Non-destructive Maturity Measurement of “Montong” Durian Using Stem Strength and Resonant Frequency

Abstract

This research studied a non-destructive measurement of maturity of “Montong” durian.
Durians, 130 fruits, were harvested in 7 stages of maturity starting from 105 days to 136 days after
blossom. The samples were taken for non-destructive measurements of the stem strength using the
uniquely built device and force-deformation responses to radial compression were recorded. The
sound of fruit tapping was also acquired for resonant frequency determination. The pulp of the
samples was later oven dried for determination of the dry matter percentage that was used as maturity
reference. The statistical correlation analysis of various stem strength related parameters showed that
the area under the force-deformation curve was positively correlated the most with the dry matter
percentage at correlation coefficient r = 0.808. The negative relationship was found for the resonant
frequency and the dry matter percentage with r = -0.448. The multiple linear regression analysis
indicated that the area under the force-deformation curve and the resonant frequency could be used in
linear combination for the best prediction with multiple coefficient of correlation (r) = 0.844 and
multiple coefficient of determination (R2) = 0.713.