• Energy Research

Abstract Tobacco seed oil has been evaluated as a feedstock for biodiesel production. In this study, all properties of the biodiesel that was produced from tobacco seed oil were examined and some solutions were derived to bring all properties of the biodiesel within European Biodiesel Standard EN14214 to verify biodiesel quality. Among the properties, only oxidation stability and iodine number of the biodiesel, which mainly depend on fatty acid composition of the oil, were not within the limits of the standard. Six different antioxidants that are tert-butylhydroquinone, butylated hydroxytoluene, propyl gallate, pyrogallol, α-tocopherol and butylated hydroxyanisole were used to improve the oxidation stability. Among them, pyrogallol was found to be the most effective antioxidant. The iodine number was improved with blending the biodiesel produced from tobacco seed oil with a biodiesel that contains more saturated fatty acids. However, the blending caused increasing the cold filter plugging point. Therefore, four different cold flow improvers, which are ethylene–vinyl acetate copolymer, octadecene-1-maleic anhydride copolymer and two commercial cold flow improvers, were used to decrease cold filter plugging point of the biodiesel and the blends. Among the improvers, the best improver is said to be octadecene-1-maleic anhydride copolymer. In addition, effects of temperature on the density and the viscosity of the biodiesel were investigated.

Rheological properties of poppy seed paste (PSP)/grape pekmez blends containing 10%, 15%, 20%, 25%, 30%, 35%, and 40% PSP were determined at different temperatures (10–40 °C). The PSP/grape pekmez blends behaved as a pseudoplastic fluid. The flow behavior index of the blends containing 10% PSP varied between 0.92 and 1.0, however, as the concentration of PSP increased to 40% the flow behavior index decreased to the range of 0.23–0.67. As the temperature increased the viscosity and the consistency coefficient (K) decreased. The activation energies (Ea) of the blends were found in the range of 23,054.8–66,059.1 kJ/kmol. The consistency coefficient increased from the range of 0.25–3.56 Pa sn to 35.63–203.01 Pa sn as the PSP concentration increased from 10% to 40%. The combined effect of the concentration, temperature and shear rate on the viscosity of the PSP/grape pekmez blends were described successfully by a simple equation. The blends showed a rheopectic time-dependent behavior. Practical applications: Rheological properties of fluid foods are necessary for designing and evaluation of food processing lines, quality control and consumer acceptability. In this study, flow behavior and the effect of temperature and PSP concentration on the rheological properties of the PSP/grape pekmez blends were determined. The effect of concentration, temperature, and shear rate on viscosity was represented by a simple equation which can be used in engineering calculations. Time-dependent flow behavior of the PSP/grape pekmez blends was also determined that it is important for the estimation of changes in the flow behavior during processing. © 2017 Wiley Periodicals, Inc.