Oxidative stability of margarine enriched with different structures of β-sitosteryl esters during storage

Oxidations of margarine incorporated with beta-sitosteryl esters of hexanoic (Sito-C6), lauric (Sito-C12), palmitic (Sito-C16) and oleic (Sito-C18: 1) acids were evaluated during storage at ambient temperature (25 degrees C) and at 55 degrees C for 20 days in comparison with native beta-sitosterol. All oxidative indices, including hydroperoxide value (HPV), thiobarbituric acid reactive substances (TBARS), p-Anisidine value (AnV) and 7-keto derivatives, tended to increase with increasing storage time. Overall, losses of sterol esters in margarine during storage at both temperatures fitted a first order kinetic model. Margarine with unsaturated ester oxidized faster (k = 0.0355 day(-1), R-2 = 0.8126) than those with saturated counterpart and native beta-sitosterol, particularly at higher temperature (55 degrees C). As a consequence, sterol structure and storage temperature were the main factors influencing the oxidative stability of margarine enriched phytosterol esters during storage.