Oxidative stability of biodiesels produced from vegetable oils having different degrees of unsaturation

•We obtained biodiesel from açai, cupuaçu, passion fruit and linseed oil.•Determined the properties of biodiesel, such as kinematic viscosity, cold filter plugging point and oxidative stability.•Evaluated the influence of antioxidants on biodiesel.•The PG antioxidant was more efficient than BHA and TBHQ for the açaí biodiesel. In the present paper, methyl esters were obtained from the transesterification of cupuaçu fat lipids (Theobroma grandiflorum) (Willd. ex Spreng.) (K. Schum.), açaí (Euterpe oleracea), passion fruit (Passiflora edulis) and linseed (Linum usitatissimum L.) oils, using a basic catalyst. The triglycerides were characterized by their fatty acid composition, and the biodiesels were characterized according to standard methods. The critical properties, such as the cold filter plugging point, kinematic viscosity and oxidative stability, of the biodiesels were studied. The influence of butyl-hydroxyanisole (BHA), propyl gallate (PG) and tert-butyl hydroquinone (TBHQ) antioxidants on the açaí, passion fruit and linseed biodiesels was evaluated at concentrations from 500 to 4000ppm. PG was found to be the most efficient antioxidant for the studied biodiesels.