The "mechanical signatures" of brittle cellular foods are known to be irregular and irreproducible. Nevertheless, their degree of jaggedness is remarkably similar and can be a measure of such foods' brittleness and perceived crunchiness/crispiness. An irregular curve's "jaggedness" is manifested by frequent direction reversals. Hence, their number can serve as a jaggedness's index. Counting the number of direction reversals in a digitized force-displacement curve can be done with a simple algorithm, implemented in any general-purpose software. The number of direction reversals is strongly correlated with the signature's apparent fractal dimension. It is also a reproducible enough parameter to monitor the loss of brittleness in snacks as a result of moisture sorption. This measure of jaggedness, however, is inapplicable to smooth force-displacement curves because in such records, the small random force fluctuations produced by the digitizing process can create a false impression of "jaggedness." Although a correction for this artifact can be introduced into the program, its utility is doubtful.