Evaluation of the Changes in Optical Properties of Peaches with Different Maturity Levels during Bruising

The main objective was to measure the optical coefficients of peaches after bruising at different maturity levels and detect bruises. A spatially resolved method was used to acquire absorption coefficient (mu(a)) and the reduced scattering coefficient (mu(s)') spectra from 550 to 1000 nm, and a total of 12 groups (3 maturity levels * 4 detection times) were used to assess changes in mu(a) and mu(s)' resulting from bruising. Maturation and bruising both caused a decrease in mu(s)' and an increase in mu(a), and the optical properties of immature peaches changed more after bruising than the optical properties of ripe peaches. Four hours after bruising, the optical properties of most samples were significantly different from those of intact peaches (p < 0.05), and the optical properties showed damage to tissue earlier than the appearance symptoms observed with the naked eye. The classification results of the Support Vector Machine model for bruised peaches showed that mu(a) had the best classification accuracy compared to mu(s)' and their combinations (mu(a) x mu(s)', mu(eff)). Overall, based on mu(a), the average detection accuracies for peaches after bruising of 0 h, 4 h, and 24 h were increased.

Automated summary

The study aimed to measure the optical coefficients of peaches at different maturity levels after bruising. Results showed that bruising caused a decrease in scattering coefficient and an increase in absorption coefficient, with immature peaches experiencing greater changes in optical properties. Optical properties showed significant changes 4 hours after bruising and could detect tissue damage earlier than visible symptoms. The Support Vector Machine model demonstrated that absorption coefficient had the best classification accuracy for bruised peaches, leading to improved detection accuracies at different time points.