Traditional Fermentation Affects the Nutraceutical Properties of Parkia biglobosa Seeds

Abstract

Parkia biglobosa seeds (African locust bean) play a crucial role in the diet and health of Western African populations. The seeds are spontaneously fermented to produce condiments used for food seasoning and stews preparation. Hence, to understand the health benefits of seed-based products from P. biglobosa, total polyphenol content, in vitro and ex vivo antioxidant properties, as well as antihypertensive activity, of fermented and non-fermented seeds were investigated. The Folin-Ciocalteu method was used to determine total polyphenol content; 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) tests were used to estimate the in vitro antioxidant activity. The ex vivo antioxidant and antihypertensive activities were evaluated by using cellular antioxidant activity in human red blood cells (CAA-RBC) and angiotensin-converting enzyme (ACE) inhibitory activity assays, respectively. The fermented seeds showed a huge increase in polyphenol content and in vitro antioxidant activities compared to non-fermented ones. The fermented seeds showed a higher potency of biological antioxidant activity than non-fermented ones by exhibiting greater protection of erythrocytes from oxidative damage at a very low dose of extracts. Both fermented and non-fermented seeds have been shown to contain peptides with ACE-inhibitory activity; however, the non-fermented seeds exerted a higher ACE-inhibitory activity than fermented ones. In conclusion, traditional fermentation positively impacted the nutraceutical and health benefits of P. biglobosa seeds. However, the non-fermented seeds should not be ignored. Both fermented and non-fermented seeds can be used as valuable ingredients for the formulation of functional foods.

Keywords: ACE inhibitor activity; CAA-RBC; Parkia biglobosa; antioxidant activity; fermentation; total phenolic content.