Moisture Induced Changes in Engineering, Thermal and Mechanical Properties of Custard Apple (Annona squamosa L.) Seeds

Abstract

Present research has been carried out to study the physical, thermal and mechanical properties of custard apple seed. The analysis assessed the effect of moisture content (7.8% to 30% d.b.) on diverse engineering properties of custard apple seeds. It was found that as the amount of moisture increased, number of properties, including seed length (L), seed width (W), and seed thickness (T), increased linearly. The results indicated the surface area of seed (Sa), volume of seed (V), angle of repose (θ) and mass of thousand seed (M₁₀₀₀), increased from 199.46 to 218.89 mm², 181.78 to 210.19 mm³, 17.3° to 31.5°, and 234.63 to 280.46 g, respectively, with an increase in moisture content. The true density (ρ_t), bulk density (ρ_b) and porosity increased 19.13%, 15.74%, and 2.2%, respectively as the moisture content increased. The static coefficient of friction (μ) increased as the amount of moisture increased for various surfaces, that is, glass, galvanized iron (GI), and stainless steel (SS) from 0.316 to 0.522, 0.311 to 0.614, and 0.289 to 0.438, respectively. Hardness and thermal property are the two novel characteristics that have been used for seed characterization. When the amount of moisture increased then texture property dropped. Thermal conductivity (λ) and specific heat per unit volume (ρ_cp) increased from 0.13 to 0.17 W m⁻¹ K⁻¹ and 0.51 to 0.73 MJ m⁻³ K⁻¹ and thermal diffusivity (α) reduced from 0.25 to 0.18, as the amount of moisture of custard apple seed raised.