Physical and Mechanical Properties of Selected Common Beans (Phaseolus vulgaris L.) Cultivated in Tanzania

Abstract

The physical and mechanical properties of foods are important, if not essential, in the design of suitable systems, machines, and structures for planting, harvesting, handling and processing of agro-products. Phaseolus vulgaris L. is a popular legume species that play an important role in human diet and among easily available sources of plant protein. However, despite its important roles, there is a lack of information on the physical and mechanical properties of common beans cultivated in Tanzania. The objective of this study was therefore focused on experimental determination of physical and mechanical properties for Uyole-96, Kablanketi, and Wanja, common beans cultivars grown in the Southern Highlands of Tanzania. Experimental results showed that the average length, width, and thickness were 19.96 mm, 8.97 mm, and 7.6 mm at a moisture content of 17.15% dry basis (db.), 13.92% db., and 14.64% db. for Uyole-96, Kablanketi, and Wanja, respectively. The results further show that the average mean diameters (Da) were 10.93, 9.35, and 9.55 mm for Uyole-96, Kablanketi, and Wanja, respectively. The geometric mean diameters (Dg) were 9.66, 8.35, and 8.80 mm for Uyole-96, Kablanketi, and Wanja, respectively, whereas sphericity was found to be 53, 64, and 58% for the same types of beans. Repose angle measuremnts were experimentally determined as 40, 36, and 35 degrees for Uyole-96, Kablanketi, and Wanja, respectively. Weight for apparent density analysis was 709.27, 686.30, and 766.10 kg/m3 for Uyole-96, Kablanketi, and Wanja, respectively, whereas the apparent densities were determined as 1142, 1158, and 1327 kg/m3, respectively, for the same types of beans. Results from the study showed that physical and mechanical properties for Uyole-96, Kablanketi, and Wanja differ significantly from other common beans cultivars cultivated in other countries. Data on physical and mechanical properties determined in this study establishes a convenient reference table for the mechanization and processing of Tanzanian common beans cultivars .