Protein meal suspensions

For the studies presented in this chapter, samples of peanut and cottonseed meal suspensions were evaluated for foam capacity, stability, and viscosity measurements as described by Cherry and coworkers (23, 24, 22). Vegetable protein suspensions at the appropriate concentration and pH were whipped in a Waring-type blender. After blending, the whipped products were transferred to a graduated cyclinder. Milliliters of foam were recorded immediately and at various time intervals to determine capacity and stability. A Brookfield viscometer and... 

Figure 8. Effect of pH and salt concentration on the foam and protein solubility properties of peanut meal suspensions (25)...

Figure 9. Gel electrophoretic properties of peanut meal proteins that are soluble in suspensions that contain various levels of salt and are at different pH values (25)...

The percentages of proteins in water-soluble extracts of suspensions of peanut meal adjusted from pH 6.7 to 4.0, then back to either 6.7 or 8.2, were less than those of the initial extract and the one-step pH change, respectively (Figure 5). Percentage of protein in soluble extracts at pH 6.7 or 8.2 was not altered greatly by the two-step pH adjustment. 

SPI hardened with an aldehyde at or near the proteins isoelectric point ("pH 4.5 for soy protein) produces a material that is thermoplastic and absorbs <10% moisture during 24 h of soaking. An aqueous suspension of the formaldehyde-hardened SPI can be used as a laminating material for Kraft paper. Laminating material made from soy plastics has similar properties to the more expensive phenol and urea laminating materials, but is less water-resistant. SPI was discontinued during the early 1950s in favor of modified soybean meals used as modifiers and extenders in PF plastics. 

Protein extracts were prepared with some modification, as described by Chung et al (1995). Briefly, 0.2 g of defatted peanut meal were suspensed in 1.5 mL of 0.05 M sodium phosphate buffer pH 8, containing 0.5 M NaCl. The mixture was stirred for 2 hr at 4° C and then centrifuged at 5000xg for 15 min. The supernatant (i.e., extract) was recovered... 

Hoffpauir and Guthrie (102) have proposed a unique method for the isolation of proteins low in ash and phosphorus contents and for the purification of protein preparations. They used anion exchange materials to increase the pH of aqueous suspensions of peanut meal and cation exchange materials to reduce the pH of the protein dispersion to the isoelectric range. The use of specially prepared aminized and phosphoryl-ated cotton fabrics as ion exchange materials has made the method practical. 

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