Abstract
This study examines the impact of puffing drying on the physicochemical and structural properties of apple slices using multispectral imaging (UV-NIR spectroscopy), FTIR spectroscopy, and chemometric analysis. Puffing drying significantly impacted apple slice quality, reducing lightness (L* from 75.00 to 43.62) and moisture content (from 10.34 to 7.41%), while increasing redness (a* from 5.41 to 12.32), acidity (from 0.37 to 0.49%), and hardness (from 422.06 to 2967.06). Despite enhanced texture, total phenolic content decreased from 3650.03 to 3307.28 mg GAE/kg, indicating some loss of nutritional compounds during processing. FTIR analysis revealed structural modifications in carbohydrates and lipids, while total phenolic content decreased, indicating thermal degradation. PCA distinguished control and puffed-dried samples, with the first principal component accounting for 98.5% of total variability. PLS regression effectively predicted lightness, redness, and hardness using FTIR spectral data. Multispectral imaging confirmed notable color and texture differences, with reduced lightness and increased surface heterogeneity. PCA of UV-NIR spectra further separated the sample groups, confirming compositional changes. These findings highlighted the potential of multispectral imaging as a non-destructive tool for monitoring drying-induced transformations.