Design and construction of a temperature controlled electric soybean roaster.

Abstract

Soybean roasting is one of the processing methods of soybeans which increases its palatability by enhancing the release of aromas and flavors. The process inactivates trypsin inhibitors and eliminates allergenic proteins thereby removing the toxicity that is present in raw soybean. This study was' carried out to design and construct a temperature controlled electric soybean to help soybean -processors to roast more easily and cheaply in a safe way. The soybean roaster was designed and developed from locally available materials for toasting of soaked soybean and it has a capacity of 2kg/batch the speed of the agitator is 40 rpm. Soaking helped in softening the texture of the dried soybean which aided the efficient roasting through convective heat transfer. The design of various machine parts was carried out by analyzing forces and effect of heat acting on them which helped in selection of proper materials to withstand the forces and heat to avoid failure. Stainless steel is recommended to be used since it is a food grade material because it is nontoxic and corrosion resistant. The performance of developed roaster and optimization of roasting time and temperature for soaked soya bean was done by response surface methodology. The results showed that the sample size increased linearly in mean diameter and unit mass decreased with decrease in moisture content. The optimized roasting time and outer temperature of coil in the developed temperature controlled electric soybean roaster is 23min, 30 sec and 200C respectively. The developed soybean roaster is suitable for roasting soaked soybean with an efficiency of 73.7%.