Antioxidative Effects of Sweet Potato (Ipomoea Batata) Tuber Peels and Leaves on Crude Groundnut Oil

Abstract

The aim of the research is to examine antioxidative effects of solvent extracts of potato leaves and tuber peels on groundnut oil stored under accelerated conditions. Sweet potato tuber peels (orange specie) and leaves were obtained, washed, dried, ground, and sieved with 40 mm mech and separately extracted with three different solvents (acetone, ethanol, ethyl acetate) for 72 hours. The efficiency of each solvent was determined as percent extractive value. The first two highest solvent extracts for potato peels and leaves were added as additives to the crude groundnut oil (CGO) at varying proportions (200 - 1000 ppm). A sample of oil containing no additives and sample with butylated hydroxyltoluene (BHT 200 ppm) were set aside for comparison. The progression of oxidation was followed by measuring the free fatty acid (FFA), acid value (AV) and peroxide value (PV) of the oils fortnightly for a period of eight weeks. Ethanol had the highest extractive values of 4.1667  and 6.4667  for leaves and peels respectively. The FFA, AV, and PV of the CGO with plant extracts were 1.952, 3.885 and 0.613 while CGO with BHT were 2.14, 4.476, and 0.736 respectively at P . This study showed that potato tuber peels and leaves had good antioxidant potential and therefore recommended to be utilized in our edible oil industries as an alternative to synthetic antioxidants.