Effects of Selected Synthetic and Natural Antioxidants on the Oxidative Stability of Shea Butter (Vitellaria paradoxa subsp. paradoxa)

Abstract

Shea butter is a plant fat extracted from kernels of shea nuts, the seeds of shea trees (Vitellaria paradoxa). The extracted fat, which has a long history of use in sub-Saharan Africa for medicinal, culinary, and other applications, serves as cocoa butter equivalents (CBEs) in the manufacture of chocolate and is an ingredient for cosmetics in the international market. Since shea butter contains relatively high levels of unsaturated fatty acids (more than 50 %), oxidation can occur during extraction and during post-harvest processing and storage. This study investigated the protective effects of synthetic butylated hydroxytoluene (BHT) and selected natural antioxidants (rosmarinic acid and gallic acid) on shea butter against oxidation. Each antioxidant (0.02%) was added to shea butter and the mixtures were placed at 90°C for 0, 72, and 144 h to accelerate oxidation. Measures of oxidation indicated the shea butter was protected from oxidation by addition of the antioxidants. The addition of antioxidants to shea butter produced no significant changes in the parameters used to measure oxidation (e.g. peroxide values, conjugated dienes and TBARS), as well as in the levels of major fatty acids. The natural antioxidants were almost as effective as the synthetic antioxidant. INTRODUCTION Shea butter, the plant fat extracted from shea nuts, the seeds of shea trees (Vitellaria paradoxa) that belongs to the Sapotaceae family. Shea trees grow wild across a belt of savanna extending from Senegal, Mali, Cote d’Ivoire, Burkina Faso, Togo, Ghana, Benin, Nigeria, Niger, Cameroon to further east in Uganda, Sudan, and Ethiopia (Chalfin, 2004; Goreja, 2004). Shea butter, which has served as a versatile fat to many Africans, is used in African cuisine as nutritional edible oil and in African traditional medicine as a treatment for rheumatism, nostril inflammation, leprosy, for soothing and healing following circumcision and preventing stretch marks during pregnancy (Tella, 1979; Chalfin, 2004; Goreja, 2004; Olaniyan and Oje 2007). Shea butter has been used in international markets as cocoa butter equivalents (CBEs) for the manufacture of chocolate, especially Europe due to shea butter’s similar physical and chemical properties (Lipp and Anklam, 1998; Alander, 2004). More recently, shea butter market is expanding in cosmetics and personal care industries due to excellent emollient activity and medicinal properties, such as anti-inflammatory and antioxidant activities (Alander and Andersson, 2002; Alander, 2004; Maranz and Wiesman, 2004; Masters et al., 2004). Shea butter generally consists of more than 90% triglycerides and a minor, though significant, unsaponifiable fraction. The triglyceride fraction is Nahm et al.: Effects of Selected Synthetic and Natural Antioxidants on the Oxi