Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/12/2011
Publication Date: 8/28/2011
Citation: Tunick, M.H. 2011. The power law and dynamic rheology in food analysis. American Chemical Society Abstracts. AGFD:045.
Technical Abstract: Protein networks impart functional and structural characteristics to food, and should be examined to gain an understanding of properties of the product. Food matrices are investigated nondestructively by small amplitude oscillatory shear analysis, which provides information on viscoelasticity, including values for elastic modulus and viscous modulus. Relationships between frequency and viscoelastic data are obtained from frequency sweeps by applying the power law, where elastic modulus equals coefficient a multiplied by frequency raised to the x power and viscous modulus equals coefficient b multiplied by frequency raised to the y power. The power law was applied to the investigation of Queso Fresco cheeses subjected to various pressure treatments and storage conditions. Power law equations for elastic and storage moduli revealed decreases in values of x and increases in values of a during aging at 4 C. The release of excess whey during storage created a stronger and more elastic protein matrix that was less sensitive to changes in frequency. Other cheeses show the opposite trend -- the matrix degrades over time because of proteolysis. Values for b and y were always lower than those of a and x, which indicates that viscous dissipation of energy was not as pronounced as elastic energy storage.