Measurement of tomato firmness by using a non-destructive mechanical sensor

A non-destructive mechanical sensor (Cantifruit) was designed to measure the firmness of tomatoes. It consists of a small plunger constrained to penetrate slightly into the fruits, by using an accurate lever mechanism. A highly significant correlation exists between firmness measurements performed with this device and the Stable Micro Systems (SMS), fitted with the same plunger dimaeter. Using the Cantifruit, data related to firmness variability and changes are easily obtained. The firmness of tomatoes varies about 12 % around its circumference. In a single lot of tomatoes picked at the same time, the variability may exceed 25 %. If the tomatoes are stored at 4-5 °C and 92-99 % relative humidity (RH), their firmness decreases by about 20 % over ten days.