In vitro Antioxidant Assay of Cocoa (Theobroma cacao) Oil and Cake

Abstract

Numerous studies have highlighted the nutritional and pharmacological importance of cocoa. In this current study, three in vitro assay methods were used to investigate the antioxidant activity of cocoa oil and cake: scavenging effect on 2,2-diphenyl-1-picryhydrazyl radical (DPPH), hydroxyl radical generated from hydrogen peroxide and peroxide oxidation by ferric thiocynate method. It was revealed that cocoa oil and cake possessed significant antioxidant activity (P<0.05) when compared with antioxidant standards: butylated hydroxyl anisole (BHA), ascorbic acid and α-tocopherol used in the assay. At 1.0-0.0625 mg/ml, the oil had percentage inhibition of 65.0-73.6% while cake had percentage inhibition of 75.4-88.7% in DPPH assay however, the % inhibition was between 98.6-98.9% for cocoa oil and 92.6-98.2% for cocoa cake at the same concentration in the hydroxyl radical scavenging assay while in the ferric thiocyanate assay, percentage inhibition of cocoa oil was approximately 94% at 0.005 - 0.4 mg/ml which is better than the activity of cocoa cake, 91% at the same concentration. The results indicate that inhibition was better with the hydroxyl radical scavenging assay and that different antioxidative mechanism is involved in the free radical scavenging activities of cocoa. The results of this study further support the medicinal and nutritional values of cocoa.