Characterization of okra seed flours, protein concentrate, protein isolate and enzymatic hydrolysates

The need to feed the increasing world population with high quality protein and the enormous post-harvest losses of okra fruits necessitated the research on okra seeds in this study. Whole flour (WF) of matured okra seed was processed to obtain defatted flour (DF), protein concentrate (PC) and protein isolate (PI), followed by hydrolysis of the protein isolate by three different proteases; pepsin (PHp), pancreatin (PHc) and trypsin (PHT) to produce hydrolysates. The okra seed flours, proteins and the hydrolysates were analyzed for changes in the functional groups using Fourier, Transform Infrared (FTIR), amino acid composition, solubility profile and some functional properties. The FTIR results showed the presence of N-H stretching, C=O stretching, C=N stretching N-H bending and C-N stretching in the samples. Protein hydrolysate had higher essential amino acids (51.32-53.01%) than unhydrolysed samples (36.31-37.99%). PI and WF had the highest water absorption and swelling capacities respectively. The solubility profiles of the samples were minimal at pH 2-4 and then increased after the isoelectric point. The PC was more soluble than PI between pH 2-8. The foaming properties of the samples was least in the absence of salt but high in the presence of 0.5 M sodium chloride. The emulsion capacity of the samples was least in the presence of 1.0 M NaCl. The in-vitro protein digestibility results showed that okra seed protein hydrolysates were more digestible (83.26-86.08%) than unhydrolyzed proteins (36.48-80.90%). The results of the antioxidant properties showed that PHp and PHT exhibited better radical scavenging and metal chelating activities respectively than the other samples. The study concluded that okra seed proteins and hydrolysates demonstrated potentials as ingredients in functional food preparation and this may be considered as a strategy to reducing the post-harvest losses of okra fruit and subsequently feeding the world with quality proteins.

Automated summary

The study found that okra seed protein hydrolysates have higher digestibility and antioxidant properties, making them potential ingredients for functional food preparation to reduce post-harvest losses of okra fruits and provide high-quality proteins for the world.