Frequency analysis of food bolus fragmentation through a vertical pipe

Abstract

The behavior of a raw carrot bolus through a vertical pipe was investigated with a laser detector. To investigate the effect of cohesiveness, samples were pre-processed in various stages, as follows: no compression, 50 % and 80 % compression, and blending with xanthan gum. First, the transit time of the bolus was measured from the time series signal of the voltage drop corresponding to the density of the food fragments. The results showed that the transit time was shorter for the bolus with greater assumed cohesiveness. Next, we analyzed the structure of the bolus flow by obtaining the power spectrum of the time series signal, which exhibited a power-law relationship of the form P(f) ~ f^−α. The value of the exponent α, reflecting the structure of the bolus flow, was also shown to be correlated with the assumed cohesiveness. Therefore, we propose that α can be used as an index to evaluate bolus cohesiveness under shear conditions.