Implications of Dehydration Processing on the Bio-Actives, Chemometrics and Fingerprinting of Allspice (Pimenta dioica L.) Leaves

Pimenta dioica (L.) or Allspice leaves is a spicy leaf and its bio-actives, nutrient and therapeutic value, is under-exploited. In this study, the leaves were dehydrated by sun (SD), shade (SHD), cross-flow (CFD), freeze (FD), low temperature low humidity (LTLH), and vacuum (VD) drying. Our focus extended beyond mere kinetics to explore the chemometrics, volatiles and bioactivity of the leaves. Modified page and Lewis models exhibited a superior fit in describing the dehydration process with high R² value (0.98 – 0.99), lower χ² and RMSE, with effective moisture diffusivity ranging from 0.26 × 10⁻⁹ to 7.47 × 10⁻⁹ m²/s. SEM exemplifies the matrix of leaf microstructures. FD and CFD retained highest total polyphenol content (70.67 ± 2.13 and 65.58 ± 1.95 mg GE/g), total flavonoid content (61.58 ± 0.95 and 43.34 ± 1.23 mg RE/g), essential oil yield (3.62 ± 0.01 and 3.23 ± 0.02%), volatiles (94.47% and 99.83%) and antioxidant activities (109.43 ± 1.15 mg TE/g and 105.88 ± 2.51). GC–MS analysis revealed eugenol, β-myrcene, chavicol, limonene and 3-octenol as a major compounds and Principal Component Analysis were explained 82.2% of the data variation in volatile compounds. Although effective, FD’s cost-effectiveness is challenging. Conversely, CFD emerged as a more economically viable option, preserving essential nutrients such as ash, protein, carbohydrates, fiber, vital multi-minerals, and intrinsic bioactive components. This study pioneers the exploration of Allspice leaves, unlocking promising avenues in the spice industry for diverse applications. It highlights the need to optimize dehydration methods to preserve nutritional content and bioactive properties, paving the way for further advancements in spice processing technologies.

Graphical Abstract