Thermal Oxidation Induces Lipid Peroxidation and Changes in the Physicochemical Properties and β -Carotene Content of Arachis Oil.

Ayodeji Osmund Falade,Ganiyu Oboh

doi:10.1155/2015/806524

Abstract

This study sought to investigate the effect of thermal oxidation on the physicochemical properties, malondialdehyde, and β-carotene content of arachis oil. Pure arachis oil was heated for 20 mins with a corresponding temperature of 220°C. Thereafter, changes in the physicochemical properties (acid, iodine, and peroxide values) of the oil samples were determined. Subsequently, the level of lipid peroxidation was determined using change in malondialdehyde content. Then, the total carotenoid and β-carotene contents were evaluated using spectrophotometric method and high performance liquid chromatography, respectively. The results of the study revealed a significant increase (P < 0.05) in the acid and peroxide values and malondialdehyde concentration of the heated oil when compared with the fresh arachis oil. In contrast, a significant decrease (P < 0.05) was observed in the iodine value, total carotenoid, 13-cis-, 15-cis-, trans-, and 9-cis-β-carotene, and total β-carotene content of the heated oil. Hence, thermal oxidation induced lipid peroxidation and caused changes in the physicochemical properties and carotenoid contents of arachis oil, thereby reducing its nutritive value and health benefit. Therefore, cooking and frying with arachis oil for a long period might not be appropriate as this might lead to a loss of significant amount of the insignificant β-carotene in arachis oil.

Highlights

Known as groundnut oil or peanut oil, is a mild tasting vegetable oil derived from peanuts or groundnuts
Chemicals and reagents used such as malondialdehyde-tetrabutylammonium salt, thiobarbituric acid (TBA), and trichloroacetic acid (TCA) were sourced from Sigma-Aldrich, Chemie GmbH (Steinheim, Germany); ethanol, methanol, hexane, dichloroethane, carbon tetrachloride, chloroform, glacial acetic acid, hydrochloric acid, and diethyl ether were sourced from BDH Chemicals Ltd. (Poole, England)
Iodine Value (IV) measures the degree of unsaturation of fatty acids; a decrease in IV as observed in this study indicates an increase in the degree of saturation of fatty acids which is a risk factor for hypercholesterolemia and some types of cardiovascular diseases [25]

Summary

Introduction

Known as groundnut oil or peanut oil, is a mild tasting vegetable oil derived from peanuts or groundnuts. Most highly refined arachis oils remove the peanut allergens and have been shown to be safe for the vast majority of peanut-allergic individuals [2]. Arachis oil is often used generally for cooking and is one of the most commonly consumed vegetable oils in Nigeria. Arachis oil has a high smoke point relative to many other cooking oils, so it is commonly used for frying foods [3]. Its major component fatty acids are oleic acid (46.8% as olein), linoleic acid (33.4% as linolein), and palmitic acid (10.0% as palmitin) [4]. The oil contains some stearic acid, arachidic acid, arachidonic acid, behenic acid, lignoceric acid, and other fatty acids

Methods

Results

Conclusion