Thermo-oxidation of cholesterol: Effect of the unsaturation degree of the lipid matrix

•The presence of triacylglycerols slowed down cholesterol degradation at 180°C.•The presence and unsaturation degree of the lipid matrix delayed the COPs formation.•Significantly higher PV was found when cholesterol was heated in absence of TAG.•Both cholesterol and triacylglycerol degradation fit a first order kinetic model. The influence of the unsaturation degree of different triacylglycerols (tristearin, triolein, trilinolein and trilinolenin) on cholesterol oxidation at 180°C, was evaluated. Cholesterol degraded faster when heated alone than in the presence of triacylglycerols; moreover, the more unsaturated the matrix, the slower the degradation of cholesterol. Both cholesterol and triacylglycerols degradation fit a first order kinetic model (R2>0.9), except for the tristearin sample. Cholesterol oxidation products (COPs) and peroxides were formed during the heating treatment. The presence of any type of lipid matrix postponed and decreased the maximum concentration of both oxidation parameters. Maximum total COPs concentrations were achieved at 20min in neat cholesterol, 120min in tristearin and triolein and 180min in polyunsaturated matrix samples. 7-Ketocholesterol was the main COP in most cases during the whole heating treatment. Both the presence of triacylglycerols and their unsaturation degree inhibited cholesterol thermooxidation at 180°C.