Use of optical absorption and scattering properties to monitor the change of chemical characteristics, particle structure and viscoelasticity during apple puree processing

This work explored the optical absorption (μa) and reduced scattering (μs') properties at 400–1050 nm (Vis-NIR) and 900–1650 nm (SWIR) of apple puree at different heating times to evaluate their changes in composition and structure. The optical absorption and scattering coefficients of μa and μs' decreased with increasing heating time. The specific μs' coefficients at 432 nm, 455 nm, 1183 nm and 1304 nm were related to particle structural changes. The partial least squares regression (PLSR) models based on μs' coefficients in the combined Vis-NIR and SWIR regions provided satisfactory estimations of puree particle area (Rp2 = 0.90) and particle perimeter (Rp2 = 0.85), whereas the μs' coefficients in the Vis-NIR region predicted puree viscosity (Rp2 = 0.83), elasticity modulus (Rp2 = 0.81) and viscous modulus (Rp2 = 0.78). Consequently, optical properties can be a potential tool to determine structural and rheological changes of apple puree. [Display omitted] •Puree viscoelastic property was highly correlated to particle size and shape.•The μa and μs' parameters decreased with the puree heating time.•Optical scattering properties highlighted puree particle structure changes.•PLS models based on μs' predicted puree structural and rheological properties.