Ageing-induced changes in nutritional and anti-nutritional factors in cowpea (Vigna unguiculata L.)

Abstract

This study examined the role of seed ageing in the control of anti-nutritional factors in cowpea (Vigna unguiculata L.). In differently aged seeds of three cultivars of V. unguiculata (V240, V78 and V585), germination ability and vigour were studied. Effort was also made to assay trypsin inhibitor, phenol and phytic acid, perform protein profiling in these seeds. High vigour lots (V240 and V585) registered maximum increases in germination of aged seeds. The contents of nutritional factors such as total protein and carbohydrate declined with decrease in seed vigour lots. Anti-nutritional factors such as phytic acid, phenolic content and trypsin inhibitor activity decreased and varied in low and high vigour seed lots. Polypeptide banding pattern significantly varied in the high, medium and low vigour seeds. Notably, proteins with the highest relative mobility of 0.98 and lowest molecular weight of 11.5 kDa and lowest relative mobility of 0.17 and highest molecular weight of 102.0 kDa were observed in all the vigour lots. Results implied the decline in vigour of V. unguiculata seeds under conditions of controlled ageing can be related to the decline in content of major nutritional factors (total carbohydrates and proteins) required for the growing embryo during seed germination. Additionally, decreases in the contents of anti-nutritional factors phytic acid and phenols, and the activity of trypsin inhibitor in particular are connected with the decrease in seed vigour irrespective of V. unguiculata cultivars. The use of short duration controlled ageing technique can, at least partially, reduce the negative effects of anti-nutritional factors, and eventually improve the nutritional quality of V. unguiculata seeds.

Keywords: Anti-nutritional factors; Cowpea; Seed ageing; Trypsin inhibitor.

Fig. 1

Protein profiles of cowpea (Vigna unguiculata L.) representing different vigour categories (Abbreviations used: V1: V240, V2: V578, V3: V585 cultivars; C: control; PM: protein marker; HV: high vigour; MV: medium vigour; LV: low vigour)