Chemical composition and nutritional potential of yam bean seeds (Pachyrhizus erosus L. Urban)

Abstract

Pachyrhizus erosus seeds were analysed for proximate composition, minerals, protein fractions, antinutritional factors, and rotenoids. The seeds showed a high content of proteins, lipids, Fe and Ca, in comparison to other legumes. Glutelins constitute the highest protein fraction, followed by globulins. Antinutritional substances detected as tannins, hemagglutinating activity and trypsin inhibitory activity, were in low concentrations. Seeds were also processed to obtain a flour which showed proper characteristics, good in vitro digestibility, significant rotenoid reduction level and amino acid composition rich in essential amino acids, except methionine.

Physicochemical Characteristics of Yam Bean (Pachyrhizus erosus) Seed Proteins

“…The results also showed that yam bean seed protein was different from that of other legumes such as soy bean (Vasconcelos et al, 2010), peas, common bean (Chan & Phillips, 1994;Morales et al, 2001) and mucuna seeds (Sridhar & Bhat, 2007) that have globulin as the dominant fraction. Santos et al (1996) reported glutelin as the most dominant protein fraction in yam bean seed protein (P. erosus) with globulins, albumins and prolamins reported at 28.8, 16.3 and 7.0%, respectively, contrary to the results of this study. This disparity may be due to the differences in soil fertility and climatic conditions where the crops were grown.…”

“…Both cooked and raw samples of the two yam bean accessions in this study exhibited considerably high IVPD (Table 3). The protein digestibility values in this study were higher than those reported for P. erosus flour by Santos et al (1996). Yam bean seed flour production by Santos et al (1996) entailed soaking, cooking, drying, milling, defatting and then drying.…”

“…The protein digestibility values in this study were higher than those reported for P. erosus flour by Santos et al (1996). Yam bean seed flour production by Santos et al (1996) entailed soaking, cooking, drying, milling, defatting and then drying. These processes may have negatively affected protein digestibility since processes like cooking and drying cause protein cross linking and lead to protein denaturation which ultimately affects protein digestibility.…”

“…The high IVPD results recorded in the current study may in part be attributed to the lower concentration of the antinutritional components in P. erosus seeds compared to other grain legumes. Santos et al (1996) reported that P. erosus seeds contained low levels of tannins (10.2 mg/100 g) and trypsin inhibitory activity (17.1 ITU) compared to other legumes. The lower IVPD in cooked samples may be due to aggregation and cross linking of yam bean seed protein following thermal treatment.…”

“…If detoxified, the yam bean seeds could provide a protein source for use in the food and non-applications such as edible and or biodegradable films and coatings (Gennadios et al, 1994). Santos et al (1996) pointed out the potential value of yam bean seed meal for human consumption after the elimination of rotenone.…”