Physical, thermal, mechanical, and nutritional properties of bitter apple (Citrullus colocynthis L.)

The physical, mechanical, thermal, and nutritional properties of bitter apple and their significance in processing, machine designing, and product development are discussed in the present study. Physical parameters of average length, width, and thickness of small, medium, and large fruit were 47.53, 59.08, and 70.63 mm; 46.62, 58.25, and 70.77 mm; and 46.00, 58.25, and 70.49 mm, respectively. The true and bulk density and porosity of bitter apple were measured as 1005 kg m−3, 465 kg m−3, and 53.69%, respectively. In this study, specific heat, thermal conductivity, and thermal diffusivity of bitter apple were found to be 3.866 ± 0.053 kJ per kg per °K, 0.58 ± 0.010 W per m °C, and 0.147 ± 0.001 × (10−7) m2 s−1, respectively. The fruit was a good source of protein (8–9%), fat (6.5–7.5%), crude fiber (7–8%), carbohydrates (58%), and energy (339.69 kcal/100 g), respectively. The results found in this study could be useful in the design and development of processing machinery for the commercial production of bitter apples. Despite having significant nutritional and medicinal value, the bitter apple is an underutilized fruit. By understanding the physical and mechanical properties of bitter apple and the development of processing machinery and post-harvest handling equipment accordingly, we can improve efficiency, reduce waste, and promote sustainability. Additionally, knowledge of the nutritional and thermal properties of bitter apples would provide for preserving the nutrients of bitter apple that may require special processing techniques.