Soya protein isolate

Metabolic Transit of Lysinoalanine. Urinary and Fecal Excretion of Protein-Bound Lysinoalanine (113). Three different alkali-treated proteins (lactalbumin, fish protein isolate, and soya protein isolate) containing, respectively, 1.79, 0.38, and 0.14 g of lysinoalanine/16 g nitrogen were given to rats and the urines and feces were collected. Lysinoalanine was measured before and after acid hydrolysis. The fecal excretion varied from 33 to 51% of the total ingested lysinoalanine and the urinary excretion varied from 10 to 25%. The higher level of lysinoalanine found after acid hydrolysis indicates that a certain quantity is excreted in the urines as combined lysinoalanine (see Table VII). The total recovery was inferior to the ingested quantity (50 to 71%) indicating that the molecule is transformed or retained in the body of the rat. 

Meyer, E., Soya Protein Isolates for Food, in Protein as Human Food, ... 

Figure 2. Time-dependence of the interfacial pressure, 49, for three curves. They represent WPC dispersed in (0.2-7) adsorbing at the A/W and the soya bean oil/water (0/W) interfaces at a subphase concentration of 10" and 10 wt%, respectively, and a soya protein isolate adsorbing at the A/W-interface at a subphase concentration of 10 wt%.

Uses Emollient, skin conditioner in cosmetics Soybean (Glycine soja) protein CAS 9010-10-0 68153-28-6 977076-84-8 EINECS/ELINCS 232-720-8 Synonyms Glycine soja Glycine soya protein Isolated soy protein Proteins, glycine soya Proteins, soy... 

For food uses, soya derivatives are used as ingredients in a wide range of consumer foods. Examples are soya oil, lecithin, soya flour in bakery products, soya protein isolates, etc. This chapter will not deal with these ingredients, but rather focus on food products made by fermentation processes. 

Table 1.44. Amino acid composition (weight-%) of plasteins with high tyrosine and low phenylalanine contents from fish protein concentrate (FPC) and soya protein isolate (SPI)...

Soya Proteins. Early attempts to make albumen substitutes from soya protein also ran into problems. A bean flavour tended to appear in the finished product. A solution to these problems has been found. Whipping agents based on enzyme modified soy proteins are now available. The advantage of enzymatic modification is that by appropriate choice of enzymes the protein can be modified in a very controlled way. Chemical treatment would be far less specific. In making these materials the manufacturer has control of the substrate and the enzyme, allowing the final product to be almost made to order. The substrates used are oil-free soy flakes or flour or soy protein concentrate or isolate. The enzymes to use are chosen from a combination of pepsin, papain, ficin, trypsin or bacterial proteases. The substrate will be treated with one or more enzymes under carefully controlled conditions. The finished product is then spray dried. 

Model protein samples. Isolated soya protein (Purina Brand Assay Protein RP 100 ) was employed in these studies and found to contain on a dry matter basis 96% crude protein, 1.4% ash, 0.2% crude fiber, and 2% N-free extract. This material was used to prepare 48 samples, which were heated in airtight metal containers ( 250-ml ) at temperatures of 90, 110, 130° C for 0.5, 1, 2, and 4 h respectively. 

A further 3 samples were prepared by heating equal masses of isolated soya protein and tap water in open vessels for 24 h at either 95, 138, or 160° C. 

Soy protein isolate. A soy protein isolate produced under mild conditions on pilot plant scale was kindly provided by Central Soya. The preparation procedure has been described elsewhere (1). Protein content (N x 6.25) was 99.4% (dry weight). 

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. 

DSC of soy isolates show two distinct and different classes of behaviom. Where proteins are in the native state, distinct denatmation transitions from the 7S and 1 IS globulins are observed. For raw materials that have been denatured during their preparation by moist heat treatment or exposure to denaturing solvent conditions, no large endotherms associated with the native proteins are seen. (Morales and Kokini 1997) Glass transitions in soya proteins have been reported previously (Morales and Kokini 1997 Mizuno et al. 2000). 

FIGURE 7.14 Solubility of protein preparations as a function of pH. (a) Turbidity (expressed as absorbancy) of solutions of a whey protein isolate, heated at 70°C for various times (indicated, minutes). (From results by S. Damodaran, see Bibliography), (b) Solubility (percentage of protein in supernatant after centrifuging) of various protein products sodium caseinate (C), peanut (P), and soya (S) proteins. (Approximate results after various sources.) (c) Solubility (as in b) of the protein in a potato juice extract (pH = 7.0, 7=0.2 molar) as a function of solvent volume (v, in ml). See text for lines 1 and 2. (After results by G. A. van Koningsveld. Ph.D. thesis, Wageningen University, 2001.)... 

Hunt, J. A. and Dalgleish, D.G. 1994. Adsorption behaviour of whey protein isolate and caseinate in soya oil-in-water emulsions. Food Hydrocolloids 8 175-187. 

Blood plasma can be refined further to give a variety of functional ingredients. Tybor et al. (1973) described a process for preparing spray-dried plasma protein isolates. Plasma protein isolates in the spray-dried form contain over 90% protein, and as such they are comparable with isolates prepared from soya or other plant materials. 

The protein sources, a soybean protein isolate (Promine F, Central Soya, Chic.) and a rapeseed protein concentrate (prepared by FRI-71 process at the Food Research Institute, Agriculture Canada, Ottawa) were suspended (10% W/V) in 0.1 N NaOH and heated at 60 C for 4 or 8 h with continuous agitation. Treatment was stopped by the rapid addition of 6 N HCl followed by cooling, adjustment of pH to 4.5, and centrifugation for 15 min at... 

While the majority of SP studies have shown lipid-lowering effects, isolated isoflavones appear to have little effeet (Hodgson et al. 1998 Simons et al. 2000 Dewell et al. 2002 Hall et al. 2006). The possible mechanisms for the h q)ocholesterolemie effeets of soy are still being investigated, but it seems fairly certain that pure isoflavones (taken out of the soya food/protein isolate) are not actively lipid-lowering. This does not rule out a possible hypocholesterolemic effect of SI... 

Table 16.29. Composition of soya protein concentrate and isolate (%)...

Lawhon JT, Rhee KC, Lusas EW 1981b. Soya protein ingredients prepared by new processes - aqueous processing and industrial membrane isolation. J Am Oil Chem Soc 58(3) 377-384. 

Choung, J.J. and D.G. Chamberlain, 1993. The effects of abomasal infusions of casein or soya-bean-protein Isolate on the milk-production of dairy-cows in midlactation. Br. J. Nutr. 69, 103-115. [3]... 

Soy isolate was prepared by the isoelectric precipitation procedure developed at the Food Protein Research and Development Center, Texas A M University System (23). A commercial soy isolate. Promine F (Central Soya Inc., Fort Wayne, IN), was also used in this study. 

These regenerated proteins are obtained from milk (casein), soya beans, corn, and peanuts. More or less complex chemical separation and purification processes are required to isolate them from the parent materials. They may be dissolved in aqueous solutions of caustic, and wet-spun to form fibers, which usually require further chemical... 

With a few exceptions, most of the detailed research has been performed on relatively few proteins. Of these, the caseins (a , B and k) and whey proteins P-lactalbumin and B-lactoglobulin) predominate. This is principally because these proteins are readily available in pure and mixed forms in relatively large amounts they are all quite strongly surfactant and are already widely used in the food industry, in the form of caseinates and whey protein concentrates or isolates. Other emulsifying proteins are less amenable to detailed study by being less readily available in pure form (e.g., the proteins and lipoproteins of egg yolk). Many other available proteins are less surface active than the milk proteins, for example, soya isolates (49), possibly because they exist as disulfide-linked oligomeric units rather than as individual molecules (50). Even more complexity is encountered on the phos-phorylated lipoproteins of egg yolk, which exist in the form of granules (51), which themselves can be the surface-active units (e.g., in mayonnaise) (52). 

---