Protein concentration ultrafiltration

Pish protein concentrate and soy protein concentrate have been used to prepare a low phenylalanine, high tyrosine peptide for use with phenylketonuria patients (150). The process includes pepsin hydrolysis at pH 1.5 ptonase hydrolysis at pH 6.5 to Hberate aromatic amino acids gel filtration on Sephadex G-15 to remove aromatic amino acids incubation with papain and ethyl esters of L-tyrosine and L-tryptophan, ie, plastein synthesis and ultrafiltration (qv). The plastein has a bland taste and odor and does not contain free amino acids. Yields of 69.3 and 60.9% from PPG and soy protein concentrate, respectively, have been attained. 

Ultrafiltration. Membranes are used that are capable of selectively passing large molecules (>500 daltons). Pressures of 0.1—1.4 MPa (<200 psi) are exerted over the solution to overcome the osmotic pressure, while providing an adequate dow through the membrane for use. Ultrafiltration (qv) has been particulady successhil for the separation of whey from cheese. It separates protein from lactose and mineral salts, protein being the concentrate. Ultrafiltration is also used to obtain a protein-rich concentrate of skimmed milk from which cheese is made. The whey protein obtained by ultrafiltration is 50—80% protein which can be spray dried. 

Ultrafiltration has become prominent as a method of protein concentration for a variety of reasons ... 

Amino Acid Content. Amino acid content of field pea products is related to protein level, method of processing, and fraction (starch or protein). The protein fraction contains fewer acidic (glu, asp) amino acids than the starch fraction and more basic (lys, his, arg) amino acids than the starch fraction. Also, there are more aromatic (tyr, phe) amino acids, leu, iso, ser, val, and pro in the protein fraction than in the starch fraction (5). An amino acid profile of pea protein concentrate shows relatively high lysine content (7.77 g aa/16 g N) but low sulfur amino acids (methionine and cystine) (1.08-2.4 g aa/16 g N). Therefore, it is recommended that air classification or ultrafiltration be used because acid precipitation results in a whey fraction which contains high levels of sulfur amino acids (12,23). Also, drum drying sodium proteinates decreases lysine content due to the Maillard reaction (33). 

Several strategies have been described for the preconcentration of sample components present at low concentrations. These techniques include zone sharpening,28-29 on-line packed columns,30 and transient capillary isotachophoresis (cITP).31-32 Other standard laboratory techniques are often used, including solid-phase extraction, protein precipitation, ultrafiltration, etc. Two important points to keep in mind when selecting a concentration protocol are the sample requirements of the method and the potential selectivity on relative concentrations of sample components. The latter point applies to purity and concentration analysis. 

W5. Windisch, R. M., and Bracken, M. M., Cerebrospinal fluid proteins Concentration by membrane ultrafiltration and fractionation by electrophoresis on cellulose acetate. Clin. Cherru 16,416-419 (1970). 

Solutions of macromolecules may be concentrated by means of polymer membranes of defined pore size. Applying a pressure or centrifugal force, small molecules pass the pores, whereas large molecules retain. The nominal cutoff of an ultrafiltration membrane (MWCO) helps you to select a membrane Molecules smaller than the MWCO will pass the membrane, whereas larger molecules are held back. This separation is not sharp and depends on protein conformation and solvent composition. Complete retention is achieved when using a membrane with a MWCO 1/3 to 1/5 of the molar mass of the macromolecule of interest. Figure 3.6 illustrates the separation of proteins by ultrafiltration. 

Whey protein concentrates (WPC), which are relatively new forms of milk protein products available for emulsification uses, have also been studied (4,28,29). WPC products prepared by gel filtration, ultrafiltration, metaphosphate precipitation and carboxymethyl cellulose precipitation all exhibited inferior emulsification properties compared to caseinate, both in model systems and in a simulated whipped topping formulation (2. However, additional work is proceeding on this topic and it is expected that WPC will be found to be capable of providing reasonable functionality in the emulsification area, especially if proper processing conditions are followed to minimize protein denaturation during their production. Such adverse effects on the functionality of WPC are undoubtedly due to their Irreversible interaction during heating processes which impair their ability to dissociate and unfold at the emulsion interface in order to function as an emulsifier (22). 

Industrially, whey proteins are prepared by ultrafiltration or diafiltration of whey (to remove lactose and salts), followed by spray drying these products, referred to as whey protein concentrates, contain 30-80% protein. 

Ultrafiltration/diafiltration of acid or rennet whey to remove varying amounts of lactose, and spray-drying to produce whey protein concentrates (30-80% protein). 

In addition to the general decrease in viscosity with increasing temperature, heating milk can also influence its rheology by heat-induced denatura-tion of cryoglobulins and/or other whey proteins. Concentration of milk, e.g. by ultrafiltration, prior to heating results in a greater increase in f/app than in milk heated before concentration. 

Proteins that remain in whey after removing casein from milk are recovered as whey protein concentrates by precipitation with added polyphosphate or other polyvalent anionic compounds, ultrafiltration, ion exchange adsorption, gel filtration, or a combined acid and heat precipitation process. Whey protein concentrates are also manufactured by a combined process involving electrodialysis, concentration, lactose crystallization, and drying (Richert 1975 Morr 1979 Marshall 1982 Anon. 1982 Muller 1982B). 

The second whey separation process uses both ultrafiltration and reverse osmosis to obtain useful protein from the whey produced in the traditional cheese manufacturing process. A flow schematic of a combined ultrafiltration-reverse osmosis process is shown in Figure 6.23. The goal is to separate the whey into three streams, the most valuable of which is the concentrated protein fraction stripped of salts and lactose. Because raw whey has a high lactose concentration, before the whey protein can be used as a concentrate, the protein concentration must be increased to at least 60-70% on a dry basis and the lactose content... 

D Alvise, N., Lesueur-Lambert, C., Fertin, B., Dhulster, P., and Guillochon, D. 2000. Hydrolysis and large scale ultrafiltration study of alfalfa protein concentrate enzymatic hydrolysate. Enzyme Microb. Technol. 27, 286-294. 

Gavaric, D.D., Caric, M., Kalab, M. 1989. Effects of protein concentration in ultrafiltration milk retentates and the type of protease used for coagulation on the microstructure of resulting gels. Food Microstruc. 8, 53-66. 

Whey protein concentrate. The whey protein used was prepared by ultrafiltration and spray drying. Protein content (N x 6.55) was 68% (dry weight). Lipid content was 7.1% (dry weight). In order to study heat induced aggregation by spectrophotometric methods the turbidity of the dilute protein dispersions was too high. The turbidity of whey protein dispersions is caused by lipids associated with proteins probably in the form of emulsified oil droplets. This fraction was removed by precipitation at pH 4.5 from dispersions made in dist. water and separated by centrifugation at 40 000 xg. 

The three proteins chosen for this study are a mildly produced soy protein isolate, kindly provided by Central Soya, a commercially available sodium caseinate (DMV, Holland) and a whey protein concentrate (WPC) obtained by ultrafiltration (UF) and spray drying of cheese whey. Analysis of the proteins is given in (4) and (11). The present protein products have been investigated , when dispersed in distilled water and in 0.2 M NaCl solution at pH 7 denoted as (0 - 7) and (0.2 - 7), respectively. 

Concentration of whev proteins. As mentioned earlier, microfiltration can be used to remove bacterias. In addition, they are capable of separating phospholipids, fats and casein fines of sweet whey or sour (acidified) whey. Ultrafiltration of whey has been well proven to provide an array of protein products of diverse compositions and properties. Inorganic membrane filtration can be used at different stages of the process to make whey protein concentrates (WPC) in powder form with a protein content reaching 50%. 

Changes in biochemical composition of CSF could serve as a useful tool for investigations of pathological processes in the CNS. CSF is also in contact wdth the blood plasma through the blood-brain barrier, thus resembling an ultrafiltrate of plasma in its protein constituents. CSF contains sugars, lipids, electrolytes and proteins. Protein concentration in CSF ranges from 0.2mg/ml to 0.8mg/ml (0.3 - 1% of serum protein concentration) wdth more than 70% of the proteins in CSF... 

Parbhoo, S.R, Ajdukiewic, A., Sherlock, S. Treatment of ascites by continuous ultrafiltration and reinfusion of protein concentrate. Lancet 1974/1 949-952... 

Nilsson JL. EouUng of an ultrafiltration membrane by a dissolved whey protein concentrate and some whey proteins. J. Membr. Sci. 1988 36 147-160. 

Mondor M, Ippersiel D, Lamarche F, and Boye JI. Production of soy protein concentrates using combination of electroacidification and ultrafiltration. J. Agric. Food Chem. 2004 52 6991-6996. 

Ultrafiltration processing for whey proteins concentration and fractionation, for recovery of lactose from milk and whey, for total milk protein concentration for the production of milk protein concentrate (MFC) or nulk protein isolate (MPl), for milk standardization for continuous mechanized manufacture of cheese and other fermented products, and for production of high-solids milk base for dried milk production. 

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