Consideration of Freshness and Taste of Japanese Tomatoes - Comparison of Laser Biospeckle, Optical Coherence Tomography, Different Sensing Technologies and Human Perception

摘要

There has been a growing interest in the application of non-invasive laser bio-speckle activity in the assessment of agricultural products such as tomato, Indian fruits, apples and so on and compare with other physical measures such as acid and starch content. In this study, we have compared characteristics of tomatoes by optical sensing along with taste and smell measurements in addition to human taste perception. We have employed non-invasive optical method of speckle imaging, smell and taste sensor devices for evaluation of freshness of tomatoes stored at room temperature. Tomatoes purchased from a local supermarket were used for measurements. Movies of biospeckle images acquired with a CMOS camera (1024x1280 pixels) binned to 240 x320 pixels sampled at the rate of 15 fps were obtained over a period of 14 sec. Calculating cross-correlation coefficient of biospeckle images at different times with that at time 0 and further quantifying the correlation coefficient (r) at 14th sec as a parameter, it has been found that correlation coefficient decreased as a function of days matching the expectations due to reduction in the cellular dynamics with age. We also conducted smell and taste measurements by electronic nose and lipid based taste sensor in addition to human sensing evaluations all which revealed that day 15 tomatoes to be tasting better. Comparison of freshness and taste revealed that freshness and taste quality do not always agree. Biospeckle can detect deterioration as early as third day. At the same time, both taste measurement and human perception results suggest for a longer storage to be delicious.