Direct Affinity Ligand Immobilization onto Bare Iron Oxide Nanoparticles Enables Efficient Magnetic Separation of Antibodies

Magnetic separation is a promising alternative to chromatography for enhancing the downstream processing (DSP) of monoclonal antibodies (mAbs). However, there is a lack of efficient magnetic particles for successful application. Aiming to fill this gap, we demonstrate the suitability of bare iron oxide nanoparticles (BION) with physical site-directed immobilization of an engineered Protein A affinity ligand (rSpA) as an innovative magnetic material. The rSpA ligand contains a short peptide tag that enables the direct and stable immobilization onto the uncoated BION surface without commonly required laborious particle activation. The resulting BION@rSpA have beneficial characteristics outperforming conventional Protein A-functionalized magnetic particles: a simple, fast, low-cost synthesis, a particle size in the nanometer range with a large effective specific surface area enabling large immunoglobulin G (IgG) binding capacity, and a high magnetophoretic velocity advantageous for fast processing. We further show rapid interactions of IgG with the easily accessible rSpA ligands. The binding of IgG to BION@rSpA is thereby highly selective and not impeded by impurity molecules in perfusion cell culture supernatant. Regarding the subsequent acidic IgG elution from BION@rSpA@IgG, we observed a hampering pH increase caused by the protonation of large iron oxide surfaces after concentrating the particles in 100 mM sodium acetate buffer. However, the pH can be stabilized by adding 50 mM glycine to the elution buffer, resulting in recoveries above 85% even at high particle concentrations. Our work shows that BION@rSpA enable efficient magnetic mAb separation and could help to overcome emerging bottlenecks in DSP.

Colloidal gas aphrons for biotechnology applications: a mini review

Colloidal gas aphrons (CGAs) are highly stable, spherical, micrometer-sized bubbles encapsulated by surfactant multilayers. They have several intriguing properties, including: high stability, large interfacial area, and the ability to maintain the same charge as their parent molecules. The physical properties of CGAs make them ideal for biotechnological applications such as the recovery of a variety of: biomolecules, particularly proteins, yeast, enzymes, and microalgae. In this review, the bio-application of CGAs for the recovery of natural components is presented, as well as: experimental results, technical challenges, and critical research directions for the future. Experimental results from the literature showed that the recovery of biomolecules was mainly determined by electrostatic or hydrophobic interactions between polyphenols and proteins (lysozyme, β-casein, β-lactoglobulin, etc.), yeast, biological molecules (gallic acid and norbixin), and microalgae with CGAs. Knowledge transfer is essential for commercializing CGA-based bio-product recovery, which will be recognized as a viable technology in the future.

Compositional Attributes of Blue Lupin (Lupinus angustifolius) Seeds for Selection of High-Protein Cultivars

Lupin is a promising protein source with a high protein concentration. Breeding efforts have resulted in the development of varieties low in quinolizidine alkaloids. The objective of this work was to evaluate 22 different blue lupin genotypes for a high protein concentration and low content of antinutritional alkaloids. These genotypes were grown under uniform controlled environmental and soil conditions, and the harvested seeds were evaluated for their composition. The low phosphorus content confirmed that the phytic acid presence was low in lupin, especially compared to other legumes. Furthermore, some of the varieties had less than 200 ppm alkaloids. Lupin proteins were rich in leucine and lysine, with the lowest amino acid concentration being methionine. There were significant differences in the protein concentration and recovery. This work demonstrated that an approach for selection of genotypes should be based on not only agronomic yields but also nutritional phenotypes, driving better decision making on future varietal selection.

The Emulsion Properties of Chicken Liver Protein Recovered through Isoelectric Solubilization/Precipitation Processes

This study investigated the feasibility to improve the emulsifying capacity of chicken liver (CL) protein using different isoelectric solubilization/precipitation (ISP) processes. The CL proteins were first solubilized at alkaline pH 10.5, 11.0, 11.5, and 12.0, followed by precipitation at pH 5.0, 5.5, and 6.0, respectively. Fresh CL paste was set as the control (raw). With the increase in solubilization pH, the protein recovery yield increased under the same precipitation pH, and the pH 12.0, 5.5 treatment obtained the highest recovery yield of 82% (p < 0.05), followed by the pH 5.0 precipitation treatments and the pH 12.0, 6.0 treatment. The particle size distribution of D3,2 and D4,3 was smaller for the pH 10.5 (except for the D4,3 of pH 10.5, 5.0) and pH 11.0 solubilization treatments than those of the other treatments (p < 0.05), regardless of precipitation pH. Compared with that of the raw control, the emulsions of the pH 10.5 and pH 11.0 solubilization treatments, and pH 12.0, 6.0 treatment showed good stability. The pH 10.5, 6.0 treatment showed the best emulsification activity, followed by the pH 10.5, 5.5, pH 11.0, 6.0, pH 12.0, 6.0, pH 10.5, 5.0, pH 11.0, 5.5, and pH 11.0, 5.0 treatments, which were uniformly distributed and were stable without the stratification of emulsions. It was concluded that CL protein recovered through suitable ISP showed potential as an emulsifier, and thus expanded the application of CL protein for human consumption.

The Effect of Precipitation pH on Protein Recovery Yield and Emulsifying Properties in the Extraction of Protein from Cold-Pressed Rapeseed Press Cake

Rapeseed is the second most cultivated oilseed after soybean and is mainly used to produce vegetable oil. The by-product rapeseed press cake is rich in high-quality proteins, thus having the possibility of becoming a new plant protein food source. This study aimed to investigate how the precipitation pH affects the protein yield, protein content, and emulsifying properties when industrially cold-pressed rapeseed press cake is used as the starting material. Proteins were extracted under alkaline conditions (pH 10.5) with an extraction coefficient of 52 ± 2% followed by precipitation at various pH (3.0–6.5). The most preferred condition in terms of process efficiency was pH 4.0, which is reflected in the zeta potential results, where the proteins’ net charge was 0 at pH 4.2. pH 4.0 also exhibited the highest protein recovery yield (33 ± 0%) and the highest protein concentration (64 ± 1%, dry basis). Proteins precipitated at pH 6.0–6.5 stabilized emulsions with the smallest initial droplet size, although emulsions stabilized by rapeseed protein precipitated at pH 5.0–6.0 showed the highest emulsion stability at 37 °C for 21 days, with a limited layer of free oil. Overall, emulsion stabilized by protein precipitated at pH 5.0 was the most stable formulation, with no layer of free oil after 21 days of incubation.

Extraction and profiling of proteins in yellow powder from sweet potato starch wastewater using response surface methodology and proteomic approach

Sweet potato starch industry produce generous high soluble solid wastewater containing various biochemicals such as proteins. The wastewater could be spray dried into a product called yellow powder (YP). Proteins in the YP were recovered and profiled in this study. The extraction conditions were optimized on dependent variables of YP material-water ratio, pH, and temperature using response surface methodology (RSM). Maximum protein yield (61.2%) using RSM were observed at a material-water ratio of 50 (mg/L), pH 9.5, and extraction temperature of 30℃. Subsequently, a total of 25 proteins were identified by proteomic analysis, which mainly were sporamins, β-amylase, starch phosphorylase, polyphenol oxidase, and superoxide dismutase. The extraction and profiling of proteins from YP would contribute to a comprehensive utilization and added value of the wastewater produced by sweet potato starch processing industry. PRACTICAL APPLICATION: This study reported the recovery (61.2%) of proteins and protein profile of yellow powder (byproducts) from sweet potato starch wastewater. These information could contribute to the valorization a yellow powder into high-value ingredients.

Protein extraction from catfish byproducts and physicochemical properties of the protein isolates

In order to optimize protein recovery from catfish byproducts by alkaline extraction, the effects of different factors, including particle size, mince-to-water ratio, pH, and extraction time were investigated. It was found that a protein recovery of about 30% could be achieved. Increases in pH (pH 10.5, 11, and 11.5) not only improved protein recovery, but also increased protein denaturation evidenced by decreased solubility, decreased α-helix, increased β-sheet, and increased random coil. The color and texture of gels made from protein isolate were greatly affected by the pH values used for protein extraction. For the gels made from fillet mince, and protein isolates extracted at pH 10.5, 11, and 11.5, the "L" values were 78.96, 60.38, 57.74, and 54.39, the breaking forces were 205, 492, 585, and 458 g, and deformation values were 10.59, 8.07, 6.73, and 5.04 mm, respectively. Electrophoresis revealed protein degradation during alkali-aided extraction with MHC, the most predominant band, showing about 50% decrease in comparison with fillet mince. It also demonstrated that gelation not only caused cross-linking, but also autolysis with 53%, 56%, 59%, and 81% decrease in MHC intensity for fillet mince, protein isolates extracted at pH 10.5, 11, and 11.5, respectively. Fillet mince and protein isolates exhibited different storage modulus patterns during temperature sweep, implying different gelation mechanisms. This study proved the protein extracted from catfish byproducts was potential to be utilized as edible food components especially in gel making. PRACTICAL APPLICATION: Catfish byproducts, which account for 70% of total weight and 50% of total protein of catfish, are normally used as animal feed, fertilizer, or even waste. This study demonstrated the potential of the utilization of catfish wastes to develop edible food components. This could reduce the total processing waste being discarded into the environment and nutrient loss, therefore increasing profitability of catfish industry.

The mineral profile affects the coagulation pattern and cheese-making efficiency of bovine milk

Natural variations in milk minerals, their relationships, and their associations with the coagulation process and cheese-making traits present an opportunity for the differentiation of milk destined for high-quality natural products, such as traditional specialties or Protected Designation of Origin (PDO) cheeses. The aim of this study was to quantify the effects of the native contents of Ca, P, Na, K, and Mg on 18 traits describing traditional milk coagulation properties (MCP), curd firming over time (CF_t) equation parameters, cheese yield (CY) measures, and nutrient recoveries in the curd (REC) using models that either included or omitted the simultaneous effects of milk fat and casein contents. The results showed that, by including milk fat and casein and the minerals in the statistical model, we were able to determine the specific effects of each mineral on coagulation and cheese-making efficiency. In general, about two-thirds of the apparent effects of the minerals on MCP and the CF_t equation parameters are actually mediated by their association with milk composition, especially casein content, whereas only one-third of the effects are direct and independent of milk composition. In the case of cheese-making traits, the effects of the minerals were mediated only negligibly by their association with milk composition. High Ca content had a positive effect on the coagulation pattern and cheese-making traits, favoring water retention in the curd in particular. Phosphorus positively affected the cheese-making traits in that it was associated with an increase in CY in terms of curd solids, and in all the nutrient recovery traits. However, a very high P content in milk was associated with lower fat recovery in the curd. The variation in the Na content in milk only mildly affected coagulation, whereas with regard to cheese-making, protein recovery was negatively associated with high concentrations of this mineral. Potassium seemed not to be actively involved in coagulation and the cheese-making process. Magnesium content tended to slow coagulation and reduce CY measures. Further studies on the relationships of minerals with casein and protein fractions could deepen our knowledge of the role of all minerals in coagulation and the cheese-making process.

Optimal Production of Protein Hydrolysates from Monkfish By-Products: Chemical Features and Associated Biological Activities

The aim of this work was the recovery of protein substrates from monkfish waste (heads and viscera) generated in the on-board processing of this species. Initially, the effect of pH, temperature, and protease concentration was studied on mixtures of a 1:1 ratio (w/v) of monkfish heads/water. The optimal conditions of proteolytic digestion were established at 57.4 °C, pH 8.31, [Alcalase] = 0.05% (v/w) for 3 h of hydrolysis. Later on, a set of hydrolysis at 5L-pH-stat reactor were run under the aforementioned conditions, confirming the validity of the optimization studies for the head and viscera of monkfish. Regarding the chemical properties of the fish protein hydrolysates (FPH), the yield of digestion was higher than 90% in both cases and the degrees of hydrolysis and the soluble protein content were not especially large (<20% and <45 g/L, respectively). In vitro digestibility was higher than 90% and the percentage of essential amino acids ranged from 40 to 42%. Antioxidant activities were higher in viscera FPH, and antihypertensive ability was superior in head FPH. The values of number average molecular weights (Mn) of monkfish hydrolysates were 600 Da in the viscera and 947 Da in the head. The peptide size distribution, obtained by size-exclusion chromatography, indicated that the largest presence of peptides below 1000 Da and 200 Da was observed in the viscera FPH.

Nitrogen-to-Protein Conversion Factors for Edible Insects on the Swiss Market: T. molitor, A. domesticus, and L. migratoria

With an increasing worldwide demand for animal protein, insects are becoming a promising sustainable option for meat protein replacement. However, reported protein contents of insects are often overestimated when calculated as "crude protein" = 6.25 × nitrogen content (N), compared to true protein contents quantified from the sum of amino acid (AA) residues. In this study, the main two types of usual nitrogen-to-protein conversion factors k p and k A were determined on the basis of true protein/total nitrogen and true protein/protein nitrogen, respectively, with focus on the three insect species legally sold on the Swiss food market. T. molitor (mealworm larvae), A. domesticus (house crickets), and L. migratoria (locusts) from various breeders were analyzed for total and amide nitrogen, chitin, and AA composition. Careful control experiments of insect samples spiked with a protein standard were conducted to establish the recovery of true protein, which was with >95% excellent. Mealworms, crickets, and locusts exhibited similar AA-profiles and true protein contents of 51, 55, and 47 g/100 g (dry weight basis), respectively. Specific conversion factors k p showed little variability between the three insect species with 5.41, 5.25, and 5.33 for mealworms, crickets, and locusts, respectively, and confirmed an average ~17% overestimation of protein contents when using 6.25 × N. The determined average k p of 5.33 is supported by extracted literature data and is suggested for general use instead of 6.25 × N to calculate more accurate insect protein contents, whereas the average pure protein conversion factor k A of 5.6 is proposed for use in the case of insect protein isolates.

Emulsifying and Anti-Oxidative Properties of Proteins Extracted from Industrially Cold-Pressed Rapeseed Press-Cake

One of the functional proteins in rapeseed—the amphiphilic protein oleosin—could be used to stabilize emulsions. The objectives of this study were to extract oleosins from cold-pressed rapeseed press-cake, optimize the extraction process, and investigate their emulsifying and anti-oxidative capacity. The proteins were recovered from industrially cold-pressed rapeseed press-cake at different alkali pHs. Emulsifying properties and oxidation rates were assessed. Oleosin extracted at pH 9 stabilized smaller emulsion droplets than oleosin extracted at pH 12, although the protein yield was higher at pH 12. Emulsions were formulated from flaxseed oil and corn oil and were stabilized by oleosin, bovine serum albumin, de-oiled lecithin and Tween 20 h and the emulsions were stored in accelerated conditions (30 °C) for 12 days. Oleosin stabilized emulsions to the same extent as commercial food-grade emulsifiers. Flaxseed oil emulsions stabilized by oleosin had a significantly lower concentration of malondialdehyde (MDA) which indicates a lower oxidation rate compared to BSA, de-oiled lecithin and Tween 20. For corn oil emulsions, oleosin and BSA had a similar capacity to delay oxidation and were significantly more efficient compared to de-oiled lecithin and Tween 20. Rapeseed oleosin recovered from cold-pressed rapeseed press-cake could be a suitable natural emulsifier with anti-oxidation properties.

The Effects of Oil Extraction Methods on Recovery Yield and Emulsifying Properties of Proteins from Rapeseed Meal and Press Cake

The agricultural sector is thought to be responsible for around 30% of the anthropogenic climate change and it is well established that high meat consumption has a tremendous impact on the environment. Rapeseed is mainly used for production of vegetable oil, but press cake has high protein content with the potential for incorporation into new plant protein-based foods. Protein was recovered from press cakes generated from different oil pressing processes. Industrially cold-pressed, hot-pressed, and solvent-extracted rapeseed press cake and the effect of heat treatment in the recovery process was assessed. Protein recovery yield, protein concentration and emulsifying properties were analyzed. Cold-pressed rapeseed press cake (RPC) recovered in the absence of heat, yielded the highest protein recovery (45%) followed by hot-pressed rapeseed meal (RM) (26%) and solvent-extracted RM (5%). Exposure to heat during recovery significantly reduced the yield for cold-pressed RPC but no difference was found for hot-pressed RM. The protein recovery yield was improved for solvent-extracted RM when heat was applied in the recovery process. The ability to stabilize emulsions was highest for protein recovered from cold-pressed RPC, followed by hot-pressed RM and solvent-extracted RM, and was in the same range as commercial emulsifying agents. Heat treatment during recovery significantly reduced the emulsifying properties for all pressing methods examined. This study suggests that cold-pressed rapeseed press cake without heat in the recovery process could be a successful strategy for an efficient recovery of rapeseed protein with good emulsifying properties.

High sensitivity LC-MS profiling of antibody-drug conjugates with difluoroacetic acid ion pairing

Reversed-phase liquid chromatography (RPLC) separations of proteins using optical detection generally use trifluoroacetic acid (TFA) because it is a strong, hydrophobic acid and a very effective ion-pairing agent for minimizing chromatographic secondary interactions. Conversely and in order to avoid ion suppression, analyses entailing mass spectrometry (MS) detection is often performed with a weaker ion-pairing modifier, like formic acid (FA), but resolution quality may be reduced. To gain both the chromatographic advantages of TFA and the enhanced MS sensitivity of FA, we explored the use of an alternative acid, difluoroacetic acid (DFA). This acid modifier is less acidic and less hydrophobic than TFA and is believed to advantageously affect the surface tension of electrospray droplets. Thus, it is possible to increase MS sensitivity threefold by replacing TFA with DFA. Moreover, we have observed DFA ion pairing to concomitantly produce higher chromatographic resolution than FA and even TFA. For this reason, we prepared and used MS-quality DFA in place of FA and TFA in separations involving IdeS digested, reduced NIST mAb and a proprietary antibody-drug conjugate (ADC), aiming to increase sensitivity, resolution and protein recovery. The resulting method using DFA was qualified and applied to two other ADCs and gave heightened sensitivity, resolution and protein recovery versus analyses using TFA. This new method, based on a purified, trace metal free DFA, can potentially become a state-of-the-art liquid chromatography-MS technique for the deep characterization of ADCs.

Optimization of protein extraction from Chlorella Vulgaris via novel sugaring-out assisted liquid biphasic electric flotation system

Microalgae biomass has been consumed as animal feed, fish feed and in human diet due to its high nutritional value. In this experiment, microalgae specie of Chlorella Vulgaris FSP-E was utilized for protein extraction via simple sugaring-out assisted liquid biphasic electric flotation system. The external electric force provided to the two-phase system assists in disruption of rigid microalgae cell wall and releases the contents of microalgae cell. This experiment manipulates various parameters to optimize the set-up. The liquid biphasic electric flotation set-up is compared with a control liquid biphasic flotation experiment without the electric field supply. The optimized separation efficiency of the liquid biphasic electric flotation system was 73.999 ± 0.739% and protein recovery of 69.665 ± 0.862% compared with liquid biphasic flotation, the separation efficiency was 61.584 ± 0.360% and protein recovery was 48.779 ± 0.480%. The separation efficiency and protein recovery for 5 × time scaled-up system was observed at 52.871 ± 1.236% and 73.294 ± 0.701%. The integration of simultaneous cell-disruption and protein extraction ensures high yield of protein from microalgae. This integrated method for protein extraction from microalgae demonstrated its potential and further research can lead this technology to commercialization.

Effects of Number of Washes and Salt Treatment on the Quality Characteristics of Protein Recovered from Alaska Pollock and Pork Leg

The aim of this study was to compare the effects of number of washes and salt addition on the meat quality in protein recovered from Alaska Pollock compared with pork leg. Various properties of protein recovered from Alaska Pollock (C, washed twice, no salt) and pork leg (T1, washed twice, no salt; T2, two washes, salt added; T3, washed four times, no salt; and T4, washed four times, salt added) were assessed in this study. Pork leg samples exhibited better color (more whiteness, less yellowness) than Alaska Pollock samples. In pork leg samples, four washes (T3, T4) during processing yielded whiter, less yellow protein than two washes (T1, T2). Overall, the textural property measures were higher in pork leg samples (T2, T3, and T4) than in other samples. Breaking force, jelly strength, and folding resistance were significantly higher in salt-treated pork leg samples (T2, T4) than in the other samples. Our findings demonstrate that protein recovered from pork leg has better color parameters, and physical strength compared with Alaska Pollock-derived protein. A higher number of wash steps and treatment with salt during processing were furthermore found to yield better color, and physical strength in the protein samples.

Effect of goat milk composition on cheesemaking traits and daily cheese production

Cheese yield is strongly influenced by the composition of milk, especially fat and protein contents, and by the efficiency of the recovery of each milk component in the curd. The real effect of milk composition on cheesemaking ability of goat milk is still unknown. The aims of this study were to quantify the effects of milk composition; namely, fat, protein, and casein contents, on milk nutrient recovery in the curd, cheese yield, and average daily yield. Individual milk samples were collected from 560 goats of 6 different breeds. Each sample was analyzed in duplicate using the 9-laboratory milk cheesemaking assessment, a laboratory method that mimicked cheesemaking procedures, with milk heating, rennet addition, coagulation, curd cutting, and draining. Data were submitted to statistical analysis; results showed that the increase of milk fat content was associated with a large improvement of cheese yield because of the higher recovery of all milk nutrients in the curd, and thus a higher individual daily cheese yield. The increase of milk protein content affected the recovery of fat, total solids, and energy in the curd. Casein number, calculated as casein-to-protein ratio, did not affect protein recovery but strongly influenced the recovery of fat, showing a curvilinear pattern and the most favorable data for the intermediate values of casein number. In conclusion, increased fat and protein contents in the milk had an effect on cheese yield not only for the greater quantity of nutrients available but also for the improved efficiency of the recovery in the curd of all nutrients. These results are useful to improve knowledge on cheesemaking processes in the caprine dairy industry.

Nutritional Quality and Physical Characteristics of Soluble Proteins Recovered from Silver Carp

The objective of this study was to evaluate the nutritional quality and physical characteristics of soluble proteins separated from silver carp at 4, 20, and 40 °C. Ground silver carp was diluted, and soluble proteins were separated by centrifugation and dried. The proximate composition (dry wt) of the protein powders averaged 82.42% protein, 3.25% lipid, and 14.50% ash. Average protein recovery yield was 11.78% with the better yields occurring at 20 °C (P < 0.05). Mineral profile revealed greater concentrations of Fe, Mg, P, and Na when compared to the initial homogenate. More saturated and monounsaturated fatty acids were recovered in the 4 °C powder and the least in the 40 °C powder (P < 0.05). Polyunsaturated fatty acids displayed a reverse trend, with the greatest concentration in the 40 °C powder and the least in the 4 °C powder (P < 0.05). The amino acid profile revealed that the protein powder met all FAO/WHO/UNO amino acid requirements for adults. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed high amounts of low and medium molecular weight (MW) proteins (10-15 and 25-50 kDa, respectively). Two-dimensional (2-D) electrophoresis indicated that the low MW proteins possessed a neutral isoelectric point relative to that of the medium MW proteins. The protein powder was significantly less soluble (P < 0.05) than whey protein concentrate 80 at every pH tested (pH 3.0 to 11.0). Similar tendencies were seen when ionic strength was shifted (0.0 to 1.1 I; P < 0.05). Soluble protein powders derived from silver carp are nutrient rich and have physical characteristics resembling whey protein concentrate. Changes in process temperature had limited effects on protein powder composition.

PRACTICAL APPLICATION

Soluble proteins contribute to 20 to 40% of fish protein and are soluble in neutral salt solutions. Much of the sarcoplasmic proteins are lost when they solubilize in processing water and are discarded similarly to how whey protein was once discarded during dairy processing. When government regulations on whey disposal were implemented, the dairy industry responded by repurposing the high-quality protein for human use and it is now a billion dollar industry. The aim of this research project was to verify the composition of an otherwise overlooked protein source.

Utilization of Slaughterhouse Waste in Value-Added Applications: Recent Advances in the Development of Wood Adhesives

Globally, slaughterhouses generate large volumes of animal byproducts. While these byproducts are an important resource of industrial protein that could potentially be utilized in various value-added applications, they are currently either underutilized in high-value applications or being used for production of relatively low-value products such as animal feed and pet food. Furthermore, some of the byproducts of animal slaughtering cannot enter food and feed chains and thus their disposal possesses a serious environmental concern. An innovative utilization of the proteinaceous waste generated by slaughterhouses comprises of waste processing to extract proteins, which are then incorporated into industrial processes to produce value-added bio-based products. In this report, we review the current processes for extraction of protein from proteinaceous waste of slaughterhouses, and utilization of the recovered protein in the development of protein-based wood adhesives.

Calcium hydroxide as a processing base in alkali-aided pH-shift protein recovery process

BACKGROUND

Protein may be recovered by using pH shifts to solubilize and precipitate protein. Typically, sodium hydroxide is used as the processing base; however, this has been shown to significantly increase sodium in the final recovered protein.

RESULTS

Protein was extracted from black bullhead catfish (Ameiurus melas) using a pH-shift method. Protein was solubilized using either sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)₂ ) and precipitated at pH 5.5 using hydrochloric acid (HCl). Protein solubility was greater when Ca(OH)₂ was used compared to NaOH during this process. Using Ca(OH)₂ as the processing base yielded the greatest lipid recovery (P < 0.05) at 77 g 100 g^-1 , whereas the greatest (P < 0.05) protein recovery yield was recorded as 53 g 100 g^-1 protein using NaOH. Protein solubilized with Ca(OH)₂ had more (P < 0.05) calcium in the protein fraction, whereas using NaOH increased (P < 0.05) sodium content.

CONCLUSION

Results of our study showed that protein solubility was increased and the recovered protein had significantly more calcium when Ca(OH)₂ was used as the processing base. Results showed both NaOH and Ca(OH)₂ to be an effective processing base for pH-shift protein recovery processes. © 2016 Society of Chemical Industry.

Plasma-Treated Microplates with Enhanced Protein Recoveries and Minimized Extractables

SiO₂ Medical Products, Inc. (SiO) has developed a proprietary technology that greatly enhances protein recoveries and reduces extractables from commercial microplates used for bioanalytical assays and storage of biologics. SiO technology is based on plasma treatment that chemically modifies the surface of polypropylene with predominantly hydrogen-bond-acceptor uncharged polar groups. The resultant surface resists nonspecific protein adsorption over a wide range of protein concentrations, thereby eliminating the need to passivate (and hence potentially contaminate) the microplates with blocking proteins. High shelf-life stability and cleanliness of the plasma-treated microplates have been demonstrated using five different proteins for two common microplate formats. The protein recovery performance of plasma-treated microplates is found to be higher compared with commercial low-protein-binding microplates.

A Systematic Approach to the Comparison of Cost Efficiency of Endopeptidases for the Hydrolysis of Atlantic Salmon (Salmo salar) By-Products

The hydrolytic and cost efficiencies of five endopeptidases (Alcalase 2.4L, Corolase 7089, Neutrase 0.8L, Promod 671L and Protex 7L) to hydrolyze Atlantic salmon by-products were compared at standardized activity levels based on a casein assay. The substrate was characterized prior to the hydrolytic experiments (pH=6.5, t=50 °C) to obtain substrate--specific constants for nitrogen to protein mass (in g) ratio, i.e. conversion factor f_N=5.23 and total amount of peptide bonds (h_tot)=9.3 mmol per g of protein. At low enzyme activity to substrate ratio, all enzymes were equally efficient in hydrolyzing the substrate. At highest enzyme activity to substrate ratio, Protex 7L, Alcalase 2.4L and Promod 671L gave higher degree of hydrolysis (DH=14.2-14.6%) than Corolase 7089 (13.2%) and Neutrase 0.8L (11.6%) after 120 min of hydrolysis. No differences were observed in protein recovery (yield of solubilized protein) relative to DH. Determination of DH was followed by the pH-STAT and o-phthaldialdehyde methods. Based on pH-STAT data, response surface regression models were established based on the combined effects of hydrolysis time and enzyme activity to substrate ratio on DH and protein recovery. The modelling approach was combined with enzyme cost to identify the most cost-efficient enzyme (Protex 7L).

pH shift protein recovery with organic acids on texture and color of cooked gels

BACKGROUND

Isoelectric solubilization and precipitation (ISP) processing uses pH shifts to separate protein from fish frames, which may increase commercial interest for silver carp. Texture and color properties of gels made from silver carp protein recovered at different pH strategies and organic acid types were compared. ISP was applied to headed gutted silver carp using 10 mol L(-1) sodium hydroxide (NaOH) and either glacial acetic acid (AA) or a (1:1) formic and lactic acid combination (F&L). Protein gels were made with recovered protein and standard functional additives.

RESULTS

Texture profile analysis and the Kramer shear test showed that protein gels made from protein solubilized at basic pH values were firmer, harder, more cohesive, gummier and chewier (P < 0.05) than proteins solubilized under acidic conditions. Acidic solubilization led to whiter (P < 0.05) gels, and using F&L during ISP yielded whiter gels under all treatments (P < 0.05).

CONCLUSION

Gels made from ISP-recovered silver carp protein using organic acids show potential for use as a functional ingredient in restructured foods.

Effect of whey concentration on protein recovery in fresh ovine ricotta cheese

Ricotta cheese, particularly the ovine type, is a typical Italian dairy product obtained by heat-coagulation of the proteins in whey. The aim of this work was to investigate the influence of whey protein concentration, obtained by ultrafiltration, on yield of fresh ovine ricotta cheese. Ricotta cheeses were obtained by thermocoagulation of mixtures with protein content of 1.56, 3.10, 4.16, and 7.09g/100g from the mixing of skim whey and ultrafiltered skim whey. A fat-to-protein ratio of 1.1 (wt/wt) was obtained for all mixtures by adding fresh cream. The initial mixtures, as well as the final ricotta cheeses, were analyzed for their composition and by SDS-PAGE. Protein bands were quantified by QuantityOne software (Bio-Rad, Hercules, CA) and identified by liquid chromatography-tandem mass spectrometry. Significant differences in the composition of the ricotta cheese were observed depending on protein concentration. Particularly, ricotta cheese resulting from the mixture containing 7.09g/100g of protein presented higher moisture (72.88±1.50g/100g) and protein (10.18±0.45g/100g) contents than that prepared from the mixture with 1.56g/100g of protein (69.52±1.75 and 6.70±0.85g/100g, respectively), and fat content was lower in this sample (12.20±1.60g/100g) compared with the other treatments, with mean values between 15.72 and 20.50g/100g. Each protein fraction presented a different behavior during thermocoagulation. In particular, the recovery of β-lactoglobulin and α-lactalbumin in the cheese increased as their content increased in the mixtures. It was concluded that concentrating ovine rennet whey improved the extent of heat-induced protein aggregation during the thermal coagulation process. This resulted in a better recovery of each protein fraction in the product, and in a consequent increase of ricotta cheese yield.

Experimental characterization of next-generation expanded-bed adsorbents for capture of a recombinant protein expressed in high-cell-density yeast fermentation

Expanded-bed adsorption (EBA) can be particularly useful in protein recovery from high-cell-density fermentation broth where conventional methods for harvest and clarification, such as continuous centrifugation and depth filtration, demand long processing times and are associated with high costs. In this work, the use of next-generation high-particle-density EBA adsorbents, including two mixed-mode resins, for the direct capture of a recombinant protein expressed in yeast at high cell densities is evaluated. Using classical experimental approaches and under different conditions (pH, salt, etc.), Langmuir isotherm parameters for these resins are obtained along with pore diffusivity values. Additional batch adsorption studies with Fastline® MabDirect, the resin that demonstrated the highest static binding capacity for the recombinant protein of interest under the conditions evaluated in this study, indicate competitive binding of nontarget proteins and approximately a 30% reduction in equilibrium binding capacity to 50 mg/mL settled bed in the presence of a 5%-10% cell concentration. Packed-bed (PB) dynamic binding capacities for the MabDirect resin (25-40 mg/mL PB) were significantly higher than for the Fastline® HSA resin and for the MabDirect MM resin in expanded-bed mode (5-10 mg/mL settled bed). Bed expansion behavior for the mMabDirect MM resin along with process yield and eluate purity are identified as a function of linear velocity and cell density, demonstrating process feasibility for pilot scale use.