Evaluation of the Physical and Thermal Properties of Normal and Modified Black Raisins

Abstract

The physical and thermal properties of black raisins within different moisture contents are important parameters during food processing. Some of the physical properties, namely moisture content, length, width, thickness, geometric mean diameter, sphericity, surface area, cross-sectional area, bulk density, true density, porosity, and the thermal properties, included thermal diffusivity, thermal conductivity, and specific heat, were determined at different percentages of total moisture (11.79% and 25.00% for black raisins). These physical and thermal properties are essential in determining the extent of compliance of raisin samples available in the Libyan market with the standard specifications for raisins. The results showed that there was a variation and significant differences in some physical properties of raisins when their moisture was modified. The results also showed a change in the values ​​of total and apparent density, porosity, and also the specific heat changed for black raisins were 3431.62 to 4070.72 j/kg.K) at different moisture levels. It is recommended studying the physical and thermal properties of raisin samples in different regions of the Libyan market.