Abstract: In order to develop a new method for crispness evaluation of crisp foods by the measurement of both their mechanical and acoustic properties, three brands of commercial potato chips were used as experimental materials in this study. A test platform was developed, consisting of a texture analyzer and an acoustic emission (AE) system. The mechanical and acoustic signals of potato chips during mechanical compression until fracture were collected continuously and the crispness of potato chips was classified by the peak value of acoustic energy signals and maximum stress. It was found that in the mechanical compression process, many intermediate peaks of stress and AE energy caused by the internal pore ruptures occurred in each sample, followed by maximum peak values of AE energy and stress upon rupture of the whole sample. Both maximum stress and AE energy showed statistical distribution characteristics among samples. Under the experimental conditions of this study, the mean maximum AE energy value was 93.51 mV·ms for brand A, and the average maximum stress was 0.035 MPa. Potato chip crispness was classified by mean maximum stress and AE energy. The crispness of the three brands of potato chips was in the decreasing order: A, B and C. These experimental data show that combined use of mechanical and acoustical measurement is feasible to evaluate the crispness of dried fruits and vegetables.

Key words: potato chips; crispness; texture; acoustic emission