A Review on the Cooking Attributes of African Yam Bean (Sphenostylis stenocarpa)

African yam bean, an underutilized legume usually cultivated for its edible tubers and seeds, is known for its nutrition-rich qualities; however, the crop’s level of consumption is low. The underutilization of the crop could be attributed to several constraints, including long cooking hours of up to 24 hours. Cooking time is an important food trait; it affects consumers’ choices, nutrients content, and anti-nutrient conditions. Additionally, foods requiring long cooking hours are non-economical in terms of energy usage and preparation time. The prolonged cooking time associated with AYB places enormous limitations on the invaluable food security potentials of the crop. Therefore, the availability of AYB grains with a short cooking time could lift the crop from its present underused status. To efficiently develop AYB grains with reduced cooking time, information on the crop’s cooking variables is a prerequisite. This review presents available information on variations in cooking time, cooking methods, and processing steps used in improving cooking time and nutrient qualities in AYB. Likewise, the review brings to knowledge standard procedures that could be explored in evaluating AYB’s cooking time. This document also emphasizes the molecular perspectives that could pilot the development of AYB cultivars with reduced cooking time.

Relationship between Salt (NaCl) Stress and Yield Components in Three Varieties of African Yam Bean (Sphenostylis stenocarpa)

Salinity has threatened the existence of many useful and multipurpose legumes such as Sphenostylis stenocarpa. To revert this situation effort must be made towards its sustainable use by encouraging domestication of improved varieties that can thrive in salt stress region. This research study was aimed at establishing the effect of salt-stress on seed germination, morphological attributes and yield response of three ­varieties Sphenostylis stenocarpa. Data were collected from the third-weekly for a period of three months (12 weeks) on plant height and number of leaves. At 12 weeks, data were collected on the following traits: number of flowers per plant, number of pods per plant, length of pod and number of seeds per pod. The data on number of seed germinated was also taken. Data collected were subjected to analysis of variance (ANOVA) and mean were separated using Least Significant Difference (LSD) test. Results obtained revealed that sodium chloride (NaCl+) significantly affected some important morphological traits of Sphenostylis stenocarpa evaluated. All varieties treated at various levels (1 kg/l, 2 kg/l and 3 kg/l) with NaCl performed poorly than those without treatment (control). This study revealed that there was no significant difference amongst all varieties of African yam been treated at 1 kg/l levels of NaCl. There was no significant different (p<0.05) among varieties of African yam bean at 0 kg/l in different morphological parameters evaluated. Salt stress significantly reduced (p<0.05) the germination of African yam bean.

Taxonomic studies of two trifoliate legumes of high economic importance in Ebonyi State, South-eastern Nigeria

Taxonomic studies of Sphenostylis stenocarpa and Centrosema pubescens based macro-morphology and foliar epidermises were carried out to determine their similarities and differences. The taxa are of high economic values as they are used as food and medicine in Nigeria. Standard methods were used to carry out the studies as qualitative and quantitative macromorphological characters of the taxa were obtained by visual observation and measuring with metre rule while foliar epidermal study followed standard methods previously used by other researchers. The taxa studied have trifoliate leaf type with leaf and leaflet arrangement alternate and opposite respectively. From the foliar epidermises, Sphenostylis stenocarpa possesses paracytic stomata on the abaxial surface and anisocytic stomata on the adaxial. The abaxial surface of Centrosema pubescens possesses anomocytic and paracytic stomata and anomocytic stomata on the adaxial surface. Cell shapes of the foliar epidermal surfaces are irregular with undulate anticlinal wall patterns except on the adaxial surface of Sphenostylis stenocarpa with pentagonal cell shape and straight anticlinal wall. The two taxa are similar in their leaf type and arrangement but differ greatly in their stomatal types.

Phytochemical composition of tubers of selected accessions of African yam bean, Sphenostylis stenocarpa (Hochst.ex A. Richmond) harms (family fabaceae)

This study is on the quantitative determination of phytochemical composition in tubers of 17 accessions of the African Yam Bean (AYB), Sphenostylis stenocarpa (Hochst.ex A. Richmond) Harms. Standard laboratory methods were followed to ascertain the presence and quantity of some phytochemicals in the tubers of the 17 AYB accessions. The result showed that variations existed among the studied accessions for the eleven phytochemical constituents. The ranges were: total alkaloid (22.195-183g\100g), Glycosides (4.338- 14.733g\100), Flavonoids (7.732- 14.037g/100), Phenols (16.448-32.287g/100), Oxalate (2.519-8.938ppm), Tannin (1.22- 4.340ppm), Saponin (1.475-5.232ppm), Hydrogen Cyanide (0.261-0.928ppm), Phytate (1.532- 5.435ppm), Trypsin Inhibitor (1.088-3.858ppm), and Organic Acid (11.537-23.904ppm). A high significant correlation was observed among the first three principal component axes whichaccounted for 90.4% of the total variation among the accessions. The cluster analysis showed the existence of two significant divergent groups. The accessions in cluster II recorded the least values for oxalate, tannins, saponins, hydrogen cyanide, phytate, trypsin inhibitor, glycoside, flavonoid and phenols while cluster I had higher values for them. The identified phytochemicals with the significant intra-specific variations seem to provide clues which underscores the possibilities of selection and improvement of these tubers for food and medicine for humans. Keywords: African Yam Bean, tubers, underexploited organ, nutritional, anti-nutritional factor, diversity, phytochemicals.