Effect of phospholipid on protein structure and solubility in the extrusion of lung proteins
1993
Prudencio-Ferreira, S.H. | Areas, J.A.G.
Bovine lung flours with residual phospholipid contents of 6.7% and 0.5% were extruded in a single-screw extruder at various temperatures and feed moistures. Disulphide bonds, followed by hydrophobic and electrostatic interactions, were the major interactions responsible for stabilization of extrudate structure. The high lipid content flour (6.7% phospholipid) presented a decrease in protein solubility after extrusion, whereas the low lipid flour (0.5% phospholipid) showed the opposite behaviour. Amino acid composition was not affected by the diverse processing conditions. Infrared spectra showed the presence of beta-sheet anti-parallel structures in the extrudates even in the most drastic conditions of processing employed. Protein solubility in buffer with reducing agents plus sodium dodecyl sulphate of both extrudates was lower in the internal core than in the edges; such behaviour was not observed in a control of soya. Optical microscopy of transverse sections of lung extrudates showed a tendency of collagen to locate on their external parts. These results can be explained by the recently proposed 'suspension model' for biopolymer extrusion.
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