Adaption of the traditional coffee pulping machine to soybean dehulling

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Date

2008-06

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Abstract

Processing of soybean for human consumption requires wet heat treatment of the beans in order to inactivate anti-nutritional factors. After hot water treatment or steaming, dehulling of the bean has always been an uphill task for household processors in Tanzania. Dehulling is done by hand rubbing, which is tedious and time consuming. The traditional coffee pulping machine was adapted to dehull boiled soybean. Seven soybean varieties namely TGX-1876-2E, Bossier, Kaleya, TGX 1805-8E, Sable, Songea and Duicker were tried. This was a development process whereby three consecutively improved versions of dehulling machines were tested. The machines were branded Ml, M2 and M3, implying first, second and third generation, respectively. Bean recovery as a measure of performance was 74.3, 77.4 and 91.8% for Ml, M2 and M3, respectively compared with 89.7% for manual dehullingfrubbing. The respective throughput was 8, 10 and 28.2 kg/h compared with 0.43 kg/h for manual dehulling. The mean dehulling efficiency of the M3 dehuller was 82.4% which was the highest. The M3 dehuller's best performance was due to use of ball bearings to support the rasping roller axle instead of sleeves and its ergonomically suitable height. The M3 dehuller could be adopted for soybean dehulling under rural livelihood conditions but the economics for owning and running it needs to be explored. Its improvement to make it moiorised is recommended to increase throughput and increase chances for adoption in medium scale soybean processing.

Description

Tanzania Journal of Agricultural Sciences, 2008, 9(1) : 93 - 100

Keywords

Soybean dehulling, Traditional coffee pulping machine, Wet heat treatment, Inactivate anti-nutritional factors

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