The Effect of Refining Process on the Oxidative Stability, Thermal Stability, and Fatty Acid Composition of Shea Olein
Korede A. O.
*
Department of Food Science, Ladoke Akintola University of Technology, Ogbomoso, Nigeria and Department of Veterinary Physiology and Biochemistry, University of Ibadan, Nigeria.
Ade-Omowaye B. I. O.
Department of Food Science, Ladoke Akintola University of Technology, Ogbomoso, Nigeria.
Akande E. A
Department of Food Science, Ladoke Akintola University of Technology, Ogbomoso, Nigeria.
Adebo O. A.
Centre for Innovative Food Research (CIFR), Department of Biotechnology and Food Technology, University of Johannesburg, South Africa.
Meijboom R.
Department of Chemical Sciences, University of Johannesburg, South Africa.
Bello O.S.
Department of Pure and Applied Chemistry, Ladoke Akintola University of Technology, Ogbomoso, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
This study examined the effects of refining process conditions on the oxidative stability, thermal stability, and fatty acid composition of shea olein. Chemical refining was applied to shea olein and involved the removal of mucilaginous substances, free fatty acids, and metal contaminants to enhance its suitability for food applications. Quality indices monitored in the refined oil included peroxide value (PV), p-anisidine value (p-AV), conjugated dienes (CD), thiobarbituric acid reactive substances (TBARS), thermal stability, and fatty acid profile. Refining losses associated with degumming, neutralization, and bleaching were 8.80%, 6.56%, and 7.56%, respectively. A reduction of 47% and 87.6% was observed in PV and CD, respectively, while p-AV and TBARS increased approximately twofold compared with the crude sample. Thermal stability decreased in the order: neutralized shea olein ~ bleached shea olein > degummed shea olein > crude shea butter. Refining increased the oleic acid content by 10.48% and reduced arachidic acid content by 13.37%. Overall, chemical refining improved the oxidative and thermal stability of shea olein; however, it also promoted the formation of secondary oxidation products and increased trans-fatty acid content. These findings highlight the need to optimize refining conditions to maximize the oil stability and enhance the industrial utilization of shea olein.
Keywords: Shea olein, refining, oxidative stability, thermal stability, fatty acid composition