Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 12/17/2008
Publication Date: 3/22/2009
Citation: Tunick, M.H., Cooke, P.H., Onwulata, C.I. 2009. Viscoelastic behavior and microstructure of protein solutions. American Chemical Society Abstracts.
Technical Abstract: Twenty percent solutions of calcium caseinate (CC), egg albumin (EA), fish protein isolate (FPI), soy protein isolate (SPI), wheat gluten (WG), and whey protein isolate (WPI) were examined during heating by small amplitude oscillatory shear measurements, which provided an indication of protein behavior. CC, SPI, and WG aggregated between 40 and 60 deg C, as evidenced by hundredfold increases in storage modulus. EA and WPI aggregated between 55 and 65 deg C, with storage modulus increasing by four orders of magnitude; FPI was basically unchanged. The storage modulus values of CC, SPI, and WG were greater than the loss modulus values throughout the temperature sweeps, signifying that elastic behavior predominated. Loss modulus was greater than storage modulus for FPI, and before aggregation of EA and WPI, representative of viscous behavior. Scanning electron microscopic imaging revealed changes during heating of CC, EA, and WPI, indicating differences at the microstructural level; the other proteins did not change. The results show that these solutions aggregate differently but predictably during heating. Knowledge of viscoelastic properties and microstructure will allow protein-enriched foods to be tailored toward specific functional properties.