Acoustical Watermelon Studies: Reaching for More Than What’s on Tap

To know whether a watermelons is ripe — before cutting into the melon — is a dream brought to exciting levels by generations of scientists, building on the wisdom and wishfulness of their ancestors. Here are three of the juicier studies published in recent times.

Acoustical Watermelon Study (1998)

Study on acoustic characteristics of the watermelon,” M.S. Kim, D. S. Choi, Y. H. Lee, and Y. K. Cho,  Journal of the Korean Society for Agriculture, 1998.

Acoustical Watermelon Study (2002)

Numerical analysis on acoustic impulse response for watermelon,” Yong Sul Kim, Dong Hoon Yang, Young Jae Choi, Tas Joo Bae, Chul Ho So, and Yun Ho Lee, Proceedings of the Korean Society for Nondestructive Testing Spring Meeting 2002. The authors report: “As we analyzed impact pulse signal and extracted featured parameters concerned with evaluation of its ripeness, we found the plausibility of progress on nondestructive evaluation of ripeness and adoption of numerical analysis on acoustic impulse response.”

Acoustical Watermelon Study (2015)

Nondestructive determination of watermelon flesh firmness by frequency response,” Rouzbeh Abbaszadeh, Ali Rajabipour, Yibin Ying, Mojtaba Delshad, Mohammad J. Mahjoob, and Hojjat Ahmadi, LWT-Food Science and Technology, vol. 60, no. 1, 2015, pp. 637-640. The authors, at Tehran University, report:

“The identification of watermelon ripeness from its appearance such as size or skin colour is very difficult. The common subjective method is usually based on the sound produced by a slap. This method is prone to human factor errors; it may be a good way only for people with much experience. This idea led researchers to study acoustic methods…. The main objective of the present work is to study the potential of laser Doppler vibrometery and vibration spectra for evaluation of watermelon firmness….

“Briefly, laser beam from the LDV device is directed to the upper surface of the sample and the vibrations are measured from the Doppler shift of the reflected beam frequency due to the motion of the surface. Amplitude and phase shift between the mentioned signals were extracted for the entire frequency range using fast Fourier transform applied to the response and the excitation signals…. [This nondestructive determination of watermelon flesh firmness by frequency response proved to be] accurate and fast.”