents from different natural and agricultural sources have been extensively studied and reviewed. However, there is a lack of reviews on biosorption utilizing industrial wastes, particularly those of food processing and pharmaceuticals. The current review evaluates the potential of these wastes as biosorbents for the removal of some hazardous contaminants. Sources and applications of these biosorbents are presented, while factors affecting biosorption are discussed. Equilibrium, kinetics, and mechanisms of biosorption are also reviewed. In spite of the wide spread application of these biosorbents in the treatment of heavy metals and dyes, more research is required on other classes of pollutants. In addition, further work should be dedicated to studying scaling up of the process and its economic feasibility. More attention should also be given to enhancing mechanical strength, stability, life time, and reproducibility of the biosorbent. Environmental concerns regarding disposal of consumed biosorbents should be addressed by offering feasible biosorbent regeneration or pollutant immobilization options.

Single and two-component cation-exchange adsorption of the two pure major whey proteins

Adsorption of pure alpha-lactalbumin (ALA) and beta-lactoglobulin (BLG) to the cation exchanger SP Sepharose FF was studied at pH 3.7 with the purpose of developing a process for isolating them from whey. Measurement of Langmuir parameters describing adsorption equilibrium in batch experiments and protein breakthrough time values in 1-ml packed-beds at a linear velocity of 158 cm/h and initial concentrations of 3 mg/ml for BLG and 1.5 mg/ml for ALA suggested the feasibility of using this adsorbent to separate the two proteins when present in a mixture. Subsequent experiments with 5-ml columns at the above concentrations and a linear velocity of 30 cm/h confirmed this and showed evidence of competitive adsorption as ALA displaced and eluted all BLG from the column in a pure form, and the remaining ALA could be eluted thereafter at high purity and with 91% recovery.

Confocal microscopy study of uptake kinetics of α-lactalbumin and β-lactoglobulin onto the cation-exchanger SP Sepharose FF

Confocal laser scanning microscopy (CLSM) was used to study single- and two-component protein uptake for alpha-lactalbumin (ALA) and beta-lactoglobulin (BLG), as models for whey proteins, to SP Sepharose FF at pH 3.7 during batch experiments in a finite bath. By coupling a fluorescent dye with the protein molecule, the penetration into individual adsorbent particles at different times during batch uptake was visualised. In a single-component system, BLG penetrated fast into the adsorbent beads and gradually filled them in a shell-wise fashion, while adsorption of ALA was mostly confined to the outer shells of the adsorbent. For the two-component studies, the results showed that ALA was able to displace BLG despite its lower affinity to the adsorbent under the employed conditions. CLSM results were then compared both qualitatively and quantitatively to their counterparts obtained in traditional experiments by indirect measurements of the protein concentration in the fluid phase. A novel quantitative approach was undertaken by modifying the simple kinetic rate model traditionally used to determine the kinetic rate constant, k(1), for batch uptake experiments, in order to describe batch uptake kinetics based on CLSM data. Although BLG results were in good agreement, there was a discrepancy in ALA results.

A quantitative approach for studying the bioactivity of nanohydroxyapatite/gold composites

This work describes a quantitative kinetic approach to assess the in vitro bioactivity of gold-doped hydroxyapatite-polyvinyl alcohol nanocomposites. The surface morphology of the in situ prepared nanocomposites as characterized by transmission electron microscopy (TEM) revealed a rod-like shape. Differential thermal analysis-thermogravimetric (DTA-TG), and fourier transformed infrared spectroscopy (FTIR) as well as zeta potential measurements of the prepared nanocomposites were carried out. Uptake profiles of Ca and P were studied onto nanocomposites of different gold concentrations after their soaking in simulated body fluid and they best followed the pseudo second-order kinetic model. The highest uptakes of both Ca and P were obtained using the nanocomposite with the lowest concentration of gold. Furthermore, sorption mechanism was described by the intraparticle diffusion model where pore diffusion was found to be the rate limiting step. The prepared nanocomposites have promising potential in orthopedic and tissue engineering applications because of their high capacity and fast uptake for Ca and P, which form apatite.

Softening of seawater and desalination brines using grafted polysaccharide hydrogels

AbstractThis paper investigates the potential of using polysaccharide hydrogels as softeners for saline solutions of seawater and reverse osmosis desalination brine. Grafting of acrylamide onto alginate and chitosan was conducted using microwave (MW) and ultraviolet (UV) irradiation techniques. The produced hydrogels: alginate (Alg-UV and Alg-MW) and chitosan (Ch-UV and Ch-MW) were characterized using X-ray diffraction and scanning electron microscopy. Hydrogel products were tested for their swelling behavior in distilled water and saline solutions, and their calcium and magnesium adsorption capacities in the pre-swollen and dry forms were measured in saline solutions. Swelling in distilled water was found to exceed that in saline solutions by 16.7–21-fold. Maximum attained swelling ratios in distilled water were 168 and 173 g/g for Alg-UV and Ch-MW grafted acrylamide hydrogels, respectively. Dry hydrogels had relative selectivity toward calcium adsorption in seawater and magnesium adsorption in brine. Fu...

Toward Separating Alpha‐lactalbumin and Beta‐lactoglobulin Proteins from Whey through Cation‐exchange Adsorption

This paper describes the cation‐exchange adsorption of the two major whey proteins, alpha‐lactalbumin (ALA) and beta‐lactoglobulin (BLG) with the purpose of establishing a process for isolating them from cow’s milk whey. The single‐ and two‐component adsorption of 1.5 mg/ml ALA and 3 mg/ml BLG to the cation‐exchanger SP Sepharose FF at 20° C using 0.1 M acetate buffer of pH 3.7 was studied. Langmuir isotherm parameters were determined for the pure proteins. In two‐component systems, BLG breakthrough curve exhibited an overshoot phenomenon that gave evidence for the presence of a competitive adsorption between the two proteins. Complete separation occurred and it was possible to obtain each of the two proteins in a pure form. The process was then applied to a whey concentrate mixture where incomplete separation took place. However, BLG was produced with 95% purity and a recovery of 80%, while ALA showed an 84% recovery with low purity.

Small/medium nuclear reactors for potential desalination applications : Mini review

Small/medium nuclear reactors (SMRs) are a promising alternative for powering large scale desalination plants. The modern generations of these systems manifest cost effectiveness and built-in safety features. The compatibility with geological and topological challenges is an added advantage. Moreover, funding opportunities and packages could be easily arranged for small/medium nuclear reactors (SMR). This mini review article provides the latest technical features of SMR nuclear plants with emphasis on pressurized light water reactors (PWR), boiling water reactors (BWR), heavy water reactors (HWR), gas cooled reactors (GCR), and liquid metal fast breeder reactors (LMFBR). Preliminary cost indicators for typical units were investigated as a part of joint effort to develop a cost database for these types of reactors. Security and safety features of small/medium reactors are identified and reviewed. This paper identifies and briefly discusses the various types of small/medium nuclear reactors to provide a preliminary evaluation and consideration of using this type of reactor in potential seawater desalination applications.

Chapter 9 – Assessment of the State-of the-Art Developments in the Extraction of Antioxidants From Marine Algal Species

Abstract There is a current increasing demand for antioxidants in food, pharmaceutical, and medical applications. Bioactive compounds, particularly sulfated polysaccharides (SPs) extracted from marine algal species were found to exhibit remarkable antioxidant activities. Various extraction methods have been reported in this regard, including conventional, as well as modern techniques, such as ultrasonic-, microwave-, and enzyme-assisted extraction. These were conducted using different solvents and under varying operating conditions of temperature, time, and solvent to substrate ratio. In this review, we critically assess the state-of-the-art methods for extracting antioxidants with emphasis on SPs, from green, red, and brown algae. The evaluation will be primarily based on the yields and antioxidant activities of the extracted SPs, in addition to other technical, economic, and environmental criteria.