Variability in condensed tannins and bitterness in spider plant genotypes

Abstract

Spider plant (Cleome gynandra L.) contributes considerably to the nutrition and medicines of communities in southern Africa. However, its utilisation is limited by its bitterness caused by condensed tannins. Unfortunately, processing options that reduce the bitterness also remove nutritionally and medicinally useful compounds. The objective of this study was to assess the genetic variability of condensed tannins and their association with
bitterness in C. gynandra so as to devise variety recommendations for either direct utilisation or for breeding programmes in Zimbabwe. Total phenolic compounds and condensed tannins were quantified in five genotypes. The amount of total phenolic compounds were not significant, but quite significant (P<0.001) for condensed tannins. Genotype CGSKGP had the highest (0.49 mg g-1) and twice as much condensed tannins as CGKEX and CGSKP. Bitterness was positively correlated with the concentrations of condensed tannins (r=0.94, P<0.05), but not with total phenolics. We identified two genotypes, CGKEX and CGSKP with less bitterness (condensed tannins) that can be used in breeding for less bitterness to reduce excessive processing that lowers the nutritional and medicinal properties of C. gynandra.

Key Words: Cleome gynandra, indigenous vegetable, nutrition, phenolic compounds