International journal of food science and technology vol:35 issue:5 pages:503-510
A 670nm, 3 mW solid-state laser diode module has been used as light source to monitor quality changes of tomatoes (c.v. Trust) stored at room temperature for 8 days. The scattering images were captured and the total number of pixels in the image was taken as an indicator of fruit ripeness. Non-destructive acoustic and traditional compression tests were used to determine the firmness of tomatoes. The results showed significant differences in image size (number of pixels) for tomatoes at different maturity stages. The image size increased during the storage period. Fruit firmness showed a negative correlation with the image size. The soft tomato corresponds to a larger image size. A second order polynomial equation expressed the relationship between the stiffness factor and the size of scattering image (r(2) approximate to 0.62). The system has the potential to be used to evaluate the ripeness of tomato fruits.