Effect of simulated gastrointestinal digestion on phenolic composition and antioxidant capacity of cooked cowpea (Vigna unguiculata) varieties

Abstract

Summary Consumption of diets rich in phenolic compounds has been associated with reduced risk of chronic diseases. The effect of cooking and simulated gastrointestinal digestion on phenolic compounds and antioxidant properties of two cowpea (Vigna unguiculata) types was determined. Phenolic acids, flavan‐3‐ols and flavonols were the main groups of phenolic compounds identified. Cooking and simulated enzyme digestion of the cooked cowpea samples rendered some phenolics less extractable (possibly by promoting binding with other food components) or more extractable (possibly by release of bound forms). Total phenolic contents and radical scavenging properties of the cowpeas were reduced upon cooking, but increased upon simulated enzyme digestion. Cowpea extracts inhibited human LDL oxidation at a concentration of 2 mg mL−1 possibly due to their phenolic content. Phenolic compounds in cowpea can potentially protect against cardiovascular diseases for which LDL oxidation is a risk factor.

Cowpea: an overview on its nutritional facts and health benefits

“…Both the cell wall preparations and the whole seeds of cowpea varieties, Betchuana white and black‐eyed pea exhibited excellent protective effects against copper‐induced oxidation of human LDL . In a study carried out by Hachibamba et al ., extracts of both cooked and digested (simulated in vitro gastrointestinal digestion) cowpea were found to effectively inhibit LDL oxidation. Cui et al .…”

“…Observational studies throughout the world indicate that increased consumption of legumes is a promising route for reducing cardiovascular disease risk factors, such as elevated blood cholesterol, blood glucose, blood pressure and body weight . The exerted effect is attributed to the presence of compounds, such as phenolics, phytic acid, dietary fiber, saponins, phytosterols, proteins and peptides, and their amino acid profiles in legumes . Cowpea and cowpea isolates are reported to show hypocholesterolemic activity in vitro and in vivo (Table ).…”

“…The exerted effect is attributed to the presence of compounds, such as phenolics, phytic acid, dietary fiber, saponins, phytosterols, proteins and peptides, and their amino acid profiles in legumes . Cowpea and cowpea isolates are reported to show hypocholesterolemic activity in vitro and in vivo (Table ). Chui et al ., Hachibamba et al .…”

“…Cowpea and cowpea isolates are reported to show hypocholesterolemic activity in vitro and in vivo (Table ). Chui et al ., Hachibamba et al . and Salawu et al .…”

“…The crude phenolic extracts of raw and processed (boiled and micronized) cowpea, as well as the extracts subjected to simulated in vitro gastrointestinal digestion, have been shown to exhibit antioxidant properties via their ability to scavenge free radicals and metal chelating properties (Table ). In addition, the extracts have also demonstrated good antioxidant activity with respect to protecting erythrocytes from oxidative hemolysis and LDL oxidation .…”