Cereal Chem 67:182-187   |  VIEW ARTICLE

Dynamic Rheological Properties of Bread Crumb. II. Effects of Surfactants and Reheating.

J. N. Persaud, J. M. Faubion, and J. G. Ponte, Jr. Copyright 1990 by the American Association of Cereal Chemists, Inc. 

Dynamic testing detected differences in the rheological properties of bread crumb that had been heated to 80 C by conventional or microwave ovens. Both G' and loss tangent of crumbs aged up to 120 hr and heated in a conventional oven were reduced to fresh bread values. Microwave heating did not fully reverse age- related changes in G', and the extent of reversal decreased as the age of the crumb at heating increased. The viscous component, G", and therefore the tangent, increased to levels higher than those of freshly baked bread. Further, as the microwave exposure time increased, the tangent continued to increase. This effect was not attributable to a higher amount of moisture loss than that occurring during conventional heating. During storage, G' of the bread crumb containing the surfactants sodium stearoyl lactylate and hydrated monoglyceride did not reflect the change in firmness measured by empirical, static compression tests. The loss tangent of the surfactant-treated crumb remained equal to that of freshly baked bread throughout the aging period. This indicated that the empirically measured firmness was a composite of both the elastic and viscous properties of the material. Without shortening in the formula, G' of the crumb increased at a greater rate and to a greater extent than with shortening. It appears that the mechanism by which sodium stearoyl lactylate and hydrated monoglyceride reduce firmness is not the same as that by which shortening reduces it.