Investigations into the dehulling of pigeon peas and mung beans

Abstract

Legumes provide a rich source of protein for animal and human consumption. They also supply a substantial amount of minerals and vitamins. Currently the world production of legumes is estimated to be 57.5 million metric tonnes. After harvest, pigeon peas (Cajanus cajan L.) and mung beans (Vigna radiata L.) are dehulled to improve cooking and nutritional qualities and to reduce cooking time. Pigeon peas and mung beans can be consumed as dehulled splits, whole, canned, boiled, roasted or ground into flour to make a variety of desserts, snacks and main dishes. These legumes are hard to dehull because of the presence of mucilages and gums which form a strong bond between the hulls and the cotyledons. To improve the dehulling characteristics of these legumes, a tangential abrasive dehulling device (TADD) was used to investigate their dehulling characteristics. Different treatments consisting of heating, soaking and heating, steaming and drying in addition to tempering were investigated. The control samples yielded less dehulled kernels and generated more fines for both pigeon peas and mung beans. Steaming at 98.0oC for 10 min and heating at 120oC for 10 min followed by tempering for 24 h yielded more dehulled kernels for both pigeon peas and mung beans compared to the other treatments.