Cooking kinetics of potato tubers determined by vibration techniques

A laser Doppler vibrometer (LDV) was used for remote sensing of potato cooking behavior. Non-destructive determinations of characteristic tuber resonant frequencies (modes M1 and M2) displayed in the amplitude–frequency plots (AFP) prior, during, and after steam cooking of the whole tubers were used to establish cooking kinetic coefficients for four different potato varieties. All measurements for a single potato were taken along the extended portion of the tuber at the same location. We found that potato softening during cooking is consistent with the kinetic equation of the first order and that the “two point” test, based on the determination of the AFP prior to and after cooking for 25 (or 15 in one case) min, yields a good estimation of the kinetic coefficient. The results suggest that the application of this method is limited to smaller tubers; the sloughing and cracking of larger tubers induced by longer cooking times confound the measurements.