Optical properties–microstructure–texture relationships of dried apple slices: Spatially resolved diffuse reflectance spectroscopy as a novel technique for analysis and process control

Abstract

The potential of spatially resolved diffuse reflectance spectroscopy in the 500–1000 nm range by means of a fiber-optics probe was investigated for acquiring scattering and absorption properties of air dried apple rings subjected to different pre-treatment conditions: without osmo-dehydration (TQ) and with osmo-dehydration for 1 (OSMO1) and 3 h (OSMO2). The fresh apple rings were produced from ‘Golden Delicious’ apples at harvest (H) and 5 month storage at 2 conditions: controlled atmosphere (CA) and normal atmosphere (NA). Microstructure properties of the dried apple rings were also obtained from X-ray micro-CT measurements. The TQ samples were found to have significantly higher scattering properties, thicker tissue, smaller pore sizes, were less crispy, and required higher snapping work or rupture energy than the OSMO1 and OSMO2 samples. On the other hand, no significant differences were observed between the scattering properties, microstructure, and textural quality of the OSMO1 and OSMO2 apple rings. From these results, it was concluded that there is a clear process–microstructure–quality relation in osmo-air-dried apples which can be measured non-destructively with spatially resolved diffuse reflectance spectroscopy. Therefore, this study confirmed the potential of spatially resolved diffuse reflectance spectroscopy for non-destructive quality assessment of air-dried apple slices, which provides perspectives for drying process optimization

Light distribution and thermal effects in the rat brain under optogenetic stimulation

“…The custom built spatially resolved spectroscopy instrument described in was used to estimate the wavelength dependent absorption, μ a , and reduced scattering coefficients, μ s ′ = μ s (1 − g ), of rat brain tissue for the spectral range between 470 nm and 1040 nm, relevant for optogenetic experiments. Briefly, the setup consists of a custom fiber‐optic probe with one source fiber emitting the light, and five fibers collecting the reflected light at distinct distances from the source.…”

Monitoring of polymer content in an emulsion polymerization using spatially resolved spectroscopy in the near infrared region and Raman spectroscopy

“…In SRS, data are collected at different angles from the excitation light source in order to collect both the transmitted and diffused light. SRS has been successfully used in food, 23 pharmaceutics, 24 and chemical applications, such as silica precipitation. 25 Emulsion polymerization consists of a heterogeneous medium that generates strong light diffusion related to particles, for which the SRS is well adapted.…”

Cross-polarized VNIR hyperspectral reflectance imaging for non-destructive quality evaluation of dried banana slices, drying process monitoring and control

“…Hot-air convective drying is commonly employed in the food industry. However, an improper drying process can lead to unwanted changes in chemical composition and structure of the fruit tissues, resulting in bad consumption quality in terms of color, texture and nutritional values (Aghbashlo et al, 2014;Maskan, 2000;Nguyen Do Trong et al, 2014;Nimmol et al, 2007;Sablani, 2006;Vega-Gálvez et al, 2012). Therefore, the banana drying process must be controlled carefully and the quality attributes of the dried fruits should not only be evaluated at the end of the processing, but also monitored during operation (Aghbashlo et al, 2014).…”