Abstract

This investigation was carried out to study some physical, mechanical and thermal properties of four cultivars of African date fruits and kernels namely ‘digila’, ‘krikri’, ‘sukur’ and ‘trigal’. The properties investigated include length, width, pulp thickness, roundness, sphericity, fruit and kernel mass, true density, bulk density and porosity. Others are angle of repose, static coefficient of friction, crushing strength and specific heat. Average fruit and kernel length of digila, krikri, sukur and trigal cultivars at the moisture contents of 17.85, 11.46, 15.85 and 12.27% (d.b.), respectively, was 38.04 and 21.98 mm, 30.70 and 22.99 mm, 33.23 and 22.40 mm and 36.08 and 22.60 mm. Corresponding average width value was 15.53 and 6.35 mm, 14.80 and 6.92 mm, 17.01 and 7.59 mm and 18.00 and 8.26 mm, for fruits and kernels. Roundness of digila, krikri, sukur and trigal fruit and kernel was 46.10 and 28.78%, 37.10 and 36.78%, 44.35 and 33.10% and 44.31 and 35.84%, respectively. Sphericity of fruit and kernel was, respectively 49.64 and 33.52% (digila), 58.81 and 37.40% (krikri), 47.85 and 35.70% (sukur) and 43.25 and 32.13% (trigal). Bulk density of the fruits of the cultivars was found to be relatively lower than that of their corresponding kernels. True density of fruits was lower than the density of water, while kernels were higher. Porosity of the fruits was 34.0, 35.21, 39.0 and 50.5% for digila, krikri, sukur and trigal and the corresponding kernel porosity was 38.8, 59.5, 30.3 and 48.6%, respectively. The angle of repose of fruit and kernel was found to be 19.82 and 34.94o (digila), 18.07 and 33.36o (krikri), 21.93 and 29.0o (sukur) and 25.49 and 20.93o (trigal). The crushing strength of both fruit and kernel was 6.74 and 10.68, 2.03 and 4.35, 13.15 and 17.64 and 5.63 and 9.67 kN/m2, for digila, krikri, sukur and trigal, respectively. Static coefficient of friction of fruit and kernel varied structural surface. Specific heat varied with cultivar and was higher for the kernel than the fruit.

Keywords:

African date palm, crushing strength, digila, krikri, Nigeria, physical properties, specific heat, sukur, trigal,

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