Soybean protein isolate

Soybean Protein Isolates. Soybean protein isolates, having a protein content of >90 wt%, are the only vegetable proteins that are widely used in imitation dairy products (1). Most isolates are derived from isoelectric precipitation, so that the soybean protein isolates have properties that are similar to those of casein. They are insoluble at thek isoelectric point, have a relatively high proportion of hydrophobic amino acid residues, and are calcium-sensitive. They differ from casein in that they are heat-denaturable and thus heat-labile. The proteins have relatively good nutritional properties and have been increasingly used as a principal source of protein. A main deterrent to use has been the beany flavor associated with the product. Use is expected to increase in part because of lower cost as compared to caseinates. There has been much research to develop improved soybean protein isolates. 

In this paper, we will explore the measurement of and the basis for the cohesive and elastic properties of a commonly used component of foods that excels in these characteristics, wheat gluten. Gluten constitutes from 10 to 16% of wheat flour, from which it may be separated by Martin, batter, or Raisio processes (2, 3). The separated wheat gluten is 70 to 80% protein, of which 85% is insoluble in saline solution. We shall also seek to correlate some of the basic concepts developed in studies of gluten to other protein systems, such as those of soybean protein isolates and concentrates. 

Even when protein ingredients are added to food in relatively small amounts, they may significantly influence some of the physical properties of the food. Hermansson (1973) found that addition of 4 percent of a soybean protein isolate to processed meat significantly affected firmness, as measured by extrusion force, compression work, and sensory evaluation. 

Reversibly insolubilized soybean protein products possess various functional properties, such as binding, emulsification effect, etc. These functionalities may appear when the native protein molecules are unfolded during heating in food processing. Therefore these products, such as soybean protein isolate, are useful as binders or emulsifiers for sausage, hams, etc. 

Fig. 7. Schematic outline for manufacture of soybean protein isolates.

Table 4-12 Magnitudes of Intercepts (K K") and Slopes ( , n") from Linear Regression of Log a versus Log G and Log G" of Different Ratios of Corn Starch (CS)-Soybean Protein Isolate (SPI) Mixtures...

Liao, H.-J., Okechukwu, P. E., Damodaran, S., and Rao, M. A. 1996. Rheological and calorimetric properties of heated com starch-soybean protein isolate dispersions. J. Texture Stud. 27 403 18. 

Separation of soy protein by EDBM has specific advantages over the conventional isoelectric precipitation used industrially for the production of soybean protein isolates. This technology does not use any added acids or bases during the process to adjust the pH of the protein solution, and the chemical effluents generated during the process could be reused at different stages in the... 

Processed soybean protein isolate FeS04 Soy iron No change Repletion (rat) 27... 

Ahmed, J., H. S. Ramaswamy, and G. S. V. Raghavan. 2008. Dielectric properties of soybean protein isolate dispersions as a function of concentration, temperature and pH. LWT— Food Science and Technology 41 71-81. 

Yamashita et al. (65) incorporated L-methionine into a soybean protein hydrolysate by means of the plastein reaction with papain. A 10 1 mixture of a peptic hydrolysate of soybean protein isolate and L-methionine ethyl ester was incubated in the presence of papain, the conditions being similar to those mentioned above. The methionine content of the plastein was 7.22 wt %, nearly seven times the original methionine content of the soybean protein isolate. To determine the location of the incorporated methionine residues, the plastein was treated with carboxypeptidase A. Methionine was liberated much faster than any other amino acid. A second portion of the plastein was methylated and then treated with lithium borohydride to reduce the COOH to CH2OH. Hydrolysis of the chemically treated plastein with 6N HC1 gave aminols in satisfactory yields. Subsequently, the aminols were converted to their DNP-derivatives, which were separated by thin layer chromatography. These experiments, together with some others, showed that 84.9% (molar basis) of the C-terminals of the plastein molecules were occupied with methionine, whereas only 14.4% of the N-terminals contained methionine. 

Deodorization. Volatile flavor components of soybean have been investigated in detail (79, 80, 81, 82). Arai et al. (83) have studied the interaction of denatured soybean protein with 1-hexanol and 1-hexanal which are the typical beany flavor compounds of raw and processed soybeans. These protein-bound compounds are liberated by treating the denatured soybean protein with pepsin (83). Noguchi et al. (84) observed that not only 1-hexanol and 1-hexanal but also other flavor compounds are effectively liberated and removed from a soybean protein isolate during treatment with an acid protease (Molsin). A subsequent study has ascribed this effect to the activity of aspergillopeptidase A, an endopeptidase, which has been identified as a main constituent of Molsin (85). Fujimaki et al. (88, 87) examined several protease preparations for their usefulness in deodorization and reported that a pepsin treatment followed by ether extraction is most effective for deodorizing some protein preparations of soybean and fish. 

In soybean concentrates and isolates much of the phytate remains associated with the protein in fact, phytate may constitute as much as 2-3% of the weight of a commercial protein isolate (57). A low-phytate soybean protein isolate can be prepared from soybean flour, however, by allowing endogenous phytase to act on the phytate in a 6% suspension of the flour at pH 5 at a temperature of 65°C (58). Hydrolysis of the phytate facilitates its separation from the bulk of the soybean protein which is then concentrated by ultrafiltration using a membrane which is permeable to phytate and its hydrolysis products but impermeable to protein. The product obtained by this method contains over 90% protein and only about 0.3% phosphorus. 

Nagano, T Y. Fukuda T. Akasaka. Dynamic viscoelastic study on the gelation properties of P conglycinin-rich and glycinin-rich soybean protein isolates. J. Agric. Food Chem. 1996, 44, 3484-3488. 

Thanh, V.H. K. Shibasaki. P-Conglycinin from soybean proteins Isolation and immunological and physicochemical properties of the monomeric forms. Biochim. Biophys. Acta 1977, 490, 370—384. 

Xiao, J.-X., H.-Y. Yu, and J. Yang, Microencapsulation of sweet orange oil by complex coacervation with soybean protein isolate/gum arabic. Food Chem., 125 (2011) 1267-1272. 

Li, H., Zhu, K., Zhou, H., Peng, W, 2012. Effects of high hydrostatic pressure treatment on allergenicity and structural properties of soybean protein isolate for infant formula. Food Chem. 132, 808-814. 

Ortiz, S.E.M., Mauri, A., Monterrey-Quintero, E.S., Trindade, M.A., 2009. Production and properties of casein hydrolysate microencapsulated by spray drying with soybean protein isolate. Food Sci. Technol. 42, 919-923. 

Pomegranate polyphenols Maltodextrin or soybean protein isolates Spray drying Preservation at high temperature [160]... 

Jia, Z.,Yong, Y., (2006) Surface Modification of Poly Acrylic Fibers (PAC) via Grafting of Soybean Protein Isolates (SPI). Iranian Polymer Journal, Vol. 15, No. 10, (October 2006), pp 789 798, ISSN 1026-1265. 

Beermann, C., Euler, M., Herzberg, J., Stahl, B., 2009. Anti-oxidative capacity of enzymatically released peptides from soybean protein isolate. European Food Research and Technology 229, 637-644. 

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... 

Wang Z, Zhou J, Wang X, Zhang N, Sun X, Ma Z (2014) The effects of ultrasonic/microwave assisted treatment on the water vapor barrier properties of soybean protein isolate-based oleic acid/stearic acid blend edible films. Food Hydrocolloids 35 51-58 Wihodo M, Moraru Cl (2013) Physical and chemical methods used to enhance the structure and mechanical properties of protein films a review. J Food Eng 114(3) 292-302 Woehl MA, Canestraro CD, Mikowski A, Sierakowski MR (2010) Bionanocomposites of thermoplastic starch reinforced with bacterial cellulose nanofibers effect of enzymatic treatment on mechanical properties. Carbohydr Polym 80 866-873 Xu YX, Kim KM, Hanna MA, Nag D (2005) Chitosan-starch composite film preparation and characterization. Ind Crops Prod 21 185-192... 

Cui Zhou. Study on application of soybean protein isolate in material areas. Wuxi Jiangnan University, 2009. 

Preparation and storage of products from both oilseeds is often inhibited by rancidity and bitter aroma defects caused mostly by volatile aroma active carbonyl compounds, e. g., (Z)-3-hexenal, (Z)-l,5-octadien-3-one and 3-methyl-2,4-nonan-dione. The rancidity-causing compounds are formed through peroxidation of linolenic acid, accelerated by the enzyme lipoxygenase and/or by hem(in) proteins (cf. 3.T.2.2). Furan fatty acids are the precursors in the case of the dione (cf. 14.3.2.2.5). Lipid peroxidation is also involved in the formation of another very potent odorant, 2-pentylpyridine, which produces grassy aroma defects in soybean products. Defatted soybean protein isolates contained 60-510 pg/kg of this compound, which with an odor threshold... 

Chen, G., Liu, H., 2008. Electrospun cellulose nanofiber reinforced soybean protein isolate composite film. Journal of Applied Polymer Science 110, 641-646. 

Cellulose/ SPI soybean protein isolate (SPI) composite reinforced by cellulose nanofibr mats [127]... 

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