A novel application of vibration technique for non-destructive evaluation of bread staling

To develop non-destructive indices for monitoring the progression of bread staling, the changes in the free vibration responses of baguette bread were examined at different storage times (days 0, 2 and 4). The storage time considerably affected the vibration responses of the bread samples. Except for natural frequencies in the x (wnx) and z (wnz) directions, vibration responses were highly correlated with instrumental texture parameters during storage of the bread; that is, the breads with firmer and less springy crumbs (the stale breads) had lower damping ratios in the x (ξx) and z (ξz) directions. The lower damping capacities of the stale breads were concomitant with their higher values of root mean square for acceleration (aRMSz) and angular velocity signal (VRMSx). The results suggested that the vibration responses are reliable indices for non-destructively monitoring the progress of staling in baguette bread.