Available and unavailable carbohydrates of some edible grain legumes

Abstract

The available and unavailable carbohydrate profiles of eleven legumes from different seed lines of
African yam bean, bambara groundnut, kidney bean, lima bean, pigeon pea and jack bean in the raw, cooked and
autoclaved forms were studied. Glucose, fructose and sucrose contents of all raw legumes varied from 0.05 to 0.22
g/100g, 0.24 – 0.90 g/100g and 1.49 – 3.25 g/100g dry matter, respectively. Raffinose ranged from 0.24 g/100g in
bambara groundnut to 0.62 g/100g in African yam bean and stachyose from 0.75 g/100g in bambara groundnut to 3.00
g/100g in lima bean. Starch content was highest in the bambara groundnut and lowest in jack bean, with pigeon pea
having intermediate value. Hemicellulose and cellulose contents were highest in jack bean, and lignin levels were
similar in various legumes. Cooking resulted in a slight decrease in available carbohydrate levels whereas the
unavailable carbohydrates were relatively unchanged by heat treatment.
Key Words: Available carbohydrates; Unavailable carbohydrates; Grain legumes; African yam bean; Bambara