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Protein retention

Other actions of estrogen include fluid retention, protein anabolism, thinning of the cervical mucus, and the inhibition or facilitation of ovulation. Estrogens contribute to the conservation of calcium and phosphorus, the growth of pubic and axillary hair, and pigmentation of the breast nipples and genitals. Estrogens also stimulate contraction of the fallopian tubes (which promotes movement of the ovum), modify the physical and chemical properties of the cervical mucus, and restore the endometrium after menstruation. [Pg.544]

In the manufacture of fresh cheeses, e. g. quark, the pasteurised skim milk is inoculated with micro-organisms (Sc. lactis, Sc. cremoris). To accelerate the thickening, the enzym chymosin is added. After ripening - with a pH value of about 4.6 - the coagulated milk must be pumped through a separator, possibly including an ultrafiltration system, in order to separate the sour whey. The ultrafiltration would separate the whey into 2 phases the permeate (water soluble) and the retentate (protein phase). Finally the quark, retentate, cream, (fruit) preparations, flavourings or spices and herbs are added. [Pg.543]

Biological value (BV) = % of absorbed nitrogen retained in body tissue complete retention = 100. Data in parentheses for control group, with no single-ceU protein in diet. [Pg.468]

Membrane-retained components are collectively called concentrate or retentate. Materials permeating the membrane are called filtrate, ultrafiltrate, or permeate. It is the objective of ultrafiltration to recover or concentrate particular species in the retentate (eg, latex concentration, pigment recovery, protein recovery from cheese and casein wheys, and concentration of proteins for biopharmaceuticals) or to produce a purified permeate (eg, sewage treatment, production of sterile water or antibiotics, etc). Diafiltration is a specific ultrafiltration process in which the retentate is further purified or the permeable sohds are extracted further by the addition of water or, in the case of proteins, buffer to the retentate. [Pg.293]

Electroultrafiltration (EUF) combines forced-flow electrophoresis (see Electroseparations,electrophoresis) with ultrafiltration to control or eliminate the gel-polarization layer (45—47). Suspended colloidal particles have electrophoretic mobilities measured by a zeta potential (see Colloids Elotation). Most naturally occurring suspensoids (eg, clay, PVC latex, and biological systems), emulsions, and protein solutes are negatively charged. Placing an electric field across an ultrafiltration membrane faciUtates transport of retained species away from the membrane surface. Thus, the retention of partially rejected solutes can be dramatically improved (see Electrodialysis). [Pg.299]

Second, most membrane materials adsorb proteins. Worse, the adsorption is membrane-material specific and is dependent on concentration, pH, ionic strength, temperature, and so on. Adsorption has two consequences it changes the membrane pore size because solutes are adsorbed near and in membrane pores and it removes protein from the permeate by adsorption in addition to that removed by sieving. Porter (op. cit., p. 160) gives an illustrative table for adsorption of Cytochrome C on materials used for UF membranes, with values ranging from 1 to 25 percent. Because of the adsorption effects, membranes are characterized only when clean. Fouling has a dramatic effect on membrane retention, as is explained in its own section below. [Pg.2039]

Diafiltration If a batch process is run so that the permeate is replaced by an equal volume of fresh solvent, unretained solutes are flushed through the system more efficiently. A major use of UF is fractionation, where a solvent, a retained solute and an unretained solute are present. An example is whey, containing water, protein, and lactose. If the retention of protein is I and the retention of lactose is 0, the concentration of protein in the retentate rises during UF. The ratio of protein to lac tose rises, but the feed concentration of lactose is unchanged in retentate and permeate. Diafiltration dilutes the feed, and permits the concentration of lactose to be reduced. Diafiltration is used to produce high-purity products, and is used to fractionate high-value products. R is always 0 for eveiy component. [Pg.2042]

The combination of diafiltration and batch concentration can be used to fractionate two macrosolutes whose retentions differ by as little as 0.2. It is possible in principle to achieve separations that are competitive with chromatography. When tanks and other equipment are considered, as well as the floor space they occupy, the economics of membrane separation of proteins may be attractive [R. van Reis, U.S. Patent 5,256,294 (1993)]. [Pg.2042]

Economic Yield Both in a high-value protein separation and in a low-value commodity concentration, economic yield is vital. Economic yield is defined as the fraction of useful product entering the process that leaves it in salable form. The yield equations used in the industry focus on retention, so they deal only with direct losses through the membrane. These losses result both in direct (product not sold) and indirect costs from a waste stream whose disposal or subsequent use may be more expensive when it is contaminated by macrosolute. There are additional indirec t losses, mainly product left in the equipment, particularly that left adhering to the membrane. Costs of cleaning and disposal or this indirect loss, while hard to measure, are usually higher than the cost of product lost through the membrane. [Pg.2042]


See other pages where Protein retention is mentioned: [Pg.891]    [Pg.220]    [Pg.90]    [Pg.316]    [Pg.318]    [Pg.891]    [Pg.441]    [Pg.454]    [Pg.53]    [Pg.168]    [Pg.346]    [Pg.703]    [Pg.70]    [Pg.102]    [Pg.5]    [Pg.794]    [Pg.801]    [Pg.445]    [Pg.891]    [Pg.220]    [Pg.90]    [Pg.316]    [Pg.318]    [Pg.891]    [Pg.441]    [Pg.454]    [Pg.53]    [Pg.168]    [Pg.346]    [Pg.703]    [Pg.70]    [Pg.102]    [Pg.5]    [Pg.794]    [Pg.801]    [Pg.445]    [Pg.54]    [Pg.54]    [Pg.142]    [Pg.465]    [Pg.470]    [Pg.409]    [Pg.414]    [Pg.517]    [Pg.337]    [Pg.296]    [Pg.20]    [Pg.214]    [Pg.1531]    [Pg.2041]    [Pg.2058]    [Pg.2223]    [Pg.2229]    [Pg.96]    [Pg.501]    [Pg.357]   
See also in sourсe #XX -- [ Pg.189 ]




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