Impact of cooking methods on the chemical and antioxidant composition of some indigenous vegetables used in different food dishes in Southeast Nigeria

Abstract

AbstractBackgroundSome wild and domesticated vegetables of Ibo ethnic tribe of Southeast, Nigeria, namelyPiper guineense,Ocimum gratissimum,Solanum melongenaL.,Gongronema latifolium,Gnetum africanumandVernonia amygdalina, have gained interest in food culinary uses due to its nutritional, antioxidant potentials and health benefits. These vegetables are rich in fiber, minerals and phyto-nutrients and have significant health benefits against degenerative disorders. Due to these facts, cooking methods aimed at better retention of nutrients and antioxidant compounds were exploited.MethodsCarefully selected fresh and shredded indigenous vegetables that are commonly used in different food dishes in Southeast Nigeria were cooked (blanched at 98 °C, 2 min and sautéed at 150 °C, 5 min). They were analyzed on a dry weight basis for minerals, vitamins, phytochemicals and antioxidant activity assayed by DPPH, ABTS and FRAP.ResultsResults exhibited wild variations showing thatOcimum gratissimumandSolanum melongenaL had higher concentrations of functional minerals Zn, Fe, K and Ca. Vitamins B1and β-carotene had higher concentrations inSolanum melongenaL,Gnetum africanumandVernonia amygdalina.Ocimum gratissimumrevealed higher concentrations of TPC and TFC and maintains strong scavenging activity in ABTS and FRAP, while %DPPH manifested stronger activity inSolanum melongenaL.Vernonia amygdalinaexhibited higher phytochemicals concentrations, especially the alkaloid content.ConclusionSautéed cooking retained more nutrients and had stronger antioxidant activity than the blanched method. Overall, these vegetables possess high concentrations of functional constituents that can make them be used to boost human nutrition and benefit the health of consumers.