30C-24 |
Use of specific antibodies to determine protein interactions involved in texturization of extruded wheat flour |
Y. JIANG, M. A. K. Partridge, and K. M. Schaich. Dept. of Food Science, Rutgers, The State Univ. of New Jersey, 65 Dudley Rd., New Brunswick, NJ 08901-8520 Extrusion of cereals is used to generate products with a wide variety of textures, but little is yet understood about the molecular changes and reorganization that are responsible for texturization. SDS-PAGE (polyacrylamide gel electrophoresis) can determine changes in protein band patterns and molecular weights but it cannot reveal identities of protein bands that move or disappear. Thus, new approaches were needed to track modifications and rearrangements of proteins caused by extrusion. Our objective was to use specific antibodies to obtain detailed information about wheat protein classes involved in fragmentation and crosslinking associated with texturization of extruded wheat flour. Flour and extrudates were extracted with 1.5% SDS with/without 2% b-mercaptoethanol to obtain all protein fractions or with 70% ethanol or 1 M urea to isolate gliadins. After fractionation by SDS-PAGE and lactic acid PAGE, proteins were stained with Coomassie blue or blotted to polyvinyl difluoride membranes for reaction with monoclonal and polyclonal wheat protein antibodies having a range of specificities. In soluble proteins, antibodies revealed crosslinked and fragmented HMW-GS and loss of lower molecular weight glutenins and C-LMW glutenins; extensive alteration of albumin/globulins and massive loss of antibody recognition; 80% loss of a, b, and g-gliadins and polymerization by intermolecular disulfide bonds; and intact, unmodified w-gliadins. Discrete bands rather than diffuse smearing of all protein classes on immunoblots indicates that the scission and crosslinking occur at specific sites, not randomly. Insoluble proteins, released by glucoamylase digestion of starch complexes, are being similarly analyzed by antibodies to provide a complete picture of protein reorganization during extrusion and to quantitate the extent of protein-protein vs protein starch crosslinking. Combined with chemical and textural analyses, this new detailed information about protein modifications and interactions will help guide extrusion processing for particular quality characteristics and facilitate applications of extrusion to new food materials.
Session 30C, Food Chemistry: Proteins
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