NOVELTY - Preparing a fuel composition, comprises: (i) preparing a bio-derived fuel component comprising a mixture of iso-saturated alkanes and normal-saturated alkanes; (ii) determining if the ratio of iso-saturated alkanes to normal-saturated alkanes in the bio-derived component is at least 2; and (iii) combining the bio-derived fuel component with a petroleum-derived component if the ratio of iso-saturated alkanes to normal-saturated alkanes in the bio-derived component is determined to be at least 2.    USE - The fuel composition is useful for powering a turbine engine (claimed); and as an aviation fuel.    ADVANTAGE - The fuel composition has improved properties such as freeze point, flash point, density, and combustion characteristics.    DETAILED DESCRIPTION - Preparing a fuel composition, comprises: (i) preparing a bio-derived fuel component comprising a mixture of iso-saturated alkanes and normal-saturated alkanes; (ii) determining if the ratio of iso-saturated alkanes to normal-saturated alkanes in the bio-derived component is at least 2; and (iii) combining the bio-derived fuel component with a petroleum-derived component if the ratio of iso-saturated alkanes to normal-saturated alkanes in the bio-derived component is determined to be at least 2, where the aromatic content of the petroleum-derived component is at least 16 vol.%, as measured by ASTM D2425, and the resulting fuel composition has (a) a flash point of at least 35 degrees C, (b) a freeze point of less than -50 degrees C, (c) a fuel density of at least 0.73 g/ml, and (d) an energy density of at least 44 MJ/kg. INDEPENDENT CLAIMS are included for:    (1) a fuel composition, comprising (a1) 59-92 vol.% of a mixture of iso-saturated alkanes and normal-saturated alkanes having a flash point of 38-60 degrees C, (b1) 8-25 vol.% of aromatic compounds, and (c1) 0.05-15 vol.% of cyclic compounds, where the weight ratio of iso-saturated alkanes to normal-saturated alkanes is at least 2, the composition has a freeze point of less than -50 degrees C, at least a portion of the fuel composition is derived from an upgraded bio-oil i.e. extracted from a bio-oil feedstock, and a byproduct from the extraction step is treated to produce a hydrogen-containing gas utilized in the upgrading step;    (2) powering a turbine engine by burning a hydrocarbon fuel, comprising combining the fuel with air in at least one combustion section of the turbine engine, and igniting the air-fuel mixture, which is directed out of the engine to provide engine power, where the fuel comprises a mixture of iso-saturated alkanes and normal-saturated alkanes having a flash point of at least 35 degrees C, and the weight ratio of iso-saturated alkanes to normal-saturated alkanes is at least 2; and    (3) lowering the freeze point of the hydrocarbon fuel composition, comprising increasing the weight ratio of iso-saturated alkanes to normal-saturated alkanes in the composition, from a ratio of 1 to at least 2.