Real-time monitoring of solar drying of melon slices with a portable NIR spectrometer: a preliminary approach

A mild solar drying process on melon slices was carried out. During the whole process, Near InfraRed (NIR) spectra (900-1700 nm) were collected continuously in reflectance mode using a portable spectrometer (Viavi Solutions). Samplings were performed for the determination of weight, moisture content (MC), water activity (a(w)) and colour. Partial least square (PLS) regressions showed good prediction ability for MC, a(w) and colour parameters: MC: R-CV(2) = 0.99; RMSECV = 2.49%; a(w): R-CV(2) = 0.97; RMSECV = 0.03; a*: R-CV(2) = 0.91; RMSECV = 1.13; b*: R-CV(2) = 0.86; RMSECV = 2.49; C*: R-CV(2) = 0.87; RMSECV = 2.52; total colour difference: R-CV(2) = 0.85; RMSECV = 1.77; Browning Index: R-CV(2) = 0.86; RMSECV = 11.00. Ratio Performance in Deviation values higher than 3 for MC and a(w) models allowed their use for the estimation of such parameters' pattern along the process, providing satisfactory predictions. These preliminary data suggested the potential applicability of NIR spectroscopy in monitoring the dehydration process.

Automated summary

A mild solar drying process was conducted on melon slices, and NIR spectra were continuously collected using a portable spectrometer. Partial least square (PLS) regressions showed good prediction ability for moisture content, water activity, and color parameters. These preliminary data suggest the potential applicability of NIR spectroscopy in monitoring the dehydration process.