Effect of fractional winterization of beef tallow biodiesel on the cold flow properties and viscosity

Biodiesel can cause performance problems at cold temperatures because of its fatty acid composition. Flow characteristics of biodiesel such as viscosity, density, cloud point and pour point increase as saturated fatty acid content of the lipid material used as a feedstock increases. Beef tallow, due to its high saturated fatty acid content, is not preferred as a feedstock in biodiesel production. In this study, it is aimed to reduce saturated fatty acid content of biodiesel obtained from beef tallow by fractional crystallization process also known as winterization. The fatty acid methyl ester contents of the filtrates obtained from crystallization were determined. In addition, cloud point, pour point, viscosity and density of biodiesel winterized were monitored. It has been detected that saturated fatty acid methyl ester content of winterized biodiesel from beef tallow reduced from 86.91% to 73.38% while unsaturated ones increased from 12.00% to 19.95% until the lowest crystallization temperature which is 16.3 °C in six steps. It was observed that density, viscosity and cold flow properties of the beef tallow biodiesel significantly improved by the removal of saturated methyl esters from the biodiesel.