A comparative study of mango solar drying methods by visible and near-infrared spectroscopy coupled with ANOVA-simultaneous component analysis (ASCA)

Abstract

The effect of mango solar drying methods (traditional and tunnel dryers) on the quality of dried mango slices was investigated by visible (VIS) and near-infrared (NIR) spectroscopy combined with the chemometric analysis methods of principal component analysis (PCA) and ANOVA-simultaneous component analysis (ASCA). Five batches of mango were investigated, each subjected to two/three different positions of three different types of dryers: electrical (reference), traditional, and tunnel dryers. The results of the visible and near-infrared spectra showed that the quality of the mango samples obtained from the electrical dryer (reference method) was the most uniform and conserved the highest content of carotenoids and chlorophyll pigments. The samples from the traditional dryer had the highest variation and content of residual water. ASCA analysis of visible and shortwave near-infrared (VIS-NIR) (including color information) showed that the batch effect was most dominant with a significance effect of 47.5%, whereas longwave near-infrared (NIR) spectra (chemistry) showed that the dryer effect was the most dominant with a significance effect of 38.3%. The factor of the fruit positions in the dryers proved not to be significant. The VIS-NIR spectrum is thus well adapted to measure the fruit maturity and the NIR spectrum has great potential to investigate and control the dryer performance. The latter clearly demonstrated that the tunnel dryer provides much more gentle and consistent drying process compared to the traditional dryer. In contrast, the samples from the traditional dryer showed chemical changes/decomposition.