Anti-nutritional constituents of six underutilized legumes grown in Nigeria.

Six underutilized legume seeds grown in Nigeria namely, red and white lima beans, brown and cream pigeon pea, African yam bean and jackbean were analysed for different anti-nutritional factors Sojasapogenol B was identified as the predominant sapogenol in lima beans and jackbeans by capillary gas chromatography. The content of total inositol phosphates and individual inositol phosphates (IP6, IP5, IP4 and IP3) were analysed by ion-pair HPLC, being in the range of other legumes. Trace quantities of lupanine were identified as the alkaloid in jackbean. alpha-Galactosides were present in all the legume seeds, stachyose being the predominant galactoside in lima beans, African yam bean and jackbean, and verbascose in pigeon pea. The haemagglutinating activity was estimated as a measure of the lectin content of the samples. African yam bean was found to have the highest heamagglutinating activity. Tannins were found to be in low quantities. The presence of these anti-nutrients in relation to the nutritional value of the legume is discussed.

Effect of natural fermentation on the content of inositol phosphates in lentils.

The effects of natural fermentation upon phytic acid and less phosphorylated inositol phosphates of Lens culinaris var vulgaris cultivar Magda-20 were investigated. Seven fermentation runs were made following a 2(2) complete factorial design with three replicated centre points to study the effect of different conditions of temperature (28, 35 and 42 degrees C) and broth concentration (79, 150 and 221 g/l). Samples were taken for each of them at daily intervals (0, 24, 48, 72 and 96 h). The pH value declined sharply in the first 24 h of fermentation, becoming stabilized from this time. The relation between lactic acid and titratable acidity presented important differences between the different fermentations, ranging from 30-80%. Phytic acid (IP6), inositol pentakis (IP5), tetrakis (IP4) and tris-(IP3) phosphates were quantitatively determined. The content of total inositol phosphates showed a maximum reduction of 63% at 72 h under the fermentation conditions of 42 degrees C and 79 g/l.

Effect of soaking, cooking and germination on the oligosaccharide content of selected Nigerian legume seeds.

The identity and quantity of and effect of processing on raffinose oligosaccharides in raw, mature seeds of lima beans (Phaseolus lunatus), pigeon peas (Cajanus cajan), African yam beans (Sphenostylis sternocarpa) and jackbeans (Canavalia ensiformis) were investigated. Sucrose, raffinose, stachyose and verbascose were identified by HPLC in all the legume seeds. The total alpha-galactoside contents of the seeds in decreasing order were African yam beans 3.84 mg/100 mg; white lima beans 3.62 mg/100 mg; cream pigeon peas 3.51 mg/100 mg; red lima beans 3.37 mg/100 mg; jackbeans 2.83 mg/100 mg and brown pigeon peas 2.34 mg/100 mg. The predominant oligosaccharide was verbascose in pigeon peas and stachyose in the other three legumes. Cooking unsoaked seeds brought about a greater reduction in the total alpha-galactoside content than soaking for nine hours. The removal of oligosaccharides was higher in legumes cooked in alkaline solution than in water. Germination quantitatively reduced raffinose, stachyose and verbascose while sucrose was increased in all seeds except red lima beans and jackbeans.