Author
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Sessa, David |
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Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only Publication Acceptance Date: 2/16/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Dicarboxyl derivatives of soy protein isolate (SPI) were generated thermochemically by reactive extrusion of equal weights of SPI with citric acid (CA), also known as 2-hydroxy-1,2,3,-propane tricarboxylic acid. The nucleophilic groups of SPI react with one of the anhydrides of CA, generated on CA when heated dry, to form either acyl and/or ester derivatives with dicarboxyl function. Specifically, CA was dissolved in a minimum amount of water and intimately blended with equal weight of SPI to give a gelatinous batter. This batter was dried at 75 deg C in a hot air oven; the dried mixture was then ground and remoisturized to about 15% moisture. This moistened mixture was subjected to reactive extrusion with two passages through a Brabender Plastic-Corder PL 2000 (3/4" laboratory extruder), single screw, 30:1 L/D, fitted with 1/1 screw and no die; zone temperatures were 140, 200, 196 deg C; speed was 20 rpm. The 2nd passage was needed to achieve the reaction efficiency and degree of carboxylation equivalent to a lengthy oven baking procedure. Evaluation of binding with 10 metal ions, each at 200 ppm demonstrated, in order of preference: Fe2+> Cu2+=Pb2+>Ag+=Li2+>Zn2+>Co2+=Ni2+=Mn2+. The SPI/CA derivative possessed a metal binding capacity equivalent to about 30-35% of a sulfonic type cation exchange resin. |
