Effect of CPPU on bulk optical properties of kiwifruit during storage in near‐infrared range

Abstract

BACKGROUND Investigating the effect of N‐(2‐chloro‐4‐pyridyl)‐N′‐phenylurea (CPPU) on the bulk optical properties of postharvest kiwifruit is helpful in understanding the mechanism of identification of CPPU‐treated kiwifruit using spectroscopy and to develop effective optical sensing techniques. In this study, the absorption coefficient μa and reduced scattering coefficient μs′ of flesh and skin of kiwifruit treated with CPPU solutions at CPPU concentration levels (CCLs) of 0, 5, 10 and 15 mg L−1 were measured by using a single integrating sphere setup over the range 950–1650 nm during 12 weeks' storage. RESULTS Generally, at the same storage period, there was no significant difference (P ≤ 0.05) on flesh's μa among the kiwifruit treated with different CCLs at absorption peaks of 970, 1190, and 1390 nm. The average flesh's μs′ of kiwifruit treated with higher CCLs at 1190 nm were larger than those treated with lower CCLs, and there was a significant difference (P ≤ 0.05) between the kiwifruit treated with 0, 5 and 15 mg L−1 CPPU solutions except for week 6. Contrasted with the μa and μs′ of kiwifruit flesh, the μa and μs′ of skin had bigger standard deviations and larger fluctuations with storage time. Additionally, the CPPU‐treated kiwifruit had higher moisture content, lower firmness, and larger cells than CPPU‐untreated kiwifruit. CONCLUSIONS This study indicates that the μs′ of flesh has potential in identifying kiwifruit treated with different CCLs during storage. © 2020 Society of Chemical Industry

Validation study on light scattering changes in kiwifruit during postharvest storage using time-resolved transmittance spectroscopy

“…In contrast, fruit storage time and the (846 nm) of the same fruit that was negatively correlated (the longer the time, the lower the ) for both storage conditions. Numerous research investigations have demonstrated a correlation between the properties of fruit and textural attributes, including factors like firmness, cell size, and so on 31 , 51 . In the present study, the values and firmness of kiwifruit flesh exhibited a simultaneous reduction over the storage period.…”

Analysis of Light Penetration Depth in Apple Tissues by Depth-Resolved Spatial-Frequency Domain Imaging

“…The differences of optical properties between non-bruised apple tissues and bruised ones can be directly used for early-stage bruise detection. It is well known that there are quite a lot of optical property measuring methods, e.g., timeresolved, spatially resolved, and integrating sphere, which have been employed for measuring optical properties of diverse agro-food products [8][9][10][11]. However, they are generally limited to point measurement and cannot attain depth-resolved information, resulting in great challenges in the nondestructive detection of early-stage bruises of apples [12,13].…”