Protein-rich Fraction Research Articles

Effect of heating method on the microbial levels and acrylamide in corn grits and subsequent use as functional ingredient for bread making

Cereal by-products represent abundant and low-cost resources of nutrients. The study is dedicated to the development of a rapid method for the treatment of corn grits to obtain value added ingredients for breadmaking. The infrared irradiation (IR) at 76°C and 90°C and vacuum microwave (VM) heating at 60°C have been applied for stabilization of corn grits. The corn grit particles were fractionated by size and it was found that the particle size fraction significantly (p<0.05) influenced the moisture and protein contents and the level of microbial population. The highest protein contents were found in particles around 0.5mm in diameter. Considerable reduction of microbial contamination by 5 log cycles, however, an increase in acrylamide formation in IR and VM corn grits up to 75.5% and 91.6%, respectively was detected. A medium strength relationship was found between protein content and acrylamide formation in heated samples (r=0.8537). Thermally stabilized protein-rich corn grits fractions were selected for wheat bread enrichment. Evidently, IR treatment was more effective to alter the physicochemical and functional properties of corn grits components. The bread of best quality and higher acceptability has been obtained by using IR heated rich in protein corn products compared to microwave heated.

How extraction method affects the physicochemical and functional properties of chia proteins

Partially defatted chia flour (CF) is a by-product of chia oil production. Here we aimed to determine how the choice of extraction method affects the physicochemical and functional properties of chia proteins. Chemical (chia protein concentrates [CPC1 and CPC2]) and dry fractionation (producing a protein-rich fraction [PRF]) methods were used, and the physicochemical and functional properties of the extracted proteins were tested. The protein content of the tested CF was 36.6%. The protein content of the PRF, CPC1, and CPC2 extracts were 49.7, 70.9 and 74.1% respectively. The chia protein extracts mostly consisted of glutelins. Although the PRF had the lowest protein content of the extracts, it presented good functional properties. The dry fractionation method is simpler than the tested chemical methods. Based on our findings, we propose that the optimal choice of chia extraction method is dependent on the desired product.

Development and characterization of spray-dried chia oil microcapsules using by-products from chia as wall material

This research deals with the characteristics of spray-dried chia oil microcapsules formulated with different wall materials, including new encapsulant agents from chia seed (protein rich fraction, PRF; chia mucilage, Muc). The performance of six different wall materials combinations was studied: sodium caseinate and lactose (NaCas + L), NaCas and maltodextrin (NaCas + Mx), PRF and Mx (PRF + Mx), and each of the previous three with the addition of Muc. The particle size, rheology, and stability of the parent emulsions were analyzed. The characterization of the powders obtained by spray-drying the parent emulsions was carried out by their moisture content, water activity, microencapsulation efficiency, glass transition temperature, morphology, oxidative stability, and dispersibility. Emulsions were reconstituted from the powders at different storage times and analyzed by their particle size and stability. The encapsulation efficiencies were NaCas + L + Muc (96.23 ± 0.40%) ~NaCas + L (95.20 ± 0.42%) > NaCas + Mx + Muc (86.65 ± 0.27%) > NaCas + Mx (71.26 ± 0.06%) > PRF + Mx (57.74 ± 3.49%) ~PRF + Mx + Muc (53.37 ± 0.99%). The addition of Muc significantly improved the ME% in microcapsules with NaCas + Mx. The induction time values (ti) of NaCas + L, PRF + Mx and NaCas + Mx systems were about two, three, and five times higher than that of chia bulk oil, respectively. Thus, the studied wall materials were efficient to protect chia seed oil against the oxidation process.

Peptides from Chia Present Antibacterial Activity and Inhibit Cholesterol Synthesis.

In previous studies, it has not been reported that protein isolated from chia interferes favorably with antibacterial activity, and reduces cholesterol synthesis. The objective of this study was to determine whether commonly used commercial microbial proteases can be utilized to generate chia protein-based antibacterial and hypocholesterolemic hydrolysates/peptides, considering the effects of protein extraction method. Alcalase, Flavourzyme and sequential Alcalase-Flavourzyme were used to produce hydrolysates from chia protein (CF), protein-rich fraction (PRF) and chia protein concentrates (CPC1 and CPC2). These hydrolysates were evaluated for their antimicrobial activity against Gram-positive (G+) and Gram-negative (G-) microorganisms. The protein hydrolysates were purified by ultrafiltration through a membrane with 3kDa nominal molecular weight, for evaluation of hypocholesterolemic activity. An inhibition zone was observed when the hydrolysate was tested against S. aureus, and minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were obtained. Peptides from chia protein with molecular mass lower than 3kDa reduced up to 80.7% of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) enzymatic reaction velocity. It was also observed that, independent of the method used to obtain chia proteins, the fractions showed relevant bioactivity. Moreover, the intensity of the bioactivity varied with the method for obtaining the protein and with the enzyme used in the hydrolysis process. This is the first report to demonstrate that chia peptides are able to inhibit cholesterol homeostasis.

Enrichment of yoghurt with oat protein fractions: Structure formation, textural properties and sensory evaluation

Despite its excellent nutritional properties, unlike other cereals oat displays poor baking properties and therefore is mainly processed in products like rolled oats or serves as raw material for the functional ingredient β-glucan. During β-glucan production, a protein-rich fraction remains as a by-product. Functionalisation of this protein-rich oat-fraction and its application as a valuable food ingredient would improve the sustainability of the process. In the present study, oat protein-enriched cow's milk yoghurt was produced. The main foci were on the characterisation of techno-functional properties, as well as on the analysis of the organoleptic perception and sensory properties by a trained panel. Cow's milk yoghurt, following a traditional formulation with addition of skim milk powder (SMP), served as a reference. Oat protein was incorporated using two preparations: oat protein concentrate (OPC) and oat protein isolate (OPI). Fermentation of yoghurt enriched with SMP, OPC or OPI was monitored via pH-value, formation of lactic acid and rheological measurements. In addition, texture analysis and measurement of syneresis were performed and sensory properties were evaluated. Yoghurt containing SMP showed the highest strength in texture analysis but also a high rate of syneresis. Addition of OPC resulted in a product, which combines nutritional benefits with the sustainable use of the by-product of oat processing as well as improved product quality with respect to syneresis and sensory evaluation, especially mouthfeel. In case of OPI, strong sedimentation took place and high syneresis was observed. It is assumed that the compatibility of oat protein with milk proteins is low, which may be compensated by gelatinisation of starch during yoghurt production.

Expanding the industrial applications of a meat co-product: Generation of low-haemoglobin content plasma by means of red cells crenation

Abstract Blood plasma is a protein-rich liquid which has many applications in food, research, pharma, pet food and animal feed industries. However, for some applications, the haemoglobin level in plasma needs to be very low to prevent, for example, interference with other proteins, colour changes or bitter/metallic taste. Plasma is obtained mainly by centrifugation, but as the processing volume increases, the haemoglobin content increases as well, and the plasma quality is considered poor. In this research, a novel process based on red cell crenation, is presented as a method to obtain low-haemoglobin content plasma, even when centrifuging at large volumes. Four factors were found to affect the plasma quality: processing time, processing volume, centrifugation force, and concentration of phosphate saline buffer in plasma. Results showed that 10% v/v 10X-(Phosphate buffered saline) treated-blood samples were able to generate better quality plasma than untreated samples regardless of the speed, volume or time employed. Additionally, an increment in the amount of recovered plasma proteins was observed. Plasma displayed similar functional properties as controls. Even more, ethyl fractionation, using Cohn's method, generated a protein-rich fraction with a SDS-PAGE profile identical to controls. By means of this novel process the recovery, revalorisation and application of blood proteins can be expanded with the concomitant environmental and economic benefit.

The impact of newly produced protein and dietary fiber rich fractions of yellow pea (Pisum sativum L.) on the structure and mechanical properties of pasta-like sheets

Two fractions from pea (Pisum sativum L.), protein isolate (PPI) and dietary fiber (PF), were newly produced by extraction-fractionation method and characterized in terms of particle size distribution and structural morphology using SEM. The newly produced PPI and PF fractions were processed into pasta-like sheets with varying protein to fiber ratios (100/0, 90/10, 80/20, 70/30 and 50/50, respectively) using high temperature compression molding. We studied protein polymerization, molecular structure and protein-fiber interactions, as well as mechanical performance and cooking characteristics of processed PPI-PF blends. Bi-modal particle size distribution and chemical composition of the PPI and PF fractions influenced significantly the physicochemical properties of the pasta-like sheets. Polymerization was most pronounced for the 100 PPI, 90/10 and 80/20 PPI-PF samples as studied by SE-HPLC, and polymerization decreased with addition of the PF fraction. The mechanical properties, as strength and extensibility, were likewise the highest for the 100 PPI and 90/10 PPI-PF blends, while the E-modulus was similar for all the studied blends (around 38 MPa). The extensibility decreased with the increasing amount of PF in the blend. The highest amounts of β-sheets were found in the pasta-like sheets with high amounts of PPI (100, 90 and 80%), by FT-IR. An increase in PF fraction in the blend, resulted into the high amounts of unordered structures as observed by FT-IR, as well as in an increase in the molecular scattering distances observed by SAXS. The water uptake increased and cooking loss decreased with increased proportions of the PF fraction, and the consistency of 10 min cooked pasta-like sheets were alike al dente texture. The new knowledge obtained in this study on the use of extraction-fractionation method to produce novel PPI and PF fractions for developing innovative high nutritious food can be of a great importance. The obtained knowledge on the pea protein and fiber processing behaviour could greatly contribute to a better control of functional properties of various temperature-processed products from yellow pea.

Supplementation of cauda epididymal plasma improves sperm characteristics following liquid preservation of ram semen at 3-5°C.

Mammalian spermatozoa remain immotile and metabolically inactive in the cauda epididymidis, thus maintaining fertility for several weeks. The aim of this study was to functionally characterise and evaluate the effect of cauda epididymal plasma (CEP) on liquid preservation of ram spermatozoa. Four experiments were conducted to investigate the effects of: (1) CEP and its fractions on sperm motility; (2) CEP (10%, 15%, 20% v/v) on liquid preservation of ram spermatozoa; (3) seminal plasma (SP; 20%, 30%, 50% v/v) on liquid-preserved spermatozoa; and (4) both CEP and post-storage SP treatment on sperm characteristics. Biochemical characterisation of ram CEP revealed high protein (30.9mgmL-1), catalase (68.9IUmL-1), alkaline phosphatase (17.5IUmL-1) activities and total antioxidant capacity (1112µM Trolox equivalent). Progressive motility of prewashed cauda spermatozoa was reduced (P<0.05) by CEP or its protein-rich fraction compared with protein-free plasma or phosphate-buffered saline. After 48h storage, total motility, rapid motility (average path velocity >75µms-1; 53.9%, 73.5% and 71.8% with 0, 15% and 20% CEP respectively) and straight line velocity (86.3, 102.1 and 102.4µms-1 with 0, 15% and 20% CEP respectively) were significantly (P<0.05) higher in the CEP-treated groups than the control. Viability and acrosomal integrity were similar between groups; however, functional membrane integrity was higher (P<0.05) in the 15% CEP-treated group. Treatment of liquid-preserved spermatozoa with either 20%, 30% or 50% SP improved (P<0.05) rapid motility and kinematics at each time point of storage compared with control. In conclusion, liquid preservation of ram spermatozoa in the presence of 15% or 20% CEP and post-storage treatment with SP significantly improve sperm characteristics.

A Strategy for the Sequential Recovery of Biomacromolecules from Red Macroalgae Porphyra umbilicalis Kützing

A nondestructive, multicomponent fractionation strategy has been developed to extract proteins and polysaccharides from the red macroalgae Porphyra umbilicalis collected along the west coast of Sweden and cultivated indoors under controlled conditions. First, a protein-rich fraction was extracted in an ice-cold alkaline solution. The overall protein content in Porphyra umbilicalis was estimated to be 30.6% of the dry weight, and out of that, 15.0% could be recovered. Water-soluble polysaccharides were then extracted from the insoluble residual fraction using sequential alkaline and acidic treatments at 90 °C for 4 h. Spectroscopic and chromatographic analyses of the polysaccharide fractions show that high-molecular-weight carrageenans were obtained from the alkaline extraction and a galactose-rich pectin substance was obtained from the acidic extraction. The insoluble fraction remaining after all extraction steps was rich in cellulose. An elemental analysis of Porphyra umbilicalis via scanning electron mi...

Formation of water disinfection byproduct 2,6-dichloro-1,4-benzoquinone from chlorination of green algae

We report that green algae in lakes and rivers can serve as precursors of halobenzoquinone (HBQ) disinfection byproducts (DBPs) produced during chlorination. Chlorination of a common green alga, Chlorella vulgaris, produced 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), the most prevalent HBQ DBP in disinfected water. Under varying pH conditions (pH6.0–9.0), 2,6-DCBQ formation ranged from 0.3 to 2.1μg/mg C with maximum formation at pH8.0. To evaluate the contribution of organic components of C. vulgaris to 2,6-DCBQ formation, we separated the organics into two fractions, the protein-rich fraction of intracellular organic matter (IOM) and the polysaccharide-laden fraction of extracellular organic matter (EOM). Chlorination of IOM and EOM produced 1.4μg/mg C and 0.7μg/mg C of 2,6-DCBQ, respectively. The IOM generated a two-fold higher 2,6-DCBQ formation potential than the EOM fraction, suggesting that proteins are potent 2,6-DCBQ precursors. This was confirmed by the chlorination of proteins extracted from C. vulgaris: the amount of 2,6-DCBQ produced is linearly correlated with the concentration of total algal protein (R2=0.98). These results support that proteins are the primary precursors of 2,6-DCBQ in algae, and control of green algal bloom outbreaks in source waters is important for management of HBQ DBPs.

Emulsion stability of sugar beet pectin fractions obtained by isopropanol fractionation

Protein rich (F1) and protein poor (F4) fractions of sugar beet pectin (SBP). Protein rich F1, protein poor F4, and control SBP were used to make oil-in-water emulsions with 0.5% or 1.5% SBP (F1_0.5, F1_1.5, F4_0.5, F4_1.5 or C_1.5) and 15% (medium chain triglyceride) MCT oil and emulsifying activity was determined. Changes in D[4,3], light microscopy and rheological parameters during storage at 32 °C for 10 days indicated that SBP fraction and concentration influenced emulsion stability. Emulsions prepared with 0.5% fraction F4_0.5, with lower protein and surface hydrophobicity, had a D[4,3] values less than 1 μm, which remained the same during storage. D[4,3] values of emulsions, prepared with the 1.5% fraction F1_1.5 with higher protein and surface hydrophobicity, increased from 1.42 to 2.09 μm at 10 d. Emulsions prepared with unfractionated control SBP were intermediate in particle size. Emulsions prepared with F4_1.5 and F1_0.5 had higher D[4,3] values of 3.45 and 4.18 μm after 10 d, respectively. There were no significant changes in viscosities of individual emulsions over 10 days. Emulsions were shear thinning or near Newtonian. Protein poor Fraction F4 with greater hydrophile/lipophile ratio formed more stable emulsions at 0.5%, but not at 1.5%, compared to protein rich Fraction F1 at 1.5%.

Optimization of the classification process in the zigzag air classifier for obtaining a high protein sunflower meal – Chemometric and CFD approach

In this study, sunflower meal is ground by a hammer mill after which air zigzag gravitational air classifier is used for separating sunflower hulls from the kernels in order to obtain protein rich fractions. Three hammer mill sieves with sieve openings diameter of 3, 2 and 1mm were used, while three air flows (5, 8.7 and 12.5m3/h) and three feed rates (30%, 60% an 90% of bowl feeder oscillation maximum rate) were varied during air classification process. For describing the effects of the test variables on the observed responses Principal Component Analysis, Standard Score analysis and Response Surface Methodology were used. Beside experimental investigations, CFD model was used for numerical optimization of sunflower meal air classification process.Air classification of hammer milled sunflower meal resulted in coarse fractions enriched in protein content. The decrease in sieve openings diameter of the hammer mill sieve increased protein content in coarse fractions of sunflower meal obtained at same air flow, and at the same time decreased matching fraction yield. Increase in air flow lead to the increase in protein content along the same hammer mill sieve. Standard score analysis showed that optimum values for protein content and ratio of coarse and fine fractions have been obtained by using a sieve with 1mm opening diameter, air flow of 12.5m3/h and 60% of the maximum feeder rate. Fraction ratio and protein content were mostly affected by the linear term of air flow and the sieve openings diameter of the hammer mill sieve in the Second Order Polynomial model. The main focus of CFD analysis was on the particle simulation and the evaluation of the separation efficiency of the zigzag classifier.

Analysis of protein enrichment during single- and multi-stage tribo-electrostatic bioseparation processes for dry fractionation of legume flour

Abstract The potential of a dry fractionation approach for the production of native plant protein concentrates has been validated for navy bean ( Phaseolus vulgaris ) flour as a model system utilizing a lab-scale tribo-electrostatic separator. For this approach, protein and carbohydrate particles in pin-milled flour were tribo-charged to different levels before being fractionated according to their acquired charge under the influence of an applied electric field. In the present study, the location and distribution of the charged protein-rich particles along the surface of the electrode plate was investigated as a function of air flow rate (laminar vs . turbulent) and electric field strength. A turbulent air flow rate at a variety of electric field strengths resulted in the formation of protein-rich particles and starch granule agglomerates affecting the production of high-purity protein concentrates. Charging the flour particles at a laminar air flow rate followed by separation under a low electric field strength enabled the production of fine protein-rich fractions with considerably higher protein contents (38.4–46.5%) but lower protein separation efficiency. The combination of a laminar air flow rate and high electrode voltage slightly reduced the protein content of the fraction (39.4–42.9%), but significantly improved the protein separation efficiency to ∼45%. To further improve the separation efficiency of the navy bean protein concentrate without compromising its protein content, a two-stage tribo-electrostatic separation approach was evaluated at a laminar air flow but different plate voltages. The combined protein-rich fraction produced by the two-stage approach had a protein content of ∼38% accounting for 60% of the total protein that was significantly higher than that of the optimized single-stage tribo-electrostatic separation, facilitating the scale-up of this dry fractionation technique for pilot-plant applications.

Development and characterization of functional O/W emulsions with chia seed (Salvia hispanica L.) by-products.

The present work investigated the physicochemical properties of O/W emulsions containing functional ingredients (oil with high ω-3 fatty acid content, protein and/or soluble fiber) from chia seeds. The effect of different protein-carbohydrate combinations (sodium caseinate and lactose, sodium caseinate and maltodextrin, chia protein-rich fraction and maltodextrin) and the presence of chia mucilage (0 and 0.2% wt/wt) in the aqueous phase of chia O/W emulsions was studied as a function of droplet size distribution, Sauter mean diameter, ζ-potential, rheological properties and backscattering profiles. The use of sodium caseinate in combination with lactose or maltodextrin produced chia O/W emulsions with small droplet size (0.22-0.27µm), high degree of uniformity in droplet size distribution, negatively charged droplets (at pH 6.5), pseudoplastic behavior and high physical stability. Emulsions with chia protein-rich fraction presented wider droplet size distribution and higher D[3,2] values than the previous ones, recording a Newtonian behavior. The addition of chia mucilage affected the physicochemical properties studied, mainly the rheological characteristics of emulsions.

An environmental assessment of electricity production from slaughterhouse residues. Linking urban, industrial and waste management systems

The food processing industry continues to grow, generating large amount of organically rich waste flows per year: these processors face significant economic and environmental pressures for appropriate conversion and disposal of these waste flows. Solid waste disposal problems, mostly in highly urbanized environments, energy shortages (primarily oil) and/or high petroleum prices, as well as environmental issues such as the shrinking landfill capacity, can all be addressed by converting waste material into useful and saleable products. This paper brings to the attention a possible strategy in order to meet the general EU directives concerning the residues utilization and percentage contribution for the total energy consumption by 2020, by evaluating the use of animal by-products (category 3, as defined in the directive 2002/1774/EC) for energy purposes. Slaughterhouse waste represents an important potential source of renewable energy: on average, 40–50% of a live animal is waste, with a potential energy content close to diesel fuel. Treatment of animal waste from slaughterhouse and the subsequent conversion to electricity is investigated as a case study in the Campania Region (Italy): the animal waste undergoes a rendering process, to separate a protein-rich fraction useful for animal meal production and a fat-rich fraction, to be combusted in a diesel engine for power and heat generation (CHP). An environmental assessment of the entire process is performed by means of LCA, providing a quantitative understanding of the plant processing. The study aims to understand to what extent electricity production from animal fat is environmentally sound and if there are steps and/or components that require further attention. The environmental impacts of the electricity production from animal waste are investigated adopting different points of view and they are also compared to the impacts of Italian electricity production (mix of fossil fuels and renewables). The study confirms that waste recovery represents a triple win solution, dealing simultaneously with human security, pollution, and, last but not least, energy recovery.

Chemical- and Solvent-Free Mechanophysical Fractionation of Biomass Induced by Tribo-Electrostatic Charging: Separation of Proteins and Lignin

Rapeseed oil cakes are proteo-lignocellulosic residues obtained after oil extraction from rapeseed seed, featuring high protein, carbohydrates, phenolic compounds, and lignin contents. Most often used as an animal diet supplement, its fiber and phenolic part might be valorized for biofuels; biomolecules and biomaterial production proved its fractionation can be achieved without alteration of its nutritional qualities or generation of effluents and wastes. In this study, an innovative dry fractionation technology combining ultrafine milling (UFM) and electrostatic separation (tES) has been developed for rapeseed oil cake fractionation into protein- and lignin-rich fractions. The physical features as well as the biochemical composition of the produced fraction have been assessed herein. Thanks to UFM–tES technology, protein-rich fractions with 38.4% more proteins than in the initial material and lignocellulosic-rich fractions with 80.0% more fibers can be obtained without either external heating or using an...

A Hybrid Dry and Aqueous Fractionation Method to Obtain Protein-Rich Fractions from Quinoa (Chenopodium quinoa Willd)

Combination of dry and aqueous fractionation is investigated to obtain protein-rich fractions from quinoa in a milder and more sustainable way compared to conventional wet fractionation. Dry fractionation of quinoa involved milling and subsequent air classification, generating a protein-enriched embryo fraction. Subsequently, this fraction was milled, suspended, and further fractionated by aqueous phase separation. The efficiency of aqueous phase separation could be improved by addition of NaCl (0.5 M). Finally, the top aqueous phase was decanted and ultrafiltered, resulting in a protein purity of 59.4 w/dw% for the 0.5 M NaCl-protein solution and a protein yield (gram protein obtained/gram protein in seed) of 62.0 %. Having used 98 % less water compared to conventional wet extraction, the hybrid dry and aqueous fractionation is a promising method for industry to create value from quinoa in a more economic and sustainable friendly way while minimizing the impact on quinoa’s native protein functionality.

Preparation of protein and mineral rich fraction from grain amaranth and evaluation of its functional characteristics

Grain amaranth was fractionated to prepare a seed coat rich fraction along with the fine seed coat, middling and flour fractions. The nutritional content of the coarse seed coat fraction and its antioxidant potential were evaluated. It was observed that, the coarse seed coat fraction contained highest protein (17.81 g/100 g), dietary fiber (25.78 g/100 g), free sugar (2.25 g/100 g), calcium (1115 mg/100 g), sodium (279 mg/100 g), magnesium (178.4 mg/100 g) and potassium (398.8 mg/100 g) contents compared to all other fractions. The carbohydrate and protein digestibility of all the fractions were more than 80%. A slight decrease in linoleic acid and a concurrent increase in palmitic acid contents were observed in coarse seed coat fraction. The total phytic acid increased and total polyphenols contents decreased in the coarse seed coat fraction compared to the native grain. The DPPH, ABTS and total antioxidant activities are comparatively high in this particular fraction. The study indicated a possibility of preparation of a protein, fiber and mineral rich fraction from grain amaranth with good antioxidant potential which can be used as a functional food ingredient.

Physicochemical characterization of a navy bean (Phaseolus vulgaris) protein fraction produced using a solvent-free method

A solvent-free electrostatic separation method was employed to separate navy bean flour (NBF) into protein-rich (PR) and starch-rich (SR) fractions. The physicochemical properties of NBF and separated fractions were compared to proteins (navy bean isolate (NBI) and 7S globulin) prepared using a wet process. Gel electrophoresis confirmed that the protein distribution in the isolated fractions was similar to that of NBF. The protein profile of NBI and 7S globulin was found to be devoid of certain proteins that were found in the NBF and PR fraction. Amino acid analysis revealed that the NBI and 7S globulin had a lower content of sulfur-containing amino acids compared to NBF and the electrostatically isolated fractions. CD and fluorescence spectroscopy confirmed that denaturation of the proteins during the acid precipitation is likely. This novel solvent-free electrostatic separation process preserves the native protein structure found in NBF and improves the recovery of some of the smaller MW proteins.

Immunomodulatory potential of a brewers’ spent grain protein hydrolysate incorporated into low-fat milk following in vitro gastrointestinal digestion

Brewers’ spent grain (BSG) protein rich fraction was previously hydrolysed using Alcalase (U) and three additional fractions were prepared by membrane fractionation; a 5-kDa retentate (U > 5), a 5-kDa permeate (U < 5) and a 3-kDa permeate (U < 3). In the present study, these fractions were added to milk, subjected to simulated gastrointestinal digestion (SGID) and their anti-inflammatory potential was investigated. The digestates caused a significant reduction (p < 0.05) in interleukin-6 (IL-6) production in Concanavalin-A (ConA)-stimulated Jurkat T cells. The samples did not significantly alter the production of IL-6 in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. IL-2 and interferon-γ (IFN-γ) production in stimulated Jurkat T cells and IL-1β and tumor necrosis factor-α (TNF-α) production in stimulated RAW 264.7 cells were not affected in the presence of the digestates. Results show that a SGID milk product supplemented with BSG hydrolysate and its associated ultrafiltered fractions can confer anti-inflammatory effects in Jurkat T cells.