Proximate, mineral and anti-nutritional compositions of raw and processed African Yambean (<i>Sphenostylis stenocarpa</i>) seeds in Cross River State, Nigeria

Abstract

African yambean (Sphenostylis stenocarpa, Hochst. Ex A. Rich, Harms) is an indigenous legume in tropical Africa. This food crop legume is highly under-exploited and very little scientific information is available in literature. In this study, the chemical composition (proximate, minerals and anti-nutritional profile) of raw and processed African yambean (AYB) seeds was investigated. Seeds of brown seed coat landraces of African yambean were collected from various locations in the Northern part of Cross River State. The seed characteristics were noted and subjected to boiling and toasting for one hour and thereafter evaluated for proximate composition, gross energy, mineral and antinutritional properties. Results showed that boiling significantly (P<0.05) increased crude Protein (CP) (22.10%), ether extract (EE) (7.53%) and gross energy (GE) (5.23 Kcal/g) compared to the raw (21.61% CP, 5.12% EE and 4.88 Kcal/g GE) as well as toasted seeds (21.41% CP, 5.195 EE and 4.51 Kcal/g GE). Toasting significantly (P<0.05) increased nitrogen free extract (NFE) (50.65%) and ash values. Processing (boiling/toasting) had significant (P<0.05) effect on mineral composition (Ca, Mg, K, Na and Fe) of the seeds except for phosphorus. Boiling significantly (P<0.05) reduced phytate (0.68%), alkaloid (0.70%) and trypsin-inhibitor (0.08 IU/mg) contents. Results have shown that African yambean seeds are rich sources of nutrients but have low human preference for food. But have a high potential as an energy/protein source in livestock feeds. The boiled AYB seeds had highest CP, mineral and lowest in anti-nutrient contents. Hence, boiling was the preferred processing method for AYB seeds.

Morphological characterization and genotypic identity of African yam bean (Sphenostylis stenocarpaHochst ex. A. Rich. Harms) germplasm from diverse ecological zones

“…Its seeds and tubers contain 25.6 and 15.9% protein, respectively (Ojuederie and Balogun, 2017; Ojuederie and Balogun, 2019). Similarly, Anya and Ozung (2019) and Sam (2019) reported protein content of 18.55 and 21.61% in seeds. The seeds have in abundance: lysine (6.21–6.60%) and methionine (1.14–1.27%) (Okorie, 2018).…”

Evaluation of Proximate, Mineral, Anti-Nutrients and Phytochemical Constituents of Indigenous Beans (Cajanus cajan, Sphenostylis stenocarpa and Phaseolus lunatus)

“…Also, Taofeek et al, 22 opined that anti-nutrients such as tannins, oxalate and trypsin inhibitor are nutritionally disadvantageous when consumed in excess as they form strong insoluble complexes with proteins and divalent metals which result in poor digestion and palatability in humans and animal. [24][25][26] Studies had revealed that excessive consumption of anti-nutrients had an adverse effect on the health status of humans and as well as useful defensive mechanism for plants against herbivours. 23 Also, results revealed that P. lunatus contained a significant amount of most phytochemicals than S. stenocarpa and C. cajan seeds ( Table 5).…”

Nutritional Composition of Grain and Seed Proteins

“…African yam bean seed contains protein with a value range between 19 and 30%. The seed is also rich in dietary fibre, carbohydrate, and essential minerals such as calcium, iron, zinc, and magnesium, with values as high as those of other vital legumes [65]. The carbohydrate composition of African yam bean is majorly starch with slowly digestible properties beneficial for diabetic patients [66].…”