Non-destructive evaluation of fruit firmness and acoustic evaluation of crispness of persimmon
Changes in fruit firmness and crispness of three cultivars of persimmon (cv. Soshu, Fuyu, and Taishuu) were measured under different storage conditions after harvest. Fruit firmness was non-destructively determined by a vibration technique using a second resonant frequency. Elastic index (EI) of the fruit obtained by the vibration method decreased exponentially during the storage. Combination of the softening curve and sensory scores predicts waiting days for an optimum acceptability by a reciprocal equation. Japanese young people recently tend to like crisp flesh of persimmon. Crisp cultivar, Taishuu, was developed in 1995 by cross-breeding. Prolonged preservation of the crisp texture of Taishuu during the storage increases its commercial values. Crispness of the flesh of Taishuu and Fuyu (soft texture, a domestic cultivar) was evaluated by an acoustic method, where a wedge-type probe was inserted into the flesh, and vibrations of the probe were monitored through a band-pass filter. Two characteristic frequency bands were found for the crispness of the Taishuu, ranging from 100 to 140 Hz and over 3,200 Hz. The acoustic evaluation method of the crispness objectively measures the crispness that has been evaluated by a subjective sensory test.
Sakurai, N., Suzuki, T., Niikawa, T., Nakano, K. and Koyama, S. (2022). Non-destructive evaluation of fruit firmness and acoustic evaluation of crispness of persimmon. Acta Hortic. 1338, 321-328
elastic index, second resonant frequency, storage, texture index, vibration