Modeling of impact parameters for nondestructive evaluation of firmness of greenhouse tomatoes

In this research, the potential of a nondestructive method for predicting firmness using impact parameters taken by a low-mass lateral impact device was explored. The tests were carried out on Bandita F1 greenhouse tomato variety at different maturity stages. In the nondestructive impact measurements, impact acceleration and contact time were sensed by an accelerometer attached on impact head, and main impact parameters such as maximum impact acceleration (A), time required to reach maximum acceleration (t) and contact time (tc) were extracted from the impact acceleration-contact time curves. Other impact parameters were derived through the theory of elasticity. These nondestructive impact parameters were compared with destructive reference parameters for predicting firmness of tomatoes. Force-deformation ratio at rupture point was used in the measurements of destructive reference parameter and this was expressed to be tomato firmness. A total of 10 (A,t,tc, A/t, A/tc, A/t2, A/tc2, (1/t)2.5, (A/t)1.25, A2.5) measured and derived impact parameters were analyzed with the destructive reference test. A correlation matrix, stepwise regression and multiple linear regression were used for statistically evaluation. The effect of maturity stages on firmness and impact parameters was investigated by ANOVA test. Statistical analysis showed that the correlations between destructive reference and nondestructive impact parameter test results were significant at 1% level except t and (l/t)2.5. The number of parameters being processed was reduced with stepwise regression analysis. The best model using MLR on variables /t, A/tc2, and A2.5 was selected for predicting tomato firmness. As a result, low-mass impact device tested in the laboratory conditions gave high prediction of firmness for greenhouse tomato. © 2016, Eesti Pollumajandusulikool. All rights reserved