N. A. Santos

Effect of the solvent composition on the profile of phenolic compounds extracted from chia seeds

This study investigated the efficiency of the extraction of phenolic compounds from seeds of chia, Salvia hispanica L. utilizing the statistical tool of mixture planning, simplex-lattice design. The solvents used were acetone, ethanol and water and the responses analyzed were total phenolic content (TPC), antioxidant activity by the capture of the free radical DPPH and ferric reduction ability (FRAP). Moderately polar mixtures were highly efficient to extract the antioxidant phenolic compounds. The best results were obtained for the water-acetone (1/3-2/3) binary mixture, presenting TPC, DPPP and FRAP values of 58.44 mg GAE/g, 250.20 μmol TE/g and 720.15 μmol TE/g, respectively. The best ternary mixture was water-ethanol-acetone (1/6-1/6-2/3), with 60.96 mg GAE/g, 380.53 μmol TE/g and 990.15 μmol TE/g, respectively. The phenolic profile showed that the acids rosmarinic, caffeic, salicylic and the flavonoids myricetin and quercetin are the compounds that most contribute to the elevated antioxidant activity.

Flow properties of biodiesel: correlation between TMDSC and dynamic viscosity

Sustainable and renewable energy has become more attractive due to its environmental benefits. Among these alternative sources, biodegradable and low emission biodiesels have been gaining attention as compared to diesel. However, their performance at low temperatures affects their commercial viability, because of engine performance problems, and when starting. Cold Filter Plugging Point, Pour Point, and Cloud Point are employed to predict the limits of operability for biodiesel. However, dynamic viscosity and TM-DSC methods are also useful to assess these properties and can be correlated. Viscosity curves were obtained, and TM-DSC revealed that the start temperature (transition liquid–solid) exhibits an increase in flow resistance for soybean, colza, sunflower, corn, and babassu oil biodiesels. The nucleation processes which occur during cooling are unique for each type of biodiesel due to the presence of different ester compositions and the values for viscosity and flow at low temperatures varied accordingly.