Analysis of crude protein, phenolic and flavonoid content of cowpea genotypes.

Abstract

Cowpea is an important but underutilized legume crop, which is contributing to food and nutritional security in Sub Sahara Africa. Cowpea plays a critical role where it is a major source of dietary protein that nutritionally complements staple low protein cereal and tuber crops. Therefore, this research aimed at comparing the ten cowpea genotypes in terms of crude protein, phenolic content and total flavonoid content. These genotypes were obtained from Makerere Regional Center of Crop Improvement (MaRCCI) and were planted using alpha lattice design in busitema university arapai campus, soroti district. Proximate and bioactive compounds of different genotypes of cowpea grains were determined using standard AOAC methods. Crude protein was analyzed using the kjeldahl method from Gulu university laboratory whereas total phenolic contents and flavonoid content was prepared in arapai laboratory and analyzed from National Semi Arid Resources Research Institute (NaSARRI) in Serere district. The bioactive compounds where analyzed considering two seasons as well as the first season for crude protein content. The crude protein content was found in the range of 20.94% to 22.31% with a mean of 21.17%. However, genotypes AYIYI, NAROCOWPEA 5(cream) and Par18*LGC070/68(deep red) was observed with higher crude protein compared to others Meanwhile, genotype Par18*LGC070/42(deep red) observed the least crude protein content of 20.94%. in terms of bioactive compounds, The TPC of the genotypes for the seasons ranged from 10.06 mgGAE/100gDW to 24.64mgGAE/100gDW for season one and 8.62 to 24.06 mgGAE/100gDW for season two respectively. High phenolic compounds where recorded in cowpea with colored seed coats i.e. Par47*LGC074/18(brown) and Par18*LGC070/68(deep red) with 24.64 and 24.06mgGAE/100gDW respectively for first and second season. NAROCOWPEA 5(cream) and Par18*LGC070/52(brown) were observed with 8.62 and 10.06 mgGAE/100gDW respectively as the lowest. Total (%) ash was found more in Par18*LGC070/52 with 3.797% and the lowest in Par47*LGC074/30 genotype with 3.180%. Basing of the nutritive value, genotypes with more crude protein and bioactive compound were recommended and more improvement to be done by breeders to increase the protein to 30 % since varieties with higher protein can be crossed basing on other researches made. Key words: cowpea, crude protein, total phenolic content, total flavonoid content.