Quantifying persimmon flesh texture using crispness index and maximum stress

Masumoto, N.; Ura, H.; Eshima, A.; Ikeda, H.

Quantifying persimmon flesh texture using crispness index and maximum stress

2018

Masumoto, N. (Fukuoka Agriculture and Forestry Research Center, Chikushino, Fukuoka (Japan)) | Ura, H. | Eshima, A. | Ikeda, H.

The fruits of Japanese persimmon (Diospyros kaki Thunb) cultivars “Akiou,” bred at the Fukuoka Agricultural Research Center, and “Taishu” have a flesh with crispy texture. As only a few reports have examined their texture, we investigated the evaluation parameters for crispy texture of persimmon fruits. Crispness index (CI) calculated by integrating the second derivative of stress values obtained during the probe insertion into the flesh could express the individual crispy texture of persimmon. The relationship between CI and the individual crispy textur value for “Akiou” and “Taishu” was estimated by logarithmic regression. The correlation coefficient of this regression was about 0.9; in contrast, the relationship between other physical properties (hardness and maximum stress) and the individual crispy texture value was not as high. Although the hardness and maximum stress of the flesh did not decrease, the CI and the individual crispy texture value decreased when “Taishu” was stored at 5 ℃ for 20 days. These results indicate that CI could objectively evaluate individual crispy texture. We compared the physical properties of other persimmon cultivars using the CI and maximum stress parameters. The value obtained by dividing CI by the maximum stress were significantly greater in “Akiou” and “Taishu” than they were in “Soshu,” “Fuyu,” and “Nishimura Wase”; the fruits of the latter three cultivars are lacking crispy texture. This indicates that CI and maximum stress are suitable for distinguishing crispy persimmon cultivars from other non-crispy persimmon cultivars.

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