Relationship optical properties and quality of kiwifruit treated with thidiazuron during storage

Abstract

The effects of varying concentrations of thidiazuron (N-Phenyl-N′-1,2,3-thiadiazol-5-ylurea, TDZ) on the quality and optical properties of kiwifruit during storage were investigated. The study aimed to improve comprehension of the mechanisms underlying the use of optical techniques for detecting TDZ-treated kiwifruit. For this purpose, kiwifruits treated with a water solution served as the control check (CK), while those treated with TDZ at concentrations of 1, 2, and 4 mg/L constituted the experimental groups. Optical properties, including the absorption coefficient (μ_a) and reduced scattering coefficient (μ_s'), and quality parameters such as single fruit weight, diameter, color, soluble solids content (SSC), moisture content (MC), and firmness index (FI), were measured. The results showed that TDZ treatment increased kiwifruit weight and diameter, and both SSC and MC rose with higher TDZ concentrations, while FI declined. Three absorption peaks (980, 1190, and 1420 nm) were identified in the μ_a of TDZ-treated kiwifruit, with μ_a increasing over storage time, while μ_s' at 1190 nm decreased. Positive correlations emerged between μ_a and SSC, MC, and FI, while μ_s' exhibited negative correlations with these quality metrics. A support vector regression (SVR) model based on μ_s' data effectively identified TDZ-treated kiwifruit, outperforming models based solely on μ_a or combined μ_a and μ_s' data, with an average prediction accuracy of 81.25%. The study demonstrated that the rational use of TDZ improved the quality of kiwifruit and provided theoretical guidance for the rapid detection of TDZ-treated kiwifruit using optical properties.