Characterization of Insect Damage, Physical and Thermal Properties of Off-Ground Harvested Almonds and Their Components as Influenced by Harvest Time

Abstract Off-ground almond harvesting is a promising alternative to conventional on-ground methods, reducing dust, microbial contamination, and insect damage. However, the high moisture content (MC) in off-ground harvested almonds requires timely mechanical drying to maintain product quality and safety. This study aimed to characterize insect damage, physical and thermal properties of off-ground harvested almonds, and their components (hulls, shells, and kernels) at early (EH) and standard (SH) harvest stages, and to provide foundational data for drying process modeling and optimization. To minimize losses from prematurely detached almonds, EH was conducted 3–4 weeks before SH, which followed local practices. Off-ground harvesting reduced infestation by 52% compared to conventional methods, demonstrating significant quality and safety advantages. EH samples consisted entirely of in-hull almonds, while SH almonds included three distinct fractions: in-hull almonds, in-shell almonds, and loose hulls. EH almonds exhibited higher MC, thermal conductivity, and specific heat, indicating greater energy demand during drying. Among components, hulls had the highest MC and thermal properties, followed by shells and kernels. These findings support a two-phase drying strategy for EH almonds, starting with high temperature for efficient hull moisture removal, followed by moderate temperature to preserve kernel quality. In SH almonds, distinct thermal behaviors between in-hull and in-shell fractions, along with significant thickness differences (24.5 ± 2.5 mm vs. 17.2 ± 1.3 mm), highlight the need for separate drying. A size-based sorting strategy prior to drying is recommended to enhance efficiency and product uniformity. Overall, this study provides essential data to guide harvest-stage-specific postharvest practices in the almond industry.