Nutritional value of African yambean (Sphenostylis stenocarpa, L): improvement by solid substrate fermentation using the tempeh fungus Rhizopus oligosporus

Abstract

The tropical African yambean (AYB, Sphenostylis stenocarpa L.) is a hardy, protein-rich under-utilised African legume. Anti-nutrients, and the excessively long cooking time (4-6 h), among other factors, limit the food use of African yambean seeds. To reduce these limitations, non-traditional, less energy consuming processing methods are required. Seeds of different varieties were (1) examined for proximate composition and (2) fermented with Rhizopus oligosporus for the production of tempeh. The traditional production process involves dehulling, soaking in water for 24 h, boiling in water for 30 min, inoculation and fermentation. In addition, the traditional procedure for preparing tempeh was modified by using 1% citric acid solution instead of water for soaking and cooking. Comparisons with traditionally cooked beans, which involved boiling in water for 4 h, were made. The traditional tempeh procedure resulted in a slight but significant increase in protein and starch (P < 0.05) and an almost complete loss of most of the anti-nutrients of AYB seeds, although the cyanogenic glycoside content of AYB-white remained high. The modified procedure resulted in a bacteria-free tempeh and the cyanogenic glycosides were no longer detectable. In vitro protein digestibility of the 1% citric acid treated sample was slightly lower than that of the water-treated sample. Both tempeh production processes were clearly more effective and less energy intensive than traditional cooking in improving nutritional quality, but only the modified method of tempeh production eliminated the possibility of cyanide poisoning.

The effect of germination on the phytase activity, phytate and total phosphorus contents of some Nigerian-grown grain legumes

“…Lima bean seeds recorded the highest phytate content (8.95 g kg −1 ) while groundnut had the lowest (3.01 g kg −1 ). Azeke et al 17 reported phytate contents of between 3 g kg −1 and 7 g kg −1 for seeds of three varieties of AYB, which is similar to the values presented in this study. The phytate content of pigeon pea seeds reported here (5.89 g kg −1 ) is lower than that reported by Oloyo18 (8.11 g kg −1 ) but higher than that reported by Sangronis and Machado19 (0.73 g kg −1 ) probably due to differences in cultivars and assay methods.…”

Effect of processing methods on the proximate composition of African yam bean (Sphenostylis stenocarpa) flours and sensory characteristics of their gruels

“…Caramelization of the sugars may have occurred during the roasting. The preference of flavor of the treated samples to the control was in agreement with previous studies [16], [29], [30] on the importance of processing to improve traditional foods. Mailard reaction products contribute to flavor of foods [16].…”

Tempeh: A semicentennial review on its health benefits, fermentation, safety, processing, sustainability, and affordability

“…In African yam bean ( Sphenostylis stenocarpa ), tempeh fermentation with 1% (v/v) citric acid added during soaking diminished cyanogenic glycoside content, which can be enzymically hydrolyzed to release cyanohydric acid that is toxic due to its ability to bind with metals, for example, Fe, Mn, and Cu (Azeke et al., 2007; Francisco & Pinotti, 2000). Tempeh fermentation is a more effective and less energy‐intensive method to prepare the African yam bean for consumption compared to the traditional preparation, which involves boiling the yam for 4 hr (Azeke et al., 2007).…”

“…These nonsoy tempehs are referred by mentioning the substrate before the word “tempeh,” for example, pigeon pea tempeh. Some of these other types of tempeh that have been studied are chickpeas, lentils, white beans, black beans broad beans (Erkan et al., 2020), black gram (Yadav & Khetarpaul, 1994), green grams (Lakshmy & Usha, 2010), yam‐beans (Azeke et al., 2007), velvet beans (Pugalenthi et al., 2005), rice bran (Nurrahma et al., 2018), barley (Feng et al., 2005), peanuts (Matsuo, 2006b), sunflower seeds (Vaidehi et al., 1985), lupin beans (Jiménez‐Martínez, Hernández‐Sánchez, & Dávila‐Ortiz, 2007), pigeon peas (Ali, 2008), quinoa (Matsuo, 2006a), oats (Cai et al., 2014), millet (Anandito et al., 2018), cowpeas (Lakshmy & Usha, 2010), koro benguk ( Mucuna pruriens ) (Winarni & Dharmawan, 2017), buckwheat kernels (Wronkowska et al., 2015), red sorghum (Hachmeister & Fung, 1993), wheat (Hachmeister & Fung, 1993), fava beans (Berghofer et al., 1998), peas (Ashenafi & Busse, 1991d), koro kratok bean ( Phaseolus lunatus ) (Pertiwi et al., 2020), jack bean ( Canavalia ensiformis ) (Puspitojati et al., 2019), okara (filtration residue of soymilk production) (Matsuo, 1996), finger millet ( Eleusine coracana ) (Mugula & Lyimo, 1999), cottonseed kernels, and corn grits (Matsuo, 2000).…”