Publication no. C-2001-1205-02R |  VIEW ARTICLE

Frequency Dependence of Viscoelastic Properties of Bread Crumb and Relation to Bread Staling (1).

F. C. Wang (2) and X. S. Sun (2,3). (1) Contribution 00-461-J from the Kansas Agric. Exp. Stn., Manhattan, KS 66506. (2) Dept. Grain Science and Industry, Kansas State University, Manhattan, KS 66506. (3) Corresponding author. E-mail: <xss@wheat.ksu.edu> Phone: 785-532-4077. Fax: 785-532-7010. Cereal Chem. 79(1):108-114. Accepted September 4, 2001. Copyright 2002 American Association of Cereal Chemists, Inc.

The viscoelastic behavior of bread crumb was studied using dynamic mechanical analysis (DMA) in the compression mode with the frequency sweep. The dynamic storage modulus (E(prime)), loss modulus (E(double prime)), and tandelta (E(double prime)/E(prime)) were measured for bread crumb aged up to three days at ambient temperature. The viscoelastic properties of bread crumb showed a characteristic frequency dependence similar to that of a soft rubberlike solid. Typical behavior of bread crumb involved a transition from rubberlike to glasslike consistency with increasing frequency. At a low frequency region, the E(prime) and E(double prime) values were relatively small and nearly constant, showing characteristics of the rubbery plateau. Then, they increased rapidly with increasing frequencies and approached a glasslike state. Tandelta was low and almost constant at low frequencies before the transition, then went through a prominent peak with increasing frequency. The frequency at which the tandelta of bread crumb started to rapidly increase was defined as the onset frequency (f(o)) of the transition. The f(o) values increased with the aging of bread crumb samples, which correlated highly to bread staling (r = 0.942). Both dynamic moduli E(prime) and E(double prime) at f(o) also increased with the aging of bread, which correlated highly to firmness obtained using a texture analyzer in a static compression mode (r = 0.941 and 0.943, respectively). DMA measurements could be helpful in characterizing bread staling.