Natural frequency as a nondestructive biophysical changes assessment of tropical fruits: Case study of durian (Durio zibethinus), mango (Mangifera indica), and 'sawo'(Arachaszapota)

摘要

Physical properties of biomaterials are usually assessed mechanically as modulus elasticity or firmness through compression, tensile or shear test. This assessment is destructive which leads to handicap for online application in agroindustry automation for fresh products. In this study an acoustic method together with a computer software was employed to determine natural frequencies of three horticultural products, i.e. durian (Durio zibethinus), mango (Mangifera indica) and "sawo" (Arachaszapota). The results the durian and mango produced two types of natural frequency, single peak and double peaks whereas the sawo generated only single peak of natural frequency. The natural frequencies of single peak fruits and the first peak natural frequencies of double peaks fruits decreased exponentially during fruit ripening with high coefficients of determination. In the case of mango and sawo fruits, the natural frequencies were also highly correlated with the firmness indices assessed by compressive and penetrometric tests. This finding suggests that the natural frequencies may be utilized as a mean of a non destructive sorting and quality evaluation of these fruits.